WO2026032041A1 - Thoracic surgical biological patch and preparation method therefor - Google Patents

Abstract

Disclosed is a thoracic surgical biological patch. The biological patch has a maximum tensile elongation greater than 17.2%, an elastic deformation rate greater than 18.3%, and a single-thread suture pulling force greater than 15.5 N. Further disclosed is a preparation method for the thoracic surgical biological patch. The thoracic surgical biological patch provided by the present invention can be used for lining and sealing incisal margins of lung and trachea tissues, promote the healing and repair of the tissues at the incisal margins, and effectively prevent various complications caused by postoperative air leakage.

Description

A biological patch for thoracic surgery and its preparation method Technical Field

This invention relates to a thoracic surgical biological patch and its preparation method.

Background Technology

Lung volume reduction surgery is an effective treatment for pulmonary or bronchial diseases, including wedge resection and local resection of the lung, lower esophageal cancer resection, pleural resection of the lung, pneumonectomy, lobectomy, and segmentectomy. Postoperative air leakage is crucial to the success of lung volume reduction surgery and is a major cause of lung function problems and other complications. The "National Expert Consensus on Perioperative Perioperative Management Strategies for Thoracic Surgery (2023)" recommends using appropriate surgical techniques to minimize or avoid visceral pleural rupture. For patients with high-risk factors such as COPD or emphysema undergoing lung surgery, standardized use of thoracic surgical biological patches with relevant indications can be used to prevent air leakage after preoperative evaluation. (Recommendation level: 1B; Expert agreement rate: 97%)

Currently, while commercially available thoracic surgical biological patches have reduced air leakage to some extent, the problem still exists. Therefore, clinical practice demands higher performance from thoracic surgical biological patches, requiring them to have better compliance, be less prone to slippage from tissues, and have excellent fit, in order to reduce surgical difficulty and postoperative complications, and to minimize intraoperative and postoperative air leakage using better technologies and products.

Summary of the Invention

This invention has found that by controlling the range of four key parameters—maximum tensile elongation, elastic deformation rate, single-line suture traction force, and the value of elastic deformation rate relative to maximum tensile elongation—the resulting biological patch exhibits excellent resilience and conformability, effectively preventing air leakage in thoracic surgery.

In this invention, the determination of maximum tensile elongation and single-line suture tensile force refers to existing literature (Li Chongchong, Liu Li, Wang Shuo, et al. Comparison of mechanical properties of allogeneic and animal-derived patches [J]. Beijing Biomedical Engineering, 2021.). The elastic deformation rate is determined using conventional methods in the field. The prepared biological patch is cut to a length of 4 cm and a width of 1 cm. The biological patch is clamped on a tensile testing machine along its length and a tensile load is applied at a speed of 100 mm/min to stretch the biological patch until it breaks. A tensile curve is plotted, and the elastic deformation rate of the biological patch is calculated based on the elastic deformation segment of the tensile curve.

As one aspect of the present invention, a thoracic surgical biological patch is provided, wherein the biological patch has a maximum tensile elongation greater than 17.2%, an elastic deformation rate greater than 18.3%, and a single-line suture traction force greater than 15.5N.

Preferably, the maximum tensile elongation of the biological patch is 17.2-51.9%.

Preferably, the elastic deformation rate of the biological patch is in the range of 18.3-39.4%.

Preferably, the single-line suture tension of the biological patch is 15.5-33.4 N.

Preferably, the elastic deformation rate of the biological patch is 49-93% of the maximum tensile elongation.

Preferably, the biological patch has a maximum tensile elongation of 25.6-51.9%, a single-line suture traction force of 17.2-33.4 N, an elastic deformation rate of 18.3-39.4%, and an elastic deformation rate accounting for 49-93% of the maximum tensile elongation.

Preferably, the thoracic surgical biological patch has two perforations located at opposite ends of the biological patch.

As another aspect of the invention, it relates to a stapler kit comprising the aforementioned thoracic surgical biological patch. Since most lung reduction surgeries currently employ a cutting stapler, the application of the patch requires pre-installation of the stapler clips, i.e., the patch is stretched and fixed to both ends of the clips before surgery.

As another aspect of the present invention, a method for preparing the above-described thoracic surgical biological patch is provided, comprising:

(1) Preprocessing:

①Immerse healthy bovine pericardial tissue sheets in hypotonic Hank's solution, and rinse repeatedly and change the hypotonic Hank's solution to remove cell fragments, nuclei and organelles that have been swollen and broken after decellularization.

② Rinse the tissue slides treated above repeatedly with physiological saline for 90-150 minutes each time, changing the physiological saline each time. The total number of rinsing times depends on whether there are no morphological cells or cell components and cell debris under the microscope of the tissue slide. Perform quantitative determination of protein and nucleic acid until no soluble protein and nucleic acid can be detected.

