将人类皮肤细胞转化为诱导多能干细胞需要植入相关基因，而这些外来基因有致癌等风险。美国科学家在最新一期《细胞》杂志上发表研究报告说，他们在上述转化完成后，首次成功地从所获得的诱导多能干细胞中移除这些基因，且保证其基本功能不受影响。
这项研究是美国白头生物医学研究所等机构的科学家完成的。他们利用病毒将“c－Myc”等4个基因植入人类皮肤细胞，将其转化为诱导多能干细胞。与此同时，他们使用一种基因编码技术，使得在基因序列中，外来基因的两端留存有特殊标志。转化完成后，他们再用一种名为“Cre”的酶识别这种标志，以此找到外来基因并将其移除。
外来基因被移除后的诱导多能干细胞仍然具备和其他干细胞类似的基本功能，但却避免了“c－Myc”等外来基因可能带来的癌变风险和其他潜在风险。
参与此项研究的科学家鲁道夫·耶尼施说，有研究者曾用老鼠细胞做过类似实验，但利用人类细胞成功进行上述试验在世界上还是首次。
此次研究所用的皮肤细胞来自帕金森氏症患者，通过上述方法培育出诱导多能干细胞后，又成功将其培育成为多巴胺神经元细胞，这是帕金森氏症患者大脑中所缺少的一种细胞。因此，相关成果有望为帕金森氏症的治疗研究带来福音。（生物谷Bioon.com）
生物谷推荐原始出处：
Cell,6 March 2009 doi:10.1016/j.cell.2009.02.013
Parkinson's Disease Patient-Derived Induced Pluripotent Stem Cells Free of Viral Reprogramming Factors
Frank Soldner1,4,Dirk Hockemeyer1,4,Caroline Beard1,Qing Gao1,George W. Bell1,Elizabeth G. Cook1,Gunnar Hargus3,Alexandra Blak3,Oliver Cooper3,Maisam Mitalipova1,Ole Isacson3andRudolf Jaenisch1,2,,
1 The Whitehead Institute, 9 Cambridge Center, Cambridge, MA 02142, USA
2 Department of Biology, Massachusetts Institute of Technology, 31 Ames Street, Cambridge, MA 02139, USA
3 Udall Parkinson Disease Research Center of Excellence, Center for Neuroredegeneration Research, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
Corresponding author
4 These authors contributed equally to this work
Summary
Induced pluripotent stem cells (iPSCs) derived from somatic cells of patients represent a powerful tool for biomedical research and may provide a source for replacement therapies. However, the use of viruses encoding the reprogramming factors represents a major limitation of the current technology since even low vector expression may alter the differentiation potential of the iPSCs or induce malignant transformation. Here, we show that fibroblasts from five patients with idiopathic Parkinson's disease can be efficiently reprogrammed and subsequently differentiated into dopaminergic neurons. Moreover, we derived hiPSCs free of reprogramming factors using Cre-recombinase excisable viruses. Factor-free hiPSCs maintain a pluripotent state and show a global gene expression profile, more closely related to hESCs than to hiPSCs carrying the transgenes. Our results indicate that residual transgene expression in virus-carrying hiPSCs can affect their molecular characteristics and that factor-free hiPSCs therefore represent a more suitable source of cells for modeling of human disease.
