The development of the mammalian gut was first described more than a century ago. Since then, it has been believed that a series of highly orchestrated developmental processes occur before the intestine achieves its final formation. The... more
The development of the mammalian gut was first described more than a century ago. Since then, it has been believed that a series of highly orchestrated developmental processes occur before the intestine achieves its final formation. The key steps include the formation of the umbilicus, the so-called “physiological herniation” of the midgut into the umbilical cord, an intestinal “rotation”, and the “return of the gut” into the abdominal cavity. However, this sequence of events is predominantly based on histological sections of dissected embryos, a 2D technique with methodological limitations. For a better understanding of spatial relationships in the embryo, we utilized microcomputed tomography (µCT), a nondestructive 3D imaging method. Here, we show the detailed processes and mechanisms of intestinal development in rat embryos, including the development of the umbilicus, the formation of loops inside the umbilical coelom, and the subsequent shift of these loops into the abdominal ca...
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Background: Nitrofen is an embryotoxic substance that can induce congenital diaphragmatic hernias in newborn rats and mice. In the past, this model has been used to characterize changes of the lungs. In this study we focused mainly on the... more
Background: Nitrofen is an embryotoxic substance that can induce congenital diaphragmatic hernias in newborn rats and mice. In the past, this model has been used to characterize changes of the lungs. In this study we focused mainly on the characteristics of the liver, its intrathoracic growth, and the expression of proteins which may be involved in this process. Methods: A total of ten newborns were exposed to nitrofen on day 11 of pregnancy. After spontaneous delivery at term (22 days), all newborns were microdissected. The liver was weighed and the intrathoracic area of the liver was measured. In a second step we dissected the intrathoracic part of the liver from other liver tissue. Tissue was stored in fluid nitrogen. Gene analysis followed by Atlas cDNA expression array and AtlasImage software. Results: Our study had the following results: (1) 8 out of 10 newborns presented with a hernia, 2 newborns had no hernias. (2) We observed a significant increase of total liver weight in ...
The pathway of abnormal embryonic development leading to congenital diaphragmatic hernia (CDH) is incompletely understood. Using a nitrofen-induced model of left CDH in rats, sequential stages of development were analyzed by scanning... more
The pathway of abnormal embryonic development leading to congenital diaphragmatic hernia (CDH) is incompletely understood. Using a nitrofen-induced model of left CDH in rats, sequential stages of development were analyzed by scanning electron microscopy. Abnormal development patterns were observed in the cells comprising the posthepatic mesenchymal plate and the adjacent liver. The septum transversum did not appear to be involved. In this article, the authors theorize that a disturbed "balance of cell growth" is responsible for the creation of the diaphragmatic defect.
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Background: Pancreatic microcirculation (PM) plays a central role in the development of acute pancreatitis (AP) [l, 2]. If PM is permanently disturbed a grave form of AP with high mortality results, whereas a self-limiting form of the... more
Background: Pancreatic microcirculation (PM) plays a central role in the development of acute pancreatitis (AP) [l, 2]. If PM is permanently disturbed a grave form of AP with high mortality results, whereas a self-limiting form of the disease results if PM remains normal [1]. In previous experiments a therapeutic benefit was demonstrated when bovine hemoglobin (bHb) was injected intravenously 15 min. after the initiation of AP [3]. The objective was to evaluate whether a delayed and therefore clinically relevant injection of bHb still has a beneficial effect on PM and on the outcome of AP. Methods: In Wistar rats, AP was induced by administration of gluco-deoxycholic acid (10 mmol/1,1 ml/kg) i.d. and cerulein (5 ng/kg/h) i.v.. Leukocytes were marked with acridine orange and PM was continuously monitored by fluorescence microscopy. At 180 min after the initiation of AP, animals received either 0.8 ml bHb, HES or 2.4 ml of NaCl i.v. at random. After 6 h, animals were sacrificed and histopathological damage of the pancreas was assessed using a validated histology score ( 0 – 16 ; no max. damage) [2]. Results: PM improved in