③ Use a surfactant solution to remove phospholipids and non-structural proteins, as well as some tissue matrix, from the tissue slices; the surfactant solution can be Tween 80, sodium dodecyl sulfate, or Triton X-100;

④ Soak in a 2.5-4% glutaraldehyde solution for 3-3.5 hours;

(2) Chemical modification:

The pretreated tissue material was placed in a hydroxychromium solution with a Cr3 ⁺ ion concentration of 0.0625 mol/ ^dm3 and an OH/Cr ratio of 0.5 for the first water bath shaking at 20-28℃ for 2-4 hours. The pH of the material treatment solution was measured and increased by 0.3-0.6 pH units with 10% _NaHCO3 . Then, a second water bath shaking was performed at 32-40℃ for 3-5 hours to obtain a monolayer sheet-like biological patch.

This invention obtains a thoracic surgical biological patch by decellularizing, removing immunogenicity from bovine pericardial tissue, and chemically modifying it. The patch has excellent biocompatibility, anti-calcification properties, and biomechanical properties necessary for therapeutic effects, and can fuse with the patient's lung tissue.

When clamping tissue, the pin holes and sutures formed after the titanium pins of the stapler pass through the biological patch will quickly shrink due to the elastic recoil deformation of the biological patch to prevent air leakage. At the same time, the elastic deformation of the patch also makes the tissue clamping more stable and reliable.

In lung volume reduction surgery, thoracic surgical biological patches can be used as pads and seals for the cut edges of lung and tracheal tissues. They not only ensure stable adhesion to lung tissue without slippage or postoperative air leakage, but also promote the healing and repair of the cut edge tissues, reduce postoperative adhesions and pain, greatly improve patient comfort, reduce foreign body sensation, and significantly improve postoperative quality of life. They also effectively prevent complications such as large-area subcutaneous emphysema, dyspnea, lung infection, incision infection, and empyema caused by postoperative air leakage in lung volume reduction surgery.

The thoracic surgical biological patch provided by this invention has one rough surface and one smooth surface. The rough surface generates significant friction when in contact with the stapler cartridge or anvil, preventing the patch from slipping during cutting and anastomosis. After installation, the smooth surface adheres well to the lung tissue, improving patient comfort and reducing the feeling of a foreign body. By surgically implanting the thoracic surgical biological patch provided by this invention, tissue fusion and reconstruction result in a reinforced lung tissue margin, and the reconstructed lung tissue possesses normal blood transport.

The thoracic surgical biological patch provided by this invention possesses excellent mechanical properties, effectively preventing intraoperative and postoperative air leakage in patients (especially those with COPD, long-term smoking, or poor lung quality due to radiotherapy and chemotherapy). Air leakage often results from a mismatch between the stapling height and tissue thickness. While the stapling height is fixed, lung tissue thickness varies among patients and at different locations. When the lung tissue is too thick or too thin relative to the stapling height, air leakage may occur after suturing. The thoracic surgical biological patch provided by this invention exhibits excellent resilience and toughness, meeting the biomechanical requirements of patients of different ages and conditions. After tissue clamping, the stapling holes and sutures formed by the staplings passing through the biological patch rapidly contract due to the patch's elastic deformation, preventing leakage. Simultaneously, the patch's elastic deformation also makes the tissue clamping more stable and secure, preventing postoperative air leakage.

Compared with biological patches made from polyglycolic acid, a high-molecular synthetic material, after implantation of the thoracic surgical biological patch obtained by this invention, the patient's own tissue cells continuously grow into the thoracic surgical biological patch. The grown tissue cells begin to divide and differentiate, among which mature fibroblasts begin to secrete collagen. The proliferation of collagen tissue thickens the thin lung tissue. At the same time, small blood vessels will form within the thoracic surgical biological patch. As the thoracic surgical biological patch integrates and reconstructs with the patient's own lung tissue, the lung tissue at the cut and suture site can be strengthened more quickly and for a longer period of time.

The thoracic surgical biological patch obtained through the process of this embodiment removes the immunogenicity of the tissue sheet itself, retains the framework of the natural biological tissue and part of the tissue matrix, has good biocompatibility with the patient's lung tissue for fusion and reconstruction, is easy for host cells to grow into and reconstruct tissue, and is suitable for the repair of various soft tissues.

Attached Figure Description

Figure 1 is a schematic diagram of a biological patch pre-placed on an anastomosis device; where A represents biological patches with different perforation distances; B represents an anastomosis device without a pre-placed biological patch; C represents a biological patch with a pre-placed anastomosis device; and D is a magnified view of part E in Figure C.

Figure labels: 1. Biological patch; 2. Perforation device; 3. Clamping piece; 4. Staple cartridge or titanium anvil; 5.

Detailed Implementation

The following detailed description illustrates the specific implementation method:

In developing this invention, the inventors first addressed the issue of air leakage during thoracic surgery. Referring to existing literature (Li Chongchong, Liu Li, Wang Shuo, et al. Comparison of mechanical properties of allogeneic and animal-derived patches [J]. Beijing Biomedical Engineering, 2021.), they used tensile strength, maximum tensile elongation, and single-line suture traction force as parameters for screening biological patches. However, after testing, it was found that the tensile strength of the obtained biological patches fluctuated significantly and was unstable. Furthermore, animal experiments revealed that the correlation between the tensile strength of biological patches and air leakage was unstable, making tensile strength unsuitable as a screening parameter. Therefore, the inventors determined the screening and evaluation parameters for biological patches to be maximum tensile elongation, elastic deformation rate, and single-line suture traction force. Clinical trials determined the optimal ranges for these three parameters to be: maximum tensile elongation range of 17.2-51.9%, elastic deformation rate range of 18.3-39.4%, and single-line suture traction force of 15.5-33.4 N. However, during this process, the inventors unexpectedly discovered that the ratio of elastic deformation rate to maximum tensile elongation also affects lung leakage.

