Cumulus cells of camel (Camelus dromedarius) antral follicles are multipotent stem cells

The mammalian ovary is a highly dynamic organ, in which proliferation and differentiation occur constantly during the entire life span, particularly in camels that are characterized by a follicular wave pattern and induced ovulation. Granulosa cells are the main cells of mature follicles. Two distinct cell types, namely, the mural and cumulus granulosa cells are distinguished on the basis of antral fluid increase. The multipotency of follicular fluid and the luteinizing cell were recently demonstrated. However, reports regarding the plasticity of cumulus cells are lacking. We obtained cumulus cells from cumulus-oocyte complexes and showed that camel cumulus cells expressed stem cell mRNA transcripts (POU5A1, KLF4, SOX2, and MYC) and were able to differentiate into other non-ovarian follicular cell types in vitro, such as neurons, osteoblasts, and adipocytes. In contrast, removal of the ooplasm (oocytectemy) showed no effect on cumulus cell proliferation and differentiation. This is the first report to identify an invaluable source of multipotent stem cells, which is routinely discarded during in vitro embryo production. The plasticity and transdifferentiation capability of camel cumulus cells definitely requires attention as it provides a cheap biological experimental model for basic research in stem cells and for understanding ovarian differentiation, both of which are relevant for use in regenerative medicine and tissue engineering in humans and animals.