期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2005
卷号：102
期号：40
页码：14302-14307
DOI：10.1073/pnas.0506970102
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Self-renewal of spermatogonial stem cells (SSCs) is the foundation for maintenance of spermatogenesis throughout life in males and for continuation of a species. The molecular mechanism underlying stem cell self-renewal is a fundamental question in stem cell biology. Recently, we identified growth factors necessary for self-renewal of mouse SSCs and established a serum-free culture system for their proliferation in vitro. To determine whether the stimulatory signals for SSC replication are conserved among different species, we extended the culture system to rat SSCs. Initially, a method to assess in vitro expansion of SSCs was developed by using flow cytometric analysis, and, subsequently, we found that a combination of glial cell line-derived neurotrophic factor, soluble glial cell line-derived neurotrophic factor-family receptor {alpha}-1 and basic fibroblast growth factor supports proliferation of rat SSCs. When cultured with the three factors, stem cells proliferated continuously for >7 months, and transplantation of the cultured SSCs to recipient rats generated donor stem cell-derived progeny, demonstrating that the cultured stem cells are normal. The growth factor requirement for replication of rat SSCs is identical to that of mouse; therefore, the signaling factors for SSC self-renewal are conserved in these two species. Because SSCs from many mammals, including human, can replicate in mouse seminiferous tubules after transplantation, the growth factors required for SSC self-renewal may be conserved among many different species. Furthermore, development of a long-term culture system for rat SSCs has established a foundation for germ-line modification of the rat by gene targeting technology.
