Krause Diane, Cantley Lloyd G
Department of Laboratory Medicine and Department of Internal Medicine, Yale University, New Haven, CT 06520, USA.
J Clin Invest. 2005 Jul;115(7):1705-8. doi: 10.1172/JCI25540.
Epithelial organs such as the intestine and skin have a relatively high rate of cell loss and thus require a reservoir of stem cells capable of both replacing the lost epithelia and maintaining the reservoir. Whether the kidney has such a stem cell niche has been a subject of great interest; the majority of data suggest that replacement of renal epithelial cells occurs via dedifferentiation and proliferation of existing tubular cells, while some studies demonstrate the presence of potential tubular stem cells in the renal interstitium. However, recent reports have suggested that the bone marrow may also be a source of stem cells for tubule turnover and/or repair. In this issue of the JCI, 2 groups explore the role of endogenous cells versus bone marrow-derived cells in mediating tubule repair. Duffield and colleagues demonstrate that bone marrow does contain cells capable of protecting the kidney from ischemic injury, but found that these cells do not act by direct incorporation into the repaired tubular segments. In contrast, Lin and coworkers found that some bone marrow-derived cells do appear to incorporate into the injured tubule as epithelial cells (see the related article beginning on page 1756). Importantly, both groups conclude that the majority of tubule repair occurs via proliferation of endogenous renal cells rather than incorporation of bone marrow-derived cells.
诸如肠道和皮肤等上皮器官的细胞损失率相对较高，因此需要一个干细胞库，既能替代丢失的上皮细胞，又能维持这个细胞库。肾脏是否存在这样的干细胞微环境一直是人们非常感兴趣的话题；大多数数据表明，肾上皮细胞的替代是通过现有肾小管细胞的去分化和增殖实现的，而一些研究则证明肾间质中存在潜在的肾小管干细胞。然而，最近的报告表明，骨髓也可能是肾小管更新和/或修复的干细胞来源。在本期《临床研究杂志》中，有两个研究小组探讨了内源性细胞与骨髓来源的细胞在介导肾小管修复中的作用。达菲尔德及其同事证明骨髓确实含有能够保护肾脏免受缺血性损伤的细胞，但发现这些细胞并非通过直接整合到修复后的肾小管节段中来发挥作用。相比之下，林及其同事发现一些骨髓来源的细胞似乎确实作为上皮细胞整合到受损的肾小管中（见第1756页开始的相关文章）。重要的是，两个研究小组都得出结论，大多数肾小管修复是通过内源性肾细胞的增殖而非骨髓来源细胞的整合来实现的。
