Human cxcl12 sdf 1α

MSCs were isolated from BM and WJ as previously described and expanded in appropriately supplemented alpha-Minimum Essential Medium (α-MEM; Gibco Invitrogen, Paisley, Scotland), at 37 °C/5% CO₂ fully humidified atmosphere [6 (link)–8 (link)]. The culture medium was replaced twice per week and on 80–90% confluency, MSCs were detached using 0.25% Trypsin–1mM EDTA (Gibco, Invitrogen), reseeded at a concentration of 2000 cells/cm² and further expanded for a total of ten passages (P) [6 (link), 7 (link)].
Cell-free supernatants from WJ- and BM-MSC cultures at P2, P6 and P10 were stored at -80 °C for quantification of FMS-like tyrosine kinase 3 ligand (FLT3L; Quantikine, R&D Systems, Minneapolis, MN, USA), Granulocyte- Colony Stimulating Factor (high sensitivity human G-CSF; Quantikine, R&D Systems), Stromal Cell-derived Factor-1α (human CXCL12/SDF-1α; Quantikine, R&D Systems) and Granulocyte Macrophage-Colony Stimulating Factor (human GM-CSF; Affymetrix, eBioscience, San Diego, CA, USA), by means of enzyme-linked immunosorbent assay.

Silk fibroin protein was extracted from raw silk (Haian Silk Company, Nantong, China) using an aqueous solvent processing method according to published protocols [14 (link)]. PGS prepolymer was synthesized from glycerol (Fisher Scientific) and sebacic acid (Sigma-Aldrich) following published methods [15 (link)]. Type I collagen from calfskin was purchased commercially (Elastin Products Company, Inc.). Recombinant human syndecan-4 and human CXCL12/SDF-1α were purchased from R&D Systems.