The inventors further verified this finding through clinical trials, confirming that when the maximum tensile elongation, elastic deformation rate, and single-line suture traction force are within a specific range, controlling the elastic deformation rate to be no less than 49% of the maximum tensile elongation will help prevent lung leakage during thoracic surgery.

I. Preparation method of biological patch

(1) Preprocessing

In this invention, the pretreatment specifically refers to the decellularization and immunogenicity removal procedures on biological tissues, which are conventional techniques in the field aimed at removing cellular tissue components and eliminating immunogenicity. This invention does not limit the specific operational process. The specific operational process can be found as follows:

①Immerse healthy bovine pericardial tissue sheets in hypotonic Hank's solution, and repeatedly rinse and replace the hypotonic Hank's solution to fully swell and break down various cells in the tissue, thereby removing cell fragments, nuclei and organelles that have been swollen and broken down after decellularization.

② Rinse the tissue slides treated above repeatedly with physiological saline for 90-150 minutes each time, changing the physiological saline each time. The total number of rinsing times depends on whether there are no visible cells or cell components and cell debris under the microscope. Quantitative determination of protein and nucleic acid is performed until no soluble protein and nucleic acid can be detected. For example, in a specific embodiment of the present invention, the preferred rinsing time with physiological saline is 90 minutes.

③ Use a surfactant solution to remove phospholipids and non-structural proteins, as well as some tissue matrix immunogenic molecules such as hyaluronic acid, various chondroitin sulfates, and mucopolysaccharides from the tissue slices; the surfactant solution can be Tween 80, sodium dodecyl sulfate (SDS), or Triton X-100. For example, in a specific embodiment of the present invention, Tween 80 is preferred.

④ Soak in a 2.5-4% glutaraldehyde solution for 3-3.5 hours. For example, in a specific embodiment of the present invention, the preferred soaking conditions are: 3 hours in a 2.5% glutaraldehyde solution.

(2) Chemical modification

Composite crosslinking modification is performed on free carboxyl groups within and/or between collagen molecules and between collagen and the tissue matrix. The crosslinking agent is a polymer of a hydroxychromium coordination compound, enabling the modified tissue sheet to acquire corresponding mechanical properties and anti-calcification properties. Specific operation can be referred to as follows: The pretreated tissue material is placed in a hydroxychromium solution with a ^Cr³⁺ ion concentration of 0.0625 mol/ ^dm³ and an OH/Cr ratio of 0.5 for the first water bath shaking. The conditions are: water bath shaking at 20-28℃ for 2-4 hours. For example, in a preferred embodiment of this invention, the first water bath shaking condition is: water bath shaking at 20℃ for 2 hours.

The pH of the material treatment solution was measured and increased by 0.3-0.6 pH units using 10% _NaHCO3 . A second water bath shaking was then performed at 32-40°C for 3-5 hours to obtain a monolayer sheet-like biological patch. For example, in a preferred embodiment of the present invention, the second water bath shaking conditions were: increasing the pH by 0.3 _units using 10% NaHCO3, followed by shaking at 32°C for 3 hours, ultimately yielding a monolayer sheet-like biological patch.

The resulting biological patch has a rough surface on one side and a smooth surface on the other. As shown in Figure 1, two or more perforations 2, slightly smaller than the width of the clamping piece 4, are made on the resulting biological patch 1, with the perforations 2 having the same direction and size. The free end of the clamping piece 4 passes through two of the perforations 2 in sequence (the distance between the two perforations 2 is selected according to the surgical needs). The position of the biological patch 1 is further adjusted manually so that the biological patch 1 is laid flat and adheres to the inner side of the clamping piece 4. The rough surface contacts the staple cartridge or anvil 5 of the stapler, and after contact, there is a large friction force, making it difficult for the biological patch 1 to slip off during cutting and anastomosis by the stapler 3. The smooth surface adheres to the lung tissue, ensuring a good fit with the lung tissue. The perforation 2 being slightly smaller than the width of the clamping piece 4 ensures that the biological patch 1 remains stretched when it is hung on the clamping piece 4, preventing it from sliding or slipping off the clamping piece 4.

