In Vitro Osteogenic and Angiogenic Potential of 3D-Printed nHA/PCL Scaffolds Functionalized with a Photo-Crosslinked CSMA Hydrogel–Exosome Composite Coating

This study aimed to develop and characterize novel 3D-printed chitosan methacryloyl (CSMA) hydrogel-functionalized nano-hydroxyapatite/polycaprolactone (nHA/PCL) scaffolds for controlled release of bone marrow mesenchymal stem cell-exosomes (BMSC-Exos), with the objective of enhancing osteogenic and angiogenic capabilities in vitro. We fabricated a biomimetic, highly porous scaffold composed of nHA/PCL using high-temperature fused deposition modeling. An interfacial bioactive layer was formed via ultraviolet-induced crosslinking of CSMA hydrogel on the scaffold and loaded bone marrow mesenchymal stem cell-exosomes. We characterized the composite scaffold to evaluate its physicochemical properties, cytocompatibility, cell migration ability, osteogenic capacity, and angiogenic capacity. The 3D-printed 20%nHA/PCL scaffold has a porosity of approximately 75%, with its surface containing four elements: carbon, oxygen, calcium, and phosphorus. The compressive strength is (13.76 ± 1.33) MPa. The CSMA hydrogel exhibits good injectability and degrades slowly over time. Exosomes with a negative charge are released slowly within the extracellular matrix hydrogel. The contact angle of the scaffold material is below 90 degrees, and the hemolysis rate is below 5%. In vitro assays demonstrated that the nHA/PCL-CSMA-Exos composite exhibited excellent biocompatibility, markedly enhanced cell proliferation and migration, and robust pro-angiogenic and osteogenic activity. The fabricated nHA/PCL-CSMA-Exos composite scaffolds demonstrated excellent physicochemical properties, biocompatibility, and cell migration ability, promoting angiogenesis, bone tissue formation and mineralization.