Regeneration of spermatogenesis by grafting testicular tissue or injecting testicular cells into the testes of sterile mice: a comparative study.

Objective: To make a comparison between two different approaches-spermatogonial stem cell transplantation and intratesticular grafting, for preservation and reintroduction of spermatogonial stem cells.

Design: Prospective experimental study.

Setting: Academic medical center and teaching hospital.

Patient(s): N/A.

Intervention(s): Intratesticular transplantation, histologic evaluation of testes.

Main Outcome Measure(s): Testicular weight, amount of green fluorescence in the testis, and immunostaining for green fluorescent protein.

Result(s): In a first experiment donor-derived spermatogenesis was found in 65% of the injected testes (41.8 +/- 72.2 mm) compared with 75% of the testes (122.1 +/- 45.6 mm) after tissue grafting. In the second series of experiments complete spermatogenesis was found in 75% of the testes after fresh grafting (93.8 +/- 21.8 mm) compared with 88% after frozen-thawed tissue grafting (84.8 +/- 45.6 mm).

Conclusion(s): Both approaches show that spermatogonial stem cells can successfully be introduced to the testis resulting in spermatogenesis. Tissue grafting produced a larger mean donor colony length and there was no significant difference between colonization efficiency using either fresh or frozen-thawed grafts. In a future clinical setting, grafting would be a simple and efficient way for reintroducing stem cells to the testis.