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WO1994012161A1 - Macrocapsules cytoprotectrices, biocompatibles et recuperables - Google Patents

Macrocapsules cytoprotectrices, biocompatibles et recuperables Download PDF

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Publication number
WO1994012161A1
WO1994012161A1 PCT/US1993/011389 US9311389W WO9412161A1 WO 1994012161 A1 WO1994012161 A1 WO 1994012161A1 US 9311389 W US9311389 W US 9311389W WO 9412161 A1 WO9412161 A1 WO 9412161A1
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WO
WIPO (PCT)
Prior art keywords
macrocapsule
alginate
microcapsules
islets
covalently
Prior art date
Application number
PCT/US1993/011389
Other languages
English (en)
Inventor
Patrick Soon-Shiong
Roswitha E. Heintz
Neil P. Desai
Original Assignee
Clover Consolidated, Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Clover Consolidated, Limited filed Critical Clover Consolidated, Limited
Priority to AU57289/94A priority Critical patent/AU5728994A/en
Publication of WO1994012161A1 publication Critical patent/WO1994012161A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/0012—Galenical forms characterised by the site of application
    • A61K9/0019—Injectable compositions; Intramuscular, intravenous, arterial, subcutaneous administration; Compositions to be administered through the skin in an invasive manner
    • A61K9/0024—Solid, semi-solid or solidifying implants, which are implanted or injected in body tissue
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/20—Pills, tablets, discs, rods
    • A61K9/2072—Pills, tablets, discs, rods characterised by shape, structure or size; Tablets with holes, special break lines or identification marks; Partially coated tablets; Disintegrating flat shaped forms
    • A61K9/2077—Tablets comprising drug-containing microparticles in a substantial amount of supporting matrix; Multiparticulate tablets
    • A61K9/2081—Tablets comprising drug-containing microparticles in a substantial amount of supporting matrix; Multiparticulate tablets with microcapsules or coated microparticles according to A61K9/50

Definitions

  • the present invention relates to a new form of biocompatible materials which envelop encapsulated or free cells to provide an immune barrier.
  • the resulting encapsulated material is generally small, but macroscopic, so that it is retrievable in situ . More specifically the present invention relates to a composition and system for treatment of diabetes.
  • Diabetes Mellitus is a serious disease afflicting over 100 million people worldwide. In the United States, there are more than 12 million diabetics, with 600,000 new cases diagnosed each year. Insulin-dependent, or Type I diabetics, require daily injections of insulin to prevent them from lapsing into coma.
  • the diabetic patient faces a 30% reduced lifespan. Multiple insulin injections given periodically throughout the day cannot duplicate the precise feedback of insulin secretion from the pancreas. The only current method of achieving minute-to-minute glucose control is by pancreas transplantation.
  • pancreas transplantation represents a significant advance in diabetes therapy, the operation is technically difficult, of limited success and use because of the problems of rejection, and it still presents a significant risk to the patient.
  • An attractive alternative would be to extract the insulin-producing cells (islets) from a donor pancreas and to inject these cells into the diabetic patient, thus effecting a cure. The use of such cells, however, would still run the risk of rejection by the host.
  • Microencapsulation of islets by an alginate-PLL- alginate membrane is a potential method for prevention of rejection by the host's immune system.
  • an alginate-PLL- alginate membrane i.e., an alginate-poly-L-lysine-alginate membrane
  • researchers are able to encapsulate living islets in a protective membrane that allows insulin to be secreted, yet prevents antibodies from reaching the islets, causing rejection of the cells.
  • This membrane (or microcapsule) protects the islet from rejection and allows insulin to be secreted through its "pores" to maintain the diabetic in normal glucose control.
  • microencapsulated islets Successful transplants of microencapsulated islets have not been clinically feasible to date due to fundamental problems of transplant rejection and/or a fibrotic reaction to the microcapsule membrane.
  • Lim and Sun, 1980 reported the first successful implantation of microencapsulated islets and described normalization of blood sugar in diabetic rats.
  • the immunoprotective membrane it is important that the immunoprotective membrane be biocompatible, allow adequate diffusion for the encapsulated cells to respond appropriately to a stimulatory signal, provide the encapsulated cells with necessary nutrients, and be retrievable.
  • Retrievability is desirable for a variety of reasons, e.g., so that accumulation of the implanted materials can be avoided, so that encapsulated cells can be removed from the recipient when no longer needed or desired (e.g., when the product(s) of the encapsulated cells are no longer needed, if the encapsulated cells fail to perform as desired, etc.), so that encapsulated cells can be removed if/when they become non-viable, and the like.
  • encapsulated cells can be removed if/when they become non-viable, and the like.
  • Biocompatibility of encapsulated islets remains a fundamental problem.
  • biocompatible is used herein in its broad sense, and relates to the ability of the material to result in long-term in vivo function of transplanted biological material, as well as its ability to avoid a foreign body, fibrotic response.
  • a major problem with microencapsulation technology has been the occurrence of fibrous overgrowth of the epicapsular surface, resulting in cell death and early graft failure. Despite extensive studies, the pathological basis of this phenomenon in alginate based capsules remains poorly understood.
  • Alginate is a polysaccharide isolated from marine brown algae including Laminaria hyperborea , Laminaria digitata , A ⁇ cophyllum nodosum and Macrocy ⁇ tis pyrifera . Alginate forms ionically crosslinked gels with most di- and multivalent cations. Calcium cations are most widely used, and give rise to a three-dimensional network in the form of an ionically crosslinked gel by inter-chain binding between G-blocks. (Skjak-Braek, 1988) .
  • mannuronic acid residues are the active cytokine inducers in alginate, and since these cytokines (IL-1 and TNF) are known to be potent stimulators of fibroblast proliferation (Otterlei et al., 1991), it was deduced that alginate capsules high in mannuronic acid content (M-content) were responsible in part for the fibrotic response reported in the past (Soon-Shiong et al. 1991) . More significantly, it has been found that this reaction could be ameliorated by increasing the guluronic acid content (G-content) of the alginate capsule since guluronic acid appears not to be immunostimulating.
  • G-content guluronic acid content
  • cyclosporin A resulted in a dose dependent inhibition of mannuronic acid-induced TNF and IL-1 stimulation of human monocytes in vitro .
  • the fibrotic reaction of the microcapsule could be ameliorated in part by an alginate formulation high in guluronic acid content, as well as a subtherapeutic course of cyclosporin A to inhibit cytokine stimulation.
  • diabetes in the spontaneous diabetic dog model has been successfully reversed by transplantation of donor islets encapsulated in high G-content alginate (Soon-Shiong et al. 1991) .
