Cryopreservation of rat Leydig cells for in vitro and in vivo studies

Leydig cells lose their ability to secrete testosterone following short-term in vitro culture. A procedure for effective storage of these cells would be useful. In this study, rat Leydig cells were cryopreserved in the presence of 10, 15 or 20% dimethylsulfoxide (DMSO) at approximately 1 degree C/min to -70 degrees C and then stored in LN2. After thawing, the cells cryopreserved in the presence of 15% DMSO showed the highest viability of over 75%. These cells secreted basal levels of testosterone in vitro as well as responded to hCG stimulation by secreting over 9-fold increase in testosterone. The viability of these cells was further confirmed by the demonstration of 3 beta-HSD positive cells under the kidney capsule of rats isografted with cryopreserved Leydig cells. This study demonstrated that purified rat Leydig cells can be cryopreserved and the cryopreserved cells retained normal function and were responsive to hCG stimulation. Cryopreservation is a simple procedure for long-term storage of functional Leydig cells.