Age-related decline in osteoprotegerin expression by human bone marrow cells cultured in three-dimensional collagen sponges

With advancing age, an increase in bone resorption relative to bone formati on results in bone loss. Bone marrow stromal cells and their products suppo rt osteoclastogenesis from hematopoietic progenitors. Another of their prod ucts, osteoprotegerin (OPG), blocks the osteoclast-stimulatory effects of O PG ligand. We tested the hypothesis that with advancing age there is a decr ease in OPG expression by human bone marrow cells. Bone marrow cells were o btained from 18 subjects (age range 38-84 years). Expression of mRNA transc ripts of OPG was assessed by quantitative competitive RT-PCR. Median number of OPG transcripts in the younger group was 0.3 zetptomoles (range 0.01 to 1.30) and was higher than in the older group's median of 0.06 (range 0 to 0.5; p < 0.05). The decline in the expression of OPG with age may increase the capacity of stromal/osteoblast cells to support osteoclastogenesis. (C) 2000 Academic Press.