  • PEG Polyethylene glycols
  • PEO polyethylene oxide
  • PEG bound to bovine serum albumin has shown reduced immunogenicity and increased circulation times in a rabbit (Abuchowski et al., 1977).
  • Drugs such as penicillin, aspirin, amphetamine, quinidine, procaine, and atropine have been attached to PEG in order to increase their duration of activity as a result of slow release (Weiner et al., 1974; Zalipsky et al., 1983).
  • PEG covalently bound to poly-L-lysine (PLL) has been used to enhance the biocompatibility of alginate-PLL microcapsules used for the encapsulation of cells.
  • PEG has been covalently bound to polysaccharides such as dextran (Pitha et al., 1979, Duval et al. , 1991), chitosan (Harris et al.,
  • Visible radiation between wavelengths of 400 - 700 nm have been determined to be nontoxic to living cells (Karu, 1990; Dupuy et al., 1988).
  • a recent review (Eaton, 1986) describes a variety of dyes and cocatalysts that may be used as polymerization initiators in the presence of appropriate visible radiation.
  • considerable interest has been expressed in the use of lasers for polymerization processes (Wu, 1990) . These polymerizations are extremely fast and may be completed in milliseconds (Decker and Moussa, 1989; Hoyle et al., 1989; Eaton, 1986).
  • the use of coherent radiation often results in the polymerization being innocuous to living cells. This arises from the use of wavelength specific chromophores as the polymerization initiators, and these chromophores are typically the only species in the polymer/cell suspension that absorb the incident radiation.
  • Type I insulin-dependent diabetes can be reversed in rats and dogs by implantation of micro-encapsulated pancreatic islets in the peritoneal cavity of these animals using both allograft (dog islets to dog recipients) and xenograft (dog islets to rat recipients) models (Soon-Shiong et al., 1991).
  • the alginate microcapsules employed in these studies provide i munoprotectivity, and result in graft survival of allografts for several months in the absence of immunosuppression.
  • the alginate gels are ionically crosslinked and, therefore, are subject to breakage and resorption as a result of ionic equilibration in vivo .
  • free microcapsules are difficult to retrieve due to their small size (200 - 600 ⁇ m) and nonlocalization within the peritoneal cavity.
  • individual spherical microcapsules provide a large exposed surface area, facilitating transport of nutrients through the membrane, while on the other hand, increasing the probability of cell adherence and fibrous overgrowth. It has been found that by reducing this exposed microcapsule surface area and/or by reducing exposure of any unbound, positively charged polylysine, while maintaining the critical diffusion capacity of the immuno-protective membrane, increased biocompatibility will ensue. By reduction of exposed microcapsule surface area, the percentage of "roughness" associated with each individual microcapsule would be reduced, resulting in improved biocompatibility. In addition, in accordance with the present invention, it has been recognized that improving mechanical integrity of the capsule is an important step in achieving long term graft function.
  • long term graft function can be achieved by entrapping or encasing biologically active material, optionally contained within a microcapsule (e.g., individual microencapsulated cells) in a macrocapsule which is bioco patible, thereby (i) increasing the cytoprotectivity of the entrapped individually encapsulated cells, (ii) reducing exposure of unbound positively charged polylysine to the host in vivo environment, (iii) enhancing the mechanical stability of the capsular membrane, (iv) reducing the exposed microcapsule surface area roughness; and (v) reducing the exposure of.
  • a microcapsule e.g., individual microencapsulated cells
  • macrocapsules of the present invention provide a system of rapid but sustained release of the material made by and secreted by the encapsulated cell(s), which in turn provides for more regulated control of physiological processes (e.g., blood glucose levels in the case of encapsulated islets) .
  • physiological processes e.g., blood glucose levels in the case of encapsulated islets
  • insulin release occurs more rapidly from encapsulated islets entrapped within a macrocapsule than from free floating microencapsulated islets, as demonstrated by the in vivo intravenous glucose stimulation studies described in Example 9, below.
  • insulin release from these gel entrapped microcapsules is sustained over a longer period of time, as demonstrated by the in vitro glucose stimulation studies described in Example 8, below.
  • the present invention also permits retrievability of the implant because of its macroscopic size and its grouping of the various microencapsulated islets into a single package or a plurality of macroscopic packages.
  • Retrievability is desirable for a variety of reasons, e.g., so that accumulation of the implanted materials can be avoided, so that encapsulated cells can be removed from the recipient when no longer needed or desired (e.g., when the product(s) of the encapsulated cells are no longer needed, if the encapsulated cells fail to perform as desired, etc.), so that encapsulated cells can be removed if/when they become non-viable, and the like.
  • the present invention overcomes the problems of the prior art by improving the cytoprotectivity and biocompatibility of implanted biological systems.
  • the present invention also provides a gel entrapment system which provides a rapid response of entrapped cells to a stimulatory signal.
  • the present invention further provides a sustained release system made from microencapsulated cells which are further packaged in a macrocapsule.
  • the present invention also provides a system that localizes microcapsules in a particular region (e.g., a region of high vascularization such as the omentum) , as well as a system which minimizes the breakage of microcapsules, and facilitates their ready retrieval.
  • the macrocapsules of the present invention may be used to entrap not only encapsulated or unencapsulated living cells, but also any chemical reagents which may have a pharmacological or physiological effect upon sustained release by the system disclosed herein.
  • FIG. 1 is a drawing of one embodiment of a macrocapsule of the present invention containing encapsulated biological material.
  • Solid core microcapsules with a PLL membrane are suspended in alginate (or other gelling system) and entrapped into a larger macrocapsule. Shown in the lower portion of the figure is the macrocapsule, with a solid or gelled interior containing microcapsules.
  • PLL is buried deep within a gelled matrix of alginate (or other gelling material) .
  • the resulting capsule is strong due to its gelled (solid) core.
  • cells are illustrated as small circles with dense stipple; microcapsules are illustrated as intermediate size circles, surrounded by a polycation (polylysine) layer (illustrated as a heavy line) ; and macrocapsule is illustrated as a large circle. Stippling throughout the microcapsules and macrocapsules illustrates the gelled insoluble form of the composition.
  • FIG. 2 is a graph of the blood glucose of rats implanted with entrapped encapsulated islets according to the present invention (filled circles •) , free-floating encapsulated islets (filled triangles) and unencapsulated islets (open circles O) over time, when the islets are xenografts (canine islets) .
  • FIG. 3 is a graph of the serum glucose response to an intravenous glucose challenge (IVGTT) in rats treated with macroencapsulated canine islets according to the present invention (filed circles •) , compared to the response in rats transplanted with free floating microencapsulated canine islets 7 days after implantation of the microcapsules and macrocapsules (filled triangles) .
