Background and Hypothesis: Somatic cell nuclear transfer (SCNT) has been developed to reprogram differentiated cells into pluripotent cells. In SCNT, reprogramming is induced by introducing somatic DNA into an enucleated oocyte. We thus hypothesized that oocyte-derived factors could direct the reprogramming of somatic cells into pluripotent cells.

Methods: Mesenchymal stromal cells (MSCs) were isolated from murine bone marrow. MSCs were characterized by flow cytometry and in vitro differentiation into osteogenic and adipogenic lineages. MSCs were co-cultured with ovarian extract obtained after superovulation of female Swiss albino mice. Proliferation of cultured MSCs was measured by MTT assay, and the expression of pluripotency markers and epithelial-mesenchymal markers was measured by quantitative real-time PCR analysis, flow cytometry and confocal immunofluorescence staining.

Results: Co-culture of MSCs with ovarian extract caused significant increase in the proliferation rate of MSCs compared to control MSCs cultured alone. MSCs co-cultured with ovarian extract expressed Oct-4 and NANOG proteins, and showed significant increase in mRNA of the pluripotency markers Oct-4, NANOG and Rex1. A mesenchymal to epithelial transition (MET) phenotype change was also observed, and measured by an increase in EpCam expression and decrease in ZEB1 expression. This study provides evidence that ovarian extract contains factors that support survival and proliferation of MSCs, and upregulate pluripotency.