OBJECTIVETo follow the fate of murine epidermal stem cells (ESCs) seeded in a syngeneic dermal equivalent implanted in vivo.

METHODSEmbryonic stem (ES) cells were induced in vitro to differentiate into ESCs. After stained with a fluorescent dye Hoechst 33342, these ESCs were seeded into a fibroblast-collagen-gelatin sponge complex, functioning as a dermal equivalent model, and implanted subcutaneously into 129/J mice, which were syngeneic to these stem cells. The fate of these cells was observed with HE staining, immunocytochemical staining or Van Gieson's staining.

RESULTSThese ESCs were clearly visible in the implant by fluorescent microscopy 3 weeks or longer after implantation. These cells remained viable, differentiated into hair follicle-like structure, glandular structure, and gave rise to additional structures displaying features resembling native dermis. A number of markers were expressed in the differentiated structures, including CD29 (integrin beta1 subunit) and cytokeratin 18 (CK18). No apparent rejection or severe side effects were observed at least during the 10 weeks following implantation.

CONCLUSIONNow that ESCs could survive in vivo in this dermal equivalent model, and differentiate into hair follicle-like structures as well as glandular structures, it is feasible to use these cells as seed cells in the study to fabricate dermal equivalent having the potential to develop dermal appendages.