STEM-CELL FACTOR STIMULATES CHICKEN OSTEOCLAST ACTIVITY IN-VITRO

Stem cell factor (SCF) is a polypeptide growth factor active on multip le cell types, mainly of hematopoietic origin, We studied the effects of avian SCF on the differentiation of chicken osteoclasts from their putative progenitors as well as on the bone-resorbing activity of term inally differentiated osteoclasts, Osteoclast formation was analyzed i n long-term cocultures of osteoblasts and nonadherent, osteoclast-depl eted bone marrow cells, Osteoclast activity was studied in short-term (48 h) cultures of bone marrow cell populations enriched for osteoclas ts, on dentine slices, SCF strongly enhanced osteoclast differentiatio n, The IL-6-related chicken myelomonocytic growth factor (cMGF) had a similar effect, and the effects of SCF and cMGF were additive, SCF, bu t not cMGF, also stimulated the bone-resorbing activity of existing os teoclasts, As osteoblasts have been found to regulate osteoclast activ ity and formation, chicken osteoblasts were tested for their ability t o express and secrete SCF, Reverse transcriptase-polymerase chain reac tion (RT-PCR) analysis showed that osteoblasts express SCF mRNA and th at parathyroid hormone increases expression levels about fourfold, SCF did not accumulate in the culture medium, but remained cell (osteobla sts) surface associated.-van 't Hof, R. J., von Lindern, M., Nijweide, P. J., Beug, H. Stem cell factor stimulates chicken osteoclast activi ty in vitro.