FIELD: medicine.SUBSTANCE: group of inventions refers to medicine, namely to dermatology, and concerns a composition for preventive or therapeutic treatment of conditions related to change of hair quantity. Composition comprises: (a) a conditioned medium enriched with biologically active compounds obtained by culturing mesenchymal stem cells (MSC) in the presence of carbon monoxide CO and/or nitrogen monoxide NO and/or HS in a gaseous medium； (b) lysate of cultured MSCs. Group of inventions also relates to a method for preparing said composition and to a method for preventive or therapeutic treatment of conditions related to change of hair quantity, involving local application of the composition.EFFECT: group of inventions provides a more reliable result, inducing stem cells of hair follicles for entry into an anagen phase, which is manifested by increase in the number of hair follicles per unit area, due to a conditioned medium enriched with biologically active compounds: Galectin-1, Thioredoxin, VEGF, Cystatin-b, IGFBP, MMIF, CRABP1, IL-6, IL-8.37 cl, 6 dwg, 2 tbl, 8 ex
