Postoperative adhesions occur frequently after abdominal surgery and gynecological surgeries, causing serious complications. For applications in laparoscopic surgery, we developed a thermally cross-linked gelatin film-cut (GC) by dividing a thermally cross-linked gelatin film (GF) into small fragments. In this study, we examined the basic biological properties of the GC and conducted anti-adhesion tests using a rat cecum abrasion model to evaluate the effects of film fragmentation, focusing on the influence of fragment size, dosage and film thickness. Solubility test results showed that GC degraded more slowly than its film counterparts. Furthermore, as the thickness and the size of the GC increased, its degradation rate decreased. In addition, the results of the collagenase degradation test demonstrated that the GC degraded more slowly than the unfragmented film and that as the thickness and size of the GC increased, its degradation rate decreased. The results of the rat anti-adhesion test demonstrated that compared with GF, GC was significantly less effective in preventing adhesion. However, compared with the untreated group, several GCs showed significantly lower adhesion scores. Some of the GCs demonstrated anti-adhesion effect similar to or better than those of hyaluronic acid and carboxymethyl cellulose (HA/CMC). In summary, increased fragment size, reduced film thickness, and an elevated dosage of GC improved anti-adhesion efficacy. Thus, GC exhibits excellent anti-adhesion effects when its geometry, thickness, and dosage are optimized. Consequently, anti-adhesive GC improves the clinical applicability of anti-adhesion materials, particularly in laparoscopic surgery.

Long-term bladder regeneration has not been successful instead of augmentation with gastrointestinal segments, as is commonly performed for bladder reconstruction. To evaluate whether or not cell-seeded bioabsorbable materials regenerate half-resected bladder in a rabbit model. Female Japanese white rabbits were divided two groups: cell-seeded material (CSM) group and Control (n = 6 each). Control rabbits underwent resection of half the bladder. CSM rabbits were sutured with cell-seeded amniotic membrane and P(LA/CL) material after bladder resection. After 6, 12, and 18 months, rabbits underwent X-ray and cystometry, and bladder tissues after 18 months were subjected to functional and histological analyses. X-ray confirmed the peristaltic movements of the reconstructed bladders in the CSM group. On cystometry, the mean maximum bladder volume, maximum bladder pressure, and 25 mL bladder volume compliance in the CSM group were significantly greater than in the Control group at 6, 12, and 18 months. In addition, organ bath studies showed good contraction under electrical stimulation with increasing stimulation frequency in the CSM group, while, the Control group showed weak contraction on both tests in the central marginal zone. Furthermore, the rates of neovascularization, urothelial and smooth muscle formation, and neurofilamentation in the CSM group were significantly greater than in the Control group. Oral mucosal cell-seeded amniotic membrane and stomach smooth muscle cell-seeded P(LA/CL) scaffold with omentum after abdominal implantation regenerated functional bladder with satisfactory epithelium and smooth muscle without scarring more than 1 year. Impact StatementRegeneration of functional bladder without using gastrointestinal segments has been a huge challenge to urological reconstruction. Various materials, such as nonbioabsorbable materials and biomaterials have been attempted to reconstruct bladder in animal models. However, the long-term results more than a year failed due to the low biocompatibility, high risks, and difficulty creating the materials. In this study, we revealed long-term bladder regeneration using cell-seeded amniotic membrane and P(LA/CL) material in a rabbit model. The new method of bladder reconstruction seems able to regenerate functional bladder with satisfactory bladder epithelium and bladder smooth muscle function without scarring for more than 1 year successfully.

