Biocompatibility of three-dimensional chondrocyte grafts in large tibial defects of rabbits.
OBJECTIVE
To evaluate biocompatibility and effects of implantation of 3-dimensional chondrocyte-agarose autografts in tibial defects in rabbits and to compare in vitro and in vivo chondrocyte-agarose constructs with respect to cell viability, differentiation, and matrix production.


METHODS
24 adult New Zealand White rabbits.


METHODS
Three-dimensional constructs with (grafted group) or without (control group) autogenous chondrocytes were implanted into tibial defects of rabbits and cultured in vitro. During an 8-week period, defects were evaluated radiographically, grossly, histologically, biochemically, and immunohistochemically. In vitro constructs were evaluated histologically, biochemically, and immunohistochemically.


RESULTS
Tibial defects had significantly higher radiographic densitometry values at 4 and 6 weeks after implantation in grafted group rabbits, compared with control group rabbits. Number of observed centers of endochondral ossification was significantly greater in defects of grafted group rabbits, compared with control group rabbits. On day 14, glycosaminoglycan concentration was significantly higher in tibial defects of grafted group rabbits, compared to defects of control group rabbits or in vitro constructs. At weeks 2, 4, and 8, glycosaminoglycan concentrations were significantly lower in the in vitro control constructs, compared with other groups. Collagen type I was present in bone and bony callous in defects of grafted and control group rabbits. Collagen type II was identified in cartilaginous tissues of grafted and control group rabbits. Collagen type X was associated with hypertrophic chondrocytes. Only type II collagen was found in the in vitro chondrocyte constructs.


CONCLUSIONS
Chondrocyte-agarose grafts are biocompatible in large tibial defects and appear to provide a cell source for augmenting endochondral ossification.
Cook
James L
JL
Comparative Orthopaedic Laboratory, University of Missouri, 379 E Campus Dr, Columbia, MO 65211, USA.
Williams
Ned
N
Kreeger
John M
JM
Peacock
John T
JT
Tomlinson
James L
JL
D000818:Animals; D001672:Biocompatible Materials; D001861:Bone Regeneration / Q000502:physiology; D016025:Bone Transplantation / Q000000981:diagnostic imaging / Q000379:methods / Q000662:veterinary*; D019902:Chondrocytes / Q000000981:diagnostic imaging / Q000637:transplantation*; D003094:Collagen / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism; D007150:Immunohistochemistry / Q000662:veterinary; D019736:Prostheses and Implants / Q000662:veterinary; D011817:Rabbits; D011859:Radiography; D011897:Random Allocation; D012685:Sepharose; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*
D001672:Biocompatible Materials; D006025:Glycosaminoglycans; D003094:Collagen; D012685:Sepharose