Ugly duckling or a swan: Exploring therapeutic potential of ricin for inhibiting unwanted hair growth

Abstract

We examined the action of ricin and related protein abrin on hair follicle (HF) and re-growth of hair. Topical application of ricin in BALB/C and C57BL/6 mice after hair removal by waxing, resulted in sparse and delayed re growth of hair. Histopathological examination revealed hair follicle dystrophy and dose-dependent reduction in the number of hair follicles. Ricin-treated hair follicles showed immediate dystrophic catagen induction and were found to be dystrophic. The characteristic features of ricin-treated hair follicles resembled chemotherapy-induced hair follicle dystrophy such as presence of many ectopic melanin granules, follicular and hair shaft distortion, and irregular diameter of hair bulbs. During in vitro human hair follicle organ culture, ricin- and abrin-treated hair follicles showed inhibition of hair shaft elongation, premature HF regression, and hair follicle dystrophy. During preclinical toxicology studies, ricin was found to be safe for sub-acute dermal test for 90 days for a dose equivalent to the human dose of 160 ?g/kg. Our novel observations propose ricin to be a promising candidate for inhibiting growth of hair follicle by inducing dystrophy without adversely affecting other skin structures