Selective Paracrine Modulation of Stromal Cells: Wharton’s Jelly MSC Secretome Enhances Adipose-Derived MSC Functionality While Maintaining Dermal Fibroblast Quiescence

Wharton’s Jelly-derived mesenchymal stem cells (WJ-MSCs) secrete a rich array of paracrine factors including growth factors, cytokines, and extracellular vesicles that hold promises for regenerative medicine. This study evaluated the effects of WJ-MSC-derived secretome on adipose-derived mesenchymal stem cells (AD-MSCs) and human dermal fibroblasts (HDFs), focusing on their adhesion, spreading, prolifer-ation, endogenous collagen secretion, and migration. Morphometric analysis revealed that the secretome enhanced cell adhesion and spreading on rat tail collagen (RTC) substrates after 24 hours. AD-MSCs showed a ~30% increase in cell spreading area (from 4007 μm² to 5081 μm² p < 0.05), though without notable shape changes. In contrast, fetal bovine serum (FBS) promoted cell elongation with reduced aspect ratio. Proliferation assays demonstrated a selective stimulatory effect of the secretome on AD-MSCs, with a significant increase at day 3, while HDFs’ proliferation remained unchanged. Cell cycle profiling showed transient S-phase accumulation in AD-MSCs (24-48h), followed by G0/G1 arrest (72h), while HDFs remained in G0/G1. Immunofluorescence analysis confirmed enhanced extracellular deposition of endogenously synthesized collagen in AD-MSCs, while no comparable response was observed in HDFs. Scratch assays showed increased migration in both cell types upon secretome exposure, compared to collagen-only controls, suggesting a paracrine-mediated pro-migratory effect. These results demonstrate that WJ-MSC secretome boosts regenerative capacity in AD-MSCs while keeping fibroblasts quiescent, highlighting its strong potential for cell-free therapies in tissue engineering, wound repair, and regenerative medicine.