Soluble yerba mate (Ilex Paraguariensis) extract enhances in vitro osteoblastic differentiation of bone marrow-derived mesenchymal stromal cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Yerba mate (Ilex paraguariensis) consumption has been associated with beneficial effects on bone health. AIM OF THE STUDY: The purpose of this study was to evaluate the mechanism by which soluble yerba mate (SYM) stimulates osteoblast differentiation of bone marrow-derived mesenchymal stromal cells (BM-MSCs). MATERIALS AND METHODS: BM-MSCs from male Wistar rats were induced towards osteoblastic differentiation with different concentrations of SYM (10, 20, and 50 µg/mL). Osteoblastic differentiation was evaluated by measuring proliferation rates, alkaline phosphatase activity, MMP-2 activity, mineralization, and gene expression of Runx2, Osterix, ß-catenin (Catnb), collagen type I (Col1a1), osteopontin (Opn), osteocalcin (Ocn), bone sialoprotein (Bsp), bone morphogenetic protein-2 (Bmp2), osteoprotegerin (Opg), and Rankl. We also analyzed cytokine production and MAP kinase pathways. RESULTS: SYM (10 µg/mL) did not show a cytotoxic effect and induced a slight increase in ALP activity; however, a great increase in mineralization was observed. SYM was also able to reduce TNF-α and IL-10 production; increase the expression of transcription factors Runx2, Osterix, and Catnb; and increase matrix proteins Opn, Bsp, Ocn, and Bmp2. We also observed a decrease in intracellular signaling of ERK, JNK, and p38 MAPK, which seemed to be related to the SYM response. CONCLUSIONS: Together, these results help to explain the promoting effect on osteoblast differentiation produced by a low SYM concentration. However, a higher SYM concentration presented deleterious effects, including cytotoxicity, decreased ALP activity, increased cytokine production, decreased bone marker gene expression, increased MAPK signaling, and significant mineralization reduction. In conclusion, our results suggest a concentration-specific direct stimulatory effect of SYM on osteoblastic differentiation in vitro.

Chronic high glucose and insulin stimulate bone-marrow stromal cells adipogenic differentiation in young spontaneously hypertensive rats.

We evaluated whether genetic predisposition is sufficient to induce changes due to chronic high glucose (HG; 25 mmol/L) in the presence or absence of insulin (HGI; 10 µg/ml) on osteogenic differentiation and markers in bone-marrow mesenchymal stem cells (BMSCs) from young Wistar (WBMSCs) and spontaneous hypertensive rats (SBMSCs) without hypertension. HG suppressed osteogenic differentiation in both the strains, observed by mineralization inhibition and decreased levels of the osteogenic markers Runx2, osterix, osteopontin, and bone sialoprotein, compared to osteogenic medium (OM) cells. In WBMSCs, the effects of HG were associated with the down regulation of ERK1/2 and up regulation of p38 activities; however, HGI did not revert the effects of HG on MAPK activities. Moreover, HG did not affect MAPK signaling in SBMSCs compared to that in OM. HGI increased mineralization in WBMSCs compared to that in OM, but not in SBMSCs. High expression of peroxisome proliferator-activated receptor-gamma and glucose transporter type 4 in OM could be related with the predisposition to adipogenic differentiation noted in SBMSCs and was confirmed by emergence of adipocyte-like cells by HGI treatment. Downregulation of p38 and upregulation of JNK activities were observed in both BMSCs treated with HGI compared to those treated by HG. Ma (osmotic control) also suppressed osteogenic differentiation in both the strains. In conclusion, we demonstrated that SBMSCs from young spontaneous hypertensive rats, without hypertension but with genetic and epigenetic predisposition, exhibited decreased osteoblastic differentiation under HG and HGI did not revert the effects of HG in SBMSCs but increased adipogenic differentiation.

Osteogenic markers are reduced in bone-marrow mesenchymal cells and femoral bone of young spontaneously hypertensive rats.

AIMS: Spontaneously hypertensive rats (SHR) and normotensive rats (W) has significant changes in bone metabolism. The purpose of this study was to investigate whether, the genetic predisposition, is sufficient to induce changes in the osteoblast differentiation and osteogenic markers in the BMSCs or in the femoral bone. For this we use young SHR rats without hypertension, but, with genetic predisposition in compared with young W. MAIN METHODS: BMSCs were cultured in a proliferation medium (MEM) or osteogenic medium. Osteogenic differentiation was analyzed by proliferation, total protein, alkaline phosphatase, mineralization, and the mRNA expression of RUNX-2, ß-cathenin, osterix, bone morphogenetic protein-2(BMP-2), osteocalcin (OCN), bone sialoprotein (BSP), collagen type I (Col I), and osteopontin (OPN). KEY FINDINGS: Osteoblast differentiation in SHR BMSCs (SHRC) had an increased proliferation compared with W BMSCs (WC). After osteogenic induction, there was greater reduction in proliferation in SHR (SHROM) than in W, in the same condition (WOM). On day 7, although no significant difference in the ALP activity was observed between SHROM and WOM, poor mineralization and osteoblast differentiation was noted in SHROM. The Osterix and ß-catenin are involved in the reduced osteoblast differentiation in SHROM. The decreased expression of osteoblast-associated proteins such as OCN, BSP, COL I and OPN revealed poor quality of extracellular matrix (ECM) in SHROM. In the femoral bone, the immunostaining of COL1, BALP, OPN and OCN in SHR was decreased compared with the W. TRAP-positive immunoreactions were observed in major extension in the SHR femur. SIGNIFICANCE: This study is the first to compare osteoblast differentiation in vitro and femoral bone from SHR and W rats. Our results demonstrated that young SHR (4weeks old), without hypertension, but with genetic predisposition, had alterations in osteoblast differentiation of BMSCs and in the femoral bone when compared with their progenitor strain, W.