Aim: to study the morphological features of reparative chondrogenesis under the influence of mesenchymal stem cells (MSC) in an experimental model of chronic damage of cartilage. Object and methods. The experiment was performed on 64 linear rats weighing 300.0 ± 35.6 g. Under combined anesthesia, a cartilage defect was produced in the loaded area of the distal femur by using a needle. Among the operated rats, 2 groups were formed. In group 1 (n = 36), MSC were injected locally on 7 days after the defect was applied, simulating chronic damage to cartilage. Rats in the control group (n = 28) additional chondrogenic stimulation was not performed. MSC were obtained after treatment of the lipoaspirate with collagenase, centrifugation, elimination of hematopoietic cells and subsequent gradual purification of the culture from weakly adhesive cells by multilayer cultivation. Animals were removed from the study on days 7, 14, 21 and 28 by intraperitoneal administration of a lethal dose of sodium thiopental. Results. On the 7th day after the introduction of MSC, the defect zone is represented by the regenerate of young immature chondroid-like tissue. Separation of the structure of the newly formed cartilage into zones and poles was not observed. Plots of granulation tissue formation were observed, consisting of a multiple network of capillaries and elements of a mesenchymal nature. Microscopy of the regenerate of rats from the control group by the indicated period mainly consisted of the elements of granulation and connective tissue, and a small amount of young immature chondroid tissue was also observed. On 14 days after the introduction of MSC in animals of the experimental group, the processes of active regenerate formation prevailed. The basis of the regenerate is represented by elements of young immature cartilage tissue. Chondrocytes mainly had a flattened and wedge-shaped and hypertrophied shape. By this period, in the control group, the basis of the regenerate is represented by a chondroid-like tissue with multiple connective tissue elements. In the areas surrounding the damage zone, signs of degenerative-dystrophic damage to the articular cartilage persisted. Signs of polar and structural disorganization persisted. In a microscopy of the preparations on the 21st day of the study, the defect zone was made by cartilage elements, both fibrous cartilage and hyaline type. The areas of hyaline-like cartilage had a weakly basophilic matrix, partial zonation and polarity were observed. In the proliferation zone, the majority of chondrocytes were in the form of isogenic groups and were arranged in the form of columns. In animals of the control group the signs of cartilage fragmentation with the formation of cracks and crevices were visualized. The cartilage surface was uneven with multiple thinning sites in the lesion area. The regenerate is represented mainly by tissue of a hyaline-fibrous nature with chondrogenic sites. On the 28th day after the introduction of MSC, the defect was performed mainly by hyaline-like cartilage. The zonality and polarity of the metaepiphyseal cartilage were clearly defined, the proliferating cartilage zone prevailed. The predominant volume of the regenerate was occupied by the intercellular matrix, chondrocytes were located in isogenic groups in the form of columns. Microscopy of preparations of the control group rats by the indicated period showed uneven thickness of the cartilage surface, its local thinning in the area of the damaged area. The defect is made mainly of cartilaginous tissue of a hyaline-fibrous nature. Conclusions. Thus, in rats of the experimental group, a significant improvement in the qualitative indicators of reparative chondrogenesis was established. Also, under the influence of MSC, the best characteristics of the dynamics of the formation of newly formed cartilage were observed.
reparative chondrogenesis, mesenchymal stem cells, cartilage morphology, damage of cartilage, chondroreparation.
«Bulletin of problems biology and medicine» Issue 2 (156), 2020 year, 299-304 pages, index UDK 616.72-018.3-007.233:611.013:572.7
