Formation of Sertoli cell-enriched tissue constructs utilizing simulated microgravity technology

Cell transplantation therapy for diabetes and Parkinson's disease offers hope for long-term alleviation of symptoms. However, successful protocols remain elusive due to obstacles, including rejection and lack of tropic support for the graft. To enhance engraftment, testis-derived postmitotic Sertoli cells have been cotransplanted with islets in the diabetic rat (Db) and neurons in the Parkinsonian rat (PD). Sertoli cell tropic, regulatory, and nutritive factors that nourish and stimulate germ cells also support isolated neurons and islets in vitro. Likewise, immunosuppressive properties of Sertoli cells, extant in the testis, are expressed by extratesticular Sertoli cells evidenced by allo- and xenograft immunoprotection of grafts in both the CNS (in the PD model) and the periphery (in the Db model). On this basis, we have created Sertoli islet cell aggregates (SICA) and Sertoli neuron aggregated cells (SNAC) using simulated microgravity culture technology developed by NASA. Isolated rat and pig Sertoli cells were cocultured with neonatal pig islets (SICA) and with immortalized N-Terra-2 (NT2) neurons (SNAC) in the HARV biochamber. Formed aggregates were assayed for desirable functional and structural characteristics. Cell viability in SICA and SNAC exceeded 90% and FasL immunopositive Sertoli cells were present in both. Sertoli cells did not interfere with insulin secretion by SICA and promoted differentiation of NT2 cells to the dopaminergic hNT cell type in SNAC. Addition of Matrigel resulted in structural reorganization of the aggregates and enhanced insulin secretion. We conclude that SICA, SNAC, and Matrigel-induced islet- and neuron-filled "Sertoli cell biochambers" are suitable for long-term transplantation treatment of Db and PD.