Abstract 3459: Genetic Expression Analysis Reveals Persistence of a Gender-Specific and Dynamic Oct4+ Cell Population in Skin of Adult Female Mice
The Pou-domain transcription factor Oct4 is a critical regulator of pluripotency in embryonic and induced pluripotent stem (iPS) cells. Oct4 expression has been reported in somatic stem cells from bone marrow and the heart. Since Oct4 might be a critical regulator of somatic stem cell pluripotency we have employed a genetic, high-fidelity reporter strategy to determine the temporo-spatial expression of Oct4 in adulte mice. Postnatal Oct4 expression was determined in Oct4-eGFP reporter mice by flow cytometry at an juvenile, pubertal or adult age (see table⇓, n=9–28), for hearts and skin the response to injury was also evaluated. The fidelity of the Oct4-GFP reporter strain was confirmed by immunofluorescence confocal microscopy and by RT-PCR. No GFP+ cells were detected in bone marrow or spleen, nor in the atria or ventricles of the myocardium under baseline and ischemic conditions. However, juvenile testis showed high numbers of GFP+ cells, which decreased significantly over time to a level of appr. 308 GFP+ cells/animal in adulthood. In addition, while levels of GFP+ cells in skin of male adult mice were very low and did not change after wound injury, skin levels in adult females were higher at baseline and increased robustly after wound injury (wound, GFP+/500.000: male 3.2±3.2 vs. female 13.2±9, n=9, p<0.05), to levels approximately 50% of Oct4 frequency in testis. In situ analysis revealed the existence of GFP+ niches morphologically distinct from hair follicles. To characterize the gene expression profile and plasticity of the postnatal Oct4+ population GFP+ cells were isolated via FACS-sorting from juvenile testis and analyzed (data will be presented). Genetic reporter studies reveal no evidence for Oct4+ cells in bone marrow or heart, but show persistence of cells in male testis and, unexpectedly, in female skin. These findings suggest an important gender difference in regenerative biology.