Smithsonian-Mason School of Conservation, George Mason University, 1500 Remount Rd., Front Royal, VA, 22630, USA.
University of Virginia, Department of Cell Biology, 200 Jeanette Lancaster Way, Charlottesville, VA, 22903, USA.
Cryobiology. 2021 Jun;100:173-179. doi: 10.1016/j.cryobiol.2021.01.010. Epub 2021 Jan 20.
Development of genomic preservation technologies for canids, especially for seasonally breeding species like the grey wolf (Canis lupus), is needed in advance of growing species conservation concerns. Here, we evaluated the efficacy of two cryopreservation protocols - needle immersion vitrification (NIV) and slow freezing (SF) on grey wolf (n = 7) testicular tissue morphology. NIV samples were equilibrated in a 7.5% v/v dimethyl sulfoxide (DMSO or Me2SO) + 7.5% ethylene glycol (EG) solution in minimum essential medium with 20% FBS for 10 min at 4 °C, then exposed to 15% DMSO + 15% EG + 0.5 M sucrose for 10 min at 4 °C before plunging into liquid nitrogen. For slow freezing, we assessed two cryoprotectant (CPA) strategies, DMSO, 15% v/v alone (SF-D) or 7.5% EG + 7.5% DMSO (SF-ED). Following thawing, there were no significant differences in seminiferous tubule area among treatment groups, although all cryopreserved tissues displayed reduced tubule size compared with fresh controls and increased apoptosis, the latter reaching significance for SF-D treated tissues. Slow freezing improved maintenance of testis architecture, with minimal detachment of seminiferous tubule basement membranes post-thaw. Spermatogonia densities were reduced in NIV tissues compared with fresh, with no differences in spermatocyte, spermatid, or Sertoli cell counts, or germ cell marker DDX4 cell densities among groups. In sum, we conclude that slow freezing better maintained morphology of cryopreserved testicular tissues compared with needle vitrification with 15% each DMSO and EG and 0.5 M sucrose, and that DMSO + EG combination SF supports cell viability. This represents a first step in the development of male gonadal tissue preservation strategies for the grey wolf.
为了应对不断增长的物种保护问题,需要预先开发犬科动物(尤其是季节性繁殖物种,如灰狼)的基因组保存技术。在这里,我们评估了两种冷冻保存方案——针浸玻璃化法(NIV)和慢速冷冻法(SF)对灰狼睾丸组织形态的效果。NIV 样本在 4°C 下用含 20% FBS 的最小必需培养基中平衡 10 分钟,使其在 7.5%v/v 二甲亚砜(DMSO 或 Me2SO)+7.5%乙二醇(EG)溶液中,然后在 4°C 下暴露于 15%DMSO+15%EG+0.5M 蔗糖 10 分钟,然后立即投入液氮中。对于慢速冷冻,我们评估了两种冷冻保护剂(CPA)策略,单独使用 15%DMSO(SF-D)或 7.5%EG+7.5%DMSO(SF-ED)。解冻后,尽管所有冷冻保存的组织与新鲜对照组相比,管腔大小均减小,凋亡增加,但处理组的生精小管面积没有显著差异,后者在 SF-D 处理的组织中达到显著水平。与新鲜对照组相比,慢速冷冻法改善了睾丸结构的维持,解冻后,生精小管基膜的分离最小。与新鲜组织相比,NIV 组织中的精原细胞密度降低,各组之间精母细胞、精子细胞或支持细胞计数或生殖细胞标记物 DDX4 细胞密度没有差异。总之,我们得出结论,与使用 15%DMSO 和 EG 各 15%和 0.5M 蔗糖的针浸玻璃化法相比,慢速冷冻法更好地保持了冷冻保存睾丸组织的形态,并且 DMSO+EG 组合 SF 支持细胞活力。这代表了开发灰狼雄性性腺组织保存策略的第一步。