Spermatogonial stem cell transplantation (SSCT) is a strategy that has demonstrated to be feasible to restore spermatogenesis in animal models when it is performed shortly after the gonadotoxic onset to destroy their endogenous germ cells. However, in the case of boys subjected to fertility preservation, future transplantations will be performed with a delay of many years. In order to study how timing of SSCT affects donor-derived spermatogenic recovery in mice, we compared the percentage of spermatogenic tubule cross-sections within testes of 59 C57BL/6NCrl mice distributed in 6 groups: group 1, untreated mice controls (n = 9); group 2, mice that received a single dose of busulfan 40 mg/kg (n = 10); group 3, mice that received two additional doses of busulfan 10 mg/kg every 5 weeks (n = 10); group 4 (SSCT-A), mice subjected to a standard SSCT performed 5 weeks after a single injection of busulfan 40 mg/kg (n = 10); group 5 (SSCT-B), mice subjected to a delayed SSCT performed 15 weeks after a single injection of busulfan 40 mg/kg (n = 10); and group 6 (SSCT-C), mice subjected to a delayed SSCT with two additional doses of busulfan 10 mg/kg every 5 weeks (n = 10). Spermatogenic recovery in standard SSCT-A and SSCT-C groups ranged between 22.29 and 22.65%, compared with a lower recovery rate of 11.54% showed in the SSCT-B group. However, donor contribution resulted higher in standard SSCT-A, representing a 69.71% of cross-sections, compared with the rest of conditions ranging from 34.69 to 35.42%. Overall, we concluded that a delay in the SSCT from the gonadotoxic onset decreases the efficiency of donor-derived spermatogenic recovery in mice.

精原干细胞移植 (SSCT) 是一种已证明在动物模型中恢复精子发生的可行策略，在性腺毒性发作后不久进行以破坏其内源性生殖细胞。但是，对于保留生育能力的男孩，未来的移植将延迟很多年。为了研究 SSCT 的时间如何影响小鼠供体来源的生精恢复，我们比较了分布在 6 组中的 59 只 C57BL/6NCrl 小鼠睾丸内生精小管横截面的百分比：第 1 组，未治疗的小鼠对照（n  = 9 ); 第 2 组，接受单剂量白消安 40 mg/kg 的小鼠（n  = 10）；第 3 组，每 5 周接受两次额外剂量的白消安 10 mg/kg 的小鼠（n  = 10); 第 4 组 (SSCT-A)，小鼠在单次注射 40 mg/kg 白消安后 5 周进行标准 SSCT（n  = 10）；第 5 组（SSCT-B），小鼠在单次注射 40 mg/kg 白消安后 15 周进行延迟 SSCT（n  = 10）；和第 6 组（SSCT-C），小鼠每 5 周接受两次额外剂量的白消安 10 mg/kg 延迟 SSCT（n = 10）。标准 SSCT-A 和 SSCT-C 组的生精恢复率介于 22.29 和 22.65% 之间，而 SSCT-B 组的恢复率较低，为 11.54%。然而，捐助者的贡献导致标准 SSCT-A 中更高，占横截面的 69.71%，而其余条件的范围为 34.69 至 35.42%。总的来说，我们得出的结论是，从性腺毒性开始延迟 SSCT 会降低小鼠供体来源的生精恢复效率。