  • IVGTT intravenous glucose challenge
  • FIG. 4 is a graph of the serum glucose response to an intravenous glucose challenge (IVGTT) in rats treated with macroencapsulated canine islets according to the present invention (filled circles •) ; compared to the response in rats transplanted with free floating microencapsulated canine islets (open squares D) .
  • IVGTT intravenous glucose challenge
  • FIG. 5 is a graph of blood glucose levels of rats implanted with entrapped encapsulated islets according to the present invention (filled circles •) over time, when the islets are xenografts (canine islets). On day 14, the entrapped encapsulated islets were retrieved. The diabetic state recurred within 24 hours following retrieval of the entrapped encapsulated islets, proving the viability of the islets entrapped within the macrocapsule of the present invention.
  • a photomicrograph (4Ox) of an empty alginate-PLL-alginate microcapsule demonstrates that cellular overgrowth (appearing as a darkened area) occurs in areas of the exposed microcapsule gel or in areas of exposed polylysine when capsular membrane integrity is lost.
  • a photomicrograph (lOOx) of an alginate-PLL-alginate encapsulated islet shows areas of "roughness" or "stress marks” associated with individual microcapsules. The surface area of such individual microcapsules is large and thus in turn, the exposure of "rough” surfaces is huge, -14- increasing the risk of cellular overgrowth.
  • imperfect covering of polylysine by an outer coat of alginate results in potential overgrowth.
  • These microencapsulated canine islets successfully reversed diabetes, but only for a short period.
  • microcapsule means a capsule of gel material surrounding biologically active material, optionally contained within a microcapsule (e.g., one or more microcapsules, where each microcapsule contains at least one living cell, such as islets or other pharmacological agent producing cells, or certain drugs or physiologically active agents) .
  • microcapsule may include "macro-membranes,” “macrogels,” “gel entrapped microcapsules,” “lace,” “noodles,” “teabags,” “threads,” “worms,” and the like, which a person of skill in the art would understand refers to the general class of compositions described herein.
  • microcapsules is generally used to refer to particles wherein the largest dimensions thereof fall in the range of about 5 up to 4000 microns
  • macrocapsules is generally used to refer to particles wherein the largest dimensions thereof fall in the range of about 500 microns up to about 50 cm.
  • biologically active material e.g., a plurality of cell- containing microcapsules
  • a thick layer of gelled material forming a microcapsule-containing macrocapsule.
  • a schematic showing a cross-section of such a macrocapsule is provided in Figure 1. Inspection of the Figure reveals that the macrocapsule itself contains no polycation or other fibrogenic surface; instead, the im unoprotective membrane (i.e., polycation such as PLL) is localized at the surface of the microcapsules, which are buried deep within the macrocapsule (and protected from exposure to the in vivo environment by thousands of molecular layers) .
  • the core of the microcapsules (as well as the macrocapsule itself) are maintained in the gelled state (i.e., crosslinked or insoluble form), in contrast to prior art encapsulation systems, wherein the core material is liquified.
  • the layer of gelled material in invention macrocapsules has a thickness of at least about 1 micron, with a thickness of at least about 20-40 microns being preferred, and a thickness of at least about 50 microns or greater being especially preferred. This provides more effective masking of the polycation layer on the microcapsule than the few molecule thickness (of alginate outer layer) achieved in the preparation of prior -16- art microcapsules.
  • the layer of gelled material in invention macrocapsules prevents direct exposure of any immunogenic agents at the microcapsule surface (e.g., polycations, unencapsulated cells, and the like) to the in vivo environment, thereby preventing immune response triggered by prior art microcapsules.
  • the layer of gelled material is exceptionally stable to long- term exposure to physiological conditions since the gelled material is ionically and/or covalently crosslinked to itself, and does not depend on an interaction with the incorporated material for strength and/or stability.
  • This is in direct contrast with alginate outer layers employed in prior art microcapsules, wherein the sole means of anchorage of the alginate outer layer to the capsule is the formation of a charge complex (i.e., ionic interaction) between the alginate and the polycation immunoprotective layer.
  • microcapsules when microcapsules are incorporated into macrocapsules, the microcapsules (and the macrocapsules themselves) are maintained in the gelled state (i.e., ionically and/or covalently crosslinked) .
  • the encapsulating matrix of the microcapsule is liquified prior to implantation.
  • Macrocapsules of the invention can be produced in a variety of shapes, i.e., in the shape of a cylinder (i.e., a geometrical solid generated by the revolution of a rectangle about one of its sides), a sphere (i.e., a solid geometrical figure generated by the revolution of a semicircle around its diameter), a disc (i.e., a generally flat, circular form), a flat sheet (i.e., a generally flat -17- polygonal form, preferably square or rectangular) , a wafer (i.e., an irregular flat sheet), a dog-bone (i.e., a shape that has a central stem and two ends which are larger in diameter than the central stem, such as a dumbell) , or the like.
  • a cylinder i.e., a geometrical solid generated by the revolution of a rectangle about one of its sides
  • a sphere i.e., a solid geometrical figure generated by the revolution of a semicircle around
  • the materials used to provide such entrapment could be alginate (preferably high G-content alginate) , or a modification of such alginate to improve its biocompatibility and stability, e.g., a polymerizable alginate allowing covalent crosslinkage, or crosslinkable or polymerizable, water soluble polyalkylene glycol, or combinations of these materials.
  • the process to cause gel entrapment of such materials can be accomplished either by ionic or covalent crosslinkage.
  • Macrocapsules contemplated for use in the practice of the present invention contain therein biologically active material, wherein said biologically active material is optionally contained within microcapsules (i.e., a plurality of microcapsules within said macrocapsule) .
  • the invention macrocapsule can be prepared from a variety of polymeric materials, such as, for example, covalently crosslinkable or polymerizable linear or branched chain PEG, mixtures of different molecular weight covalently crosslinkable or polymerizable linear or branched chain PEGs, ionically crosslinkable alginate, combinations of alginate and covalently crosslinkable or polymerizable PEG and modified alginate that is capable of being covalently and ionically crosslinked, and the like.
  • Macrocapsules prepared in accordance with the present invention comprise biologically active material encapsulated in the above-described biocompatible crosslinkable material, wherein the macrocapsule has a volume in which the largest physical dimension is greater -18- than 1 mm.
  • Macrocapsules can contain "free” (i.e., unmodified by any coating) cells or groups of cells therein.
  • macrocapsules may contain cells or groups of cells which are themselves encapsulated within microcapsules.
