Antler blood enhances the ability of stem cell-derived exosomes to promote bone and vascular regeneration.

Background: Bone marrow mesenchymal stem cells (BMSC)-derived exosomes (Exos) are important in promoting bone and vascular regeneration. Antler blood (ALB) is a valuable traditional Chinese medicine with potent regenerative effects. However, there is still a lack of clarity regarding the relationship between ALB and BMSC-Exos.

Methods: Primary BMSCs were isolated from SD Rats, and BMSC-derived Exos (BMSC-Exos) were harvested and identified accordingly. ALB was treated with the solution contained pepsin and hydrochloric acid to simulated gastrointestinal digestion in vitro. Furthermore, the liquid chromatography-mass spectrometry (LC-MS) was performed to determine the components of digested ALB. Moreover, ALB was utilized to intervene on BMSCs to produce specialized Exos (Exos-ALB), of which the angiogenesis functions were detected both in vitro and in vivo. For the potential mechanism, both high-throughput sequencing and proteomics were performed.

Results: The main components of ALB consist of amino acids and peptides. Both ALB and BMSC-Exos exhibited significant promotion of bone and blood vessel formation, respectively. Moreover, ALB and BMSC-Exos could increase the expression of BMP-2, RUNX2, and ALP, but reduce the Osteopontin (OPN) expression. Notably, Exos-ALB exhibited the strongest performance in these functions, whereas the presence of miR-21-5p inhibitor can partially counteract the effects of Exos-ALB. The proteomics reveal differential genes associated with bone minimization, angiogenesis, osteoblast differentiation, vesicle-mediated transport, and the Wnt signaling pathway.

Conclusion: ALB enhances the ability of BMSCs-derived Exos to promote bone and vascular regeneration, which may be related to the up-regulation of miR-21-5p.