Exosome-functionalized alginate/gelatin composite scaffolds: synergistic enhancement of osteogenic differentiation for bone tissue engineering.

Abstract

This study investigates the osteogenic potential of exosome (Exo)-loaded alginate/gelatin (OA/Gel) macromolecular composite scaffolds for human adipose-derived stem cells (hASCs). OA/Gel scaffolds were fabricated and crosslinked with EDC, followed by the incorporation of Exo at concentrations of 0.5, 1, 2, and 4 µL. The scaffolds were characterized in terms of morphology, porosity, swelling behavior, mechanical properties, and cell adhesion. Osteogenic differentiation was assessed through alkaline phosphatase activity, Alizarin Red staining, and RT-PCR for Runt-related transcription factor 2, alkaline phosphatase, and bone gamma-carboxyglutamic acid-containing protein expression. Scanning electron microscopy analysis revealed interconnected pores predominantly within the range of 100-200 μm, with OA/Gel scaffolds demonstrating reduced pore size and enhanced mechanical strength compared to single-component scaffolds. The OA/Gel macromolecular scaffold exhibited optimal pore architecture (~ 180 μm), superior cell adhesion and proliferation, and significantly upregulated osteogenic markers at days 7 and 21. These findings suggest that Exo-loaded OA/Gel scaffolds, particularly at a concentration of 2.0 µL Exo, provide a favorable three-dimensional microenvironment for hASC osteogenic differentiation, highlighting their potential as a promising biomaterials for bone tissue engineering applications.