Fibroblast growth factor-2 promotes the repair of partial thickness defects of articular cartilage in immature rabbits but not in mature rabbits.
OBJECTIVE
To investigate cartilage response to fibroblast growth factor-2 (FGF-2) with increasing age in vivo, we examined the effect of FGF-2 on partial thickness defects of immature and mature rabbits.


METHODS
Sixty-nine Japanese white rabbits (34 immature rabbits, 35 mature rabbits) were examined. We made experimental partial thickness defects in articular cartilage of the knees. Then, we injected FGF-2 into the knees eight times, immediately after surgery and every 2 days for 2 weeks. A single dose of FGF-2 was 10 ng/0.1 ml or 100 ng/0.1 ml. In the control group, 0.1 ml saline was injected on the same time schedule. The rabbits were sacrificed at intervals following surgery that ranged from 2 to 48 weeks. The specimens were stained with toluidine blue and examined microscopically. We used a modified semiquantitative scale for evaluating the histological appearance of repair.


RESULTS
In immature rabbits, the cartilage repair in the FGF-2 (100 ng)-treated group was significantly better than that of the other groups. The defects were almost completely repaired with chondrocytes that showed a round to polygonal morphology, and large amounts of extracellular matrix with intense metachromatic staining. In mature rabbits, however, there was apparently no effect from FGF-2 in either group.


CONCLUSIONS
Application of FGF-2 facilitated cartilage repair in partial thickness defects in immature rabbits, but not in mature ones.
Yamamoto
Tetsuya
T
Department of Orthopaedic Surgery, Osaka-Minami National Hospital, Kawachinagano, Japan. yamatetsu@ommc-hp.jp
Wakitani
Shigeyuki
S
Imoto
Kazuhiko
K
Hattori
Takako
T
Nakaya
Hiroyuki
H
Saito
Masanobu
M
Yonenobu
Kazuo
K
D000375:Aging / Q000473:pathology* / Q000502:physiology; D000818:Animals; D002358:Cartilage, Articular / Q000187:drug effects / Q000293:injuries* / Q000473:pathology; D019902:Chondrocytes / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D016222:Fibroblast Growth Factor 2 / Q000627:therapeutic use*; D007270:Injections, Intra-Articular; D008297:Male; D011817:Rabbits; D011994:Recombinant Proteins / Q000627:therapeutic use; D014945:Wound Healing / Q000187:drug effects* / Q000502:physiology
D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2