  • Biologically active materials contemplated for encapsulation include individual living cells or groups of living cells, biological materials (for diagnostic purposes, e.g., for in vivo evaluation of the effects of such biological materials on an organism, and conversely, the effects of the organism on the materials) , tumor cells (for evaluation of chemotherapeutic agents) , human T-lymphoblastoid cells sensitive to the cytopathic effects of HIV; pharmacologically active drugs; diagnostic agents, and the like.
  • the term "living cells” refers to any viable cellular material, regardless of the source thereof. Thus, virus cells, prokaryotic cells, and eukaryotic cells are contemplated.
  • Specifically contemplated cells include islets of Langerhans (for the treatment of diabetes) , dopamine secreting cells (for the treatment of Parkinsons disease) , nerve growth factor secreting cells (for the treatment of Alzheimer's disease) , hepatocytes (for treatment of liver dysfunction) , adrenaline/angiotensin secreting cells (for regulation of hypo/hypertension) , parathyroid cells (for replacing thyroid function) , norepinephrine/metencephalin secreting cells (for the control of pain) , hemoglobin (to create artificial blood) , and the like.
  • Covalently crosslinkable and/or polymerizable polyethylene glycols contemplated for use in the practice of the present invention include linear or branched chain PEGs (including STAR PEGs) modified with a substituent X which is capable of undergoing free radical -19- polymerization (X is a moiety containing a carbon-carbon double bond or triple bond capable of free radical polymerization; and X is linked covalently to said PEG through linkages selected from ester, ether, thioether, disulfide, amide, imide, secondary amines, tertiary amines, direct carbon-carbon (C-C) linkages, sulfate esters, sulfonate esters, phosphate esters, urethanes, carbonates, and the like) .
  • Examples of such covalently crosslinable polyethylene glycols include vinyl and allyl ethers of polyethylene glycol, acrylate and methacrylate esters of polyethylene glycol, and the like.
  • PEGs having a wide range of molecular weights can be employed in the practice of the present invention, thus mixtures of different molecular weights of covalently crosslinkable PEGs contemplated for use in the practice of the present invention include PEGs having a MW in the range of about 200 up to 1,000,000 (with molecular weights in the range of about 500 up to 100,000 preferred, and PEGs having molecular weights in the range of about 1000 to 50,000 being the presently most preferred) .
  • PEGs having a MW in the range of about 200 up to 1,000,000 with molecular weights in the range of about 500 up to 100,000 preferred, and PEGs having molecular weights in the range of about 1000 to 50,000 being the presently most preferred
  • Such PEGs can be linear or branched chain (including STAR PEGs) .
  • STAR PEGs are molecules having a central core (such as divinyl benzene) which is anionically polymerizable under controlled conditions to form living nuclei having a predetermined number of active sites. Ethylene oxide is added to the living nuclei and polymerized to produce a known number of PEG "arms", which are quenched with water when the desired molecular weight is achieved.
  • the central core can be an ethoxylated oligomeric glycerol that is used to initiate polymerization of ethylene oxide to produce a STAR PEG of desired molecular weight.
  • Alginates contemplated for use in the practice of the present invention include high G-content alginate, high M-content alginate, sodium alginate, and the like; -20- covalently crosslinkable alginates contemplated for use in the practice of the present invention include alginates modified with a substituent X which is capable of undergoing free radical polymerization (X is a moiety containing a carbon-carbon double bond or triple bond capable of free radical polymerization; and X is linked covalently to said alginate through linkages selected from ester, ether, thioether, disulfide, amide, imide, secondary amines, tertiary amines, direct carbon-carbon (C-C) linkages, sulfate esters, sulfonate esters, phosphate esters, urethanes, carbonates, and the like) .
  • Examples of covalently crosslinkable alginates include allyl and vinyl ethers of alginate, acrylate and methacrylate
  • Combinations of alginate (ionically and/or covalently crosslinkable) and covalently crosslinkable PEG contemplated for use in the practice of the present invention include combinations of any two or more of the above-described alginates and PEGs.
  • a small amount of a co onomer can optionally be added to the crosslinking reaction to increase the polymerization rates.
  • suitable comonomers include vinyl pyrrolidinone, acrylamide, methacrylamide, acrylic acid, methacrylic acid, sodium acrylate, sodium methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate (HEMA) , ethylene glycol diacrylate, ethylene glycol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylol propane triacrylate, trimethylol propane trimethacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, glyceryl acrylate, glyceryl methacrylate, and the like.
  • Free radical polymerization of the above- described modified materials can be carried out in a -21- variety of ways, for example, initiated by irradiation with suitable wavelength electromagnetic radiation (e.g. , visible or ultraviolet radiation) in the presence of a suitable photoinitiator, and optionally, cocatalyst and/or comono er.
  • suitable wavelength electromagnetic radiation e.g. , visible or ultraviolet radiation
  • free radical polymerization can be initiated by thermal initiation by a suitable free radical catalyst.
  • free radical initiators can be employed in the practice of the present invention.
  • photoinitiators thermal initiators, and the like.
  • suitable UV initiators include 2,2- dimethoxy-2-phenyl acetophenone and its water soluble derivatives, benzophenone and its water soluble derivatives, benzil and its water soluble derivatives, thioxanthone and its water soluble derivatives, and the like.
  • a system of dye also known as initiator or photosensitizer
  • cocatalyst also known as cosynergist, activator, initiating intermediate, quenching partner, or free radical generator
  • Suitable dyes are ethyl eosin, eosin, erythrosin, riboflavin, fluorscein, rose bengal, methylene blue, thionine, and the like;
  • suitable cocatalysts are triethanolamine, arginine, methyldiethanol amine, triethyla ine, and the like.
  • Microcapsules contemplated for use in the practice of the present invention can be formed of a variety of biocompatible gel materials, such as, for example, alginate, covalently crosslinkable alginate (i.e., modified alginate that is covalently and ionically crosslinkable) , covalently crosslinkable PEG, combinations of any of the above-described alginates and any of the above-described PEGs, as well as the optional presence of one or more comonomers, as described above. -22-
  • Microcapsules employed in the practice of the present invention are optionally treated with an immunoprotective coating, as described by Lim in U.S. Patent No. 4,352,883, incorporated by reference herein (Lim refers to this immunoprotective coating as a "permanent semi-permeable membrane”) .
  • Immunoprotective materials contemplated for use in the practice of the present invention include polycations (such as polyamino acids [e.g., polyhistidine, polylysine, polyornithine, and the like]; polymers containing primary amine groups, secondary amine groups, tertiary amine groups or pyridinyl nitrogen(s) , such as polyethyleneimine, polyallyla ine, polyetheramine, polyvinylpyridine, and the like.
