Repair of osteochondral defects in a rabbit model using a porous hydroxyapatite collagen composite impregnated with bone morphogenetic protein-2.

Articular cartilage has a limited capacity for spontaneous repair, and an effective method to repair damaged articular cartilage has not yet been established. The purpose of this study was to evaluate the effect of transplantation of porous hydroxyapatite collagen (HAp/Col) impregnated with bone morphogenetic protein-2 (BMP-2). To evaluate the characteristics of porous HAp/Col as a drug delivery carrier of recombinant human BMP-2 (rhBMP-2), the rhBMP-2 adsorption capacity and release kinetics of porous HAp/Col were analyzed. Porous HAp/Col impregnated with different amounts of rhBMP-2 (0, 5, and 25 µg) was implanted into osteochondral defects generated in the patellar groove of Japanese white rabbits to evaluate the effect on osteochondral defect regeneration. At 3, 6, 12, and 24 weeks after operation, samples were harvested and subjected to micro-computed tomography analysis and histological evaluation of articular cartilage and subchondral bone repair. The adsorption capacity was 329.4 µg of rhBMP-2 per cm(3) of porous HAp/Col. Although 36% of rhBMP-2 was released within 24 h, more than 50% of the rhBMP-2 was retained in the porous HAp/Col through the course of the experiment. Defects treated with 5 µg of rhBMP-2 showed the most extensive subchondral bone repair and the highest histological regeneration score, and differences against the untreated defect group were significant. The histological regeneration score of defects treated with 25 µg of rhBMP-2 increased up to 6 weeks after implantation, but then decreased. Porous HAp/Col, therefore, is an appropriate carrier for rhBMP-2. Implantation of porous HAp/Col impregnated with rhBMP-2 is effective for rigid subchondral bone repair, which is important for the repair of the smooth articular surface.

Survival of deep-sea shrimp (Alvinocaris sp.) during decompression and larval hatching at atmospheric pressure.

We report successful larval hatching of deep-sea shrimp after decompression to atmospheric pressure. Three specimens of deep-sea shrimp were collected from an ocean depth of 1157 m at cold-seep sites off Hatsushima Island in Sagami Bay, Japan, using a pressure-stat aquarium system. Phylogenetic analysis of Alvinocaris sp. based on cytochrome c oxidase subunit gene sequences confirmed that these species were a member of the genus Alvinocaris. All 3 specimens survived to reach atmospheric pressure conditions after stepwise 63-day decompression. Two of the specimens contained eggs, which hatched after 10 and 16 days, respectively, of full decompression. Although no molting of the shrimp larvae was observed during 74 days of rearing under atmospheric pressure, the larvae developed conventional dark-adapted eyes after 15 days.