Examples 1-24

The main differences in the preparation process of the biological patches in Examples 1-24 are shown in Table 1 below:

Table 1: Main differences in the preparation methods of Examples 1-24

II. Determination of tensile strength, maximum tensile elongation, and single-thread suture tension.

Good mechanical properties can reduce or even prevent air leakage in the lungs, decrease postoperative complications, improve the compliance of biological patches, and enhance patient comfort. To explore the relationship between mechanical parameters and air leakage, compliance, and comfort of thoracic surgical biological patches, the inventors first reviewed the literature and, based on existing literature (Li Chongchong, Liu Li, Wang Shuo, et al. Comparison of mechanical properties of allogeneic and animal-derived patches [J]. Beijing Biomedical Engineering, 2021.), measured the tensile strength, maximum tensile elongation, and single-line suture traction force of the biological patches obtained in Examples 1-24 (ten biological patches were obtained for each example, and the parameters were measured according to the literature, and the average value was taken). The measurement results are shown in Table 2 below.

Table 2: Maximum tensile elongation, tensile strength and single-line suture pull force of Examples 1-24

Table 2 above shows that the tensile strength of the 10 biological patches obtained in each of Examples 1-24 fluctuates greatly and the values are unstable. This may be because there are other influencing factors on the tensile strength of the biological patches that the inventors have not discovered, making it impossible to accurately control the tensile strength of the biological patches. This is not suitable for use as surgical materials.

The biological patches obtained in Examples 1-24 have a maximum tensile elongation range of 15.6-51.9%, a tensile strength range of 16.3-39.5 MPa, and a single-line suture traction force range of 5.1-33.4 N.

Ten biological patches were obtained in each embodiment, and each patch was cut to a length of 4cm and a width of 1cm to test whether it could be pre-placed on the anastomosis device.

The biological patch needs to be appropriately stretched before being placed into the anastomosis device, which is related to the maximum tensile elongation. Theoretically, the higher the maximum tensile elongation, the better. If the maximum tensile elongation is too low, the biological patch will break after being stretched only a short distance. Specifically, taking 10 biological patches from Example 21 (maximum tensile elongation 15.6 ± 0.1%) and assembling them into anastomosis devices, 9 were found to have broken, and 1 showed a significant crack. Taking 10 biological patches from Example 14 (maximum tensile elongation 16.3 ± 0.5%) and assembling them into anastomosis devices, 7 were found to have broken, and 3 showed significant cracks. This demonstrates the strength and toughness of the biological patch; it is extremely difficult to deform, and once deformed, it quickly enters permanent deformation and rapidly breaks.

It was found that the biological patches with maximum tensile elongation of 15.6% and 16.3% could not meet the requirements for installation on the stapler. Since the biological patches obtained in other embodiments met the tensile requirements and could be pre-placed on the stapler, the maximum tensile elongation of the biological patch obtained in Example 3, 17.2 ± 0.2%, was chosen as the minimum maximum tensile elongation required for installation on the stapler.

Animal experiments were conducted on the embodiments (Examples 1-13, Examples 15-20 and Examples 22-24) that met the requirements of the pre-installed anastomosis device.

III. Animal Experiments

Because the lungs of white pigs share many similarities with those of humans in terms of anatomical structure and physiological function, they are ideal animal models for studying human lung diseases and injuries. Furthermore, their moderate size facilitates experimental manipulation and management. Compared to smaller animals such as mice and rats, white pigs offer more maneuvering space, making surgical procedures easier for researchers. Additionally, white pigs are easy to raise and manage under laboratory conditions, are less prone to postoperative infections, are easier to control in long-term care, and have a high long-term survival rate.

Healthy laboratory animals were purchased in accordance with SOP-5 procedures for the acquisition and receipt of laboratory animals. The animals were provided by Jiangxi Yinshe Biotechnology Co., Ltd. (License No. SCXK(赣)2023-0002). All animals were being used for animal experiments for the first time at the start of the experiment. All test animals underwent quarantine before surgery, and only those that passed the quarantine were included in this study.

1. Selection Criteria

The animal meets the requirements of the National Animal Quarantine Management Regulations; weighs between 50-60 kg; has normal physiological indicators; and has no obvious serious animal diseases.

2. Feeding

The laboratory animals are tracked and managed in accordance with the SMP-5 laboratory animal care management regulations. The animals are fed an appropriate amount of feed twice a day and can drink water freely through the automatic water supply system. Both the feed and water are clean and safe.

3. Grouping and Quantity

1-month experimental group: 110 pigs in total; 3-month experimental group: 110 pigs in total; gender not limited, randomly assigned to groups. Examples 1-13, Examples 15-20 and Examples 22-24 (22 examples in total), each example used 10 pigs (5 pigs in the 1-month experimental group and 5 pigs in the 3-month experimental group) for the experiment, and the 10 biological patches obtained in each example corresponded to one pig.

Animal information was recorded during the experiment, including weight, surgery time, survival days, and biological patch information.

Preoperative blood routine, blood biochemistry, coagulation function, and blood gas were measured.

Blood routine, blood biochemistry, coagulation function, and blood gas were measured 1 month and 3 months after surgery.

