Effect of age and sampling site on the chondro-osteogenic potential of rabbit marrow-derived mesenchymal progenitor cells

Four sequential bone-marrow aspirations from the ipsilateral tibia and ilia c crest of New Zealand White rabbits, aged 4 months or 1, 2, or 3 years. we re assayed ill vitro and in vivo for their chondro-osteogenic potential. No nhematopoietic cells from the samples of hone marrow were isolated and expa nded in culture: their colony-forming efficiency was determined, and secund -passage marrow-derived cells, referred to as mesenchymal progenitor cells, were loaded into porous calcium-phosphate ceramic cubes as carrier vehicle s for an in vivo cartilage and bone-formation assay. The cubes were placed subcutaneously in nude BALB/C mice for 3 and 6 weeks. On histological exami nation, the cubes were scored for the presence of bone and cartilage in the ir pores, and average values for age groups and location were compared. At aspiration, the samples From the iliac crest exhibited an overall reduction in cell concentration with increasing age, and at the first harvest time, they showed a decrease in colony-forming efficiency and cube score with inc reasing age. This study demonstrated that repeated bone-marrow aspirations may be performed and may have an enhancing effect on the osteochondral prog enitor cells of older animals.