  • Treatment with such immunoprotecting materials can be carried out in a variety of ways, e.g., by crosslinking surface layers of an alginate gelled core containing encapsulated cells with polymers having acid-reactive groups such as amine or imine groups.
  • semipermeability of the immunoprotecting coating can be controlled by proper selection of the molecular weight of the immunoprotecting polymer, its concentration, and the degree of crosslinking with the underlying gel.
  • Molecular weight of the immunoprotecting polymer can also vary, depending on the degree of permeability desired. Typically molecular weights will fall between about 1,000 and 100,000 or higher.
  • Presently preferred immunoprotecting polymers employed in the practice of the present invention fall in the range of about 10,000 up to 50,000.
  • Optional treatment with immunoprotective coating can be avoided especially when the macrocapsular or microcapsular material is covalently crosslinkable, so that the desired porosity (or immunoprotectivity) may be achieved through judicious selection of the polymerizable macromonomers employed (i.e., polymerizable alginate, polymerizable PEG, and the like) , as well as mixtures of such monomers.
  • the polymerizable macromonomers employed i.e., polymerizable alginate, polymerizable PEG, and the like
  • multiple alginate-PLL-alginate microcapsules are entrapped in an alginate macrocapsule.
  • the microcapsules employed preferably have solid gel cores.
  • the alginate employed can be ionically and/or covalently crosslinkable.
  • the introduction of polycations to control microcapsule porosity and/or to provide an immunoprotecting barrier is optional because the desired porosity (or immunoprotectivity) may be achieved by using suitable concentrations of modified alginate or by using modified alginate having different degrees of substitution with the moiety X, or combinations of such modified alginate.
  • Another presently preferred embodiment of the invention involves the photopolymerization of an aqueous physiological covalently crosslinkable linear or branched chain PEG (e.g., a PEG-diacrylate solution, or polymerizable equivalent) containing suspended alginate microcapsules (e.g., alginate-PLL-alginate).
  • PEG a physiological covalently crosslinkable linear or branched chain PEG
  • suspended alginate microcapsules e.g., alginate-PLL-alginate.
  • the microcapsules employed preferably have solid gel cores.
  • the appropriate free radical initiators and cocatalysts are used with visible light sources such as a laser or a mercury lamp.
  • a solid (i.e., non-liquified) gel of PEG is formed around the alginate microcapsules which in addition to providing mechanical support and retrievability, forms a nonfibrosing, cell nonadherent, and immunoprotective coating around the microcapsules.
  • the polycation layer is optional because the PEG macrocapsule can readily provide immunoprotectivity by selection of appropriate molecular weights and concentrations of crosslinkable PEGs.
  • multiple alginate-PLL-alginate microcapsules are entrapped in a macrocapsule comprising ionically and/or covalently crosslinkable alginate, and covalently crosslinkable PEG.
  • the polycation layer is optional because the PEG macrocapsule can readily provide immunoprotectivity by selection of appropriate molecular weights and concentrations of crosslinkable PEGs.
  • multiple alginate-PLL-alginate microcapsules are entrapped in an (ionically and/or covalently crosslinkable) alginate macrocapsule, followed by a covering of PEG such that PEG and alginate are in intimate contact, and the PEG is exposed on the surface of the macrocapsule.
  • the polycation layer is optional because the PEG outer coat can readily provide immunoprotectivity by selection of appropriate molecular weights and concentrations of crosslinkable PEGs.
  • biologically active material is entrapped directly in a macrocapsule comprising ionically and/or covalently crosslinkable alginate, and/or covalently crosslinkable linear or branched chain PEG.
  • PEG of molecular weight 18500 (abbreviated 18.5k, also available commercially as PEG 20M) was modified chemically using the following procedure to incorporate acrylate functionalities into the molecule which rendered it polymerizable.
  • Other PEGs ranging in molecular weights from as low as 200 to as high as (but not limited to) 35000 could also be modified by the same procedure. -25-
  • PEG 18.5k was dried thoroughly by heating in a vacuum oven at 80°C for 24 hours.
  • the PEG could be dissolved in toluene and the solution distilled wherein any moisture could be removed as an azeotrope with toluene.
  • 20g of dry PEG were dissolved in 200-250 ml of dry toluene (acetone, benzene, and other dry organic solvents may also be used) .
  • a twofold molar excess of acryloyl chloride was used (0.35 ml) and a base, triethyl amine (0.6 ml) was added to remove HC1 upon formation. Before addition of acryloyl chloride, the solution was cooled in an ice bath.
  • the reaction was carried in a round bottomed flask under argon with constant reflux for 24 hours.
  • the reaction mixture was filtered to remove the insoluble triethyl amine hydrochloride while the filtrate was added to an excess of ether to precipitate PE diacrylate.
  • the product was redissolved and precipitated twice for further purification and any remaining solvent removed in vacuum.
  • Other purification schemes such as dialysis of a PEG-water solution against deionized water followed by freeze drying are also acceptable. Yield: 17g.
  • An esterification reaction between PEG and acrylic acid may be carried out in an organic solvent such as toluene.
  • a small amount of acid such as p-toluene sulfonic acid may be used to catalyze the reaction. Excess of one of the reactants (acrylic acid) will drive the reaction towards the products. The reaction is refluxed for several hours.
  • a reaction between PEG and allyl chloride in a dry solvent catalyzed by small amounts of stannic chloride also results in a polymerizable PEG.
  • Harris (1985) describes a number of protocols involving PEG chemistry from which alternative synthetic schemes are provided.
  • PEG derivatives prepared by the techniques outlined in examples 1 and 2 were dissolved in aqueous bicarbonate buffered saline (such as 5-40 wt%, or other buffer) at pH 7.4.
  • the photosensitizer, ethyl eosin (O.Ol ⁇ M up to 0.1M), a cocatalyst, triethanolamine (O.Ol ⁇ M up to 0.1M), and comonomer, vinyl pyrrolidinone (0.001 to 10%, but not essential) were added to the solution which was protected from light until the photopolymerization reaction.
  • other initiators cocatalysts, comonomers and wavelengths of laser radiation may be used, the selection of which is well known in the art.
  • a small quantity of the prepared solution was taken in a test tube and exposed to visible radiation either from an argon ion laser at a wavelength of 514 nm at powers between 10 W to 2 W, or a 100 watt mercury arc lamp which has a fairly strong emission around 514 nm.
  • the gelling time was noted and found to be extremely rapid with the laser (on the order of milliseconds) and fairly rapid with the mercury lamp (on the order of seconds) and varied with the concentrations of polymer, initiator, cocatalyst, and comonomers in the system.
  • a different initiating system from the one above was used to produce PEG gels.
