Stem Cell Biology Department, Indian Council of Medical Research - National Institute for Research in Reproductive Health, Jehangir Merwanji Street, Parel, Mumbai, 400012, India.
Stem Cell Rev Rep. 2017 Dec;13(6):713-724. doi: 10.1007/s12015-017-9756-y.
Stem cells have fascinated scientists for a long time and huge research efforts have been put into them as they have the potential to regenerate diseased organs. Besides embryonic stem cells (ES) and induced pluripotent stem cells (iPS), it has been postulated that pluripotent stem cells (PSCs) may also exist in various adult tissues. They are thought to be more primitive than the adult stem cells (ASCs), serve as a backup pool to give rise to ASCs and thus play a crucial role in maintaining life-long homeostasis. These PSCs could also be the embryonic stem cells in adult tissues that were proposed to initiate cancers according to the Embryonic Rest Hypothesis put forth in the nineteenth century. However, the very presence of PSCs in adult tissues is mired with controversies. This article is a sincere attempt to review research carried out by various investigators over the last two decades and various attempts to demonstrate their presence in adult tissues. Such adult PSCs could be the ideal stem cell candidates to bring about endogenous regeneration compared to ES/iPS cells grown in Petri dish and also score better over ASCs which in fact are tissue committed progenitors with limited regenerative potential that differentiate from the PSCs. PSCs in adult tissues have remained elusive until now as they possibly get unknowingly discarded due to their small size and inability to pellet at 1000-1200 rpm (250 g). They will likely prove to be a game changer in the field of stem cells biology, for regenerative medicine and for our understanding of cancer initiation.
干细胞长期以来一直令科学家着迷，由于它们具有使病变器官再生的潜力，因此投入了大量的研究工作。除了胚胎干细胞 (ES) 和诱导多能干细胞 (iPS) 之外，人们还假设多能干细胞 (PSC) 可能也存在于各种成人组织中。它们被认为比成人干细胞 (ASC) 更原始，作为 ASC 的后备池出现，因此在维持终生动态平衡中起着至关重要的作用。这些 PSC 也可能是成人组织中的胚胎干细胞，根据 19 世纪提出的胚胎残余假说，它们被认为会引发癌症。然而，成人组织中 PSC 的存在存在争议。本文真诚地尝试回顾过去二十年来各个研究人员进行的研究以及各种证明它们在成人组织中存在的尝试。与在 Petri 盘中生长的 ES/iPS 细胞相比，这种成人 PSC 可能是实现内源性再生的理想干细胞候选物，而且比 ASC 得分更高，实际上 ASC 是组织定向祖细胞，具有有限的再生潜力，从 PSC 分化而来。到目前为止，成人组织中的 PSC 仍然难以捉摸，因为它们由于体积小且无法在 1000-1200rpm（250g）下沉淀而可能被无意识地丢弃。它们很可能会成为干细胞生物学、再生医学以及我们对癌症发生的理解领域的游戏规则改变者。