the bHbtreated animals regarding the change in leukocyte adherence after intervention (360 min — 180 min) compared to the NaCl group (6% (±5) vs. 16% (±3);p < 0.001) and regarding the change in functional capillary density compared to the HES treated animals ( -11% (±5) vs. -25% (±9),p = 0.001) and compared to the NaCl group ( -11% (±5) vs. -24% (±8); p = 0.002). Histological damage was less in the bHb group compared to the HES group [6.75 (5.25 – 7.75) vs. 9 (7.5 – 10.5); p = 0.001] and compared to the NaCl group [6.75 (5.25 – 7.75) vs. 12 (8.25 – 14); p < 0,001). Serum-amylase and serum-TAP levels were reduced in the bHb group by 788 U/L (±1708) and 12.3 nM/L (±9.4), respectively while it increased in the NaCl group by 3003 U/L (±2263) and 3.9 nM/L (±5.6) (p = 0.002 and p = 0.001), respectively. No differences were seen between the HES and NaCl groups regarding the serum parameter. Conclusion: Delayed therapeutic intervention with bHb improves PM and has a beneficial effect on the development of AP.
A hypothesis in respect to the teratogenesis of bladder exstrophy and its variants is offered. The central feature of this hypothesis is the abnormal persistence of the caudal position of the insertion of the body stalk on the embryo. As... more
A hypothesis in respect to the teratogenesis of bladder exstrophy and its variants is offered. The central feature of this hypothesis is the abnormal persistence of the caudal position of the insertion of the body stalk on the embryo. As a consequence of this, the normal advance and interposition of mesenchymal tissue to the midline becomes impossible. The cloaca cannot be translocated backwards into the body cavity, and the cranial end of the cloacal membrane remains in contact with the inferior aspect of the low-set body stalk. This, in contrast to the previously proposed abnormal rostral extension of the cloacal membrane, causes a wedge-effect resulting in the lateralization of the abdominal wall structures and also in the prevention of the midline fusion of the genital hillocks (labioscrotal or genital folds). A cloacal membrane normally is an unstable structure lacking mesoderm, and it retains these characteristics in the superficial and infraumbilical position to be described. It has a strong tendency to disintegrate. It may rupture at variable times and to a variable extent. The consequence of such an embryonic event is either a typical bladder exstrophy or one of the variants of the exstrophy malformation. Three different variants are presented that the proposed embryologic hypothesis can readily explain.
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Improvement of cell culture conditions in hepatic tissue engineering may permit cell/tissue banking and the generation of liver tissue equivalents for transplantation. In these systems, continuous hepatotrophic stimulation is still... more
Improvement of cell culture conditions in hepatic tissue engineering may permit cell/tissue banking and the generation of liver tissue equivalents for transplantation. In these systems, continuous hepatotrophic stimulation is still necessary. We investigated the stimulatory effects of pancreatic islets on hepatocytes in co-culture and characterized the stimulatory mechanisms. Hepatocytes and pancreatic islets were harvested from Lewis rats. Cells were cultured on collagen dishes either with nonstimulated media (controls and co-cultures with low or high islet rate) or stimulated media (controls and co-cultures). To characterize stimulatory mechanisms, additional co-cultures with membrane separation, with antiinsulin, antiglucagon, and with both antibodies were examined. Hepatocyte numbers, albumin secretion rate by enzyme-linked immunoadsorbent assay, and monoethylglycinxylidid biotransformation values by fluorescence polarization immunoassay were assessed. A radioimmunoassay measured insulin and glucagon concentrations. In groups with nonstimulated media, cell number was higher in co-cultures with low islet rate, and albumin secretion rate was increased in co-cultures with high islet rate compared to controls. MEGX biotransformation was decreased in co-cultures. In groups with stimulated media, co-culture had no impact on cell number or albumin secretion rate. Hepatocyte numbers and albumin secretion rates were not changed in co-cultures after membrane separation. Islet effects on hepatocytes were reduced in co-cultures with antiinsulin, antiglucagon, or both antibodies. Pancreatic islets provide stimulation for hepatocytes in vitro. Islet effects were mediated by soluble factors, and are dependent on insulin and glucagon. These results permit further investigations towards three-dimensional transplantable hepatocyte-islet devices for continuous in vitro and in vivo stimulation.
