: Bone defects caused by trauma, tumour resection, or degenerative diseases remain a major clinical challenge, highlighting the need for bioactive scaffolds capable of supporting bone regeneration. In the present study, a polydopamine-modified electrospun poly(vinyl alcohol)/chitosan (PVA-CS-DOPA) nanofibrous scaffold was developed and functionalized with human adipose-derived stem cell (hADSC)-derived exosomes to enhance osteogenic differentiation. Isolated extracellular vesicles exhibited a nanoscale particle size distribution centred at approximately 115 nm, negative surface charge (-35 mV), spherical morphology, and positive immunoreactivity for the exosomal marker CD81 with absence of calnexin contamination. Cellular uptake analysis showed progressive internalisation of fluorescently labelled exosomes, increasing from approximately 25% at 2 h to 50% at 4 h, 66% at 8 h, and 72% at 24 h. In vitro biocompatibility assays confirmed favourable cell viability and proliferation on all scaffold groups, with enhanced responses in exosome-containing scaffolds. Osteogenic differentiation assays revealed significantly elevated alkaline phosphatase activity during early differentiation, particularly at 12 μg/mL exosome concentration on day 7. At later stages, higher exosome concentrations promoted stronger matrix mineralisation, as confirmed by Alizarin Red S staining at day 14, suggesting accelerated osteogenic maturation. Immunocytochemical analysis on nanofibrous scaffolds further demonstrated enhanced expression of osteogenic proteins, including type I collagen and osteopontin. Collectively, these findings suggest that exosome-functionalized PVA-CS-DOPA nanofibrous scaffolds provide a biocompatible and osteo-inductive platform with suitable mechanical performance for non-load-bearing bone tissue engineering applications.
Mahmoudifard et al. (Fri,) studied this question.