4. Experimental Procedure

① Preoperative preparation; ② Perform preoperative blood tests according to routine examination requirements and record preoperative data; ③ During surgery, administer general anesthesia to the experimental pig, intubate, provide mechanical ventilation, and disinfect and prepare the skin; ④ In the supine position, open the abdomen to expose it, free the lung tissue, and select a suitable location; make an incision; ⑤ Attach a 4cm long and 1cm wide biological patch to a disposable anastomosis device, place the pre-placed biological patch anastomosis device in the predetermined position, and adjust its angle and depth to ensure close contact with surrounding tissues; ⑥ Carefully examine the anastomosis and biological patch, observe whether the biological patch is fixed and stable, whether the patch and lung tissue are well anastomosed, and whether the resilience of the biological patch meets the requirements. Pour warm saline into the pleural cavity and observe whether there is air leakage at the nail holes and sutures. After confirming that there is no air leakage, close the abdomen.

After surgery, the test animals were transferred to the observation room for observation and were supported by ventilators until they regained consciousness and could stand and move. They were then transferred to the animal house for rearing. Alternating 12-hour/12-hour lighting was provided daily, and the animals were given appropriate amounts of feed once in the morning and once in the afternoon, with free access to water. Their mental state, appetite, respiration, wound complications, and other adverse symptoms were observed daily.

Postoperative care includes continuous intramuscular injection of ceftriaxone sodium 2g for one week to combat infection. Daily observation of the animal's mental state, appetite, respiration, wound healing progress, and any signs of nausea, vomiting, subcutaneous emphysema, respiratory distress, lung infection, wound infection, or empyema is crucial. The surgical wound should be disinfected with povidone-iodine until healed. Regular veterinary examinations and blood tests should be conducted, and anti-infection prevention and treatment measures should be implemented based on the results. Postoperative medication administration and adverse events (including death and infection) within 24 hours should be recorded.

Upon reaching the end of the test, visually inspect the patch for integrity, defects, and air leaks, as well as for thrombi on the surface and changes such as bleeding or necrosis in the surrounding tissues.

5. Evaluation Criteria for Animal Experiments

① Whether there is air leakage at the anastomosis and surrounding tissues during and after surgery. ② Whether the biological patch can fit tightly at the anastomosis. ③ The incidence of postoperative complications during the rearing period, such as infection, rejection, etc. ④ Gross specimen observation of the biological patch: The test animals were sacrificed at 1 and 3 months after surgery to observe whether the anastomosis healed well and whether the biological patch promoted tissue regeneration and repair. ⑤ Histological examination: At 1 and 3 months after surgery, surgical biological patch and tissue specimens were collected for histological examination to observe for signs of thromboembolism, inflammation, necrosis, etc.

6. Results of animal experiments

(1) The maximum tensile elongation range is 17.2-51.9%, which can meet the requirements for installation on the stapler.

No lung leaks were observed in pigs using the biological patches from 13 different examples, namely Examples 1, 4-6, 8-13, 18, and 23-24.

Pigs without lung leaks underwent successful surgery. The bio-patch adhered tightly to the lung tissue, with no air leakage at the resection margin, and no instrument malfunctions occurred during the operation. The lung resection margin was smooth and without air leakage or exudate. At the follow-up endpoints of 1 month and 3 months, scar tissue formed at the lung resection margin but did not decompose. This indicates that the bio-patch can act as a scaffold, promoting the repair and healing of the lung resection margin. This demonstrates the good biocompatibility of thoracic surgical bio-patches, their ability to integrate well with surrounding tissues, and their promotion of lung resection margin repair and healing.

During the operation, the anesthetized animal's vital signs were normal, and no adverse events occurred.

Postoperatively, examination of the animal's complete blood cell count, morphology, and quality showed no abnormalities; white blood cell, red blood cell, hemoglobin, and platelet counts were stable, and no significant abnormalities were found in routine blood tests. Liver and kidney function values were almost within the normal range, with no abnormalities observed.

During the period of survival and rearing, the animals were generally in good condition, with normal body temperature, diet and excretion, good independent activity, and no obvious abnormal signs such as weight loss, fever, anorexia, or mania. They successfully lived to the end.

(2) The single-line suture tension reflects the biological patch's ability to resist shear force. If the single-line suture tension is too small, tearing is likely to occur at the nail holes and sutures. The biological patches obtained in Example 3 (single-line suture tension 5.1±0.3N), Example 2 (single-line suture tension 12.5±0.1N), and Example 16 (single-line suture tension 14.9±0.3N) showed obvious tearing at the nail holes, and the tearing intensified over time. However, the biological patch in Example 19 (single-line suture tension 15.5±0.5N) did not show obvious tearing. This indicates that in order to fix the biological patch with titanium nails and prevent tearing at the nail holes and sutures, the single-line suture tension of the biological patch should not be less than 15.5N, that is, the range of single-line suture tension of the biological patch is 15.5-33.4N.

(3) Theoretically, the biological patch pre-placed onto the anastomosis device needs to have a certain tensile strength to help ensure the compliance of the biological patch and prevent lung leakage. However, animal experiments have shown that:

The biological patches obtained using Examples 2, 3, 7, 15-17, 19, 20, and 22 resulted in air leakage in the lungs.

