Fig. 2. Characterization of WJ-MSCs and their CM. (A) Comparative analysis of nanoparticles in 2D-WJ-CM and 3D-WJ-CM. The distribution of nanoparticles by size, total concentration per milliliter, peak size (nm), and median size (nm) were measured using ZetaView (TWIN PMX-220; Particle Metrix). (B) Comparison of protein volume and their EV purity (particle number/protein concentration) in 2D-WJ-CM and 3D-WJ-CM. (C) Total expression of TGF-β1 per 1×10⁹ particles in EVs. TGF-β1 levels were significantly higher in 3D-WJ-CM compared to those in 2D-WJ-CM. (D) Flow cytometry analysis of MSC-positive surface marker CD90/105 and negative surface marker CD45 in 2D-MSCs and 3D-MSCs. 2D: two-dimensional, WJ: Wharton’s jelly, CM: conditioned media, 3D: three-dimensional, MSC: mesenchymal stem cell, EV: extracellular vesicle, TGF-β1: transforming growth factor-β1. Results with a p-value<0.05 were considered statistically significant. **p<0.01, ***p<0.001, ****p<0.0001.