Cortical Bone Stem Cell-Derived Exosomes Alter Wound Healing Response in Cardiac Fibroblasts and Cardiac Endothelial Cells

Rationale: Post-myocardial infarction (MI) results in remodeling that leads to the development of heart failure. We have previously seen improvements in post-MI wound healing and scar formation as a result of administration of cortical bone stem cell derived exosomes (CBSC exosomes). Objectives: We sought to further elucidate the mechanism through which CBSC exosomes improved scar formation and altered wound healing through in vitro experimentation. We continued to explore the unique characteristics of CBSC exosomes in order to understand why they have anti-fibrotic effects. Methods and Results: We performed migration assays on cardiac endothelial cells and cardiac fibroblasts, and saw alterations in cell migration in both cell types upon treatment with mCBSC CM and mCBSC exosomes. We discovered that migration of CECs was reduced by 20% under the influence of mCBSC CM and mCBSC exosomes, but rescued when exosomes were removed from mCBSC CM. We discovered that the removal of exosomes from mCBSC CM slowed cardiac fibroblast migration by 40%. We saw a decrease in the quantity of pro-fibrotic mRNA in cardiac endothelial cells and cardiac fibroblasts after treatment with mCBSC exosomes. Adult cardiac endothelial cell mRNA levels of VEGFA, Col4A1, and VCAM were reduced nearly two fold from control untreated cell levels following mCBSC exosome treatment. Adult cardiac fibroblast Col1A1, Col3A1, Col4A1, and MMP2 mRNA levels were reduced one-fold from control untreated cell levels following mCBSC exosome treatment. Conclusions: Our findings show that the wound healing induced by CBSC treatment post-MI involves a mechanism altering the migration of endothelial cells, sustaining the migratory capabilities of fibroblasts, and decreasing the production of pro-fibrotic mRNA in cardiac fibroblasts and cardiac endothelial cells.