Mechanisms underlying the formation of group #1 scars

In response to trauma with damage to the vascular network, an inflammatory process occurs in the skin, which is a natural protective reaction of the body. The purpose of the inflammatory reaction is to remove fragments of damaged skin and, ultimately, to close the skin defect with newly formed tissue in order to maintain homeostasis. The inflammatory reaction in this case is adequate, which leads to the formation of various types of group No. 1.

Processes aimed at maintaining the body's homeostasis through wound healing begin in the first 24 hours after injury, but reach their peak no earlier than the 5th day.

The first reaction of tissues in response to damage is accompanied by vasodilation, leukocyte diapedesis, which together with dermal macrophages cleanse the wound of cellular detritus, after which the next stage of the wound healing process begins - the collagen synthesis phase. Collagen production is one of the most important moments in wound healing, since it is collagen fibers that replace a deep wound defect. A scar is essentially a "patch" of tightly packed collagen fibers. Collagen synthesis depends not only on the functional activity of fibroblasts, but also on the condition of the wound, the biochemical processes occurring in it, the microelement composition of tissues, and the general condition of the macroorganism. Thus, a deficiency of ascorbic acid, which serves as a cofactor in the hydroxylation of proline to the state of hydroxyproline, can lead to a collagen deficiency and a delay in the process of scar formation. Successful hydroxylation of proline residues is impossible without the dictate of iron.

After the 7th day, collagen synthesis in the wound, where the process of physiological inflammation occurs, gradually decreases. At this stage of physiological healing, it can be said that wound reconstruction depends on the balance between collagen formation and its degradation, since for normal wound healing, collagen must not only be synthesized but also destroyed. Collagen degradation is triggered by highly specialized enzymes called tissue collagenases, synthesized by macrophages, leukocytes, fibroblasts and epithelial cells. Collagenase activity is impossible without a sufficient concentration of potassium and magnesium in the tissues. Zinc is a very important element in wound healing. Zinc deficiency is accompanied by dysfunctions of the endocrine system and a decrease in local and general immunity. Without a sufficient level of zinc in the wound, epithelialization is difficult. An important factor for wound healing is the supply of tissues with oxygen, since hypoxia causes excessive fibrogenesis, which adversely affects the relief of the scar.

However, scar tissue consists not only of collagen fibers, but also of cellular elements, which are its main active elements. The interaction of cells is carried out through cytokines, such as platelet growth factor, transforming growth factor beta, basic fibroblast growth factor, epidermal growth factor, etc. Due to cellular interaction in the wound, a sequence of processes is carried out that lead to the elimination of the defect in the skin.

The intercellular substance also plays an important role, as it facilitates intercellular interaction, movement of cells and cytokines in the wound and information exchange. Accordingly, a deficiency of glycosaminoglycans will contribute to a delay in the process of wound cleansing and scar formation.

Thus, we see that cellular regeneration and hyperplasia of connective tissue components of the dermis in order to maintain homeostasis is a chain of physiological reactions, the result of which is the appearance of a scar. The body has become healthy, nothing threatens it anymore, but a mark in the form of a scar of one form or another remains on the skin. And this becomes an exclusively aesthetic disadvantage for the individual.

All physiological scars formed as a result of the normal physiological reaction of the body in response to trauma have the same histological structure. It has already been said above that normal scar tissue is a dynamic connective tissue structure, which changes its pathomorphological picture quite radically not only depending on the duration of its existence, but also on the type of healing, area and depth of the initial defect.

Depending on the period of existence, scar tissue has a certain number and ratio of cellular, fibrous and intercellular elements. However, it is equally important to know what morphological structures and elements participate in the healing of a skin defect, since this is the possibility of preventing scarring or improving the appearance of scars, that is, scar prevention. Recent studies of wound healing mechanisms do not exclude the possibility of scarless healing of deep wound defects of the skin with "wet" management of the wound surface. A moist environment allows skin cells to freely interact with each other, moving along the intercellular matrix with the help of adhesive molecules and transmitting information through cytokines and corresponding receptors about the restoration of the normal structure of damaged tissues.

In support of this version, it was found that fetal skin injuries in the intrauterine period heal without scars. This is due to the fact that in the intrauterine period, favorable conditions are created for migration and exchange of information between skin cells due to the amniotic fluid. Keratinocytes and fibroblasts exchange information, coordinating the synthesis and breakdown of collagen, proliferative and synthetic activity, and the need and speed of migration. Due to this, collagen does not accumulate in the wound, and keratinocytes, moving freely, quickly and without scars fill the wound defect.