The Synergic Effect of Terpenoid and Steroidal Saponins Can Improve Bone Healing, by Promoting the Osteogenic Commitment of Adipose Mesenchymal Stem Cells: An In Vitro Study

Bone regeneration involves several biological processes that consistently impact the quality of tissue healing. An important step consists of the local recruitment and differentiation of mesenchymal stem cells that migrate in the site to regenerate from bone marrow. Mesenchymal stem cells (MSCs) may be pushed towards osteogenic commitment by specific substances, often naturally present in plants. Yunnan Baiyao (YB) is a Chinese herbal medicine, mainly working through the synergic effect of terpenoid and steroidal saponins. YB is well known for its numerous biomedical effects, including the ability to favor improved bone tissue healing. In our in vitro study, we used adipose mesenchymal stem cells (ADSCs) as a study-model: We selected samples to harvest and isolate ADSCs and investigate their viability; moreover, we performed bone-related gene expression to evaluate the differentiation of MSCs. To confirm this behavior, we analyzed alkaline phosphate activity and calcium deposition, with ADSCs cultured in basal and osteogenic media, with YB at different concentrations in the medium, and at different time-points: 7, 14 and 21 days. Our results indicate that the synergic effect of terpenoid and steroidal saponins slightly favor the late ADSCs differentiation towards the osteoblasts phenotype. In osteogenic committed cells, the treatment with the lower dose of YB promoted the up-regulation of the alkaline phosphatase gene (ALPL) at day seven and 14 (p < 0.01); at day 21, the alkaline phosphatase (ALP) activity showed a slight increase, although in basal condition it maintains low rates. We assume that such molecular synergy can promote the osteogenic commitment of adipose mesenchymal stem cells, thus improving the timing and the quality of bone healing.