In vitro and in vivo differentiation of induced pluripotent stem cells into male germ cells.

The introduction of induced pluripotent stem cell (iPSC) lines has been a breakthrough in the field of stem cell research. However, the extent of pluripotency among those cell lines tends to be variable due to their different epigenetic signatures. Mouse iPS cell line 4.1 has been established via retroviral transfer of human transcription factors Oct4, Sox2, Klf4, and c-Myc; the germline competence of this line has not been determined. In the present study, we induced the differentiation of miPS-4.1 cells into male germ cells, in vivo and in vitro. In the in vitro model, the behavior of miPS-4.1 cells was identical to that of differentiating mouse embryonic stem cells (ESCs). We obtained primordial germ cell-like cells (PGC-LC) that were positive for alkaline phosphatase (AP) activity. In continuous culture, these cells expressed pluripotent marker Oct4 and male germline markers C-kit and MVH. For our in vivo model, miPS-4.1 cells were co-transplanted with neonatal testicular cell suspension. We observed ectopically reconstituted seminiferous tubule structures, in which the miPS-4.1 cells were homing and developing. In conclusion, we successfully induced the differentiation of miPS-4.1 cells into male germ cells, albeit their epigenetic characteristics. Our study provides a system to examine the mechanisms of male germ cell development and might help to supply an effective treatment for male infertility in the future.

Cai H ，Xia X ，Wang L ，Liu Y ，He Z ，Guo Q ，Xu C ... -  《-》

[Induction and characterization of induced pluripotent stem (iPS) cells: a review].

Cheng D ，Lei L ，Lu Z ，Li Z ，Wang H ... -  《-》

Direct Reprogramming of Human Primordial Germ Cells into Induced Pluripotent Stem Cells: Efficient Generation of Genetically Engineered Germ Cells.

Bazley FA ，Liu CF ，Yuan X ，Hao H ，All AH ，De Los Angeles A ，Zambidis ET ，Gearhart JD ，Kerr CL ... -  《-》

Adenoviral gene delivery can reprogram human fibroblasts to induced pluripotent stem cells.

Zhou W ，Freed CR 《-》

The timing of retroviral silencing correlates with the quality of induced pluripotent stem cell lines.

Induced pluripotent stem (iPS) cells can be generated from somatic cells by introducing the four transcription factors Oct4, Sox2, Klf4, and c-Myc. Given that iPS cell technology may be useful for medical applications, the quality of iPS cells needs to be maintained during prolonged cultivation. However, it is unclear whether there are any differences in stability among different iPS clones. We infected mouse embryonic and adult fibroblasts with retroviruses encoding Oct4, Sox2, Klf4, c-Myc, and green fluorescent protein (GFP). We obtained embryonic stem (ES) cell-like colonies with silenced retroviral transgenes and divided these colonies into two groups: ES cell-like colonies that underwent retroviral silencing (i) on around day 14 (called early iPS) or (ii) on around day 30 (called late iPS), after infection. We compared morphology, proliferation efficiency, pluripotency marker expression, and karyotype between early iPS and late iPS cells. Early iPS cells were more stable than late iPS cells. At passage 20, most of the early iPS clones maintained ES cell-like morphology, expressed pluripotency markers, and showed proliferation efficiency similar to ES cells. Furthermore, early iPS clones derived from both embryonic and adult fibroblasts gave rise to chimeras and could show germ line competency. In contrast, late iPS clones tended to lose their ES cell-like morphology and normal karyotype in prolonged culture. Our results provide useful information on the efficient derivation of stable iPS cells that may be useful for germline transmission in mouse. This study suggests that early completion of full reprogramming allows for superior iPS cell generation.

Okada M ，Yoneda Y 《-》