Cui Lei, Yin Shuo, Liu Wei, Li Ningli, Zhang Wenjie, Cao Yilin
Department of Plastic and Reconstructive Surgery, 9th People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
Tissue Eng. 2007 Jun;13(6):1185-95. doi: 10.1089/ten.2006.0315.
Multipotent mesenchymal stem cells (MSCs) in adult tissue are known to be less immunogenic and immunosuppressive. Previous study showed that primary cultures of human adipose-derived stem cells (ADSCs) shared their immunomodulatory properties with other MSCs. However, whether passaged human ADSCs can retain their immunomodulatory effect after in vitro expansion remains unknown. In addition, the mechanism of ADSC-mediated immunomodulatory effect remains to be elucidated. This study aimed to investigate these issues by using passaged human ADSCs as an in vitro study model. Flow cytometry showed that passaged ADSCs expressed human leukocyte antigen (HLA) class I but not class II molecules, which could be induced to express to a high level with interferon-gamma (IFN-gamma) treatment. The study found that passaged ADSCs could not elicit lymphocyte proliferation after co-culturing with them, even after IFN-gamma treatment. In addition, either IFN-gamma-treated or non-treated ADSCs could inhibit phytohemagglutinin (PHA)-stimulated lymphocyte proliferation. Moreover, passaged ADSCs could serve as the third-party cells to inhibited two-way mixed lymphocyte reaction (MLR). Further study using a transwell system also showed that this type of immunosuppressive effect was not cell-cell contact dependent. In defining possible soluble factors, we found that passaged ADSCs significantly increased their secretion of prostaglandin E2 (PGE2), but not transforming growth factor-beta (TGF-beta) and hepatocyte growth factor (HGF), when they were co-cultured with MLR. Furthermore, the result demonstrated that only PGE2 production inhibitor indomethacine, but not TGF-beta- and HGF-neutralizing antibodies, could significantly counteract ADSC-mediated suppression on allogeneic lymphocyte proliferation. These results indicated that in vitro expanded ADSCs retain low immunogenicity and immunosuppressive effect, and PGE2 might be the major soluble factor involved in the in vitro inhibition of allogeneic lymphocyte reaction.
已知成体组织中的多能间充质干细胞（MSC）免疫原性较低且具有免疫抑制作用。先前的研究表明，人脂肪来源干细胞（ADSC）的原代培养物与其他MSC具有共同的免疫调节特性。然而，传代后的人ADSC在体外扩增后是否能保留其免疫调节作用仍不清楚。此外，ADSC介导的免疫调节作用机制仍有待阐明。本研究旨在以传代后的人ADSC作为体外研究模型来探讨这些问题。流式细胞术显示，传代后的ADSC表达人类白细胞抗原（HLA）I类分子，但不表达II类分子，经γ干扰素（IFN-γ）处理后可诱导其高水平表达。研究发现，传代后的ADSC与淋巴细胞共培养后不能引发淋巴细胞增殖，即使在IFN-γ处理后也是如此。此外，经IFN-γ处理或未处理的ADSC均可抑制植物血凝素（PHA）刺激的淋巴细胞增殖。而且，传代后的ADSC可作为第三方细胞抑制双向混合淋巴细胞反应（MLR）。使用Transwell系统的进一步研究还表明，这种免疫抑制作用不依赖细胞间接触。在确定可能的可溶性因子时，我们发现传代后的ADSC与MLR共培养时，其前列腺素E2（PGE2）的分泌显著增加，但转化生长因子-β（TGF-β）和肝细胞生长因子（HGF）的分泌未增加。此外，结果表明，只有PGE2产生抑制剂吲哚美辛，而不是TGF-β和HGF中和抗体，可显著抵消ADSC介导的对同种异体淋巴细胞增殖的抑制作用。这些结果表明，体外扩增的ADSC保留低免疫原性和免疫抑制作用，且PGE2可能是参与体外抑制同种异体淋巴细胞反应的主要可溶性因子。
