The Ratio of Morphological Variants of Monocytes During Dermal Regeneration After Frostbite in Rats

Monocytes and macrophages play one of the key roles in the processes of tissue formation and repair. Currently, there is great interest in the study of these cells due to their potential in therapeutic regeneration as they participate in the immune response and regulation of haematopoiesis. However, data on the role of morphological variants of monocytes, localized in the red bone marrow and circulating in the peripheral blood, in the process of skin repair after thermal damage are extremely scarce and incomplete. The purpose of this study was to analyse the involvement of bone marrow and peripheral blood monocytes with different morphological characteristics in the reparative regeneration following acute local cold injury to the skin in rats. Materials and methods. The research was conducted on apparently healthy mature outbred rats (n = 100) weighing 200–220 g. All experimental animals were divided into 5 groups of 20 individuals each: the control and four experimental (3, 7, 14 and 21 days after frostbite) groups. Third-degree frostbite was modelled by applying a metal weight cooled in liquid nitrogen (−196 °C) to the depilated skin of the rat’s back for 3 min. The area of damage was 4.9 cm2. The study used methods of histological analysis of the skin, blood and red bone marrow. Results. During the regeneration of the intercellular matrix of the dermis, no sharp fluctuations in the content of the morphological variants of monocytes (polymorphonuclear monocytes, monocytes proper and promonocytes) were recorded in the bone marrow and the blood. On the 3rd day after injury, proliferation and differentiation were the dominant processes, and by the 7th day, intensive cell migration was observed. By days 14 and 21, the levels of various forms of monocytes returned to their initial values.