ABSTRACT Spermatogonial stem cells (SSCs) are unipotent adult stem cells, capable of differentiating into sperm cells. SSCs can be cultured in vitro for a long time. SSCs expressing Oct4, a pluripotency marker, and are the only adult cells which pluripotency can be induced under defined culture conditions. However, because 2D culture imposes limitations in cell junction formation, cell shape, metabolism, response to stimuli, and cell interface with medium, mechanistic studies on reprogramming of SSCs using feeder cells still have many challenges. Recent studies have shown that a culture system using a bio-matrix can be used in long-term feeder-free SSCs culture and for induction of pluripotency in SSCs. However, the bio-matrix cannot be the optimal micro-environment in mechanistic studies because it creates a physical barrier to growth factors and other signaling molecules. To overcome this effect of the matrix, we reprogrammed SSCs into pluripotent ESC-like cells, so-called germline-derived pluripotent stem cells (gPSCs) by using a 3D scaffold, in which cells are less responsive to external stimuli than in 2D cultures. Thus, we confirm the possibility of SSC reprogramming in the spheroidal state and suggest the utility of 3D scaffolds as a tool for studying the mechanism of SSC reprogramming into gPSCs without a bio-matrix.

中文翻译：

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精原干细胞重编程为球状多能干细胞

摘要 精原干细胞 (SSC) 是单能成体干细胞，能够分化为精子细胞。SSCs 可以在体外长期培养。表达 Oct4（一种多能性标记物）的 SSC 是唯一可在特定培养条件下诱导多能性的成体细胞。然而，由于 2D 培养在细胞连接形成、细胞形状、代谢、对刺激的反应以及细胞与培养基的界面方面存在局限性，因此使用饲养细胞对 SSC 进行重编程的机制研究仍然存在许多挑战。最近的研究表明，使用生物基质的培养系统可用于长期无饲养层的 SSC 培养和诱导 SSC 的多能性。然而，生物基质不能成为机械研究中的最佳微环境，因为它对生长因子和其他信号分子形成了物理屏障。为了克服基质的这种影响，我们通过使用 3D 支架将 SSC 重新编程为多能 ESC 样细胞，即所谓的生殖系衍生多能干细胞 (gPSC)，其中细胞对外部刺激的反应不如 2D 培养。因此，我们确认了 SSC 在球体状态下重编程的可能性，并建议使用 3D 支架作为研究 SSC 重编程为 gPSC 机制的工具，而无需生物基质。其中细胞对外部刺激的反应不如二维培养。因此，我们确认了 SSC 在球体状态下重编程的可能性，并建议使用 3D 支架作为研究 SSC 重编程为 gPSC 机制的工具，而无需生物基质。其中细胞对外部刺激的反应不如二维培养。因此，我们确认了 SSC 在球体状态下重编程的可能性，并建议使用 3D 支架作为研究 SSC 重编程为 gPSC 机制的工具，而无需生物基质。