Scientists have succeeded in growing the special stem cellsthat direct the sperm production process outside of the body. Themethod has only been proven in mice, but researchers hope itmay apply to humans. The ability to culture these cells is an initialstep that could lead in multiple directions, including correcting thesperm of infertile men, genetic engineering in humans (if ethicallyacceptable), and generating embryonic stem cells without thecontroversial step of creating an embryo. This ability would makeit possible to swap mutated genes in cells for normal or improvedones. In the case of infertile men, for example, the sperm productioncells would be removed, genetically treated, and put backin the testis, where they should produce normal sperm.
Researchers also hope to learn how to make the cells producesperm outside the body. The genetically altered sperm could thenbe used directly for in vitro fertilization. This technique would beuseful in animal breeding; however, the ethics of human usage isstill a matter of debate.
This technique might also be used to solve the controversialissue of embryonic stem cells. The sperm production cells havemany of the same characteristics as embryonic stem cells and areonly a couple of developmental steps away from them.Researchers hope to be able to "walk them backward" to becomeembryonic stem cells. These could then be converted into thespecialized cell types needed to repair damaged organs.