By mimicking the extracellular matrix, nonwoven fabrics can function as scaffolds for tissue engineering application ideally, and they have been characterized regarding their fiber diameter and fiber spacing (spacing size) in vitro. We chronologically examined the in vivo effects of these fabrics on the cellular response and tissue remodeling. Four types of nonwoven polyglycolic acid fabrics (Fabric-0.7, Fabric-0.9, Fabric-3, and Fabric-16 with fiber diameters of 0.7, 0.9, 3.0, and 16.2 μm and spacing sizes of 2.0, 19.3, 19.0, and 825.4 μm, respectively) were implanted into the rat dorsum and subjected to histologic and immunohistochemical analyses from day 3 to 70. With Fabric-0.7, inflammatory cells (mainly M1 macrophages) and myofibroblasts with collagen type III accumulated mainly on the surface of the fabric and did not infiltrate inside the fabric initially, likely due to the narrow fiber space. Massive formation of collagen type I then appeared with the degradation of the fabrics, and finally, the remodeled tissue turned into a dense scar. With Fabric-0.9 and Fabric-3, inflammatory cells (predominantly M2 macrophages) were seen in all layers of the fabric initially. A mild increase in collagen type I was then seen, with few myofibroblasts, and the remodeled tissue ultimately showed a relatively little scar with an adequate thickness of the tissue induced by the fabrics. With Fabric-16, inflammatory cells (predominantly M1 macrophages) infiltrated into all layers of the fabric initially along with many myofibroblasts, especially in the hole. Lately, massive formation of collagen type I was noted due to the slow degradation of the fabric, with the shrinking of the fabric substantially, and the remodeled tissue finally turned to a dense scar. These findings suggest that optimizing the spacing size as well as the fiber diameter of artificial scaffolds may control the cellular response and tissue remodeling and facilitate favorable tissue regeneration without scar formation.

BACKGROUND: To overcome the unfavorable issues associated with conventional anti-adhesive HA/CMC film, we developed an anti-adhesive thermally cross-linked gelatin film. OBJECTIVE: We tried to clarify the re-attachability of the film and the required properties concerning the film thickness, stiffness and anti-adhesion effect. METHODS: To determine the optimal thickness, 5 kinds of the thickness of gelatin film and the conventional film were analyzed by the tensile test, shearing test, buckling test and tissue injury test. Finally, using the optimal film thickness, we tried to clarify the anti-adhesion effect of the reattached film. RESULTS: The tensile and shearing test showed gelatin films ≥30 μm thick had greater tensile strength and a smaller number of film fractures, than the conventional film. The buckling and tissue injury test showed gelatin films ≥60 μm thick had higher buckling strength and worse injury scores than the conventional film. The anti-adhesive effect of re-attached gelatin film using optimal thickness (30–40 μm) found the anti-adhesion score was significantly better than that of the control. CONCLUSIONS: Provided it has an optimal thickness, gelatin film can be reattached with enough physical strength not to tear, safety stiffness not to induce tissue injury, and a sufficient anti-adhesion effect.

Bax, one of thebcl-2 family genes, is expressed in a number of untransformed cell lines and various breast tissues, whereas only weak or no expression has been detected in breast cancer cell lines and malignant breast tissue. Human breast cancer MCF-7 cells, which have a weakbax gene expression, were stably transfected withpCX2neo bax, encoding humanbax; and two unique clones,MCF-7/bax-1 andMCF-7/bax-2, that expressed different levels ofbax were generated. Sensitivity to cisplatin (CDDP) and etoposide (VP-16) was examined and each stable transfectant was more sensitive to these agents than the parental MCF-7 cells. The degree of enhancement in sensitivity to these anticancer agents was dependent on the expression level ofbax. The enzyme-linked immunosorbent assay (ELISA), which quantifies DNA damage, demonstrated that this sensitization was due to apoptosis. Thus, we suggest that exogenousbax-α overexpression may be one of the factors determining cellular chemosensitivity in MCF-7 breast cancer cells and that it could be applied therapeutically to enhance chemosensitivity in breast cancer cells.