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To investigate the hepatocytic differentiation of mesenchymal stem cells (MSCs) in co-cultures with fetal liver cells (FLC) and the possibility to expand differentiated hepatocytic cells. MSCs were marked with green fluorescent protein... more
To investigate the hepatocytic differentiation of mesenchymal stem cells (MSCs) in co-cultures with fetal liver cells (FLC) and the possibility to expand differentiated hepatocytic cells. MSCs were marked with green fluorescent protein (GFP) by retroviral gene transduction. Clonal marked MSCs were either cultured under liver stimulating conditions using fibronectin-coated culture dishes and medium supplemented with stem cell factor (SCF), hepatocyte growth factor (HGF), epidermal growth factor (EGF), and fibroblast growth factor 4 (FGF-4) alone, or in presence of freshly isolated FLC. Cells in co-cultures were harvested, and GFP+ or GFP- cells were separated using fluorescence activated cell sorting. Reverse transcription-polymerase chain reaction (RT-PCR) for the liver specific markers cytokeratin-18 (CK-18), albumin, and alpha-fetoprotein (AFP) was performed in different cell populations. Under the specified culture conditions, rat MSCs co-cultured with FLC expressed albumin, CK-1...
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Background/Purpose The embryology of ventral body wall malformations is only partially understood, although their incidence is relatively common. As only few experimental data exist on the development of those defects, the aim of our... more
Background/Purpose The embryology of ventral body wall malformations is only partially understood, although their incidence is relatively common. As only few experimental data exist on the development of those defects, the aim of our study was to compare the teratogenic effect of trypan blue (TB) and suramin (SA) in their capability to induce umbilical and supraumbilical abdominal wall malformations in a chicken egg model. Materials and Methods A total of 255 fertilized chicken eggs were incubated at 38°C and 75% relative humidity. Embryos were treated in ovo on incubation day 2.5 (Hamburger/Hamilton (HH) stage 13). The eggshell was windowed, and solutions of TB or SA were injected into the coelomic cavity at the region of the umbilicus. The window was closed and the embryos reincubated until examination on day 8 (HH 34). Results A total of 60 embryos survived in each group. The largest number of embryos presented with defects in the umbilical and supraumbilical region (25% in the SA group and 40% in the TB group). A combination of both defects (thoracoabdominoschisis) was seen in 20% of the TB and 8.3% of the SA groups, respectively. Associated anomalies found in both groups were head and eye defects, abnormal pelvic configurations, leg deformities, and mild forms of cloacal exstrophies. Conclusions TB and SA have both a high potential to induce umbilical and supraumbilical ventral body wall malformations in chicken embryos. This novel animal model might help to establish a more profound understanding of the developmental steps in ventral body wall formation and the embryology for its malformations.
