CULTURE-EXPANDED HUMAN PERIOSTEAL-DERIVED CELLS EXHIBIT OSTEOCHONDRAL POTENTIAL INVIVO

Periosteal cells were enzymatically liberated from human rib periostea obtained from autopsies of 37 donors with an age distribution ranging from 25 weeks of gestation to 88 years old. These cells were introduced into cell culture and subcultured when they reached confluence. After subculture, the adherent periosteal-derived cells showed a nondescript, fibroblast-like morphology in cell culture. The cells from various passages of each donor were tested for in vivo osteochondrogenic potential with three different assay methods in athymic mice: (a) inoculation assay-the cells were directly inoculated into a subcutaneous site, (b) porous ceramics assay-the cells were combined with porous calcium phosphate ceramics, and this composite graft was implanted into a subcutaneous site, and (c) diffusion chamber assay-the cells were loaded into diffusion chambers and cultured in the peritoneal cavity. Frozen-preserved and recultured periosteal-derived cells were also assayed in the same way. In cases of donors younger than 19 years old, cultured, periosteal-derived cells from up to several passages consistently formed bone and/or cartilage in each of the three assays. Frozen-preserved and recultured cells from these donors also formed bone and/or cartilage after introduction into the three in vivo assays. In cases of donors older than 22 years of age, cultured, periosteal-derived cells formed neither bone nor cartilage in vivo. Cultured muscle fibroblasts from some of the same donors did not form bone or cartilage when assayed in vivo under identical conditions. These results suggest that periosteal cells with osteochondrogenic potentials can be liberated from the periosteum of a rib of human donors up to a certain age. Importantly, this potential is retained after enzymatic liberation, cell culture, subculturing, and freeze preservation. The present results suggest that culture-expanded human periosteal-derived cells from young donors may be useful in the repair of skeletal defects to foster cell-mediated regeneration of skeletal tissues, and that this methodology can be used to elucidate cellular, molecular, and genetic disorders in various metabolic bone diseases and skeletal dysplasias.