Purpose: The availability of autologous erectile tissue composed of corporal smooth muscle and endothelial cells would be beneficial in patients undergoing penile reconstruction. We previously showed that cultured cavernous cells seeded on polymer scaffolds form corporal muscle when implanted in vivo. However, to reconstruct corporal tissue endothelial and corporal muscle cells are necessary. In this study we investigated the possibility of developing tissue composed of corporal cells in vivo by combining smooth muscle and endothelial cells.
Materials and methods: Human corporal smooth muscle and endothelial cells were seeded on biodegradable polyglycolic acid polymer scaffolds at concentrations of 20 x 10(6) and 10 x 10(6) cells per cm3, respectively. A total of 60 polymer scaffolds seeded with cells and 20 control polymers without cells were implanted in the subcutaneous space of 20 athymic mice. Mice were sacrificed 1, 3, 5, 7, 14, 21, 28 and 42 days, respectively, after implantation. Immunocytochemical and histochemical analyses were performed with antifactor VIII, antipancytokeratins and anti-alpha actin antibodies.
Results: Histologically the retrieved polymers seeded with corporal smooth muscle and endothelial cells showed the formation of multilayered smooth muscle strips adjacent to endothelial cells 7 days after implantation. Increased organization of the smooth muscle tissue and accumulation of endothelium lining the luminal structures were evident by 14 days. A well organized tissue construct was noted 28 and 42 days after implantation. There was no evidence of tissue formation in controls. Immunocytochemical analysis using antifactor VIII to identify native vasculature only and antipancytokeratins to identify ECV 304 endothelial cells only distinguished the origin of the vascular structures in each construct. Anti-alpha-actin confirmed the smooth muscle phenotype.
Conclusions: Human corporal smooth muscle and endothelial cells seeded on biodegradable polymer scaffolds formed vascularized corpus cavernosum muscle when implanted in vivo. To our knowledge this is the first demonstration in tissue engineering in which capillary formation was facilitated by the addition of endothelial cells in composite tissue in vivo.