Specifically, the experimental group using the biological patches obtained in Example 2 (tensile strength 16.3±2.2MPa), Example 19 (tensile strength 19.5±2.3MPa), Example 3 (tensile strength 20.2±2.5MPa), Example 17 (tensile strength 20.4±5.3MPa), Example 20 (tensile strength 22.9±1.4MPa), Example 15 (tensile strength 25.4±1.9MPa), Example 16 (tensile strength 25.5±3.3MPa), Example 22 (tensile strength 29.5±1.6MPa), and Example 7 (tensile strength 39.5±3.1MPa) experienced air leakage in the lungs.

However, no air leakage was observed in embodiments with similar tensile strength to these embodiments. For example, embodiments 12 (tensile strength 19.1±4.9 MPa) and 18 (tensile strength 21.6±3.4 MPa), which have similar tensile strength to embodiments 19 and 3, did not exhibit air leakage. Similarly, embodiments 4 (tensile strength 24.3±3.1 MPa) and 8 (tensile strength 26.2±4.7 MPa), which have similar tensile strength to embodiments 15 and 16, did not exhibit air leakage. Furthermore, embodiments 6 (tensile strength 31.8±2.1 MPa), 9 (tensile strength 27.8±1.5 MPa), 11 (tensile strength 30.7±2.6 MPa), 23 (tensile strength 33.2±4.1 MPa), and 24 (tensile strength 33.7±4.2 MPa), which have similar tensile strength to embodiments 22 and 7, all did not exhibit air leakage.

Since relying on tensile strength to explore whether biological patches will cause lung leakage is unstable, it is necessary to reconsider the mechanical parameters that can indicate lung leakage.

Based on years of research on the application of animal-derived biomaterials in thoracic surgical implantation, the inventors discovered that the imperfect fit between the anastomotic staple height and tissue thickness is a significant cause of air leakage in the lungs. While the anastomotic staple height is fixed, lung tissue thickness varies among different patients and in different locations. When the lung tissue is too thick or too thin relative to the staple height, air leakage at the lung resection margin may occur. Therefore, bio-patches need to possess excellent resilience. The inventors aim to introduce "elasticity" into bio-derived patches and replace "tensile strength" with "elastic deformation rate." They will continue to explore thoracic surgical bio-patches that prevent air leakage by comprehensively considering three mechanical parameters: elastic deformation rate, maximum tensile elongation, and single-suture traction force.

IV. Determination of elastic deformation rate

1. Measurement Method

A 4cm long and 1cm wide biological patch was clamped along its length onto a tensile testing machine. A tensile load was applied at a speed of 100mm/min to stretch the biological patch until it broke. A tensile curve was plotted, and the elastic deformation rate of the biological patch was calculated based on the elastic deformation segment of the tensile curve during the test.

2. Measurement Results

Table 3: Elastic deformation rate of Examples 1-24

Table 3 shows that the elastic deformation rate of the biological patches obtained in Examples 1-24 is relatively stable, and the range of elastic deformation rate is 8.9-39.4%.

Aside from the possibility that tearing at the nail holes and sutures was the cause of lung leakage in the experimental groups corresponding to Examples 2, 3, and 16, based on the results of animal experiments, the inventors unexpectedly discovered that 7 pigs developed lung leakage using the biological patches obtained in Examples 20 (elastic deformation rate 12.7±0.1%) and 22 (elastic deformation rate 14.9±0.4%); 4 pigs developed lung leakage using the biological patches obtained in Examples 19 (elastic deformation rate 15.4±0.7%) and 7 (elastic deformation rate 16.2±1.1%); only 3 pigs developed lung leakage using the biological patch obtained in Example 15 (elastic deformation rate 17.2±1.9%); and only 1 pig developed lung leakage using the biological patch obtained in Example 17 (elastic deformation rate 17.5±0.6%). That is, as the elastic deformation rate increases, the number of pigs with lung leakage decreases continuously, and the elastic deformation rate of the biological patches obtained in these examples is lower than that of the examples without lung leakage.

Therefore, the inventors hypothesized that a higher elastic deformation rate makes it less likely for air leakage to occur in the lungs. Based on the results of animal experiments, it can be preliminarily proven that the inventors' introduction of "elastic deformation rate" was correct. It is speculated that the cause of air leakage in the lungs is due to the poor resilience of the biological patch, its slightly poor adhesion to the pig's tissue, and insufficient contractile elasticity at the nail holes and sutures, thus leading to air leakage in the lungs.

Based on animal experiments, it can be preliminarily determined that the elastic deformation rate of biological patches should be controlled within the range of 18.3-39.4%.

V. Clinical Trial 1

1. Inclusion criteria, exclusion criteria, and collection of clinical data

(1) Inclusion criteria

① Age: 18-75 years old, gender not limited; ② Meets the clinical surgical indications, including lung volume reduction surgery of various lung resection surgeries (surgical approach is not required, traditional open, laparoscopic, and robotic are all acceptable); ③ Can understand the purpose of the trial, is willing to participate and sign the informed consent form, and is willing to accept relevant examinations and clinical follow-up.

(2) Exclusion criteria

① Patients who require mechanical ventilation in the intensive care unit after surgery; ② Patients who need to be converted to open thoracotomy due to bleeding or severe pleural adhesions during surgery; ③ Patients diagnosed with bronchopleural fistula after surgery; and patients who die during hospitalization or whose clinical data is incomplete.

