Aromatase activity of human mesenchymal stem cells is stimulated by early differentiation, vitamin D and leptin

Abstract

Human mesenchymal stem cells (hMSCs) are multipotent cells present in bone marrow, which differentiate into osteoblasts and adipocytes, among other lineages. Oestrogens play a critical role in bone metabolism; its action may affect the adipocyte to osteoblast ratio in the bone marrow. In hMSCs, oestrogens are synthesized from C19 steroids by the enzyme aromatase cytochrome P450. In this study, we assessed whether aromatase enzymatic activity varied through early osteogenic (OS) and adipogenic (AD) differentiation. Also, we studied the effect of leptin and 1,25 dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ) on aromatase cell activity. Finally, we analysed whether conditions that modify oestrogen generation by cells affected hMSCs differentiation. For these purposes, hMSCs derived from postmenopausal women (65-86 years old) were cultured under basal, OS or AD conditions, in the presence or the absence of leptin and 1,25(OH) 2 D 3 . Aromatase activity was measured by the tritiated water release assay and by direct measurement of steroids synthesized from 3 H-labelled androstenedione or testosterone. Our results showed that different OS and AD patterns of aromatase activity developed during the first period of differentiation (up to 7 days). A massive and sharp surge of aromatase activity at 24 h characterized early OS differentiation, while increased but constant aromatase activity was increased through adipogenesis. Both leptin and vitamin D increased aromatase activity during osteogenesis, but not during adipogenesis; finally, we showed that favourable aromatase substrates concentration restrained MSCs adipogenesis but improved osteogenesis. Thus, it could be inferred that a high and early increase of local oestrogen concentration in hMSCs affects their commitment either restraining AD or facilitating OS differentiation, or both.

Proliferation and differentiation of human adipocyte precursor cells: Differences between the preperitoneal and subcutaneous compartments

“…Cells were kept in differentiation medium for 4, 7, and 11 days, replacing it every 2 days [Shahparaki et al, 2004;Pino et al, 2006]. …”

Marrow Fat and Bone: New Insights from Mice and Humans

“…The skeletal response to falling estrogen levels has also been demonstrated in vitro and in vivo. In the former, in human MSCs, reciprocal estrogen regulation of osteogenic and adipogenic differentiation has been reported [84,85]. In the latter, bone biopsy samples from postmenopausal women revealed that estrogen replacement was associated with markedly reduced adipocytes compared to women without estrogen replacement (Khosla, personal communication).…”

Uticaj estrogena na pojavu temporomandibularnih disfunkcija

“…Za ekstragonadalna mjesta sinteze estrogena se smatraju: masno tkivo, mozak, koža, hrskavica i kost. Bez obzira na malu ukupnu količinu lokalno stvorenog estrogena ne može se zanemariti njegov funkcionalni značaj [29]. Potvrđeno je da kostohondralni hondrociti kod zečeva stvaraju estradiol lokalno [30] .…”