| Articular cartilage defects resulted from trauma, osteoarthritis and osteochondritis diseases is a major challenges for the orthopedic surgeons. Because of the unique feature of articular cartilage which is avascular and the differentiated chondrocytes trapped within compact matrix, mobilization of regenerative cells to areas of injury is insufficient; cartilage tissue has a limited self-regenerative capacity. None of the current surgical options for treating cartilage defects are satisfactory, including lavage and debridement, shaving the cartilage surface, perforating the underlying subchondral bone, periosteal or perichondrial or cartilage transplantation and osteotomy. These procedures are insufficient to resurfacing large articular cartilage defect with lasting hyaline-like cartilage. Cartilage damage may lead to gradual degeneration of joint and ultimately artifical prosthesis needed.Engineered cartilage tissue offers a new strategy for the repair and regeneration of damage or diseased articular cartilage. The first clinical application of autologous chondrocyte implantation (ACI) was reported by Mats Brittberg in 1987. Since then, more than 10,000 cases have been performed worldwide. ACI-P is considered as the first generation tecqnic which is injected autologous chondrocytes beneath the periosteal flap. The second generation (ACI-M) is base on the type I /III collagen membrane or hyaluronate derived scaffold. Now all three procedures are used extensively worldwide. ACI or tissue engineered cartilage has shown very promising results, and high percentage of hyaline-like cartilage tissue would present in the cartilage defects. Retrospective studies of more than 1,000 cases over 10 years showed that 74% had good to excellent resultsMany factors influence the quality of tissue engineered cartilage and the keyelements include cells, scaffolds and transplanting methods. The purpose of this study was to establish a simple, safe, effective and low-cost procedure to construct engineered articular cartilage, which can be used for clinical treatment.Autologous chondrocyte is still the only one permitted in clinical usage. Even the limit cartilage tissue could be obtained from biopsies, and the limit capacity of proliferation of mature chondrocytes. The first technical challenge is in vitro generation of human chondrocytes from the little biopsies ranged from 200 to 300 milligrams. Isolating chondrocytes from the biopsy is the first key process and the quantity of living cells obtained will determine directly proliferating quantity and quality of the collection cells, So, size of cutting cartilage pieces, procedures for digesting and the methods of collecting cells, the proper concentration of trypsine and collagenase were studied, The resaults showed that for adult human articular cartilage biopsies, cutting the biopsies to sand-like, digesting with 0.2% collagenase in medium, and collecting cells by one step may be the optimum procedure. Different medium, different cytokines, and different serum were also compared, The results showed that: 1,Adding some supplement substances such as vitamin C, proline, insulin and none essential amino acids (NEAA) are necessary. 2, The optimal concentration of four cytokines,FGF-2, TGF-P1, PDGF-bb and HGF, when used separately, is 50ng/ml, 1ng/ml, 1ng/ml, 20ng/ml respectively. While 5ng/ml FGF-2 combined with Ing/ml TGFbeta1 could achieve the best effect, adding PDGF-bb, HGF or both could not enhance proliferation.3, Human AB serum is better than fetal bovine serum (FBS), the proper concentration of human AB serum is 10% .Three transplanting materials of ACI were applied in the full-thickness defects in femoral condyles of adult rabbits, 1, chondrocytes, 2,conglomeration of chondrocyte, 3,chondrocyte-seeded collagen scaffold, all transplanted beneath the periosteal flap. The primary results showed that last two methods had better resultsthan that of chondrocytes injecting. Also we compared the methods for fixing periosteal flap, and...
|
PDF Full Text Request