Center for Neuropsychiatry, China Medical University Hospital, Taichung, Taiwan.
Cell Transplant. 2010;19(10):1261-79. doi: 10.3727/096368910X507204. Epub 2010 Jun 3.
Cellular senescence induces changes in cellular physiology, morphology, proliferative capacity, and gene expression. Stem cell senescence might be one of the major issues of limited efficacy of stem cell transplantation. In this study, we demonstrated that implantation of human umbilical cord mesenchymal stem cells (hUCMSCs) cultured in human umbilical cord serum (hUCS) significantly enhanced neuroplasticity and angiogenesis in stroke and ischemic limb models. Immunophenotypic analysis indicated that hUCMSCs cultured in hUCS had more small and rapidly self-renewing cells than those expanded in FCS. The main cause of greater senescence in FCS-cultured cells was increased generation of reactive oxygen species (ROS). Proteome profiling showed significantly more senescence-associated vimentin in FCS-cultured hUCMSCs than in hUCS-cultured hUCMSCs. In contrast, there was significant upregulation of heat shock protein 27 (Hsp27) in the hUCS-cultured hUCMSCs. By gene targeting, we found that overexpression of Hsp27 may downregulate vimentin expression through inhibition of the nuclear translocation of p65 (NF-κB signaling). Thus, an interaction between Hsp27 and vimentin may modulate the degree of senescence in hUCS- and FCS-cultured hUCMSCs. In summary, hUCMSCs exhibiting senescence are detrimental to cell engraftment and differentiation in animal models via activation of NF-κB pathway. Human stem cells incubated in hUCS might reduce the senescent process through upregulation of Hsp27 to increase implantation efficiency.
细胞衰老会引起细胞生理、形态、增殖能力和基因表达的变化。干细胞衰老可能是干细胞移植疗效有限的主要问题之一。在这项研究中，我们证明了在人脐带血清（hUCS）中培养的人脐带间充质干细胞（hUCMSCs）的植入显著增强了中风和缺血肢体模型中的神经可塑性和血管生成。免疫表型分析表明，在 hUCS 中培养的 hUCMSCs 比在 FCS 中扩增的细胞具有更多的小而快速自我更新的细胞。FCS 培养细胞衰老程度增加的主要原因是活性氧（ROS）的产生增加。蛋白质组谱分析显示，在 FCS 培养的 hUCMSCs 中，衰老相关的波形蛋白明显多于 hUCS 培养的 hUCMSCs。相反，hUCS 培养的 hUCMSCs 中热休克蛋白 27（Hsp27）显著上调。通过基因靶向，我们发现 Hsp27 的过表达可能通过抑制 p65（NF-κB 信号通路）的核转位来下调波形蛋白的表达。因此，Hsp27 和波形蛋白之间的相互作用可能调节 hUCS 和 FCS 培养的 hUCMSCs 中衰老的程度。总之，表现出衰老的 hUCMSCs 通过激活 NF-κB 通路，对动物模型中的细胞植入和分化不利。孵育在 hUCS 中的人干细胞可能通过上调 Hsp27 来减少衰老过程，从而提高植入效率。
