ABSTRACT
BACKGROUND: A lot of researches have proved that polyglicolide acid (PGA), as a stent material, has been successfully used to construct engineered tissues, such as cartilage, bone and tendons, in nude mice or even big mammal. Whether the incubation of vascular endothelial cells and smooth muscle cells in the polyglicolide acid may subcutaneously construct vessel-like structure in nude mice needs a further study.OBJECTIVE: To verify the feasibility of forming vessel-like structure in the nude mice by subcutaneous implantation of polyglicolide acid cocultured with vascular endothelial cells and smooth muscle cells derived from newborn umbilical vein.DESIGN: Contrast study.SETTING: Tissue Engineering Key Laboratory, Medical College, Shanghai Jiao Tong University.MATERIALS: This study was performed at Tissue Engineering Key Laboratory, Medical College, Shanghai Jiao Tong University from January to June 2002. Belly band was derived from newborn babies in our department of obstetrics & gynecology. The parturien provided the informed consent, and this study was approved by the local research ethics committee. Twenty-six nude mice (3-4 weeks old, clean grade, irrespective of gender) were selected in this study. The animal experiment received confirmed consent from the local ethic committee. Polyglicolide acid was provided by Albany International Research Co.METHODS: Vascular endothelial cells and smooth muscle cells derived from newborn umbilical vein were incubated on a piece of polyglicolide acid to produce cell-material compound. In addition, the compound covered around the silicone tube to form a tube-like structural substance. Subsequently, the tube-like structural substance was subcutaneously implanted in 20 nude mice, which were regarded as an experimental group. And then, polyglicolide acid alone was subcutaneously transplanted in the rest 6 nude mice, which was regarded as a control group.MAIN OUTCOME MEASURES: Gross observations of cell-material compound by 2 and 6 weeks after transplantation;HE staining and immunohistochemical staining.detection; expression of factor Ⅷ and α-smooth muscle actin.RESULTS: Twenty-six nude mice were included in the final analysis. ① Gross observation: At 2 weeks after implantation,both the experimental and control groups formed tubular structures, however, at 6 weeks after implantation, the tubular structure still remained in experimental group but not in the controls. ② Histological observation and immunohistochemical detection: The histological examination of the engineered vessel showed that at 2 weeks, the vessels in both group contained mainly undegraded PGA fibers, while at 6 weeks, the PGA fibers were almost completely degraded in both groups and in the control group only fibrous-like tissue formed. Contrastly, in experimental group a typical vascular structure formed, Masson's trichrome stain, which stains collagen green, smooth muscle fibers red and cells purple, showed significant amounts of stainable collagen and smooth muscle fibers in the wall of the engineered vessel, furthermore,immunohistochemistry examination revealed that there were an endothelial cell layer formed in the inner surface of the engineered vessel which was confirmed by positive staining of yon Willebrand factor, meanwhile, the smooth muscle cells in the wall of the engineered vessel were confirmed by the positive staining of smooth muscle α-actin.CONCLUSION: The subcutaneous implantation of polyglicolide acid cocultured with vascular endothelial cells and smooth muscle cells may form vessels, which are similar to normal vascular histological structure.
ABSTRACT
Objective This study investigates feasibility of replacing urinary epidermal cells with foreskin epidermal cells to reconstruct engineered anterior urethra with acellular collagen matrix. Methods A cellular collagen matrices were generated from allogeneic rabbit bladder submucosa.In 6 rabbits,autologous foreskin epidermal cells isolated,in vitro expanded and labeled with Brdu before seeding onto a tubular collagen matrix of 2 cm long.In 12 male rabbits, urethral mucous defect was created and urethroplasty was performed with tubular collagen matrix seeded with epidermal cells (n=6) in experimental group or matrix without cells seeding (n=6) in control group.Urethrography was performed at 1,2,and 6 months postoperatively.Urethras grafts were harvested and analyzed grossly and histologically at the same time points. Results In control group, gross and urethrography demonstrated urethral stricture of repaired defects at all time points.Histology showed a single layer of epidermal cell with unorganized and crassitude muscle fiber bundles in submucosa layer.In contrast, urethrography showed a patency of repaired urethral defect with the maintenance of a wide urethral caliber in experimental group without sign of strictures at any time points. Histologically,the graft seeded with epidermal cell had a multi-layers epidermal cells by 1 month,which demonstrated the presence of a epidermal cells layer with a normal submucosa structure.The immunoflorescent staining of Brdu confirmed the presence of implanted epidermal cells.In addition, the implanted cells also express keratin when stained with anti-pancytokeratins AE1/AE3 antibody.At 2 month,histology showed relatively normal urethral architecture with vessel abundance in submucosa structure.The staining of Brdu showed decreased at implanted epidermal cells and epithelial phenotypes were confirmed immunocytochemically using pancytokeratins AE1/AE3.At 6 month,the graft structure show multi-layers epidermal cells without staining of Brdu. Conclusions Urethra reconstruction was better achieved with cell seeded acellular collagen matrix when compare with acellular matrices alone.Foreskin epidermal cells seems succeeded in replacing urethral epidermal cells for urethra reconstruction.