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ABSTRACT It is still generally believed that the defect in congenital diaphragmatic hernia results from failure of the so-called pleuroperitoneal canals (PPCs) to close at the end of the embryonic period (8th gestational week).... more
ABSTRACT It is still generally believed that the defect in congenital diaphragmatic hernia results from failure of the so-called pleuroperitoneal canals (PPCs) to close at the end of the embryonic period (8th gestational week). Furthermore, it is assumed that gut could enter the thoracic cavity through this defect, causing compression and finally hypoplasia of the lung. However, this sequence of embryological events has never been studied, and many details even of normal diaphragmatic development are still unknown. Using scanning electron microscopy and a new animal model of congenital diaphragmatic hernia (CDH), the nitrofen rat model, the normal embryology of the diaphragm was reinvestigated and, for the first time, the crucial developmental steps of congenital diaphragmatic hernia formation were studied. The basic results were: (1) In normal development, the PPCs are never wide enough to allow herniation of gut loops. (2) The formation of the defect happens in an early embryonic period. (3) The early ingrowth of liver through the defect is of major importance for the formation of CDH. In another set of experiments, the nitrofen rat model of congenital diaphragmatic hernias was used to study the cellular mechanisms involved during epithelial and mesenchymal growth and differentiation in normal and in abnormal lungs. These results, combined with selected culture techniques (eg, branching morphogenesis and epithelio-mesenchymal interaction) probably open new ways to a better understanding of the mechanisms that finally lead to an abnormal lung in CDH.
Surfactant proteins (SP's) have been described as inherent proteins of the human central nervous system (CNS). Their distribution pattern in brain tissue and altered cerebrospinal fluid (CSF) - concentrations in different CNS... more
Surfactant proteins (SP's) have been described as inherent proteins of the human central nervous system (CNS). Their distribution pattern in brain tissue and altered cerebrospinal fluid (CSF) - concentrations in different CNS pathologies are indicative of their immunological and rheological importance. The aim of this study has been to investigate when - compared to the lungs - SP's are expressed in the developing rat brain and which functional components in the CNS participate in their production. Brain and lung tissue from embryonal (days 10, 12, 14, 16, 17 and 20), newborn, and adult rats were harvested and investigated for expression of SP-A, SP-B, SP-C and SP-D using immunofluorescence microscopy in order to identify and compare the time points of their occurence in the respective tissue. To better identify the location of SP expression in the rat brain, SP's were colocalized with use of an astrocyte marker (GFAP), a neuronal marker (NeuN), an endothelial marker (CD...
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Research Interests: Nuclear medicine, Biopsy, Humans, Male, Infant, and 4 moreJejunum, Clinical Sciences, Ileum, and Gastric mucosa
Intestinal obstruction in newborns is associated with intestinal motility disorders after surgery. Alterations in the enteric nervous system (ENS) might cause abnormal peristalsis, which may then result in intestinal motility disorders.... more
Intestinal obstruction in newborns is associated with intestinal motility disorders after surgery. Alterations in the enteric nervous system (ENS) might cause abnormal peristalsis, which may then result in intestinal motility disorders. We aimed to quantify alterations in the myenteric plexus after a ligation and to test if these alterations were reversible. Small intestines of chicken embryos were ligated in ovo at embryonic day (ED) 11 for either 4 d (ED 11-15) or 8 d (ED 11-19). Both treated groups and control group were sacrificed and intestinal segments examined by means of both light and electron microscopy. The number of proximal myenteric ganglia increased (ED 19, 30.7 ± 3.16 versus 23.1 ± 2.03; P &lt; 0.001) in the 8-d ligature group but had values similar to the control group in the 4-d ligature group. The size distribution was skewed toward small ganglia in the 8-d ligature group (ED 19, 83.71 ± 11.60% versus 3.88 ± 4.74% in the control group; P &lt; 0.001) but comparable with the control group in the 4-d ligature group. Subcellular alterations in the 4-d ligature group were reversible. The pathologic alterations in the ENS were fully reversible in the 4-d ligature group. This reversibility might be linked to the degree of immaturity of the ENS.
