An Experimental Study On Autologous Adipose Derived Stem Cells Loaded Onto Human Umbilical Cord Wharton’s Jelly Matrix-derived Scaffold For Repair Of Full-thickness Articular Cartilage Defects Of The Knee In Rabbits

Background:It is difficult to repair articular cartilage damage without blood vessels, lymphatic vessels and nervous tissue. For a small area of the damage of articular cartilage, Even if the repair, most of the repair is fibrocartilage repair. The fibrocartilage repair ultimately failed under normal stresses and friction, leading to degenerative arthritis. There are big differences in structure and functions between degenerative arthritis and hyalinecartilage. As the treatment of advanced technology, there are methods to repair cartilage damage, such as cut bone angioplasty, joint cleaning method, drilling technique, microfracture and transplantation of osteochondral autografts or allografts, but these methods all can’t get satisfactory results. With the development of Biomedical Engineering, the concept of cartilage tissue engineering is applied to the cartilage defects treatment, and has been paid attention by researchers. Tissue engineering covers three aspects:seed cells, material scaffolds and cytokine. Seed cells combined with material scaffolds are commonly used in construction of tissue engineering cartilage, the study of right seed cells and cartilage scaffold is always one of the hot spots in this field. Umbilical cord Wharton jelly matrix is rich in hyaluronic acid, glycosaminoglycan and collagen, with similar components to natural chondrocyte extracellular matrix. Therefore, human umbilical cord-extracted Wharton jelly matrix is likely to become an ideal tissue engineering scaffold material of cartilage tissue.Objective:New Zealand White rabbit which has similar anatomic structure with knee joint was chosen as animal model. This thesis is to study the methods of adipose derived stem cells (ADSCs) isolation, cultivation and amplification and induction in vitro. To evaluate the reparative effects of autologous Adipose derived stem cell loaded Human Umbilical Cord Wharton’s Jelly Matrix-Derived Scaffold for repairing knee articular cartilage defects in rabbit.Methods:The experiment was carried out in Institute of Orthopedics, General Hospital of Chinese PLA.The adipose derived stem cells (ADSCs) were isolated from New Zealand White rabbit by collagenase and were cultured and amplified in vitro, then were induced into chondrocytes. The induced ADSCs were seeded in the human umbilical cord Wharton’s jelly matrix-derived scaffold at a final cell density of107/ml, and cultured for one week in order to construct tissue engineered cartilage. The full-thickness defect of knee cartilage in rabbits were repaired by the tissue engineered cartilage and compared with only scaffold group and blank group. After surgery three months, general observation, histological examination, glycosaminoglycan (GAG) and total collagen quantification, biomechanical test were applied to analyze the results.Results:(1) ADSCs isolated from the back of rabbit neck adipose tissue, and then were induced into chondrocytes. Staining results (Toluidine blue staining, Safranin O staining, Collagen Ⅱ immunohistochemistry) following induction were all positive.Results confirmed that the induced cells of adipose derived stem cells had characteristics of cartilage cells.(2) Induction of adipose derived stem cells combined with human umbilical cord Wharton’s jelly matrix-derived scaffold continue to induction cultured for7days, living cells rate is high. Observation with SEM:some cells loaded onto scaffold had a good adhesiveness after vitro induction cultured for one week.These cells had uniform distribution. There were large numbers of extracellular matrix secreted in the pore canal.(3) Adipose derived stem cells loaded human umbilical cord Wharton’s jelly matrix-derived scaffold had been used to repair full-thickness defects of knee articular cartilage in rabbits. Applied statistical methods to analyze the consequence of general observation, histological examination, glycosaminoglycan (GAG) and total collagen quantification and biomechanical test, showed that all groups had different degrees of tissue repair. In the experimental group the most of defect were repaired by hyaline cartilage. While in only scaffold group the most of defect were repaired by fibrous tissue. In blank group the defect were repaired with less fibrous tissue or not repaired.Conclusion:(1) It is feasible to use the stem cells isolated from the adipose tissues as the seed cells of cartilage tissue engineering.(2) Tissue engineered cartilage using human umbilical cord Wharton’s jelly matrix-derived scaffold seeded with ADSCs can well repair the rabbit knee articular cartilage defects.Human umbilical cord Wharton’s jelly matrix-derived scaffold can be used as good cartilage tissue engineering scaffold.