  • a UV photoinitiator, 2,2- dimethoxy-2-phenyl acetophenone was added to a solution of polymerizable PEG in aqueous buffer at a concentration of 1000 - 1500 ppm. This solution was exposed to long wave UV radiation from a 100 watt UV lamp. The time required for gellation was of the order of seconds and was a function of the concentrations of initiator and addition of other polymerizable monomers such as vinyl pyrrolidone (0.001 to 10%) .
  • a UV laser may also be used for the photopolymerization.
  • Other UV photoinitiators may also be used (e.g., benzoin ethyl ether).
  • Microcapsules of alginate or any other material containing cells or enzymes or drugs may be delivered and retrieved from an implant using varying geometries of the microcapsule-containing PEG gels.
  • a large number of individual microcapsules may be localized to a preferred -28- region in the peritoneal cavity (or other implantation site) by embedding these microcapsules in a crosslinked PEG gel.
  • Various geometries may be considered for implantation such as cylindrical rod, circular disk, flat plate, dog bone, and long cylindrical "laces” or "threads” or “worms.”
  • the cell containing microcapsules were suspended in a physiological solution of PEG 18.5K diacrylate (30 wt%; PEGs of varying molecular weights may be used) containing triethanolamine (O.Ol ⁇ M up to 0.1M), ethyl eosin (O.Ol ⁇ M up to 0.1M), and vinyl pyrrolidinone (0.001 to 10%).
  • PEG 18.5K diacrylate (30 wt%; PEGs of varying molecular weights may be used
  • triethanolamine O.Ol ⁇ M up to 0.1M
  • ethyl eosin O.Ol ⁇ M up to 0.1M
  • vinyl pyrrolidinone 0.001 to 10%
  • a suspension is disposed in a hypodermic needle having a suitable gauge needle or cannula and the emergent stream is expelled into a buffered solution (which may have multivalent cations if alginate is used in the suspension) and simultaneously exposed to laser radiation from a suitable lamp source if photopolymerization is required for the reaction.
  • the lamp could be a laser light source or a UV light source depending upon the material to be polymerized and the photoinitiator used, as is known in the art.
  • Crosslinking is instantaneous, i.e., the emerging stream is photocrosslinked as fast as it is extruded, resulting in the formation of a "lace” or "noodle.” Gels or other geometries can be produced from appropriate molds fabricated for the purpose. -29-
  • Canine islets were isolated from donor pancreata by collagenase digestion and purified using a physiological islet purification solution. Islets were then encapsulated in an alginate-polylysine alginate microcapsule by the following process: Ten thousand purified islets were suspended in 1.8% solution of Na alginate (G content 64%) and via an air-droplet generating device, islets were entrapped in alginate gel beads by crosslinking alginate in 0.8% CaCl 2 solution. A polylysine membrane was formed following suspension of these alginate encapsulated islets in a 0.1% polylysine solution for 4-8 minutes. The encapsulated islet was then coated with an outer layer of alginate by suspension in 0.2% alginate for 5 minutes.
  • a cylindrical tube i.e., a lace, approximately 1-5 mm in diameter
  • alginate encasing these microencapsulated islets was then produced as follows:
  • microencapsulated islets were suspended in 1.8% alginate in the ratio of 1 volume microcapsule pellet to 4 volumes of alginate, and extruded into a solution of divalent cations containing CaCl 2 alone, or a combination of barium and calcium chloride.
  • the ratio of barium and calcium chloride as a combination of divalent cations crosslinking agent could vary from 1:10 to 1:100
  • spherical macrocapsules containing microencapsulated islets can be prepared by introducing -30- droplets of the above-described solution (i.e., microencapsulated islets in alginate solution) into a bath containing polyvalent cations (e.g., Ca ), as described above.
  • a bath containing polyvalent cations e.g., Ca
  • compositions and materials used in the design of retrievable systems are acceptable and advantageous.
  • the crosslinked alginate or PEG spheres (or lace) containing alginate microcapsules may be replaced in the appropriate situations by an ionically and/or covalently crosslinked alginate spheres.
  • Combinations of alginate and PEG may also be used.
  • the following variations, among others, are possible: (i) PEG alone, crosslinked as described above; mixtures of different molecular weight crosslinkable PEGs (linear or branched chain) may be used to adjust permeability of the resultant gels; (ii) Alginate alone, ionically crosslinked;
  • Ionic crosslinking of alginate can be accomplished with either Ca ++ alone or a combination of Ba and Ca ++ in a ratio of 1:10 to 1:100 (Ba:Ca) .
  • the alginate referred to in the preceding paragraph may be replaced with a modified alginate that is chemically crosslinkable in addition to its ionic gelling capabilities.
  • the modified alginates mentioned herein are described in detail in copending patent application Serial No. 07/784,267, incorporated by reference herein in its entirety.
  • the PLL referred to above may also be replaced with a modified PLL that is covalently crosslinkable.
  • the modified PLL mentioned herein is described in detail in copending patent application Serial No. 07/784,267, incorporated by reference herein in its entirety.
  • gel entrapment of microencapsulated islets provides several unexpected advantages with regard to insulin secretion: (i) rapid response of insulin release to a glucose stimulus, and (ii) once the insulin is released, a slow return to basal state, providing a sustained, continuous release over a longer period. Both of these responses are important in improving the homeostatic control of glucose metabolism in the diabetic recipient.
  • islets from the same canine pancreatic donor were used in both free floating microencapsulated and gel entrapped microencapsulated groups. Furthermore to ensure no variability in the integrity and formation of the microcapsules themselves, the islets were all encapsulated in one batch process and then divided into two — one half being used for free floating implantation and the remaining half entrapped in an alginate macrocapsule (i.e., gel entrapped microencapsulated islets) prior to implantation.
  • urine volume increases. Following STZ injection, urine volume exceeds 30 ccs per day and is indicative of the diabetic state. With resolution of diabetes, urine volume falls to normal levels. Reduction in urine volume coincided with the fall in serum glucose, providing further evidence that graft function and survival of macroencapsulated islets was superior to both free unencapsulated islets and free floating microencapsulated islets.
  • urine volume in free floating microencapsulated group rose to diabetic levels (>30mls.), indicating onset of graft failure, while the rats receiving gel entrapped microcapsules (i.e., macrocapsules) maintained a normal level of urine output, indicating ongoing graft function.
  • An IVGTT provides an in vivo assessment of the kinetics of insulin release in response to an intravenous glucose challenge.
  • K-value a numerical value
  • the fall in serum glucose in response to an intravenous glucose challenge was studied in both the rats receiving macroencapsulated and free floating microencapsulated islets. Serum glucose was measured at 1, 4, 10, 20, 30, 60 & 90 minutes following an intravenous injection of 0.5cc per kg of 50% dextrose. As can be seen in FIG.