Polyglycolic acid (PGA) mesh fabric is widely used for reinforcing injured tissues during surgeries. However, PGA induces chronic inflammation and adhesion. The purpose of this study is to develop PGA reinforcement "without PGA-induced adhesion." We developed a reinforcement fabric unified with PGA mesh and alginate foam. The antiadhesive effects of sodium alginate foam and calcium alginate foam were evaluated in rats. Sodium alginate foam unified with PGA mesh fabric exhibited strong effects that limit the extent and severity of adhesion, whereas calcium alginate foam unified with PGA mesh was less effective in preventing adhesion. In the sodium alginate group, fibroblasts and collagen fibers around implanted sites were sparse and the material degraded rapidly by macrophage ingestion. Fibroblasts and collagen fibers play a major role in adhesion formation and their excessive proliferation results in postoperative adhesion. Thus, inhibiting their increase is the key in preventing PGA-induced adhesion. The reinforcement that is composed of PGA mesh unified with sodium alginate foam strongly inhibited PGA-induced adhesion and showed excellent handling during surgery and could be easily applied with a one-step procedure.

To create more useful, effective and safer anti-adhesion materials, we developed a thermally cross-linked gelatin film. In this study, we examined the physical properties of the film such as the physical strength and the adhesiveness to reveal the handling properties and biological properties, such as the anti-adhesion effect, the influence on cell proliferation, and the cytotoxicity to reveal the anti-adhesion mechanism, especially in comparison with the conventional hyaluronic acid and carboxymethylcellulose film (the conventional film). A tensile test under dry and wet conditions and shearing stress test showed that the gelatin film has significant higher maximum tensile stress and fracture strain than the conventional film. In the study using a rat model of cecum adhesion, the anti-adhesion effect of the gelatin film was significantly superior to that of the conventional film. In the cell proliferation test, the number of fibroblast cells on the gelatin film increased at each time point, while no cell proliferation was observed on the conventional film. Furthermore, in the cytotoxicity test using a colony assay and Live/Dead assay, the extract of the gelatin film had no cytotoxicity, while the extract of the conventional film had cytotoxicity considerably. These results suggest that the gelatin film provides better handling than the conventional film, due to better physical strength and ductility of the film. In addition, the gelatin film has a significantly greater anti-adhesion effect than the conventional film without any cytotoxicity. Therefore, the gelatin film is quite favorable as an anti-adhesion material. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 689-696, 2018.

Postoperative air leaks remain a major cause of morbidity after lung resection. This study evaluated the effect of a combination of polyglycolic acid (PGA) sheet and alginate gel on pulmonary air leaks in rats. Four pulmonary sealing materials were evaluated in lung injury: fibrin glue, combination of PGA sheet and fibrin glue, alginate gel, and combination of PGA sheet and alginate gel. With the airway pressure maintained at 20 cmH 2 O, a 2 mm deep puncture wound was created on the lung surface using a needle. Lowering the airway pressure to 5 cmH 2 O, each sealing material was applied. The lowest airway pressure that broke the seal was measured. The seal-breaking pressure in each experimental group was fibrin, 10.4±6.8 cmH 2 O; PGA + fibrin, 13.5±6.5 cmH 2 O; alginate gel, 10.3±4.9 cmH 2 O; and PGA + alginate, 35.8±11.9 cmH 2 O, respectively. The seal-breaking pressure was significantly greater in the PGA + alginate gel group than in the other groups (p<0.01). There were no significant differences among the other three groups. Alginate gel combined with a PGA sheet is a promising alternative to fibrin glue as a safe and low-cost material for air leak prevention in pulmonary surgery.