(3) Collection of clinical data

Collect patient data that meet the criteria: ① Demographic data: gender, age, body mass index (BMI), smoking history; ② Preoperative assessment data: lung function (forced expiratory volume in one second (FEV1%) and the ratio of forced expiratory volume in one second to forced vital capacity (FEV1%/FVC%)), peripheral blood lymphocyte count, albumin, prognostic nutritional index (PNI); ③ Surgical data: surgical site, surgical procedure (lobectomy or segmentectomy), whether lymph node dissection was performed during the operation, whether pleural adhesions were present, pathological results were amphipathic or malignant, whether there was air leakage in the test lung expansion method; (4) Postoperative stage: daily air leakage assessment after surgery, pleural pressure difference 12 hours after surgery.

2. Experimental Grouping

Experimental group: Divided into 13 groups, each using a biological patch obtained from one of the 13 embodiments consistent with animal experiments for clinical trials. Each group consisted of 10 patients who underwent lung volume reduction surgery using the biological patch obtained from each embodiment. Before surgery, the biological patch was pre-placed on the anastomosis device.

Control group: Patients who underwent surgery using only a stapler for closure/anastomosis were selected.

3. Test Procedure

1. Test Procedure

The specific procedures of the trial include: (1) signing informed consent; (2) screening cases, confirming clinical inclusion and exclusion criteria, and simultaneously completing baseline data collection; (3) determining the operation time; (4) enrolling the experimental group or control group according to the randomization grouping; (5) performing the operation; (6) observing the air leakage and recording it in the surgical report; (7) assessing the postoperative condition of the subjects; and (8) completing the follow-up of the subjects before discharge, 1 month after surgery, and 3 months after surgery according to the relevant examination requirements in the protocol.

All patients underwent surgery under general anesthesia. During the operation, the affected lung was closed and resected using a stapler, and the bronchus was severed using the same stapler. After thorough hemostasis, a suitable amount of warm saline was poured into the pleural cavity for pleural lavage, and lung ventilation was performed simultaneously to observe for air leakage in the lung tissue and bronchial stumps. Leaking lung wounds or bronchial stumps were reinforced with absorbable sutures, and warm saline was poured into the pleural cavity again to observe for leakage. Once no leakage was confirmed, the chest was closed. Postoperatively, one or two closed pleural drainage tubes were placed to the pleural dome and connected to a pleural drainage bottle containing 500ml of saline. Postoperatively, the pleural drainage bottle was monitored for leakage, and symptomatic treatment was provided, such as oxygen nebulization, expectorants and bronchodilators, nutritional support, and anti-infection treatment.

4. Test Methods

Prospective, multicenter, randomized controlled, open-label, and superior.

5. Test Results

(1) Comparison of general data

A clinical trial was first conducted with 150 eligible patients, and the incidence of air leakage in these patients is shown in Table 4 below.

Table 4: Results of Clinical Trial 1

Note: Other lung volume reduction surgeries include pneumonectomy and pleural resection. The number before the slash "/" indicates the number of cases with air leakage; the slash "/" indicates the number of cases with air leakage.
The following is the total number of patients.

The results in Table 4 show that:

(1) Based on the range of maximum tensile elongation (17.2-51.9%), elastic deformation rate (18.3-39.4%), and single-line suture traction force (15.5-33.4N) determined in previous experiments, the experimental group using the biological patch obtained in Example 6 (elastic deformation rate 19.9±1.1%) experienced lung leakage. Theoretically, the higher the elastic deformation rate, the better. The inventors speculate that the elasticity of the biological patch needs to be further improved to ensure that the biological patch can further seal the nail holes and sutures to meet the requirements of frequent lung expansion and contraction.

Further comparison of the elastic deformation rates of the biological patches obtained in Example 6 (elastic deformation rate 19.9±1.1%), Example 11 (elastic deformation rate 18.3±0.2%), and Example 24 (elastic deformation rate 18.4±0.3%) revealed that the elastic deformation rate of the biological patch obtained in Example 6 as a percentage of the maximum tensile elongation (41%) was relatively small. Therefore, the inventors hypothesized a correlation between the elastic deformation rate as a percentage of the maximum tensile elongation and clinical outcomes, which was further verified in clinical trials.

Table 5: Elastic deformation rate as a percentage of maximum tensile elongation in Examples 1-24

As can be seen from Table 5, the elastic deformation rate of the biological patches obtained in Examples 1-24 is 31-93% of the maximum tensile elongation.

VI. Clinical Trial II

1. Based on the preparation method of biological patches, a biological patch with the following parameters is obtained by adjusting the preparation method.

Table 6: Biomechanical parameters of Examples 25-26

Table 7: Main differences in the preparation methods of Examples 25-26

Based on Clinical Trial 1, 20 patients undergoing lung volume reduction surgery were further enrolled. Examples 25 and 26 (10 patients in each example, regardless of the lung resection site) were used to further verify the effect of the elastic deformation rate as a percentage of the maximum tensile elongation on the clinical application effect. The experimental results are shown in Table 8.