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The combination of ex vivo gene transfer and a sufficient transplant model for hepatocytes may permit treatment of single enzyme-based metabolic liver diseases. Induction of replicative potential (priming) in hepatocyte cultures may... more
The combination of ex vivo gene transfer and a sufficient transplant model for hepatocytes may permit treatment of single enzyme-based metabolic liver diseases. Induction of replicative potential (priming) in hepatocyte cultures may enhance the efficiency of gene transfer under stable in vitro conditions. It is known that hepatocyte replication is increased in vivo after partial hepatectomy. We investigated the effect of partial hepatectomy prior to cell isolation on hepatocytes in vitro. Male Lewis rats served as donors. Hepatocytes were isolated by collagenase digestion from either intact livers or from livers 48 h after 70% hepatectomy (PH). Cells were seeded on collagen-coated culture dishes with hormone-supplemented culture media. Hepatocyte morphology, number, albumin secretion rate, and mono-ethyl-glycin-xylidid (MEGX)-biotransformation capacity were assessed on days 1, 3, and 5 in culture. PH significantly increased hepatocyte number and albumin secretion of cultured hepatocytes over the whole observation period. In contrast, MEGX-biotransformation capacity was significantly decreased. Morphology of cultured hepatocytes was not affected by PH prior to hepatocyte isolation. These results suggest a prolonged and complex response of hepatocytes to PH in vitro. Hepatocyte priming by PH is a promising approach toward stable cultures of proliferating hepatocytes and may provide a model for in vitro studies of hepatic regeneration mechanisms. Further research on hepatocyte priming toward an application in ex vivo gene transfer and hepatic tissue engineering seems justified.
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An unusual case of segmental dilatation of the colon (SDC) with a broad membranous bridge in the distal part of the dilated bowel is presented. To our knowledge, this association has not been previously reported and might provide further... more
An unusual case of segmental dilatation of the colon (SDC) with a broad membranous bridge in the distal part of the dilated bowel is presented. To our knowledge, this association has not been previously reported and might provide further insight into the underlying etiology of SDC.
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Hepatocyte transplantation using polymeric matrices is under investigation as an alternative therapy for metabolic liver diseases. Long-term engraftment of hepatocytes in polymers has been demonstrated. However, the metabolic activity of... more
Hepatocyte transplantation using polymeric matrices is under investigation as an alternative therapy for metabolic liver diseases. Long-term engraftment of hepatocytes in polymers has been demonstrated. However, the metabolic activity of hepatocytes in such devices has never been assessed in direct comparison with liver grafts. Hepatocyte and partial liver transplantation were evaluated in the scurvy-prone osteogenic disorder Shionogi rat model. Biodegradable poly glycolic acid matrices seeded with hepatocytes equivalent to 20% of the recipient&#39;s liver mass, or 20% liver grafts were heterotopically transplanted into ascorbic acid- (AsA) deficient recipients. Recipients of cell-free matrices or AsA-deficient liver grafts served as controls. Recipients were set on AsA-free diet after transplantation. Plasma AsA levels, AsA concentrations in liver and adrenal gland tissue, and body weight ratios were assessed and H&amp;E histology was performed. Recipients from the control groups showed symptoms of scurvy at 1 month after cessation of AsA supply. Hepatocyte transplantation and auxiliary liver transplantation prevented symptoms of scurvy and increased plasma and tissue AsA levels and body weight ratios. AsA levels in recipients of 20% liver grafts were comparable to normal control animals. Hepatocytes transplanted in polymeric matrices are able to compensate for liver-based metabolic deficiencies. Hepatocyte transplantation improves plasma AsA levels in AsA-deficient recipients. However, auxiliary liver grafts are superior to hepatocyte grafts in improving metabolic parameters. Further research work is needed to increase the efficiency of liver cell transplantation with regard to a clinical application.