To create anti-adhesive materials to be more effective and safer, we developed a thermally cross-linked gelatin film that showed superior anti-adhesive effects with excellent peritoneal regeneration. However, it may act as a convenient scaffold for tumor cell growth, thereby accelerating peritoneal dissemination when used in surgery for abdominal tumors. In this study, we tried to clarify this issue using mouse carcinomatous peritonitis models. First, we examined the in vitro tumor cell growth of mouse B16 melanoma or Colon26 cells on the gelatin film or the conventional hyarulonate/carboxymethylcellulose film. Tumor cell growth on each film was significantly lower than that of the control (no film). Next, we conducted the following in vivo experiments: After the parietal peritoneum was partially removed and covered with each film or without any film, mice were inoculated intraperitoneally with B16 melanoma or Colon26/Nluc cells expressing NanoLuc luciferase gene. At 7 days after the operation, we measured the weight of B16 melanoma tumors or the NanoLuc activity of Colon26/Nluc cells using in vivo imaging at the injured sites. There were no significant differences in the weight of the tumors and the NanoLuc activity among the three groups. We also observed the survival time of mice receiving the same operation and treatments. There was no significant difference in the survival time among the three groups. These results suggest that the gelatin film will likely not accelerate peritoneal dissemination as a convenient scaffold for tumor cell growth when used in surgery for abdominal tumors. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2122-2130, 2018.

AimAdhesion after pelvic surgery causes infertility, ectopic pregnancy, and ileus or abdominal pain. The materials currently available for clinical use are insufficient. The purpose of this study was to develop an anti-adhesive material that overcomes the limitations of conventional anti-adhesive agents.MethodsThe adhesion prevention effects of three methods - a two-layered sheet composed of gelatin film and gelatin sponge, Seprafilm and INTERCEED - were evaluated in 37 dogs. Anti-adhesive effects were investigated macroscopically and microscopically in a cauterized uterus adhesion model. Cell growth on the materials in vitro using human peritoneal mesothelial cells, fibroblasts and uterine smooth muscle cells were also evaluated.ResultsThe two-layered gelatin sheet had significantly superior anti-adhesive effects compared to the conventional materials (Seprafilm and INTERCEED). A single-cell layer of mature mesothelium formed three weeks after surgery in the gelatin group. Peritoneum regeneration in the Seprafilm and INTERCEED groups was delayed and incomplete in the early phase. Little inflammation around the materials occurred and cell growth was significantly proliferated with the gelatin sheet.ConclusionThe anti-adhesive effects of a two-layered gelatin sheet were superior to conventional agents in a cauterized canine uterus model, demonstrating early regeneration of the peritoneum, little inflammation and material endurance. The newly developed two-layered gelatin sheet is a useful option as an anti-adhesive agent for deeply injured and hemorrhagic sites.

Background/objective: Uncontrolled surgical bleeding is associated with increased morbidity, mortality, and hospital cost. Topical hemostatic agents available today have problems controlling hemostatic effects; furthermore, their handling is difficult and they are unsafe. Methods: We devised a new hemostatic agent comprising gelatin sponge and film designed to be applied to the bleeding site, thereby creating a topical hemostatic agent made of gelatin alone. The gelatin was prepared by alkali treatment to eliminate viral activity. Hemostatic effects, surgical handling, and tissue reactions of the materials, namely a two-layer sheet of gelatin, TachoSil, and gelatin sponge, were evaluated using 21 dogs' spleens. Results: The two-layer gelatin sheet and gelatin sponge exhibited superior hemostatic effects (100% hemostasis completed) compared with TachoSil (0-17% hemostasis). The gelatin matrix immediately absorbed blood flowing from wounds and activated the autologous components in the absorbed blood that promoted coagulation at the bleeding site. The two-layer gelatin sheet had the best surgical handling among the evaluated materials. Materials made of gelatin were associated with fewer inflammatory reactions compared with materials of TachoSil. Conclusion: The two-layer sheet of gelatin is a useful topical agent because of its superior hemostatic effects and usability, and is associated with a lower risk of transmitting diseases and inflammatory reactions. (C) 2016 Asian Surgical Association and Taiwan Robotic Surgery Association. Publishing services by Elsevier B.V.

