Influence of Periosteum Location on the Bone and Cartilage in Tissue-Engineered Phalanx

This study investigated the influence of periosteal tissue of different origins on the calcification at the diaphysis and chondrocyte maturation at the epiphysis in an engineered phalanx. We hypothesized that the periosteum from long bones would better provide donor cells for bone formation and signals for maturation of the joint cartilage.

Periosteum was harvested from 4 locations (cranium, mandible, radius, and ilium) of calf bones. A human phalangeal bone-shaped, biodegradable, 3-dimensional scaffold hydroxyapatite-poly L-lactic-ɛ-caprolactone (HA-P[LA/CL]) was prepared using a human phalangeal bone-shaped template. A bioengineered human phalanx was fabricated by combining periosteal grafts with biodegradable copolymers. The joint cartilage region (chondrocyte/polyglycolic acid [PGA] composite) was subsequently sutured to the phalangeal bone region (periosteum/HA-P[LA/CL] composite) with absorbable sutures to make a human phalangeal bone model. These were then implanted in nude mice for maturation of the constructs. Macroscopic, radiographic, histological, and immune-histochemical evaluations were carried out to determine the relative influence of the periosteal graft source on bone and cartilage formation at 10 and 20 weeks after implantation.

Calcification localized under the periosteum was noted in the cranium, radius, and ilium groups after 10 weeks, which markedly expanded at the modelled diaphysis after 20 weeks. The width in the minor axis direction tended to increase with time after grafting in the cranium group, whereas the longitudinal length increased in the radius and ilium groups. The joint cartilage thickness changed with time depending on the type of periosteum, and periosteum collected from the radius and ilium was associated with the greatest cartilage thickness in the joint cartilage maturation process.

These results suggest that periosteum collected from radius of calves demonstrated superior bone formation and chondrocyte maturation in the engineered phalanx compared with other sources of periosteum.

The osteogenic capacity depends on the periosteal source regardless of intramembranous or endochondral ossification. The appropriate periosteal choice is essential in the phalangeal bone and cartilage tissue engineering. The results are important for broadening tissue engineering possibilities for clinical application.