Dynamic Loading Regulates Meniscus-Like Matrix Production in Human Mesenchymal Stromal Cell-Seeded PET Scaffolds

Meniscal injury is a leading cause of early-onset osteoarthritis, yet regenerative options remain limited. This study investigates a nonwoven polyethylene terephthalate (PET) scaffold for meniscus tissue engineering and assesses its capacity to support mesenchymal stromal cell (MSC) proliferation and chondrogenic differentiation under dynamic loading. Human MSCs are seeded onto PET scaffolds (400-420 g/m², 85% porosity) and cultured for up to 21 days under basal medium (Ctr), chondrogenic differentiation conditions (ChD), or ChD combined with dynamic loading (ChD + Dyn, 12% strain, 1 Hz, 1 h/day, 5 days/week). PET scaffolds support uniform MSC adhesion and colonization. Compared with ChD alone, ChD+Dyn significantly increases cell proliferation and transiently upregulated chondrogenic markers (SOX9, ACAN, COL1A1, COL2A1) while suppressing the hypertrophic marker COL10A1. Although collagen deposition and construct biomechanics remained unchanged over 21 days, glycosaminoglycan accumulation was reduced in the ChD + Dyn group compared with ChD. RNA sequencing revealed distinct mechanosensitive transcriptional signatures induced by dynamic loading, particularly in genes associated with extracellular matrix remodeling, mechanotransduction, and developmental signaling pathways. These findings demonstrate that nonwoven PET provides a mechanically robust scaffold for meniscus tissue engineering and that dynamic loading promotes MSC proliferation while transiently regulating chondrogenic differentiation and mechanoadaptive matrix remodeling toward a meniscus-like phenotype.