Serum albumin coated bone allograft (BoneAlbumin) results in faster bone formation and mechanically stronger bone in aging rats

Abstract

Serum albumin coated bone allografts (BoneAlbumin) have successfully supported bone regeneration in various experimental models by activating endogenous progenitors. However, the effect of tissue aging, linked to declining stem cell function, has yet to be explicitly examined within the context of BoneAlbuminꞋs regenerative capacity. Stem cell function was tested with an in vitro attachment assay, which showed that albumin coating increases stem cell attachment on demineralized bone surfaces in an aging cell population. Bone regeneration was investigated in vivo by creating critical size bone defects on the parietal bones of aging female rats. Demineralized bone matrices with and without serum albumin coating were used to fill the defects. Bone regeneration was determined by measuring the density and the size of the remaining bone defect with computed tomography. MicroCT and mechanical testing were performed on the parietal bone explants. In vivo CT and ex vivo microCT measurements showed better regeneration with albumin coated grafts. Additionally, the albumin coated group showed a two-fold increase in peak fracture force compared to uncoated allografts. In the present study, serum albumin coated demineralized bone matrices successfully supported faster and functionally superior bone regeneration in aging rats. Since stem cell function, a key contributor of bone remodeling, decreases with age and serum albumin is an effective activator of endogenous progenitor cells, this method could be an effective and safe adjuvant in bone regeneration of aging adult and osteo-compromised populations.