The effect of topical ramipril and losartan cream in inhibiting scar formation

The renin-angiotensin system (RAS) plays an important role in scar formation. We have previously shown that oral administration of ramipril and losartan could inhibit scarring. For easier application, here we developed a series of topical ramipril and losartan creams in different concentrations and formulations to explore the effect on scar formation in a C57BL/6 mouse scar model. The harvested scar tissues were analyzed with H&E staining, Masson staining and immunohistochemical staining. We found the group treated with 0.2% losartan urea cream (Prep. 1) or 0.1% ramipril cream (Prep. 2) had significantly smaller scars compared to the negative control, while the proliferation of fibroblasts was less active and the collagen fibers were more regular; both groups showed similar efficacy with the positive control (triamcinolone acetonide urea). We also found that drug transdermalness couldn’t directly determine the efficacy. Our findings indicate that local application of angiotensin converting enzyme inhibitor drugs (ACEIs) and angiotensin receptor blocker drugs (ARBs) can reduce scarring by reducing the expression of collagen I, collagen III, phosphorylated small mothers against decapentaplegic 3 (p-Smad3) and transforming growth factor-β 1 (TGF-β1). This may provide new insight on scar treatment in clinic.