Background and study aims: Recently, the shielding method with polyglycolic acid (PGA) fabric and fibrin glue (P-F method) has been reported to prevent serious complications after endoscopic submucosal dissection (ESD). However, the effectiveness and mechanism to prevent complications by this method remain unclear and the corresponding basic research has not been fully conducted. Methods and results: We examined the effectiveness and mechanism of the P-F method, using a surgical ESD model of canine stomach and in vitro experiments. In the model experiment treated by P-F method or no treatment (control), ulcer perforation or penetration occurred only in the control group, but not in the P-F group. Microscopically, the P-F group showed less damages of the ulcer lesion than that of the control group, showing thicker granulation tissues including PGA fibers on the third day and excellent mucosal regeneration on the fourteenth day. In vitro culture experiments showed that fibroblasts proliferated at a significantly higher rate on PGA than on fibrin or a complex thereof. However, under hydrochloric acid treatment, fibroblasts were protected by fibrin, followed by the complex of both, and PGA. Conclusion: The P-F method exhibited a protective effect against gastric juice by fibrin glue to reduce tissue damages and a scaffold function of PGA fabric to induce better granulation formation at the earlier phase, resulting in excellent long-term tissue repair, on ulcer lesion following ESD, although the results were based on basic experiments.

Background: The incidence of postoperative pancreatic fistula (POPF) after distal pancreatectomy is approximately 30%. The most serious complications of pancreatic resection, such as mortality and prolonged hospitalization, are unresolved despite the proposal of various surgical procedures. We developed a new polyglycolic acid (PGA) fabric composed of fine diameter fibers to prevent POPF, and macroscopically and microscopically evaluated the effects of applying it to the pancreatic remnant. Methods: The ventral pancreatic surface was cauterized to create the experimental model of POPF in 33 female Wistar/ST rats. The injured sites were wrapped with nonwoven PGA fabrics of different fiber diameters and porosities in the treated rats; one group of rats remained untreated. Survival, incidence of generalized peritonitis, and microscopic findings around the pancreas were investigated. Results: The PGA fabrics acted as a scaffold for tissue repair and resulted in superior survival. Generalized peritonitis was milder in the PGA treated groups. With the new PGA fabric, abundant fibroblast infiltration and a uniformly-developed, self-organized barrier wall prevented both pancreatic leak and spread of inflammation. Conclusion: Application of the newly developed PGA fabric to the pancreatic remnant prevented POPF, and the essential factor for preventing pancreatic leak was the early formation of a self-organized barrier.

