Department of Gastroenterology & Hepatology, Erasmus MC-University Medical Center and Postgraduate School Molecular Medicine, Rotterdam NL-3015 CE, The Netherlands.
Exp Biol Med (Maywood). 2014 Jan;239(1):105-15. doi: 10.1177/1535370213506802. Epub 2013 Nov 13.
Human mesenchymal stem/stromal cells (MSCs) have been explored in a number of clinical trials as a possible method of treating various diseases. However, the effect of long-term cell expansion in vitro on physiological function and genetic stability is still poorly understood. In this study, MSC cultures derived from bone marrow and liver were evaluated for the presence of aberrant cells following long-term expansion. In 46 independent cultures, four batches of transformed MSCs (TMCs) were found, which were all beyond the culture period of five weeks. These aberrant cells were first identified based on the appearance of abnormal cytology and the acquirement of growth advantage. Despite common MSC markers being diminished or absent, TMCs remain highly susceptible to lysis by allogenic natural killer (NK) cells. When transplanted into immunodeficient mice, TMCs formed sarcoma-like tumors, whereas parental MSCs did not form tumors in mice. Using a combination of high-resolution genome-wide DNA array and short-tandem repeat profiling, we confirmed the origin of TMCs and excluded the possibility of human cell line contamination. Additional genomic duplication and deletions were observed in TMCs, which may be associated with the transformation event. Using gene and microRNA expression arrays, a number of genes were identified that were differentially expressed between TMCs and their normal parental counterparts, which may potentially serve as biomarkers to screen cultures for evidence of early transformation events. In conclusion, the spontaneous transformation of MSCs resulting in tumorigenesis is rare and occurs after relatively long-term (beyond five weeks) culture. However, as an added safety measure, cultures of MSCs can potentially be screened based on a novel gene expression signature.
人骨髓间充质干细胞（MSCs）在许多临床试验中被探索为治疗各种疾病的可能方法。然而，长期在体外细胞扩增对生理功能和遗传稳定性的影响仍知之甚少。在这项研究中，评估了源自骨髓和肝脏的 MSC 培养物在长期扩增后是否存在异常细胞。在 46 个独立的培养物中，发现了四批转化的 MSC（TMC），这些细胞均超过了五周的培养期。这些异常细胞首先根据异常细胞学的出现和获得生长优势来识别。尽管常见的 MSC 标志物减少或缺失，但 TMC 仍极易被同种异体自然杀伤（NK）细胞溶解。当移植到免疫缺陷小鼠中时，TMC 形成肉瘤样肿瘤，而亲本 MSC 则不会在小鼠中形成肿瘤。通过使用高分辨率全基因组 DNA 芯片和短串联重复序列分析相结合的方法，我们确认了 TMC 的起源，并排除了人细胞系污染的可能性。在 TMC 中观察到额外的基因组重复和缺失，这可能与转化事件有关。使用基因和 microRNA 表达谱，鉴定出 TMCs 与其正常亲本之间存在差异表达的许多基因，这些基因可能潜在地作为筛选培养物中早期转化事件证据的生物标志物。总之，MSC 自发转化导致肿瘤发生的情况很少见，并且发生在相对较长的时间（超过五周）后培养。然而，作为额外的安全措施，基于新型基因表达谱，可以对 MSC 培养物进行潜在的筛选。