  • Gel entrapped microencapsulated islets were implanted into STZ induced diabetic rats and followed for 14 days. Normal serum glucose levels were achieved within 3 days, and was maintained for the entire observation period. On the 14th day, the acrogelled encapsulated islets were retrieved and examined microscopically.
  • a photomicrograph (lOOx) of a macrocapsule containing canine islets according to the present invention retrieved from the peritoneal cavity of an STZ-diabetic Lewis rat 14 days after implantation demonstrates a smooth surface on the outer exposed layer of the macrocapsule, with no evidence of cellular overgrowth.
  • Encapsulated viable individual canine islets can be seen contained within the macrocapsule. At the time of retrieval, this diabetic rat was normoglycemic.
  • Serum glucose levels were monitored in the rat following retrieval of the macrogelled encapsulated islets. As can be seen in FIG. 5, within 24 hours after retrieval of the macrocapsule serum glucose levels rose to greater than 200 mg%, indicating that the macrogelled encapsulated islets was responsible for normalization of the serum glucose, and providing further evidence of the immunoprotectivity and biocompatibility of the macrocapsule.
  • gel entrapment provides a smoother outer surface, a reduced exposed surface area and hence increased -41- biocompatibility than free floating microencapsulated islets.
  • gel entrapment increases the mechanical stability of encapsulated islets and provides a retaining matrix even if the individual capsules were to break.
  • Islets from a healthy canine donor were isolated employing conventional methods (e.g., collagenase digestion) . Islets were then microencapsulated as described above (see, for example. Example 6) , in conventional alginate-PLL-alginate microcapsules
  • microcapsules were then further entrapped (i.e., encapsulated) into macrocapsules (spherical beads about 4000-8000 microns) of ionically crosslinked alginate by extrusion of a suspension of microcapsules in an alginate solution into a bath containing calcium chloride. Approximately 60-80 microcapsules were entrapped within a single macrocapsule.
  • the transplantation was performed under general anaesthesia through a 1.5 ventral idline incision, and the macrocapsules aseptically introduced into the peritoneal cavity through a stainless steel funnel.
  • the dog received a transplant dose of about 20,000 islets/kg body weight.
  • the incision was then closed by sutures.
  • a regimen of prednisolone was maintained for 14 days post-transplant as an anti-inflammatory.
  • Fasting blood glucose, plasma C-peptide, urine output and body weight were measured daily for the first 14 days post-transplant, and every 7 days thereafter.
  • Intravenous glucose tolerance tests (IVGTT) were performed 7 days prior to transplantation, 14 and 30 days post-transplantation, and every 30 days thereafter.
  • Homozygous Gunn rats having a deficiency of the liver enzyme uridine diphosphate glucuronyl transferase (UDPGT) and resultant elevated serum bilirubin levels (a condition commonly known as jaundice) were chosen as a model of hepatic deficiency.
  • Heterozygous Gunn rats which carry the abnormal gene, but are free from jaundice were chosen as the donors of hepatocytes for cellular transplant. -43-
  • the donor liver was cannulated via the portal vein with silicone tubing (i.d. 0.025 inch, o.d. 0.047 inch) and perfused with 100 ml of 0.05% collagenase (Sigma, Type IV) in 15 minutes.
  • the hepatocytes were then harvested into a sterile beaker and washed three times with RPMI medium. Viability of the isolated hepatocytes was tested by acridine orange/propidium iodide staining and found to be greater than 80%.
  • the hepatocytes were encapsulated into conventional alginate-PLL-alginate microcapsules as described above. These microcapsules were further entrapped (or encapsulated) in spherical macrocapsules of ionically crosslinked alginate (as described above. Approximately 50-100 microcapsules were entrapped in a single macrocapsule. Each recipient received -10 encapsulated hepatocytes. The macrocapsules were implanted in the peritoneal cavity of the recipients.
  • recipient bilirubin levels Prior to transplantation, recipient bilirubin levels were 5.3 ⁇ 0.3 mg%. By the second week post- transplantation, serum bilirubin levels were reduced to 2.05 ⁇ 1.05 mg%, which was significantly lower than pre- transplant levels. These reduced levels were maintained for an average of 73 ⁇ 4 days. All recipients received cyclosporin A as an anti-inflammatory (10 mg/kg, i.e., at levels lower than required to prevent immune rejection. Thus, the feasibility and efficacy of the macrocapsule of the invention is demonstrated for in vivo transplantation of hepatocytes.

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Abstract

L'invention concerne une macrocapsule servant à encapsuler des microcapsules contenant un matériau biologiquement actif, tel que des cellules vivantes ou des cellules vivantes libres, de façon à augmenter la biocompatibilité du système au moyen de la diminution de l'étendue et de la rugosité de la surface des matériaux biologiques microencapsulés; de l'augmentation de la stabilité mécanique desdits matériaux; de l'amplification de caractéristiques de cytoprotection en augmentant la distance de diffusion du matériau biologique encapsulé des cytotoxines sécrétées in vivo; de la possibilité de la récupération dudit matériau; enfin, de la constitution d'un système de libération prolongée des produits cellulaires. L'invention concerne également le procédé de préparation de ladite macrocapsule contenant les microcapsules.
PCT/US1993/011389 1992-11-24 1993-11-23 Macrocapsules cytoprotectrices, biocompatibles et recuperables WO1994012161A1 (fr)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0635040A4 (fr) * 1992-04-08 1995-10-04 Vivorx Inc Procedes d'encapsulage et compositions d'encapsulage reticulees biocompatibles.
