Background and Aim: Mesenchymal stem cells (MSCs) transplanted into the testes of rats with testicular failure can help rescue fertility. However, the low viability of transplanted MSCs limits the success of this treatment. This study aimed to determine the effectiveness of MSCs cultured under hypoxia to increase the fertility rate in rats (Rattus norvegicus).

Materials and Methods: Bone marrow-derived MSCs (200 million cells/rat) were transplanted into male rat models with induced infertility (10 rats/treatment group) after 4 days of culture in 21% O₂ (normoxia) and 1% O₂ (hypoxia). Ten fertile and 10 untreated infertile rats served as controls. In the infertile male rats that had been fasted from food for 5 days, the fasting condition induced malnutrition and then resulted in testicular failure.

Results: The results indicated that the MSCs cultured under hypoxic conditions were more effective than those cultured in normoxic conditions as a treatment for testicular failure in infertile male rats based on the increased number of cells expressing p63 as a quiescent cell marker and ETV5 as a transcription factor expressed in Sertoli and germ cells. Furthermore, the structure of the seminiferous tubules, which contain spermatogonia, primary and secondary spermatocytes, and spermatid, Sertoli, and Leydig cells, was improved in infertile male rats treated with the MSCs cultured under hypoxic conditions.

Conclusion: The testicular transplantation of MSCs cultured under hypoxic conditions was an effective treatment for testicular failure in rats.

Keywords: fertility, hypoxia culture, malnutrition, stem cell, testicular failure.