Regeneration of Functional Bladder Using Cell-seeded Amnion and P(LA/CL) Scaffolds.

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 Statement Regeneration 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.

Effects of Fiber Diameter and Spacing Size of an Artificial Scaffold on the In Vivo Cellular Response and Tissue Remodeling.

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.

The influences of a novel anti-adhesion device, thermally cross-linked gelatin film on peritoneal dissemination of tumor cells: The in vitro and in vivo experiments using murine carcinomatous peritonitis models.

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.