Reparative and Inflammatory Changes in Wounds in Animals with Different Resistance to Hypoxia

Individual  resistance  to  hypoxia  largely  determines  the  severity  of  inflammatory  processes and, probably, can affect the regeneration of the skin wound.

The aim was to study reparative and inflammatory changes in the wound in Wistar rats with different resistance to hypoxia.

Material and methods. The study was performed on mature male Wistar rats weighing 300–350 g. Before the experiment, the resistance of animals to hypoxia was determined. Rats were classified as highly resistant to hypoxia (HR), in which the time to take a lateral position in the pressure chamber “at a height” of 11,500 m was more than 360 s (n=5), to low-resistant (LR) – less than 40 s (n=5). A full-thickness wound with a diameter of 16 mm was applied to the animals  in  the  interscapular zone of the back.  On  the  7th  day  after  the infliction of the wound, a histological and  morphometric study was performed. The proliferative activity of cells in the granulation tissue of the wound was determined  immunohistochemically using  the  Ki-67  marker.  Real-time  PCR  was used  to  evaluate  the  level  of expression of the Hif-1α, Nf-κB, and Vegf genes.

Results. It was shown that in rats with high resistance to hypoxia, the total number of cells and, among them, the number of inflammatory cells was higher than in rats with low resistance to hypoxia. However, the percentage of inflammatory cells in the compared groups did not differ significantly. Cell proliferative activity, as measured by the number of Ki-67 positive cells, was higher in rats with high resistance to hypoxia. In the granulation tissue of highly resistant to hypoxia rats, the expression of the Vegf gene was statistically significantly higher than in low-resistant animals, while there were no statistically significant differences in the level of expression of the Hif-1α, Nf-κB genes.

Conclusion. In rats with high resistance to hypoxia, on the 7th day of healing of a full-thickness skin wound, reparative processes in it are more pronounced. In  the  horizontal  layer  of  fibroblasts,  there  are  more  cells,  among  them  inflammatory  ones  -  histiocytes  and macrophages, which is combined with a higher number of proliferating Ki-67 positive cells and the expression level of vascular endothelial growth factor (Vegf).

1. Andreev AA, Ul'yanov IA, Torgun PM, Glukhov AA, Alexeeva NT. Karyometric Parameters of Skin Fibroblasts in the Early Stages of Wound Healing. Journal of Anatomy and Histopathology. 2021;10(1):92-96. (In Russ.) doi: 10.18499/2225-7357-2021-10-1-92-96

2. Gavrilenko AV, Pavlova ОV, Vachratyan PE. The Use of Fibroblasts and Ceratinocytes in Complex Treatment of Venous Trophic Ulcers. Pirogov Russian Journal Of Surgery. 2008;10:25–8. (In Russ.)

3. Dzhalilova DSh, Kosyreva AM, Diatroptov ME, Makarova MA, Makarova OV. Liver and Lung Morphology and Phagocytic Activity of Peripheral Blood Cells during Systemic Inflammatory Responce in Male Rats with Different Resistance to Hypoxia. Clinical and Experimental Morphology. 2019;29(1):47–55. (In Russ.) doi: 10.31088/2226-5988-2019-29-1-47-55

4. Dzhalilova DSh, Makarova OV. Ustoichivost' k gipoksii i sistemnyi vospalitel'nyi otvet. Moscow: Gruppa MDV, 2022. (In Russ.)

5. Kudykin MN, Izmaĭlov SG, Beschastnov VV, Kletskin AE, Mukhin AS, et al. Combined Treatment of Trophic Ulcers. Flebologiya. 2008;3:16–20. (In Russ.)

6. Ponomarenko EA, Diatroptova MA, Mkhitarov VA, N.A. Zolotova, Mikhailova LP, Artem’eva KA, et al. Biochemical And Molecular Biological Characterization of Rat’s Dermal Fibroblast Culture in Hypoxia. Morfologičeskie vedomosti. 2022 Dec 14;30(4):60–6. (In Russ.) doi: 10.20340/mv-mn.2022.30(4).720

7. Shmakova TV, Kananykhina EYu, Bol’shakova GB. Cellular mechanisms of scarless wound healing in mammals. Kliničeskaâ i èksperimentalnaâ morfologiâ. 2019 Jan 1;8(2):5–11. (In Russ.) doi: 10.31088/2226-5988-2019-30-2-5-11

8. Bonifant H, Holloway S. A review of the effects of ageing on skin integrity and wound healing. British Journal of Community Nursing. 2019 Mar;24(3):28–33. doi: 10.12968/bjcn.2019.24.Sup3.S28

9. Kierans SJ, Taylor CT. Regulation of glycolysis by the hypoxia-inducible factor (HIF): implications for cellular physiology. The Journal of Physiology. 2020 Oct 15;599(1):23–37. doi: 10.1113/JP280572

10. Pham K, Parikh K, Heinrich EC. Hypoxia and Inflammation: Insights From High-Altitude Physiology. Frontiers in Physiology. 2021 May 26;12. doi: 10.3389/fphys.2021.676782

11. Stothers CL, Luan L, Fensterheim BA, Bohannon JK. Hypoxia-inducible factor-1α regulation of myeloid cells. Journal of Molecular Medicine. 2018 Nov 1;96(12):1293–306. doi: 10.1007/s00109-018-1710-1

12. Semenza GL. Oxygen Sensing, Hypoxia-Inducible Factors, and Disease Pathophysiology. Annual Review of Pathology: Mechanisms of Disease. 2014 Jan 24;9(1):47–71.. doi: 10.1146/annurevpathol-012513-104720