Those factors present in both SS-AF-MSC-CM and hDF-CM, but not detectable in BMSC-CM, included IL-8, FGF-4, angiopoietin-2, HGF, PD-ECGF and MMP-9, while SS-AF-MSCs also secreted PDGF-AB/BB. This evidence concerns the gene MMP9 and atrial fibrillation.