Rat skin inflammation markers change in response to calcium hydroxyapatite and hyaluronic acid administration

In the research, the level of some markers of skin inflammation in Wistar rats was examined after injection of calcium hydroxyapatite and hyaluronic acid drugs of various concentrations, where the nature, degree, extent of tissue damage and the general condition of the animals in general were close to humans’. Each drug was evaluated according to several indicators (MDA content, activity of neutrophil elastase, acid phosphatase, and catalase) to understand the measure of the adequacy of the body's response to the intensity of the stimulus. A biochemical analysis of the skin of laboratory rats after the injection of the studied drugs showed that the safest drugs contain nonstabilized 4% hyaluronic acid. Either in pure form or in a 1: 1 mixture with calcium hydroxyapatite at a concentration of 55.7%, since in 2 months after their injection in the skin of experimental animals, markers of inflammation (elastase, acid phosphatase and MDA levels), catalase and API activity were found at the normal level. The injection of drugs containing stabilized 2% hyaluronic acid and calcium hydroxyapatite 55.7%, as well as stabilized 2.6% hyaluronic acid and calcium hydroxyapatite at a concentration of 1% caused prolonged LPO activation, increased level of inflammation markers and decreased API. The injection of calcium hydroxyapatite drugs without hyaluronic acid, even at a 1: 1 dilution with saline, also caused prolonged LPO activation, an increased level of inflammation markers and a decreased API, and, in addition, revealed a significant increase in acid phosphatase activity, which is an indicator of the integrity of cell membranes. The obtained results made it possible to analyze the features of the molecular response and regulation of inflammation upon injection of calcium hydroxyapatite and hyaluronic acid drugs of different concentrations, which will help in prescribing of treatment.