Dressel Ralf, Guan Kaomei, Nolte Jessica, Elsner Leslie, Monecke Sebastian, Nayernia Karim, Hasenfuss Gerd, Engel Wolfgang
Department of Cellular and Molecular Immunology, University of Göttingen, Heinrich-Düker-Weg 12, 37073 Göttingen, Germany.
Biol Direct. 2009 Aug 28;4:31. doi: 10.1186/1745-6150-4-31.
Multipotent adult germ-line stem cells (maGSCs) represent a new pluripotent cell type that can be derived without genetic manipulation from spermatogonial stem cells (SSCs) present in adult testis. Similarly to induced pluripotent stem cells (iPSCs), they could provide a source of cellular grafts for new transplantation therapies of a broad variety of diseases. To test whether these stem cells can be rejected by the recipients, we have analyzed whether maGSCs and iPSCs can become targets for cytotoxic T lymphocytes (CTL) or whether they are protected, as previously proposed for embryonic stem cells (ESCs).
We have observed that maGSCs can be maintained in prolonged culture with or without leukemia inhibitory factor and/or feeder cells and still retain the capacity to form teratomas in immunodeficient recipients. They were, however, rejected in immunocompetent allogeneic recipients, and the immune response controlled teratoma growth. We analyzed the susceptibility of three maGSC lines to CTL in comparison to ESCs, iPSCs, and F9 teratocarcinoma cells. Major histocompatibility complex (MHC) class I molecules were not detectable by flow cytometry on these stem cell lines, apart from low levels on one maGSC line (maGSC Stra8 SSC5). However, using a quantitative real time PCR analysis H2K and B2m transcripts were detected in all pluripotent stem cell lines. All pluripotent stem cell lines were killed in a peptide-dependent manner by activated CTLs derived from T cell receptor transgenic OT-I mice after pulsing of the targets with the SIINFEKL peptide.
Pluripotent stem cells, including maGSCs, ESCs, and iPSCs can become targets for CTLs, even if the expression level of MHC class I molecules is below the detection limit of flow cytometry. Thus they are not protected against CTL-mediated cytotoxicity. Therefore, pluripotent cells might be rejected after transplantation by this mechanism if specific antigens are presented and if specific activated CTLs are present. Our results show that the adaptive immune system has in principle the capacity to kill pluripotent and teratoma forming stem cells. This finding might help to develop new strategies to increase the safety of future transplantations of in vitro differentiated cells by exploiting a selective immune response against contaminating undifferentiated cells.
This article was reviewed by Bhagirath Singh, Etienne Joly and Lutz Walter.
多能成体生殖系干细胞（maGSCs）代表了一种新的多能细胞类型，可从成年睾丸中的精原干细胞（SSCs）不经基因操作获得。与诱导多能干细胞（iPSCs）类似，它们可为多种疾病的新型移植疗法提供细胞移植来源。为了测试这些干细胞是否会被受体排斥，我们分析了maGSCs和iPSCs是否会成为细胞毒性T淋巴细胞（CTL）的靶标，或者它们是否像先前对胚胎干细胞（ESCs）所提出的那样受到保护。
我们观察到，无论有无白血病抑制因子和/或饲养细胞，maGSCs都能在长期培养中维持，并仍保留在免疫缺陷受体中形成畸胎瘤的能力。然而，它们在免疫健全的同种异体受体中被排斥，并且免疫反应控制了畸胎瘤的生长。我们将三个maGSC系与ESCs、iPSCs和F9畸胎癌细胞进行比较，分析了它们对CTL的敏感性。除了一个maGSC系（maGSC Stra8 SSC5）上有低水平表达外，通过流式细胞术在这些干细胞系上未检测到主要组织相容性复合体（MHC）I类分子。然而，使用定量实时PCR分析在所有多能干细胞系中都检测到了H2K和B2m转录本。在用SIINFEKL肽脉冲处理靶细胞后，所有多能干细胞系都被源自T细胞受体转基因OT-I小鼠的活化CTL以肽依赖性方式杀死。
多能干细胞，包括maGSCs、ESCs和iPSCs，即使MHC I类分子的表达水平低于流式细胞术的检测限，也会成为CTL的靶标。因此，它们不能免受CTL介导的细胞毒性作用。所以，如果呈现特定抗原且存在特定活化的CTL，多能细胞在移植后可能会通过这种机制被排斥。我们的结果表明，适应性免疫系统原则上有能力杀死多能和形成畸胎瘤的干细胞。这一发现可能有助于开发新策略，通过利用针对污染的未分化细胞的选择性免疫反应来提高未来体外分化细胞移植的安全性。
本文由Bhagirath Singh、Etienne Joly和Lutz Walter审阅。
