Cell：科学家发现能修复受损肌肉的干细胞

生物谷

    科学家在小鼠模式中证实，大约有10％的肌肉卫星细胞具有干细胞自我修复新生、增生的能力，使受损的肌肉细胞经过发育的过程而变为成熟的肌细胞，此研究发表于6月1日的Cell期刊。由霍华休斯医学院（Howard  Hughes  Medical  Institute）的Michael  Rudnicki博士主导研究进行。

    骨骼肌纤维被嵌在一个由胶原蛋白所组成的管子内，每条显微上都含有数百个卫星细胞，这些细胞座落在肌肉纤维及胶原蛋白之间，当肌肉受伤或受到压力，这些细胞就会被活化，开始进行修复工作，在细胞分裂及发育的同时，也会衍生出另一群子代的卫星细胞，以备不时之需。

    Rudnicki博士表示："成年老鼠以及成年人的肌肉都含有一群肌肉卫星细胞，长久以来科学家们都怀疑这群细胞的主要功能可能是进行肌肉组织的修复。"只是不知道这些卫星细胞是否为真正的干细胞，于是，研究团队便以小鼠的卫星细胞作为研究对象。

    研究人员以Myf5基因作为指标，因为Muf5会在成熟的肌细胞中被表现，结果发现大约有10%的卫星细胞不表达Myf5，而在不表达Myf5的细胞中，有时也会发现有Myf5-positive的细胞，有点像是细胞不同发育程度的区别。当卫星细胞不表达Myf5而分裂时，其中一个子细胞会与肌显微接触，另一个则与胶原蛋白接触，两个子细胞开始了它们截然不同的命运，与肌纤维接触的细胞会表现Myf5，进而发育为成熟的记西班；而另一个与胶原蛋白接触的细胞则无法表现Myf5，则变为新的卫星细胞。（生物谷援引华文生技网）

原始出处:

Cell, Vol 129, 999-1010, 01 June 2007

Article

Asymmetric Self-Renewal and Commitment of Satellite Stem Cells in Muscle

Shihuan Kuang,¹ Kazuki Kuroda,¹ Fabien Le Grand,¹ and Michael A. Rudnicki¹,²,

¹The Sprott Center for Stem Cell Research, Ottawa Health Research Institute, Molecular Medicine Program, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada
²University of Ottawa, Department of Medicine, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada

Corresponding author
Michael A. Rudnicki
mrudnicki@ohri.ca

Satellite cells play a central role in mediating the growth and regeneration of skeletal muscle. However, whether satellite cells are stem cells, committed progenitors, or dedifferentiated myoblasts has remained unclear. Using Myf5-Cre and ROSA26-YFP Cre-reporter alleles, we observed that in vivo 10% of sublaminar Pax7-expressing satellite cells have never expressed Myf5. Moreover, we found that Pax7⁺/Myf5⁻ satellite cells gave rise to Pax7⁺/Myf5⁺ satellite cells through apical-basal oriented divisions that asymmetrically generated a basal Pax7⁺/Myf5⁻ and an apical Pax7⁺/Myf5⁺ cells. Prospective isolation and transplantation into muscle revealed that whereas Pax7⁺/Myf5⁺ cells exhibited precocious differentiation, Pax7⁺/Myf5⁻ cells extensively contributed to the satellite cell reservoir throughout the injected muscle. Therefore, we conclude that satellite cells are a heterogeneous population composed of stem cells and committed progenitors. These results provide critical insights into satellite cell biology and open new avenues for therapeutic treatment of neuromuscular diseases.