Evaluation of Serum Albumin-Coated Bone Allograft for Bone Regeneration: A Seven-Year Follow-Up Study of 26 Cases

We have previously reported that serum albumin-coated bone allograft (BoneAlbumin, BA) is an effective bone substitute. It improves bone regeneration at the patellar and tibial donor sites six months after harvesting bone-patellar tendon-bone (BPTB) autografts for primary anterior cruciate ligament reconstruction (ACLR). In the present study, we examined these donor sites seven years after implantation. The study group (N = 10) received BA-enhanced autologous cancellous bone at the tibial and BA alone at the patellar site. The control group (N = 16) received autologous cancellous bone at the tibial and blood clot at the patellar site. We evaluated subcortical density, cortical thickness, and bone defect volume via CT scans. At the patellar site, subcortical density was significantly higher in the BA group at both time points. There was no significant difference in cortical thickness between the two groups at either donor site. The control group's bone defect significantly improved and reached the BA group's values at both sites by year seven. Meanwhile, the bone defects in the BA group did not change significantly and were comparable to the six-month measurements. No complications were observed. There are two limitations in this study: The number of patients recruited is small, and the randomization of the patients could have improved the quality of the study as the control group patients were older compared to the study group patients. Our 7-year results seem to demonstrate that BA is a safe and effective bone substitute that supports faster regeneration of donor sites and results in good-quality bone tissue at the time of ACLR with BPTB autografts. However, studies with a larger number of patients are required to definitively confirm the preliminary results of our study.

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

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 BoneAlbumin's 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 (CT). Microcomputed 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 twofold increase in peak fracture force compared with uncoated allografts. In the present study, serum albumin-coated demineralized bone matrices successfully supported faster and functionally superior bone regeneration in aging rats. Because stem cell function, a key contributor of bone remodelling, 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.