COL1A1 and graft versus host disease: In parallel, the mRNA expression levels of collagen type 1 α1 (COL1A1), 1 α2 (COL1A2), and 3 α1 (COL3A1) were significantly reduced in skin tissue after both hBM and hAD MSC treatments, compared to those in allogeneic Scl-GVHD controls.