Application of Intelligent Monitoring of Percutaneous Partial Oxygen Pressure in Evaluating the Evolution of Scar Hyperplasia

The study aimed to investigate the dynamic changes of percutaneous partial oxygen pressure during the development and evolution of a hypertrophic scar. Twenty cases of hypertrophic scar patients at different stages were selected. A percutaneous oxygen monitor was used to measure oxygen partial pressure in the scar and normal skin tissue at 14, 30, 60, and 90 days after surgery. The changes of oxygen partial pressure, tissue structure, HIF-1α, and VEGF expression in the scar tissue were observed, and the correlation was analyzed. In the scar maturation process, with the prolongation of time, the partial oxygen pressure in the tissue increased gradually. The expression intensity of HIF-1α and VEGF decreased gradually, HIF-1α was positively correlated with VEGF (r = 0.98, P < 0.01 ), there was a negative correlation between oxygen partial pressure and HIF-1 α expression (r = −0.92, P < 0.01 ), and it was negatively correlated with VEGF (r = −0.88, P < 0.01 ). TcPO2 measurement can be used to assess scar maturity; HIF-1 α and VEGF may play an essential role in regulating partial oxygen pressure in the scar tissue.

Mechanobiology of Cutaneous Scarring

The last phase of cutaneous wound healing produces the scar. Under normal circumstances, the immature scar then undergoes the scar maturation process over several months. This process involves tissue remodeling, which associates with a natural decrease in the inflammation and the numbers of blood vessels, collagen fibers, and fibroblasts. However, sometimes the scar maturation process is not properly engaged because inflammation continues in the scar. Consequently, the immature scar stage is prolonged. This results in the pathological scars called hypertrophic scars and keloids. Many factors that prolong the inflammatory stage have been identified. However, multiple lines of evidence acquired in recent years suggest that mechanical force can be an important cause of pathological scar development.

Principles of Cell Circuits for Tissue Repair and Fibrosis

Tissue-repair is a protective response after injury, but repetitive or prolonged injury can lead to fibrosis, a pathological state of excessive scarring. To pinpoint the dynamic mechanisms underlying fibrosis, it is important to understand the principles of the cell circuits that carry out tissue-repair. In this study, we establish a cell-circuit framework for the myofibroblast-macrophage circuit in wound-healing, including the accumulation of scar-forming extracellular matrix. We find that fibrosis results from multistability between three outcomes, which we term ‘hot fibrosis’ characterized by many macrophages, ‘cold fibrosis’ lacking macrophages, and normal wound-healing. The cell-circuit framework clarifies several unexplained phenomena including the paradoxical effect of macrophage depletion, the limited time-window in which removing inflammation leads to healing, the effects of cellular senescence, and why scar maturation takes months. We define key parameters that control the transition from healing to fibrosis, which may serve as potential targets for therapeutic reduction of fibrosis.

Formation and evaluation of bilio-digestive and interintestinal anastomoses by the method of high-frequency electric welding of tissues in experiment

Objective. To develop a new method of the anastomoses formation, that would allow to form bilio-digestive and entero-entero anastomoses both on unchanged and inflamed tissues. Маterials and methods. In experimental on 50 laboratory rabbits the single-layer everting cholecysto-entero and entero-entero anastomoses on the Roux-defunctionalized loop of small intestine was created by the method of a high-frequency electric welding. The welding anastomoses were formed both on non-inflamed tissues and in the setting of biliary peritonitis. Patency, hermeticity, strength, macroscopic and microscopic pictures of the obtained joints were evaluated at different postoperative periods. Results. All anastomoses, formed by the method of a high-frequency electric welding, were not only patent and hermetic, but also sufficiently strong (40 – 100 mm Hg). The tissues were joined using thermo-adhesion; a coagulation scar was rather narrow, its complete epithelization was accomplished in 3 mo, and a scar maturation completed – in 6 mo. Conclusion. The method of a high-frequency electric welding permits to form both, bilio-digestive and inter-intestinal, anastomoses of equal reliability in the settings of non-inflamed and inflamed tissues.