Estrogen deficiency does not decrease the in vitro osteogenic potential of rat adipose-derived mesenchymal stem cells

Osteoporosis due to estrogen deficiency is an increasing bone health issue worldwide: new strategies are being studied for regenerative medicine of bone pathologies in these patients. The most commonly used cells for tissue engineering therapy are the bone marrow mesenchymal stem cells (BMSCs), but they might be negatively affected by aging and estrogen deficiency. Besides the general advantages of adipose-derived mesenchymal stem cells (ADSCs) over BMSCs, ADSCs also seem to be less affected by aging than BMSCs, but in the literature, little is known about ADSCs in estrogen deficiency. The present study investigated the in vitro behavior of ADSCs, isolated from healthy (SHAM) and estrogen-deficient (OVX) rats. Phenotype, clonogenicity, viability, and osteogenic differentiation, at both cellular and molecular levels, were evaluated with or without osteogenic stimuli. Pro-inflammatory cytokines, growth factors, and adipogenic differentiation markers were also analyzed. There were no significant differences between OVX and SHAM ADSCs in some analyzed parameters. In addition, clonogenicity, osteopontin (Spp1) gene expression, alkaline phosphatase (ALP) activity at 2 weeks of culture, total collagen (COLL), osteocalcin (Bglap) gene expression and production, and matrix mineralization were significantly higher in OVX than in SHAM ADSCs. Besides the increase in some osteogenic markers, peroxisome proliferator-activated receptor gamma (Pparg) gene was also more expressed in OVX in osteogenic medium, with a concomitant estrogen receptor 1 (Esr1) gene expression decrease. These results underlined that ADSCs were not affected by estrogen deficiency in an osteogenic microenvironment.