Telmisartan impairs the in vitro osteogenic differentiation of mesenchymal stromal cells from spontaneously hypertensive male rats.

Telmisartan (TELM) is an angiotensin II (Ang II) type 1 receptor (Agtr1) antagonist, with partial agonism for Pparg, and has been shown to affect bone metabolism. Therefore, the aim of this study was to investigate the effects of TELM in the in vitro osteogenic differentiation of bone marrow-derived mesenchymal stromal cells (BMSC) from spontaneously hypertensive rats (SHRs). BMSC were obtained from male SHR, and the osteogenic medium (OM) was added to the cells concomitantly with TELM (0.005, 0.05, and 0.5 µM). Undifferentiated BMSC, in control medium (CM), showed an increased viability, while the addition of OM reduced this parameter, and TELM did not show cytotoxicity in the concentrations used. BMSC in OM had an alkaline phosphatase (ALP) activity peak at d10, which decreased at d14 and d21, and TELM reduced ALP at d10 in a dose-dependent manner. Mineralization was observed in the OM at d14, which intensified at d21, but was inhibited by TELM. Agtr1b was increased in the OM, and TELM inhibited its expression. TELM reduced Opn, Ocn, and Bsp and increased Pparg expression, and at the higher concentration TELM also increased the expression of adipogenic markers, Fabp4 and Adipoq. In addition, TELM 0.5 µM increased Irs1 and Glut4, insulin and glucose metabolism markers, known to be regulated by Pparg and to be related to adipogenic phenotype. Our data shows that TELM inhibited the osteogenic differentiation and mineralization of SHR BMSC, by favoring an adipogenic prone phenotype due to Pparg upregulation.

ß1-adrenergic receptor but not ß2 mediates osteogenic differentiation of bone marrow mesenchymal stem cells in normotensive and hypertensive rats.

The sympathetic nervous system regulates bone remodeling via adrenergic receptors on the surface of bone cells. Herein, we evaluated the role of beta-adrenergic receptors (ADRBs) in osteoblastic differentiation of bone marrow mesenchymal stem cells (BMSCs) derived from normotensive (Wistar) and spontaneously hypertensive rats (SHRs). BMSCs were cultured in a proliferation medium or osteogenic medium (OM). Cells cultured in OM were treated with carvedilol (Cv) or nebivolol (Nb).In OM, cell proliferation was decreased in both strains. In Wistar rats, Cv increased BMSC proliferation and increased alkaline phosphatase (ALP) activity in OM. Both Cv and Nb decreased ALP activity. In addition, Cv and Nb reduced mineral deposition in Wistar rats. Moreover, NB decreased mineralization in SHRs, exhibiting superior efficacy. In OM, cells from Wistar rats and SHRs showed Adrb1 and Adrb2 expression. On day 7, Nb, but not Cv, reduced Adrb1 levels in BMSCs from Wistar rats. Nb inhibited Adrb2 in both strains, and Cv demonstrated superior efficacy. In BMSCs from Wistar rats, both antagonists inhibited Runx2, osterix, and ß-catenin; in SHRs, Cv and Nb inhibited only osterix. Cv decreased osteopontin (Opn), osteocalcin (Ocn), and bone morphogenetic protein (Bmp2) in BMSCs from Wistar rats, inhibiting only Opn in SHRs. Nb effectively inhibited Ocn, bone sialoprotein, and Bmp2, but not Ocn, in BMSCs from Wistar rats, while suppressing Opn in BMSCs from SHRs. In addition, Nb inhibited p-p38 in BMSCs from Wistar rats; Cv inhibited p-p38 in BMSCs from SHRs. In Wistar rats, both antagonists inhibited p-ERK and reduced p-JNK; Cv reduced these expressions only in SHRs. In conclusion, ADRB1, but not ADRB2, could be involved in the osteogenic differentiation of BMSCs from Wistar rats and SHRs. The high ADRB1 expression might suppress the effect of ADRB2 on BMSCs.