Immunohistochemical profile of the dermis at the injection of polylactic acid

The regeneration of the skin in the event of damage to the introduction of fillers is due to the resulting inflammatory reaction of the dermis. Among the vast group of fillers used in aesthetic medicine, polylactic acid, which is recommended as a “scaffold” forming factor that induces collagen synthesis by fibroblasts with subsequent transformation of this type of cells into myofibroblasts, has proven itself quite well. The aim of the study was to analyze the immunohistochemical status of the dermis with the introduction of an implant from polylactic acid. The study was performed on 30 rats with subdermal administration of the drug in a volume of 0.05 ml. Evaluation of the results was carried out two weeks later, 1, 2 and 4 months after the injection. Morphological evaluation was carried out in sections stained with hematoxylin and eosin according to Van Gieson and Mallory and Masson reactions. Immunohistochemical detection of type I and type III collagen was performed using polyclonal antibodies. Vimentin was used to assess the status of fibroblasts, and the marker CD68 to assess macrophages. The effect of remodeling of extracellular matrix was studied using α-SMA actin. It was shown that the response of the dermis to the implant is of a phase nature, begins with a subclinical inflammatory reaction, followed by encapsulation of each individual microsphere, and ends with dermal fibroplasia. This leads to the effect of increasing the volume of tissue and the result is achieved not only by properties of the introduced product, but also by the reaction of the body to its introduction. The detected activation of collagen synthesis by fibroblasts can be used as a regulator of the volume of the extracellular matrix of the dermis.