Event Abstract Back to Event The influences of thermally cross-linked gelatin film for intraperitoneal dissemination of tumor cells Hiroe Miyamoto1, Hiroyuki Tsujimoto1, Koki Yamanaka1, Han Pei1, Tsunehito Horii1, Hiroko Torii1, Yuki Ozamoto1 and Akeo Hagiwara1 1 Doshisha University, Department of Medical Life System, Japan Introduction: To prevent adhesion formation after abdominal surgery, we have developed a thermally cross-linked gelatin film and previously reported its superior anti-adhesive effects with excellent peritoneal regeneration[1]. However, it may act as a scaffold convenient for tumor cell growth, thereby accelerating peritoneal dissemination when used in surgery for abdominal tumors since the gelatin film is made from a degenerated product of collagen which is the most abundant extracellular matrix protein in mammals and has been used as a scaffold in the field of regeneration medicine. In this study, we tried to clarify this issue in in vitro and in vivo experiments using mouse B16 melanoma cells and its carcinomatous peritonitis model, compared with HA/CMC film which is an anti-adhesive material composed of polysaccharides and has been used clinically. Materials, Methods and Results: At first, we examined the influence of the gelatin film for in vitro tumor cell growth. B16 melanoma cells were cultured on the gelatin film, HA/CMC film or without any film. Each viable cell number was counted with time. As the result, B16 melanoma cells grew on the gelatin film and HA/CMC film significantly lower than those in the control group. Next, we examined the influence of the gelatin film for peritoneal dissemination using B16 melanoma carcinomatous peritonitis model. After laparotomy, small parts of bilateral parietal peritoneum were removed mechanically. The injured site were covered with the gelatin film, HA/CMC film or without any films (control). Then, each mouse was inoculated intraperitoneally with the B16 melanoma cells, which has intrinsic black melanin pigmentation. At 7 days after the inoculation, the tumor weight of B16 melanoma at the injured sites were measured. The result showed no significant differences of the tumor weight among three groups. Furthermore, there was also no significant differences of the mean survival time of the mice among three groups with the gelatin film, HA/CMC film or without any films. Discussion: In the in vitro experiment, the gelatin film as well as the HA/CMC inhibited the growth of B16 melanoma cells unexpectedly, compared with the control group. In the in vivo experiments using B16 melanoma carcinomatous peritonitis model, both films did not influence the tumor growth or the survival times of the mice inoculated with the tumors. These results suggests that the both types of films do not enhance the tumor growth at the injured sites at least. Conclusions: Thermally cross-linked gelatin film does not act as a scaffold convenient for tumor cell growth, thereby accelerating peritoneal dissemination, when used in surgery for abdominal tumors. References:[1] H. Tsujimoto, A. Tanzawa, H. Miyamoto, T. Horii, M. Tsuji, A. Kawasumi, A. Tamura, Z. Wang, R. Abe, S. Tanaka, K. Yamanaka, M. Matoba, H. Torii, Y. Ozamoto, H. Takamori, S. Suzuki, S. Morita, Y. Ikada, A. Hagiwara, “Biological properties of a thermally crosslinked gelatin film as a novel anti-adhesive material: Relationship between the biological properties and the extent of thermal crosslinking”, Journal of Biomedical Materials Research Part B: Applied Biomaterials. 2015; 103(7):1511-1518 Keywords: Regenerative Medicine, Scaffold, Biodegradable material, medical application Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Biomaterials for cancer therapy Citation: Miyamoto H, Tsujimoto H, Yamanaka K, Pei H, Horii T, Torii H, Ozamoto Y and Hagiwara A (2016). The influences of thermally cross-linked gelatin film for intraperitoneal dissemination of tumor cells. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.00139 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Hiroe Miyamoto Hiroyuki Tsujimoto Koki Yamanaka Han Pei Tsunehito Horii Hiroko Torii Yuki Ozamoto Akeo Hagiwara Google Hiroe Miyamoto Hiroyuki Tsujimoto Koki Yamanaka Han Pei Tsunehito Horii Hiroko Torii Yuki Ozamoto Akeo Hagiwara Google Scholar Hiroe Miyamoto Hiroyuki Tsujimoto Koki Yamanaka Han Pei Tsunehito Horii Hiroko Torii Yuki Ozamoto Akeo Hagiwara PubMed Hiroe Miyamoto Hiroyuki Tsujimoto Koki Yamanaka Han Pei Tsunehito Horii Hiroko Torii Yuki Ozamoto Akeo Hagiwara Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Postoperative intra-abdominal or intrathoracic adhesions sometimes cause significant morbidity. We have designed three types of alginate-based treatments using strongly cross-linked (SL), weakly cross-linked (WL), and non-cross-linked (NL) alginate with calcium gluconate. In rat experiments, we compared the antiadhesive effects of the three types of alginate-based treatments, fibrin glue treatment (a standard treatment), and no treatment against adhesions caused by polyglycolic acid (PGA) mesh (PGA-induced adhesions). The antiadhesive materials were set on the PGA sheet fixed on the parietal peritoneum of the abdomen. Fifty-six days later, the adhesions were evaluated macroscopically by the adhesion scores and microscopically by hematoxylin-eosin staining and immunostaining. We also tested the fibroblast growth on the surface of the antiadhesive materials in vitro. The antiadhesive effects of WL and NL were superior to the no treatment and fibrin glue treatment. A microscopic evaluation confirmed that the PGA sheet was covered by a peritoneal layer constructed of well-differentiated mesothelial cells, and the inflammation was most improved in the NL and WL. The fibroblast growth was inhibited most on the surfaces of the NL and WL. These results suggest that either the WL or NL treatments are suitable for preventing PGA-induced adhesions compared to SL or the conventional treatment.

