A 3D ColMA-Based Tenogenic Microenvironment Unveils the Behavior of Tendon Stem/Progenitor Cells (TSPCs) from Tendinopathic Surgical Explants

Tendon injuries present significant clinical challenges due to limited intrinsic healing and complex pathological mechanisms. Here, we developed a novel 3D bioprinted methacrylated type I collagen (ColMA) scaffold integrated with Growth Differentiation Factor-5 (GDF-5)-loaded Poly (lactic-co-glycolic acid) (PLGA) nanoparticles and dynamically cultured it under perfusion to establish a tenogenic microenvironment in vitro. Pathological human Tendon Stem/Progenitor Cells (hTSPCs) derived from tendinopathic surgical explants were encapsulated to investigate their impaired extracellular matrix (ECM) deposition and associated pro-inflammatory signaling. GDF-5-loaded nanoparticles (average diameter 140 ± 40 nm) were fabricated via microfluidic-assisted nanoprecipitation and homogeneously incorporated within the ColMA synthetic ECM to enable sustained growth factor release. Continuous perfusion culture (1 mL/min) ensured efficient mass transfer and supported cell viability above 70% over 21 days. Pathological hTSPCs exhibited impaired ECM remodeling, characterized by the absence of type I collagen and a 2.56-fold increase in type III collagen at day 7, indicative of a fibrotic-like phenotype. Western blot densitometry demonstrated a 5.31-fold elevation in secreted tenomodulin at day 14, while ECM analysis verified a type III to type I collagen ratio of 4.5. In addition, a markedly pro-inflammatory cytokine profile was observed, with elevated secretion of interleukin-6 (IL-6) and interleukin-8 (IL-8) from day 7 onward, consistent with the chronic inflammatory status of cells derived from pathological tendon tissues. This modular 3D platform represents a robust in vitro model for mechanistic studies and the advancement of personalized regenerative strategies targeting chronic tendon disorders.