Human bone chips release of sclerostin and FGF-23 into the culture medium: an in vitro pilot study

Signaling molecules derived from osteocytes have been proposed as a mechanism by which autografts contribute to bone regeneration. However, there have been no studies that determined the role of osteocytes in bone grafts.

Herein, it was examined whether bone chips and demineralized bone matrix release sclerostin and FGF-23, both of which are highly expressed by osteocytes.

Bone grafts from seven donors were placed in culture medium. Immunoassay showed that bone chips released sclerostin (median 1.0 ng/ml) and FGF-23 (median 9.8 relative units/ml) within the first day, with declining levels overtime. Demineralized bone matrix also released detectable amounts of sclerostin into culture medium, while FGF-23 remained close to the detection limit. In vitro expanded isolated bone cells failed to release detectable amounts of sclerostin and FGF-23.

These results suggest that autografts but also demineralized bone matrix can release signaling molecules that are characteristically produced by osteocytes.