Serum albumin coating of demineralized bone matrix results in stronger new bone formation

Abstract

Blood serum fractions are hotly debated adjuvants in bone replacement therapies. In the present experiment, we coated demineralized bone matrices (DBM) with serum albumin and investigated stem cell attachment in vitro and bone formation in a rat calvaria defect model. In the in vitro experiments, we observed that significantly more cells adhere to the serum albumin coated DBMs at every time point. In vivo bone formation with albumin coated and uncoated DBM was monitored biweekly by computed tomography until 11 weeks postoperatively while empty defects served as controls. By the seventh week, the bone defect in the albumin group was almost completely closed (remaining defect 3.0 ± 2.3%), while uncoated DBM and unfilled control groups still had significant defects (uncoated: 40.2 ± 9.1%, control: 52.4 ± 8.9%). Higher density values were also observed in the albumin coated DBM group. In addition, the serum albumin enhanced group showed significantly higher volume of newly formed bone in the microCT analysis and produced significantly higher breaking force and stiffness compared to the uncoated grafts (peak breaking force: uncoated: 15.7 ± 4 N, albumin 46.1 ± 11 N). In conclusion, this investigation shows that implanting serum albumin coated DBM significantly reduces healing period in nonhealing defects and results in mechanically stronger bone. These results also support the idea that serum albumin coating provides a convenient milieu for stem cell function, and a much improved bone grafting success can be achieved without the use of exogenous stem cells.

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

“…The idea is strongly supported by the current experiment, where albumin coating was shown to attach twice as many BMSCs compared with uncoated DBMs. This ratio was nearly the same in previous work, in which stem cells originating from young donors were used (Horvathy, Vacz, et al, ). Those results showed the same attachment pattern, but the cell number was twofold higher at every time point, indicating the decreased functionality of aging multipotent cells.…”

“…In the case of albumin‐treated grafts (Graft + Albumin; BoneAlbumin), protocol was followed by the guidelines of OrthoSera GmbH: graft soaking in 20% human albumin solution (Biotest, Hungary) was performed prior to standard freeze drying (frozen at −80°C and freeze dried at −50°C overnight). The albumin content in the BoneAlbumin group was determined previously (Horvathy, Vacz, et al, ). All chemicals were purchased from Sigma‐Aldrich Co., Budapest, Hungary.…”

“…Serum albumin‐coated bone allograft (BoneAlbumin) has been intensively investigated lately, with outcomes data demonstrating an ability of BoneAlbumin to facilitate new bone formation in non‐union and critical size defect models in rats (Horvathy, Vacz, et al, ; Skaliczki et al, ; Weszl et al, ). BoneAlbumin was also shown to decrease donor site morbidity and enhance bone formation after anterior cruciate ligament reconstruction with bone‐patellar tendon‐bone autografts (Schandl et al, ).…”

Ketamine decreases cell viability of bone explants and impairs bone healing in rats

“…In Experiment 1, until the 11th week, anesthesia was performed 6 times, during surgery and then biweekly [1]. On the 11th week, animals were sacrificed with carbon dioxide, and a last CT scan was performed as well.…”

“…Regeneration is a complex process influenced by uncountable factors, for example, anesthesia-related stress, substances or radiation. The present work is based on an observation from previous experiments investigating bone healing [1,2]. In order to observe the dynamics of bone remodeling in a rat critical size calvaria model, in vivo computed tomography scans were performed under ketamine-xylazine anesthesia.…”