RELATIONSHIP OF DONOR SITE TO CHONDROGENIC POTENTIAL OF PERIOSTEUM IN-VITRO

Periosteum has been shown in vitro and in vivo to have a chondrogenic potential that permits it to be used for cartilage regeneration. A use ful donor site should have good chondrogenic potential, availability o f a large quantity of periosteum, and relative ease of access, and it should be associated with a low rate of morbidity. We hypothesized tha t the chondrogenic potential of periosteum varies from one bone to ano ther and among different regions of the periosteum from a single bone. A total of 370 periosteal and 37 fascia lata (control) explants were taken from the skull, the ilium, the scapula, the upper, middle, and l ower medial proximal tibia, the posterior proximal tibia, and the dist al tibia of 2-month-old New Zealand rabbits. The explants were culture d for 6 weeks in agarose/Dulbecco's modified Eagle medium to which 10 ng/ml of transforming growth factor-beta 1 was added during the first 2 weeks. Skeletal muscle and fascia lata were used as controls. In add ition, the thickness, cell density, and total cell count of the cambiu m layer were measured in 24 explants from the donor sites on the ilium and the upper, middle, and lower proximal tibia. At 6 weeks, histomor phometry and quantitative collagen typing were performed. The perioste al donor sites could be grouped into three categories according to cho ndrogenic potential: ilium (best), scapula and tibia, and skull (no ch ondrogenesis). The scapular periosteum was slightly better than that f rom the tibia. Within the tibia, the upper and middle zones of the pro ximal region were similar and were slightly better than the lower prox imal tibia or the distal tibia. The cellularity of the cambium layer c orrelated positively with the amount of cartilage as a percentage of t he total area. The results of this study indicate that iliac periosteu m exhibited the best overall chondrogenic potential in vitro but that periosteum from the traditionally used medial proximal tibia also was excellent. Periosteum from the skull was not chondrogenic. The chondro genic potential of periosteum varies from bone to bone and within the periosteum from one bone. This variation in chondrogenic potential amo ng donor sites may be due to a difference in the total cell count of t he cambium layer.