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Aim of this study was to analyse the effect of gastric perforation induced peritonitis and a pneumoperitoneum (PP) on the ultrastructure of the parietal peritoneum. After randomisation rats allocated to groups I and II were subjected to... more
Aim of this study was to analyse the effect of gastric perforation induced peritonitis and a pneumoperitoneum (PP) on the ultrastructure of the parietal peritoneum. After randomisation rats allocated to groups I and II were subjected to standardized gastrotomy simulating gastric perforation. After a 12-h-interval a PP was induced in groups I and III. After PP for 60 min a primary fixant was injected intraperitoneally as the abdominal wall was still extended, as well as 30 s, 2 h and 12 h after release of the PP. In groups II and IV simple puncture of the abdomen was performed. Animals were sacrified and tissue specimens taken from the parietal peritoneum of the left diaphragm were analysed using raster electronic miroscopy (REM: 100x to 5000x). In group II (gastric perforation without PP) microvilli appeared shrunk and coarse, while integrity of the mesothelial cell layer remained intact up to 2 h after abdominal puncture. In group I (gastric perforation with PP) distortion of the mesothelial cell layer with concomittant opening of stomata to the submesothelial tissue was observed already in specimens harvested as the abdominal wall was still extended. Concomittantly scarce microvilli appearing coarse and thickened were laid flat on top of the mesothelial cells. After desufflation a rapid process of mesothelial desintegration with disruption from the submesothelial layer and vanishing of microvilli occurred. In REM analysis of parietal peritoneum premature distortion and desintegration of the mesothelial cell layer was observed after exposure to increased abdominal pressure and to gastric perforation-induced peritonitis.
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Today liver transplantation is the only curative option for the treatment of end-stage liver diseases. A major limitation of liver transplantation is the donor organ shortage. Therefore, tissue engineering based cell transplantation is... more
Today liver transplantation is the only curative option for the treatment of end-stage liver diseases. A major limitation of liver transplantation is the donor organ shortage. Therefore, tissue engineering based cell transplantation is currently under investigation with the aim to replace liver tissue and function. The principle of tissue engineering is the notion of an interaction between a cell and a three-dimensional matrix. The matrix serves as a scaffold and guides a three-dimensional cell assembly. In addition, the matrix provides for a regulation of cell proliferation and function by cell-matrix interactions. In cultures of hepatocytes a regulation of cell proliferation and specific function by using three-dimensional matrices and by modifying the surface with isolated molecules of the extracellular matrix has been demonstrated. Furthermore, a beneficial effect of a flow bioreactor system on cell viability and function was observed. In addition, a system for heterotopic hepat...
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Congenital diaphragmatic hernia (CDH) occurs sporadically with an incidence of 1:2,500 live births. Despite the progress in neonatal intensive care, CDH remains associated with a mortality of at least 30 % in isolated cases. The in... more
Congenital diaphragmatic hernia (CDH) occurs sporadically with an incidence of 1:2,500 live births. Despite the progress in neonatal intensive care, CDH remains associated with a mortality of at least 30 % in isolated cases. The in essence surgically correctable defect of the diaphragm enables the prenatal herniation of abdominal organs into the thoracic cavity. The resulting abnormal development of the airways and pulmonary vessels causes neonatal respiratory insufficiency and persistent pulmonary hypertension. The condition can be diagnosed prenatally and the degree of pulmonary hypoplasia, which determines the postnatal course, can be measured to make an -individual prognosis. In severely affected patients, prenatal surgery may improve neonatal outcome by reversing pulmonary hypoplasia. This is currently implemented by percutaneous fetoscopic endoluminal tracheal occlusion (FETO) to trigger fetal lung growth. Although there are no maternal complications, preterm rupture of the me...
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The origin of putative liver cells from distinct bone marrow stem cells, e.g. hematopoietic stem cells or multipotent adult progenitor cells was found in recent in vitro studies. Cell culture experiments revealed a key role of growth... more
The origin of putative liver cells from distinct bone marrow stem cells, e.g. hematopoietic stem cells or multipotent adult progenitor cells was found in recent in vitro studies. Cell culture experiments revealed a key role of growth factors for the induction of liver-specific genes in stem cell cultures. We investigated the potential of rat mesenchymal stem cells (MSC) from bone marrow to differentiate into hepatocytic cells in vitro. Furthermore, we assessed the influence of cocultured liver cells on induction of liver-specific gene expression. Mesenchymal stem cells were marked with green fluorescent protein (GFP) by retroviral gene transduction. Clonal marked MSC were either cultured under liver stimulating conditions using fibronectin-coated culture dishes and medium supplemented with SCF, HGF, EGF, and FGF-4 alone, or in presence of freshly isolated rat liver cells. Cells in cocultures were harvested and GFP+ or GFP- cells were separated using fluorescence activated cell sorti...
