Experimental Study On Canine Adipose Tissue-derived Mesenchymal Stem Cells Repairing Canine Cartilage Tissue Injury

Stem cells have a low degree of differentiation,with the potential for self-replication and multi-directional differentiation,and are considered to be the "seed cells" for the treatment of various diseases.Adipose mesenchymal stem cells(AD-MSCs)are derived from the mesoderm and can differentiate into other homologous mesodermal mesenchymal cells under different in vitro conditions.It can also differentiate into bone cells,chondrocytes,and epithelial cells.The component of articular cartilage is hyaline cartilage,which has good elasticity and wear resistance and acts as a buffer decompression in the motor system.However,matured articular cartilage is an extracellular matrix containing collagen II as its main component.The cell content is small,and the environment in which it is located lacks the nutrition of blood vessels.Therefore,it is difficult to repair the articular cartilage after it is damaged by lesions such as trauma or inflammation.Therefore,using AD-MSCs as a "seed cell" to repair cartilage tissue damage has become a worthwhile solution.After routinely feeding the pathological model for 15 weeks,the pathological model was surgically sampled and tested as follows:(1)General observation: The experimental group can fill the cartilage tissue defect better than the control group,and the new tissue is larger and thicker.(2)Positive GFP fluorescence of newly born cartilage-like tissue: It was proved that canine AD-MSCs implanted into the joint cavity by injection were successfully implanted in the defect site of cartilage tissue.(3)HE staining showed that there were a large number of cavernous cell clusters in the neonatal tissues of the experimental group and the control group,but the ECM staining of the experimental group was uniform and the stromal section was smooth,suggesting that the newborn tissue components of the experimental group are closer to the original position,hyaline cartilage.(4)Immunofluorescence staining of type II collagen: In the experimental group,strong type II collagen positive staining was observed,whereas in the control group,only a few weak positive staining was detected,demonstrating that the newborn tissue of the experimental group had a higher content of type II collagen.Protein composition,which is consistent with the characteristics of hyaline cartilage.(5)Real-time fluorescence quantitative PCR detection of COL 2a1 m RNA levels: The COL 2a1 content of the experimental group was significantly higher than that of the control group,with significant differences(p < 0.05).This result also supports the results of immunofluorescence staining of type II collagen,demonstrating that the newborn cartilage-like tissue of the experimental group is closer to hyaline cartilage in situ.This experiment clarified the feasibility of directly transplanting primary canine AD-MSCs into the joint cavity to repair cartilage tissue defects,and provided clinical evidences for the future treatment of cartilage tissue damage by stem cells.