US5529914A (en) * 1990-10-15 1996-06-25 The Board Of Regents The Univeristy Of Texas System Gels for encapsulation of biological materials
EP0762874A4 (fr) * 1992-12-30 1997-08-06 Clover Cons Ltd Systemes de conditionnement de substances biologiquement actives dans des macrocapsules recuperables, biocompatibles et cytoprotectrices
US5738876A (en) * 1995-03-03 1998-04-14 Metabolex, Inc. Method of solution overcoating with gelling polymer
US5916790A (en) * 1995-03-03 1999-06-29 Metabolex, Inc. Encapsulation compositions, and methods
US6126936A (en) * 1995-03-10 2000-10-03 Biohybrid Technologies Llc Microcapsules and composite microreactors for immunoisolation of cells
EP1011518A4 (fr) * 1996-11-26 2001-01-24 Univ California Transplant de tissu biologique recouvert d'un revetement d'alginate multicouche stabilise adapte a la transplantation et procede de preparation associe
WO2001030146A1 (fr) * 1999-10-22 2001-05-03 3M Innovative Properties Company Matiere active encapsulee et immobilisee dans des microperles d'hydrogel
US6287558B1 (en) 1997-08-01 2001-09-11 Biohybrio Technologies Llc Devices containing cells or tissue and an agent that inhibits damage by a host cell molecule
WO2002067971A3 (fr) * 2001-02-22 2003-12-31 Novartis Ag Traitement de la neovasculatisation oculaire
EP1418228A1 (fr) * 1994-01-13 2004-05-12 The Rogosin Institute Cellules sécrétoires macro-encapsulées
EP1162952A4 (fr) * 1999-03-09 2005-06-15 Vivorx Inc Systemes de confinement biocompatibles et cytoprotecteurs pour substances actives au plan biologique, et leurs procedes de fabrication
WO2008060786A3 (fr) * 2006-10-06 2009-05-07 Baxter Int Microcapsules contenant des microparticules modifiées en surface et leurs procédés de formation et d'utilisation
CN103301788A (zh) * 2012-03-09 2013-09-18 中国科学院大连化学物理研究所 Peg接枝改性的海藻酸盐-壳聚糖微胶囊及制备和应用
US11655343B2 (en) * 2016-03-24 2023-05-23 Takeda Pharmaceutical Company Limited Alginate hydrogel compositions
US12097306B2 (en) 2016-12-13 2024-09-24 Takeda Pharmaceutical Company Limited Conformal coating of biological surfaces
US12364791B2 (en) 2023-07-19 2025-07-22 Takeda Pharmaceutical Company Limited Conformal coating of biological surfaces

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4663286A (en) * 1984-02-13 1987-05-05 Damon Biotech, Inc. Encapsulation of materials
EP0301777A1 (fr) * 1987-07-28 1989-02-01 Queen's University At Kingston Microencapsulation multiple à membrane
US4833081A (en) * 1985-09-20 1989-05-23 United Kingdom Atomic Energy Authority Bioreactor having cells in beads in a matrix
US5084350A (en) * 1990-02-16 1992-01-28 The Royal Institution For The Advance Of Learning (Mcgill University) Method for encapsulating biologically active material including cells

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4663286A (en) * 1984-02-13 1987-05-05 Damon Biotech, Inc. Encapsulation of materials
US4833081A (en) * 1985-09-20 1989-05-23 United Kingdom Atomic Energy Authority Bioreactor having cells in beads in a matrix
EP0301777A1 (fr) * 1987-07-28 1989-02-01 Queen's University At Kingston Microencapsulation multiple à membrane
US5084350A (en) * 1990-02-16 1992-01-28 The Royal Institution For The Advance Of Learning (Mcgill University) Method for encapsulating biologically active material including cells

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5529914A (en) * 1990-10-15 1996-06-25 The Board Of Regents The Univeristy Of Texas System Gels for encapsulation of biological materials
US5801033A (en) * 1992-02-28 1998-09-01 The Board Of Regents, The University Of Texas System Gels for encapsulation of biological materials
US6258870B1 (en) 1992-02-28 2001-07-10 Board Of Regents, The University Of Texas Systems Gels for encapsulation of biological materials
EP0635040A4 (fr) * 1992-04-08 1995-10-04 Vivorx Inc Procedes d'encapsulage et compositions d'encapsulage reticulees biocompatibles.
EP0762874A4 (fr) * 1992-12-30 1997-08-06 Clover Cons Ltd Systemes de conditionnement de substances biologiquement actives dans des macrocapsules recuperables, biocompatibles et cytoprotectrices
EP1666585A1 (fr) * 1994-01-13 2006-06-07 The Rogosin Institute Cellules sécrétoires macro-encapsulées
EP1418228A1 (fr) * 1994-01-13 2004-05-12 The Rogosin Institute Cellules sécrétoires macro-encapsulées
US5738876A (en) * 1995-03-03 1998-04-14 Metabolex, Inc. Method of solution overcoating with gelling polymer
US6020200A (en) * 1995-03-03 2000-02-01 Metabolex, Inc. Encapsulation compositions and methods
US5916790A (en) * 1995-03-03 1999-06-29 Metabolex, Inc. Encapsulation compositions, and methods
US6126936A (en) * 1995-03-10 2000-10-03 Biohybrid Technologies Llc Microcapsules and composite microreactors for immunoisolation of cells
EP1011518A4 (fr) * 1996-11-26 2001-01-24 Univ California Transplant de tissu biologique recouvert d'un revetement d'alginate multicouche stabilise adapte a la transplantation et procede de preparation associe
US6287558B1 (en) 1997-08-01 2001-09-11 Biohybrio Technologies Llc Devices containing cells or tissue and an agent that inhibits damage by a host cell molecule
EP1162952A4 (fr) * 1999-03-09 2005-06-15 Vivorx Inc Systemes de confinement biocompatibles et cytoprotecteurs pour substances actives au plan biologique, et leurs procedes de fabrication
US6375968B1 (en) 1999-10-22 2002-04-23 3M Innovative Properties Company Encapsulated active material immobilized in hydrogel microbeads
AU779200B2 (en) * 1999-10-22 2005-01-13 3M Innovative Properties Company Encapsulated active material immobilized in hydrogel microbeads
WO2001030146A1 (fr) * 1999-10-22 2001-05-03 3M Innovative Properties Company Matiere active encapsulee et immobilisee dans des microperles d'hydrogel
WO2002067971A3 (fr) * 2001-02-22 2003-12-31 Novartis Ag Traitement de la neovasculatisation oculaire
US9238057B2 (en) 2001-02-22 2016-01-19 Novartis Ag Method for treating ocular neovascularization
WO2008060786A3 (fr) * 2006-10-06 2009-05-07 Baxter Int Microcapsules contenant des microparticules modifiées en surface et leurs procédés de formation et d'utilisation
CN103301788A (zh) * 2012-03-09 2013-09-18 中国科学院大连化学物理研究所 Peg接枝改性的海藻酸盐-壳聚糖微胶囊及制备和应用
US11655343B2 (en) * 2016-03-24 2023-05-23 Takeda Pharmaceutical Company Limited Alginate hydrogel compositions
US12338330B2 (en) 2016-03-24 2025-06-24 Takeda Pharmaceutical Company Limited Alginate hydrogel compositions
US12097306B2 (en) 2016-12-13 2024-09-24 Takeda Pharmaceutical Company Limited Conformal coating of biological surfaces
US12364791B2 (en) 2023-07-19 2025-07-22 Takeda Pharmaceutical Company Limited Conformal coating of biological surfaces

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