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Hepatocyte transplantation using polymeric matrices is under investigation as an alternative therapy for metabolic liver diseases. Long-term engraftment of hepatocytes in polymers has been demonstrated. However, the metabolic activity of... more
Hepatocyte transplantation using polymeric matrices is under investigation as an alternative therapy for metabolic liver diseases. Long-term engraftment of hepatocytes in polymers has been demonstrated. However, the metabolic activity of hepatocytes in such devices has never been assessed in direct comparison with liver grafts. Hepatocyte and partial liver transplantation were evaluated in the scurvy-prone osteogenic disorder Shionogi rat model. Biodegradable poly glycolic acid matrices seeded with hepatocytes equivalent to 20% of the recipient's liver mass, or 20% liver grafts were heterotopically transplanted into ascorbic acid- (AsA) deficient recipients. Recipients of cell-free matrices or AsA-deficient liver grafts served as controls. Recipients were set on AsA-free diet after transplantation. Plasma AsA levels, AsA concentrations in liver and adrenal gland tissue, and body weight ratios were assessed and H&E histology was performed. Recipients from the control groups showe...
Pulmonary sequestrations have no communication with the bronchial tree. Therefore they are usually airless. However, in the presence of a fistula to the esophagus or the stomach, they might contain air or could even be emphysematic. Such... more
Pulmonary sequestrations have no communication with the bronchial tree. Therefore they are usually airless. However, in the presence of a fistula to the esophagus or the stomach, they might contain air or could even be emphysematic. Such a case in a newborn is presented. This very rare anomaly is frequently named "communicating bronchopulmonary foregut malformation". This malformation has to be included in the differential diagnosis of multicystic lung diseases. Diagnosis can be made preoperatively by esophagography and Doppler sonography.
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The combination of ex vivo gene transfer and a sufficient transplant model for hepatocytes may permit treatment of single enzyme-based metabolic liver diseases. Induction of replicative potential (priming) in hepatocyte cultures may... more
The combination of ex vivo gene transfer and a sufficient transplant model for hepatocytes may permit treatment of single enzyme-based metabolic liver diseases. Induction of replicative potential (priming) in hepatocyte cultures may enhance the efficiency of gene transfer under stable in vitro conditions. It is known that hepatocyte replication is increased in vivo after partial hepatectomy. We investigated the effect of partial hepatectomy prior to cell isolation on hepatocytes in vitro. Male Lewis rats served as donors. Hepatocytes were isolated by collagenase digestion from either intact livers or from livers 48 h after 70% hepatectomy (PH). Cells were seeded on collagen-coated culture dishes with hormone-supplemented culture media. Hepatocyte morphology, number, albumin secretion rate, and mono-ethyl-glycin-xylidid (MEGX)-biotransformation capacity were assessed on days 1, 3, and 5 in culture. PH significantly increased hepatocyte number and albumin secretion of cultured hepatocytes over the whole observation period. In contrast, MEGX-biotransformation capacity was significantly decreased. Morphology of cultured hepatocytes was not affected by PH prior to hepatocyte isolation. These results suggest a prolonged and complex response of hepatocytes to PH in vitro. Hepatocyte priming by PH is a promising approach toward stable cultures of proliferating hepatocytes and may provide a model for in vitro studies of hepatic regeneration mechanisms. Further research on hepatocyte priming toward an application in ex vivo gene transfer and hepatic tissue engineering seems justified.