Osteoimmune Modulation and Guided Osteogenesis Promoted by Barrier Membranes Incorporated with S-Nitrosoglutathione (GSNO) and Mesenchymal Stem Cell-Derived Exosomes.

The use of polycaprolactone (PCL) for bone defects in a clinical setting is limited due to a lack of bioactivity. Exosomes derived from mesenchymal stem cells (MSCs) have an important immunoregulatory potential and together with S-nitrosoglutathione (GSNO) they possess therapeutic potential for bone regeneration. In this study, PCL was modified with GSNO and MSC-derived exosomes and the impact on macrophages and osteogenes is evaluated. MSC-derived exosomes exhibited a cup-shaped morphology and were internalized by macrophages and human bone marrow-derived mesenchymal stromal cells (hBMSCs). The pattern of internalization of scaffold-immobilized exosomes was similar in RAW264.7 cells and hBMSCs after 4h and 24h of co-culture. Assessment of macrophage morphology under inflammatory conditions by scanning electronic microscopy (SEM) and confocal microscopy demonstrated macrophages were significantly elongated and expression of pro-inflammatory genes markedly decreased when co-cultured with PCL/PDA + GSNO + exosome scaffolds. Furthermore, this scaffold modification significantly enhanced osteogenic differentiation of hBMSCs. This study demonstrated the possibility of using a GSNO- and exosome-based strategy to adapt barrier membrane scaffolds. PCL/PDA + GSNO + exosome scaffolds may serve as an important barrier membrane for osteogenesis and tissue regeneration.