Table 8: Results of Clinical Trial 2

Compared to the example in Clinical Trial 1 where no air leakage occurred, the maximum tensile elongation, elastic deformation rate, and single-suture traction force of the biological patches obtained in Examples 25 and 26 all met the application requirements mentioned in Clinical Trial 1, except that the elastic deformation rate as a percentage of the maximum tensile elongation was less than 49% (Example 24: elastic deformation rate as a percentage of the maximum tensile elongation was 49%). Table 8 further demonstrates that the elastic deformation rate as a percentage of the maximum tensile elongation is indeed related to air leakage. Although the air leakage situation in Examples 25 and 26 was improved, it is still unacceptable in the medical field.

The mechanical properties of biological patches need to meet the requirements of specific surgical sites. Compared with biological patches used in digestive surgery, which are used to prevent fluid leakage and bleeding, biological patches used in thoracic surgery are used to prevent air leakage. Because liquids are more viscous than gases, biological patches used to prevent lung air leakage need to have better elasticity. Based on animal experiments, Clinical Trial 1, and Clinical Trial 2, biological patches with the following biomechanical parameters—maximum tensile elongation ranging from 17.2% to 51.9%, elastic deformation rate ranging from 18.3% to 39.4%, single-suture traction force of 15.5% to 33.4 N, and an elastic deformation rate of 49% to 93% of the maximum tensile elongation—possess excellent biomechanical properties, ensuring proper adhesion between the biological patch and lung tissue and preventing lung air leakage.

In addition, excluding the embodiments that could not be installed on the anastomosis device, and the embodiments in animal experiments and clinical trials that showed lung leakage, the biological patches obtained in Examples 1, 4-5, 8-13, 16, 18 and 23-24 meet the requirements for application in thoracic surgery. The specific parameter ranges are: maximum tensile elongation 25.6-51.9%, single-line suture traction force range 17.2-33.4N, elastic deformation rate range 18.3-39.4%, and the elastic deformation rate as a percentage of the maximum tensile elongation is 49-93%.

The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims (10)

A thoracic surgical biological patch, characterized in that: the maximum tensile elongation of the biological patch is greater than 17.2%, the elastic deformation rate is greater than 18.3%, and the single-line suture traction force is greater than 15.5N. The thoracic surgical biological patch according to claim 1 is characterized in that: the maximum tensile elongation of the biological patch is 17.2-51.9%. According to claim 2, the thoracic surgical biological patch is characterized in that the elastic deformation rate of the biological patch ranges from 18.3% to 39.4%. The thoracic surgical biological patch according to claim 3 is characterized in that: the single-line suture traction force of the biological patch is 15.5-33.4N. According to claim 4, the thoracic surgical biological patch is characterized in that: the elastic deformation rate of the biological patch accounts for 49-93% of the maximum tensile elongation. The thoracic surgical biological patch according to any one of claims 1-5 is characterized in that: the maximum tensile elongation of the biological patch is 25.6-51.9%, the single-line suture traction force ranges from 17.2-33.4N, the elastic deformation rate ranges from 18.3-39.4%, and the elastic deformation rate accounts for 49-93% of the maximum tensile elongation. The thoracic surgical biological patch according to any one of claims 1-6 is characterized in that: the thoracic surgical biological patch is made from bovine pericardium. The thoracic surgical biological patch according to any one of claims 1-7 is characterized in that the thoracic surgical biological patch has two perforations, the two perforations being located at opposite ends of the biological patch. Anastomosing device kit including the thoracic surgical biological patch of any one of claims 1-8. The method for preparing the thoracic surgical biological patch according to any one of claims 1-7 is characterized by comprising: (1) Preprocessing: ①Immerse healthy bovine pericardial tissue sheets in hypotonic Hank's solution, and rinse repeatedly and change the hypotonic Hank's solution to remove cell fragments, nuclei and organelles that have been swollen and broken after decellularization. ② Rinse the tissue slides treated above repeatedly with physiological saline for 90-150 minutes each time, changing the physiological saline each time. The total number of rinsing times depends on whether there are no morphological cells or cell components and cell debris under the microscope of the tissue slide. Perform quantitative determination of protein and nucleic acid until no soluble protein and nucleic acid can be detected. ③ Use a surfactant solution to remove phospholipids and non-structural proteins, as well as some tissue matrix, from the tissue slices; the surfactant solution can be Tween 80, sodium dodecyl sulfate, or Triton X-100; ④ Soak in a 2.5-4% glutaraldehyde solution for 3-3.5 hours; (2) Chemical modification: The pretreated tissue material was placed in a hydroxychromium solution with a Cr3 ⁺ ion concentration of 0.0625 mol/ ^dm3 and an OH/Cr ratio of 0.5 for the first water bath shaking at 20-28℃ for 2-4 hours. The pH of the material treatment solution was measured and increased by 0.3-0.6 pH units with 10% _NaHCO3 . Then, a second water bath shaking was performed at 32-40℃ for 3-5 hours to obtain a monolayer sheet-like biological patch.