Cell-based tissue-engineered allogeneic implant for cartilage repair

The potential for using of allogeneic cartilage chips, transplanted in a bi ologic polymer with articular chondrocytes, as a tool for articular cartila ge repair was studied. Small lyophilized articular cartilage chips were mix ed with a cell/fibrinogen solution and thrombin to obtain implantable const ructs made of fibrin glue, chondrocytes, and cartilage chips. Specimens wer e implanted in the subcutaneous tissue on the backs of nude mice (experimen tal group A). Three groups of controls (groups B, C, and D) were also prepa red. Group B consisted of fibrin glue and cartilage chips without chondrocy tes. Group C consisted of fibrin glue and chondrocytes without cartilage ch ips, and group D was composed solely of fibrin glue. All samples were caref ully weighed before implantation in the mice. The constructs were harvested from the aninals at 6, 9, and 12 weeks, examined grossly, and weighed. The samples were then processed and stained with hematoxylin and eosin for his tological examination. Gross evaluation and weight analysis of the construc ts at the time of retrieval showed retention of the original mass in the sa mples made of fibrin glue, chondrocytes, and cartilage chips (group A) and demonstrated a cartilaginous consistency upon probing. Specimens from const ructs of fibrin glue and cartilage chips without chondrocytes (control grou p B) retained most of their volume, but were statistically lighter than spe cimens from group A and were much softer and more pliable than those in gro up A. Samples of specimens from constructs of fibrin glue and chondrocytes (groups C) and fibrin glue alone (group D) both showed a substantial reduct ion of their original masses over the experimental time periods when compar ed to the samples in groups A and B, although specimens from group C demons trated new cartilage matrix formation. Histological analysis of specimens i n experimental group A demonstrated the presence of cartilage chips surroun ded by newly formed cartilaginous matrix, while specimens of control group B showed only fibrotic tissue surrounding the devitalized cartilage pieces. Cartilaginous matrix was also observed in control group C, in which cartil age chips were absent, whereas only fibrin glue debris was observed in cont rol group D. This study demonstrated that a composite of fibrin glue and de vitalized cartilage can serve as a scaffold for chondrocyte transplantation , preserve the original phenotype of the chondrocytes, and maintain the ori ginal mass of the implant. This may represent a valid option for addressing the problem of articular cartilage repair.