PADMA 28: a multi-component herbal preparation with retinoid-like dermal activity but without epidermal effects

PADMA 28, a multi-component herbal mixture formulated according to an ancient Tibetan recipe, was assessed for effects on human dermal fibroblasts and epidermal keratinocytes in monolayer culture, and for effects on human skin in organ culture. PADMA 28 stimulated survival of fibroblasts in monolayer culture. In fibroblast monolayer culture and human skin organ culture, levels of matrix metalloproteinase-1 (MMP-1; interstitial collagenase) were reduced and type I procollagen production was increased. When keratinocytes were examined, there was no evidence of growth stimulation over a wide range of PADMA 28 concentrations. At high concentration, PADMA 28 inhibited keratinocyte proliferation. When organ cultures of human skin were treated with PADMA 28, there was no evidence of hyperplastic growth in the epidermis. Topical treatment of rhino mice with PADMA 28 failed to induce epidermal hyperplasia and was completely non-irritating. The ability to stimulate collagen production and inhibit the major collagen-degrading enzyme in skin without inducing a hyperplastic response in the epidermis may provide a basis for development of the herbal preparation as a "skin-repair" agent.