3D environment with BMP-2-releasing nanocarriers enhances osteogenic commitment of human tendon stem cells

This study presents a three-dimensional bioprinted scaffold engineered to promote the osteogenic differentiation of human tendon stem/progenitor cells (hTSPCs), isolated from tendon explants. The construct integrates human Bone Morphogenetic Protein-2 (hBMP-2)-loaded poly(lactic-co-glycolic acid) nanocarriers (PLGA-NCs; mean size 140 +/- 40 nm) within a gelatin methacryloyl hydrogel. Bioprinting under optimized conditions preserved high cell viability (85%), ensuring a reliable platform for subsequent biological evaluation. Dynamic perfusion culture over 21 days supported continuous nutrient delivery and efficient removal of metabolic byproducts, as corroborated by compartmental modeling. This environment significantly enhanced hTSPCs proliferation and osteogenic commitment, evidenced by a 20-fold increase in osteopontin expression (p < 0.05), an 8-fold upregulation of osteocalcin (p < 0.05), and extensive calcium and protein deposition, confirmed by Alizarin Red S staining and Western blot analysis. In contrast, static monolayer cultures exposed to soluble hBMP-2 (20 ng ml-1) exhibited reduced osteogenic activity, highlighting the superiority of the bioprinted dynamic system. The platform was specifically designed to provide a short, localized hBMP-2 pulse from PLGA-NCs, effectively priming early differentiation while minimizing overall growth factor exposure. These findings demonstrate the potential of combining biofabrication and NC-based delivery for spatiotemporally controlled growth factor presentation, paving the way for advanced in vitro models that more closely recapitulate complex tissue regeneration.