Human osteoclast formation and activity on an equine spongy bone substitute

Abstract

The aim of the present study was to evaluate the in vitro formation and activity of human osteoclasts (OCLs) generated on a new type of xenograft for bone substitution, an equine spongy bone. Peripheral blood mononuclear cells from healthy volunteers were used to generate OCLs in vitro in the presence of macrophage colony stimulating factor (M-CSF) and receptor activator of NF-kappaB ligand (RANKL) on bovine bone slices (positive control) and equine spongy bone. Morphological and biochemical methods were used to assess OCLs formation and activity. Cells generated after 21 days of culture on equine spongy bone showed similar morphology to those on the positive control and displayed typical OCL markers and features, indicating that this material supported OCL formation. Moreover, these cells were functionally active on equine spongy bone with statistically significant differences compared with the control in the release of tartrate-resistant acid phosphatase (TRAcP5b) at days 14 and 21 of culture. With regard to the resorption, on equine bone, OCLs formed smaller discontinuous island-like lacunae rather than the typical lobulated, tracking resorption lacunae observed on the control. This study enables clinicians to tailor the usage of equine spongy bone and presents a model, which can be applied to the preclinical assessment of bone substitute material's resorbability and resorption rates.