In order to prevent postoperative adhesion and the related complications, a thermally crosslinked gelatin (TCG) film was developed and the basic biological properties were examined, paying special attention to the relationship between these properties and the extent of crosslinking of the film. The gelatin films crosslinked thermally for five different time periods (0, 1, 3, 8, and 14 hours) were developed and the following tests were performed. Regarding the material characterization of the films, the water content, the water solubility, and the enzymatic degradation for collagenase were found to be closely related to the duration of thermal crosslinking. In an in vitro study conducted to examine the cell growth of fibroblasts cultured on the films, the degree of cell growth, except no crosslinked film, was less than that observed in the control group, thus suggesting that such effects of the films on fibroblast cell growth may be related with their anti-adhesive effects. In in vivo tests, the films crosslinked for longer time periods (3, 8, and 14 hours) were retained for longer after being implanted into the abdominal cavity in rats and showed a significant anti-adhesive effect in the rat cecum adhesion models, indicating that the biodegradability and anti-adhesive effects of the TCG films depend on the duration of thermal crosslinking. In order to develop useful and effective anti-adhesive gelatin film, it is very important to optimize duration of the thermal crosslinking.

To generate a more effective and safer anti-adhesive material, we developed a new thermally cross-linked gelatin film. We previously reported that this film had superior anti-adhesive effects compared to cellulose film and could be used safely on the intestinal anastomosis in canine models. To evaluate the handling of the gelatin film during surgery, we investigated the physical properties of the gelatin film and compared it with cellulose film. We performed tensile and shear tests to evaluate the maximum loads, the elastic modulus and the fracture strains of the gelatin film, paying special attention to the relationship between the time required for the thermal cross-linking and those physical properties. The maximum tensile and shear loads of each thermally cross-linked gelatin film were significantly higher than those of cellulose film. The fracture strains of each gelatin film were also significantly higher than those of cellulose film. However, there were no significant differences in the elastic modulus between the gelatin films and the cellulose film in terms of both the tensile and shear tests. There were no significant differences in these physical properties among the gelatin films allowed to thermally cross-link for different lengths of time. In conclusion, thermally cross-linked gelatin film has a higher physical strength and ductility than cellulose film, regardless of the time allowed for thermal cross-linking. These physical properties of the gelatin films are considered to be advantageous for their handling during surgery.

To generate a more effective and safer anti-adhesive material, we have developed a new type of thermally cross-linked gelatin film. In this study, we preclinically examined the anti-adhesive efficacy of this film and evaluated the possibility applying the film safely onto fresh intestinal anastomoses, compared with hyaluronate and carboxymethyl-cellulose (HA/CMC) film. Using a canine adhesion model, the degree of adhesion for each film was evaluated by adhesion scoring systems and histological observation. Three weeks after surgery, only the gelatin film showed significantly superior anti-adhesive effects compared to the control (no treatment), in particular, exhibiting excellent re-peritonization. Next, in a canine anastomosis model, the anastomoses were wrapped directly by each film and the bursting pressures of the anastomoses were examined 3 and 7 days after surgery. The gelatin film did not significantly affect either the bursting pressures or the healing process, compared with the control. However, the HA/CMC film significantly decreased the bursting pressures measured at 3 days after surgery. In conclusion, the thermally cross-linked gelatin film had satisfactory anti-adhesive effects with excellent re-peritonization. It could be safely applied to intestinal anastomoses without decreasing the bursting pressures. The gelatin film is considered to be quite favorable as an anti-adhesive material.