Kim Jae Hyung, Shin Sang-Hyun, Li Tian Zhu, Suh Hwal
Department of Medical Engineering, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul, 120-752, Korea.
J Tissue Eng Regen Med. 2016 Jan;10(1):E1-13. doi: 10.1002/term.1754. Epub 2013 Jul 30.
Niche appears important for preventing the spontaneous differentiation or senescence that cells undergo during in vitro expansion. In the present study, it was revealed that human bone marrow-derived mesenchymal stem cells (hBM-MSCs) undergo senescence-related differentiation into the myocardial lineage in vitro without any induction treatment. This phenomenon occurred over the whole population of MCSs, much different from conventional differentiation with limited frequency of occurrence, and was accompanied by a change of morphology into large, flat cells with impeded proliferation, which are the representative indications of MSC senescence. By culturing MSCs under several culture conditions, it was determined that induction treatment with 5-azacytidine was not associated with the phenomenon, but the serum-starvation condition, under which proliferation is severely hampered, caused senescence progression and upregulation of cardiac markers. Nevertheless, MSCs gradually developed a myocardial phenotype under normal culture conditions over a prolonged culture period and heterogeneous populations were formed. In perspectives of clinical applications, this must be prevented for fair and consistent outcomes. Hence, the biomimetic 'niche' was constituted for hBM-MSCs by cultivating on a conventionally available extracellular matrix (ECM). Consequently, cells on ECM regained a spindle-shape morphology, increased in proliferation rate by two-fold and showed decreased expression of cardiac markers at both the mRNA and protein levels. In conclusion, the outcome indicates that progression of MSC senescence may occur via myocardial differentiation during in vitro polystyrene culture, and this can be overcome by employing appropriate ECM culture techniques.
生态位对于防止细胞在体外扩增过程中发生自发分化或衰老似乎很重要。在本研究中，发现人骨髓间充质干细胞（hBM-MSCs）在没有任何诱导处理的情况下，在体外会经历与衰老相关的向心肌谱系的分化。这种现象在整个间充质干细胞群体中都会发生，这与传统的分化不同，传统分化发生频率有限，并且伴随着形态变化为大的扁平细胞，增殖受到阻碍，这是间充质干细胞衰老的典型表现。通过在几种培养条件下培养间充质干细胞，确定用5-氮杂胞苷进行诱导处理与该现象无关，但血清饥饿条件（在此条件下增殖严重受阻）会导致衰老进程和心脏标志物的上调。然而，在正常培养条件下，经过长时间培养，间充质干细胞会逐渐形成心肌表型，并形成异质群体。从临床应用的角度来看，为了获得公平和一致的结果，必须防止这种情况。因此，通过在常规可用的细胞外基质（ECM）上培养，为hBM-MSCs构建了仿生“生态位”。结果，在ECM上的细胞恢复了纺锤形形态，增殖率提高了两倍，并且在mRNA和蛋白质水平上心脏标志物的表达均降低。总之，结果表明，在体外聚苯乙烯培养过程中，间充质干细胞的衰老进程可能通过心肌分化发生，并且可以通过采用适当的ECM培养技术来克服。
