MMP1 and systemic sclerosis: Concerning their ability to improve ECM remodeling, we noted that mice treated with iNOS−/−-MSC disclosed reduced expression of tissue inhibitor of metalloprotease-1 (TIMP-1), and higher matrix metalloproteinase (MMP)1/TIMP1 ratio compared with HOCl-SSc mice, indicating enhanced remodeling capacity, similar to what is observed using WT-MSC (Figure 2D).