一项新研究表明，未受精卵子可作为干细胞的一个可靠来源，从而避免了胚胎来源的干细胞可能引起的伦理问题。
胚胎干细胞已被证明是多种疾病的有效疗法。但一些人反对利用胚胎干细胞，因为胚胎干细胞的获得是以破坏本可以发育为人的胚胎为代价。这些伦理问题阻碍了胚胎干细胞疗法的研究，科学家因而积极寻找其它可能的干细胞来源。
为了避过使用胚胎干细胞所带来的伦理问题，Wake Forest大学的Kent E. Vrana博士和他的同事研究了雌猴未受精卵子衍生的干细胞。有关研究结果发表在最新一期的《美国科学院院刊》（PNAS）的网络版上。
研究人员发现，经过两年多的生长和发育这些未受精卵子产生的干细胞的外表和活动与胚胎衍生的干细胞一样。而且，当用适当的化学物质处理时，这些细胞能分化为各种细胞类型，如心肌细胞和神经细胞等，这种多能性对于其治疗价值至为重要。
“干细胞分化为其它细胞类型的能力都是以胚胎干细胞作为参照。”文章的高级作者、密歇根州立大学的Jose B. Cibelli博士称。“当然，我们必需检查这些未受精卵子衍生的干细胞能否治愈动物疾病，然后才能下结论这两种细胞类型是可互换的。”他还指出这样的实验已开始进行。
美国法律禁止政府资金用于胚胎干细胞研究，Cibelli 指出。但他说，宗教团体可以接受使用未受精卵子作为干细胞的来源，因为未受精卵子不会发育为人。
Nonhuman primate parthenogenetic stem cells
Kent E. Vrana *, Jason D. Hipp *, Ashley M. Goss *, Brian A. McCool *, David R. Riddle , Stephen J. Walker , Peter J. Wettstein , Lorenz P. Studer ¶, Viviane Tabar ¶, Kerrianne Cunniff ||, Karen Chapman **, Lucy Vilner **, Michael D. West **, Kathleen A. Grant *, and Jose B. Cibelli ¶
*Center for Neurobehavioral Study of Alcohol, Department of Physiology and Pharmacology and Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC 27157; Department of Microbiology and Immunology, Mayo Clinic, Rochester, MN 55905; ¶Sloan- Kettering Cancer Center, New York, NY 10021; **Advanced Cell Technology, Worcester, MA 01605; ||Millennium Pharmaceuticals, Cambridge, MA 02139; and Department of Animal Science-Physiology, Michigan State University, East Lansing, MI 48824
Parthenogenesis is the biological phenomenon by which embryonic development is initiated without male contribution. Whereas parthenogenesis is a common mode of reproduction in lower organisms, the mammalian parthenote fails to produce a successful pregnancy. We herein describe in vitro parthenogenetic development of monkey (Macaca fascicularis) eggs to the blastocyst stage, and their use to create a pluripotent line of stem cells. These monkey stem cells (Cyno-1 cells) are positive for telomerase activity and are immunoreactive for alkaline phosphatase, octamer-binding transcription factor 4 (Oct-4), stage-specific embryonic antigen 4 (SSEA-4), tumor rejection antigen 1-60 (TRA 1-60), and tumor rejection antigen 1-81 (TRA 1-81) (traditional markers of human embryonic stem cells). They have a normal chromosome karyotype (40 + 2) and can be maintained in vitro in an undifferentiated state for extended periods of time. Cyno-1 cells can be differentiated in vitro into dopaminergic and serotonergic neurons, contractile cardiomyocyte-like cells, smooth muscle, ciliated epithelia, and adipocytes. When Cyno-1 cells were injected into severe combined immunodeficient mice, teratomas with derivatives from all three embryonic germ layers were obtained. When grown on fibronectin/laminin-coated plates and in neural progenitor medium, Cyno-1 cells assume a neural precursor phenotype (immunoreactive for nestin). However, these cells remain proliferative and express no functional ion channels. When transferred to differentiation conditions, the nestin-positive precursors assume neuronal and epithelial morphologies. Over time, these cells acquire electrophysiological characteristics of functional neurons (appearance of tetrodotoxin-sensitive, voltage-dependent sodium channels). These results suggest that stem cells derived from the parthenogenetically activated nonhuman primate egg provide a potential source for autologous cell therapy in the female and bypass the need for creating a competent embryo.
Related article:Kent E. Vrana, Jason D. Hipp, Ashley M. Goss, Brian A. McCool, David R. Riddle, Stephen J. Walker, Peter J. Wettstein, Lorenz P. Studer, Viviane Tabar, Kerrianne Cunniff, Karen Chapman, Lucy Vilner, Michael D. West, Kathleen A. Grant, and Jose B. Cibelli
Nonhuman primate parthenogenetic stem cells
PNAS published September 22, 2003, 10.1073
