A human placental extract: <i>in vivo</i> and <i>in vitro</i> assessments of its melanocyte growth and pigment‐inducing activities

<jats:title>Abstract</jats:title><jats:p><jats:bold>Background</jats:bold> The authenticity of various prototype human placental extracts with biological activity, such as that inducing vitiligo repigmentation, is under serious criticism, mainly due to a lack of demonstration at the cellular level. Considering the present worldwide scenario with regard to the occurrence and treatment of vitiligo, a thorough scientific exploration of such extracts should be undertaken.</jats:p><jats:p><jats:bold>Method</jats:bold> One such prototype placental preparation was prepared, and was evaluated with regard to its melanogenic action in C57BL/6J mice <jats:italic>in vivo</jats:italic> and its mitogenic and melanogenic activity on B16F10 mouse melanoma cells and normal human melanocytes <jats:italic>in vitro</jats:italic>. The extract was applied topically to mice with age‐induced prolonged telogenic phase of hair growth (grey body coat hair). Standard <jats:sup>3</jats:sup>H‐thymidine incorporation and spectrophotometric methods were followed to illustrate mitogenic and melanogenic effects at the cellular level.</jats:p><jats:p><jats:bold>Results</jats:bold> The resurgence of blue skin, followed by shiny black hair, at the regions of application of the extract demonstrated the reversal of the age‐induced prolonged telogenic phase of hair growth to the anagenic phase after topical application of the extract on C57BL/6J mice. Further support was obtained from histology where, at the extract‐treated sites, the development of new melanogenic centers and hair follicles was observed. During <jats:italic>in vitro</jats:italic> studies, the vehicle‐free extract constituents stimulated both mitogenesis and melanogenesis of B16F10 mouse melanoma cells in a concentration‐dependent manner. The cell morphology and extent of melanogenesis also showed significant changes. In addition, two known melanocyte activity‐modulating peptides, endothelin‐1 (ET‐1) and adrenocorticotropic hormone (ACTH), were determined in the extract, chiefly in the total lipid fraction, indicating their effective cutaneous permeation.</jats:p><jats:p><jats:bold>Conclusions</jats:bold> The extract was found to be a potent mitogen in the <jats:italic>in vitro</jats:italic> condition and a potent melanogen in both the <jats:italic>in vitro</jats:italic> and <jats:italic>in vivo</jats:italic> situations. This strongly suggests its therapeutic potential for the repigmentation of vitiligo patches.</jats:p>