hMSC preparation

Commercially available human placenta–derived MSCs, passage 1 (Zenbio, catalog number: CA-10, lot number: ZB0003) were expanded to passage 5. Cells were cultured in Dulbecco’s Modified Eagle Medium (Life Technologies) supplemented with 10% fetal bovine serum (Biowest) and 1% penicillin/streptomycin (Life Technologies) at 37°C, 5% CO₂. Aliquots of cells were cryopreserved in 10% dimethylsulfoxide/Dulbecco’s Modified Eagle Medium/vapor phase nitrogen tank. Aliquots were thawed once and suspended in 0.1% bovine serum albumin (BSA)/saline solution (Sigma-Aldrich). Cell number and viability were assessed using trypan blue exclusion (Life Technologies), and cell number was determined using an automated cell counter (TC20, BioRad). Cells were resuspended in sterile 0.1% BSA/saline solution at a concentration of 2.5 million cells/mL; a total number of 10⁷ hMSCs were prepared in a syringe and kept on ice. Cells were infused into the coronary artery within 2 h after preparation. One control pig received the same volume of vehicle only (0.1% BSA/saline).