| Budget Amount *help |
¥3,920,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
1) Establishement and maintenance of mouse spermatogonial stem cell lines:
Three transgenic mice (Tg) lines were used; ubiquitous GFP expressing Tg, Acrosin-GFP Tg expressing GFP at mid-meiosis onward, and Haspin-GFP Tg expressing GFP at haploid stage. Spermatogonial stem cell lines, also called germline stem cells (GS cells) were established from these three Tg mice.
2) Ex vivo spermatogenesis from GS cells:
In order to induce spermatogenesis form GS cells in vitro, GS cells of Acrosin-GFP Tg and Haspin-GFP Tg were cultured in various conditions such as different feeder cells. So far, however, GFP expression, marker of meiosis, was not detected in our experience.
In our trial for ex vivo spermatogenesis, we have found that seminiferous tubules can be reconstituted de novo from dissociated fetal or neonatal testis cells in the subcutis of nude mice. We took advantage of the reconstitution ability of immature testis cells to get GS cells integrated in them. Those GS cells underwent differentiation up to spermatid (haploid) stage which was used for insemination to end up produce healthy pups.
3) Organ culture of testis tissues:
Our experience of cell culture for spermatogenesis was rather discouraging and it becomes evident for us to convert to another strategy. Using acrosin- and haspin-GFP Tg mice testis tissue, 3-14 days old, we evaluated organ culture method. When 7 or more days old pups were used, haspin-GFP become positive in a culture condition. Basic favorable culture condition includes 32℃, 10% fetal bovine serum, vitamins, and so on. Further improvement could be possible in near future.
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