Identification of a specific Sertoli cell marker, Sox9, for use in transplantation.

The immunoprivileged environment of the testes was first described in the 1930s, and the Sertoli cell was later identified as the main cell type responsible for this phenomenon. Recent work has examined the possibility of recreating this immunoprivileged environment at heterotopic sites using isolated Sertoli cells. These studies have focused on protection of pancreatic islets and neuronal cells from immune destruction in the hopes of reversing type I diabetes and Parkinson's disease. The absence of a definitive marker for identifying Sertoli cells at the transplant site has been an obstacle to this research. The current study examines the presence of a nuclear transcription factor, Sox9, which is preferentially expressed in Sertoli cells. Syngeneic Lewis rat Sertoli cells were transplanted into the renal subcapsular space and a subcutaneous site in Lewis female rats and examined histologically 21 days later. In addition, porcine Sertoli cells were transplanted into the renal subcapsular space in female SCID mice. Control testes and the transplant sites were examined immunohistochemically using an antibody to Sox9. The results from the study demonstrate that Sox9 expression is restricted to the Sertoli cells of the neonatal rat and porcine testis, indicating high homology between species. In addition, Sox9 expression was also observed in the testicular-like tubules that formed in both syngeneic and xenogeneic heterotopic transplants in rats and SCID mice. The Sox9 expression was restricted to the regions where Sertoli cells would be found in the native testis. These results suggest that the Sox9 protein is a useful marker in identifying Sertoli cells in heterotopic transplants in a manner similar to insulin as a marker for pancreatic islets.

A hydrogel material for plastic and reconstructive applications injected into the subcutaneous space of a sheep.

Soft tissue reconstruction using tissue-engineered constructs requires the development of materials that are biocompatible and support cell adhesion and growth. The objective of this study was to evaluate the use of macroporous hydrogel fragments that were formed using either unmodified alginate or alginate covalently linked with the fibronectin cell adhesion peptide RGD (alginate-RGD). These materials were injected into the subcutaneous space of adult, domesticated female sheep and harvested for histological comparisons at 1 and 3 months. In addition, the alginate-RGD porous fragments were seeded with autologous sheep preadipocytes isolated from the omentum, and these cell-based constructs were also implanted. The results from this study indicate that both the alginate and alginate-RGD subcutaneous implants supported tissue and vascular ingrowth. Furthermore, at all time points of the experiment, a minimal inflammatory response and capsule formation surrounding the implant were observed. The implanted materials also maintained their sizes over the 3-month study period. In addition, the alginate-RGD fragments supported the adhesion and proliferation of sheep preadipocytes, and adipose tissue was present within the transplant site of these cellular constructs, which was not present within the biomaterial control sites.