OBJECTIVETo study the cellular phenotype conversion of human mesenchymal stem cells (MSCs) cocultured with human sweat gland cells (SGCs) and the contribution of extracellular signal-regulated kinase (ERK) pathway in the process.

METHODSMSC and SGC were isolated, amplified , and identified with two-step immunohistochemistry method. The primary SGCs were heat-shocked at 47 degrees C. Then the supernatants were collected immediately and 24hr later. The 3rd passage of MSCs were divided into control, SGC supernatant (cells were cultured in DMEM/F12 medium containing 30% SGC supernatant), SGC supernatant + EGF (cells were cultured in DMEM/F12 medium containing 30% SGC supernatant and 50 microg/L EGF), and SGC supernatant + PD98059 (cells were cultured in DMEM/F12 medium containing 30% SGC supernatant and 10 micromol/L PD98059) groups. The positive expression of CK7and CEA in MSCs were detected on the 7th post-stimulation day (PSD) by flow cytometry. The expression of ERK and phosphorylated ERK were determined with Western blotting.

RESULTSThe positive expression rate of CK7 and CEA was (5.76 +/-0.10)%, (2.01 +/- 0.09)% in SGC supernatant group; (7.31 +/- 0.21)% and (7.27 +/- 0.12)% in SGC supernatant + EGF group; and (1.63 +/- 0.11)%, (1.54 +/- 0.07)% in SGC supernatant + PD98059 group; they were all obviously higher than that in control group (P < 0.01). Moreover, ERK expression was observed in all groups. The expression of pERK in SGC supernatant + EGF group was higher than that in SGC supernatant group, but almost no expression of pERK was found in the SGC supernatant + PD98059 and control groups.

CONCLUSIONIndirect coculture of MSCs with SGCs can induce the phenotype conversion of MSCs through ERK pathway.