Morphological investigation of reparative processes in the area of the defect of cartilage tissue of the external ear of the rabbit after the local application of allogenic mesenchymal stem cells

Abstract

Purpose: to study the features of the restoration of rabbits outer ear elastic cartilage tissue in the area of the defect after its filling with allogeneic mesenchymal stem cells (MSCs). Materials and methods: Studies were performed on 24 sexually mature rabbits. All animals under general anaesthesia underwent surgery to create a standardized linear defect and were divided into experimental (15 rabbits) and control (9 rabbits) groups. In the experimental group, the defect was filled with suspensions of MSCs in the amount of 5 million cells, and in the control group of cells was not introduced. MSCs were obtained from the umbilical cord of rabbits by the enzymatic method. After the first passage of the MSCs culture, was studied MSCs stem potential and tested ability to differentiating. Material for morphological studies was taken after 1, 2 and 3 months, cryostat sections were prepared hematoxylin-eosin and picrofuxin staining were performed according to van Gizon, as well as morphometry. Results: The introduction of suspensions of allogeneic MSCs in the experiment in the cartilage defect of the outer ear of rabbits causes healing with the activation of pre-existing embryonic cartilage cells, the appearance of cells in a state of division in the adjacent zone, activation of angiogenesis and promotes fibrotization with a predominance of loose connective tissue 1 month after surgery. After 3 months, a more pronounced activation of chondrogenesis is observed with the growth of chondrocytes and their increased number in lacunae, the appearance of isogenic groups of cells, which is combined with vascular activation and the growth of dense scar connective tissue,increased fibroblasts and the number of collagen fibers in the defect area, as well as in the absence of a complete restoration of the characteristic cartilage structure. At that time, in the control group, in the process of defect healing 1 month after the operation, along with the detection of a reduced zone of activation of cartilage chondrocytes and collagen fibers, the development of destructive-dystrophic processes of chondrocytes and the extracellular cartilage matrix was observed. The morphometry data quantitatively confirm a more pronounced activation of chondrogenesis in the areas adjacent to the cartilage defect under the conditions of MSC injection compared to the control. The difference is 20.8% 1 month after the operation and 14.2% 3 months later. The results obtained indicate the promise of using MSCs to activate reparative processes in the area of rabbits outer ear cartilage tissue defect.