Objective To induce islet allograft long-term survival through cotransplantation of islet cells with sertoli cells.Methods Testicular sertoli cells were prepared by digestion with collagenase, trypsin and DNase, and were cultured for 48 hours. Collagenase digested and Ficoll purified donor (Wistar rat) islets were cotransplanted with allogeneic sertoli cells in the absence of systemic immunosuppression. Terminal leoxynucleotidyl transferase-mediated X-dUTP nick-end labeling (TUNEL) was used to label apoptosis of lymphocytes surrounding the islet graft.Results Cotransplantation of islets and 1 × 107 sertoli cells reversed the diabetic state for more than 60days in 100% (6/6) of the chemically diabetic Sprague Dawley rats. Grafts consisting of islets alone or islets plus 1 × 105 sertoli cells survived only for 5 - 6 days. Apoptosis of lymphocytes surrounding the islets was quite clear.Conclusion Cotransplantation of islets with FasL+ sertoli cells induces local immune privilege and allows long-term graft survival without systemic immunosuppression.
Objective To study the interaction between telomerase activity and abnormalities of the p16 gene in liver metastases of colorectal carcinoma.Methods Telomerase activity was detected by a non-isotopic PCR-based telomeric repeat amplification protocol (TRAP) assay, and homozygous deletions of the p16 gene were detected by a semiquantitative multiplex polymerase chain reaction in tissue samples from 24 liver metastases of colorectal carcinoma and 5 primary colorectal carcinomas.Results Telomerase activity was observed in 19 (79.2%) of 24 liver metastases of colorectal carcinoma.Telomerase activity was also observed in all 5 primary colorectal carcinomas and in 3 of their liver metastatic samples. The incidence of telomerase activity in liver metastases of colorectal carcinoma was not significantly correlated to tumor diameter, number of tumors, cirrhosis, and HBsAg. Homozygous deletions of the p16 gene were found in 9 of 24 (37.5%) liver metastases of colorectal carcinoma. Homozygous deletions of the p16 gene were observed in 2 of the 5 primary colorectal carcinomas and in 1 of the matching liver metastatic cancers. There was a correlation between telomerase activity and homozygous deletions of the p16 gene.Conclusions There is a correlation between telomerase activity and homozygous deletions of the p16gene in liver metastases of colorectal carcinoma, suggesting its crucial role in liver metastases. However,telomerase activation and homozygous deletions of the p16 gene might not be the initiating event in liver metastases of colorectal carcinoma.
