Evaluation of processed bovine cancellous bone matrix seeded with syngenic osteoblasts in a critical size calvarial defect rat model

Abstract

Autologous bone graftsCurrently, autologous bone grafting is the gold standard for osteogenic bone replacement. This procedure is highly efficient in reconstructing bone defects even under problematic conditions. However, the use of autologous bone grafts is limited by a significant donor site morbidity that increases with the amount of bone harvested [1]. Biomaterials for bone replacement AbstractIntroduction: Biologic bone substitutes may offer alternatives to bone grafting procedures. The aim of this study was to evaluate a preformed bone substitute based on processed bovine cancellous bone (PBCB) with or without osteogenic cells in a critical size calvarial defect rat model. Methods: Discs of PBCB (Tutobone ® ) were seeded with second passage fibrin gel-immobilized syngenic osteoblasts (group A, n = 40). Cell-free matrices (group B, n = 28) and untreated defects (group C; n=28) served as controls. Specimens were explanted between day 0 and 4 months after implantation and were subjected to histological and morphometric evaluation. Results: At 1 month, bone formation was limited to small peripheral areas. At 2 and 4 months, significant bone formation, matrix resorption as well as integration of the implants was evident in groups A and B. In group C no significant regeneration of the defects was observed. Morphometric analysis did not disclose differences in bone formation in matrices from groups A and B. Carboxyfluorescine-Diacetate-Succinimidylester (CFDA) labeling demonstrated low survival rates of transplanted cells. Discussion: Osteoblasts seeded into PBCB matrix display a differentiated phenotype following a 14 days cell culture period. Lack of initial vascularization may explain the absence of added osteogenicity in constructs from group A in comparison to group B. PBCB is well integrated and represents even without osteogenic cells a promising biomaterial for reconstruction of critical size calvarial bone defects.

Mineral status and mechanical properties of cancellous bone exposed to hydrogen peroxide for various time periods

“…Bone graft substitutes must be a match for natural bone in terms of mechanical strength against torsion, bending, and shear stress (Kneser et al 2006;Ohgushi et al 2003). Moreover, the substitutes must be flexible and degradable when bone remodeling takes place (Kneser et al 2006;Stützle et al 1998;Kadiyala et al 1997).…”

“…2a). Consequently, hydrogen peroxide (no more than 50%) has been used as a deproteinating agent by some authors, to remove the bulk of cells, tissue and proteins from bone tissues (Kneser et al 2006;Guizzardi et al 1995).…”

“…Moreover, the substitutes must be flexible and degradable when bone remodeling takes place (Kneser et al 2006;Stützle et al 1998;Kadiyala et al 1997). It is well known that natural trabecular frameworks and bone matrix consist mainly of type I collagen fibers (consisting of two a1 chains and one a2 chain) and noncollagenous proteins.…”

“…Processed cancellous bone, of either allogenic or xenogenic origin, represents another alternative to autogenous bone graft and exhibits many beneficial properties (Kneser et al 2006;Meyer et al 2008). Because the structure of apatite is similar across species, it was believed that natural bone hydroxyapatite without organic matrix was potentially a better basis for bone grafting than synthetic materials (Accorsi-Mendonça et al 2008;Guizzardi 1995).…”

De novo Generation of an Axially Vascularized Processed Bovine Cancellous-Bone Substitute in the Sheep Arteriovenous-Loop Model

“…Our PBCB matrix has been assessed in a few preclinical studies in vitro and in vivo using a small-animal model [4,5,21]. Furthermore, successful application in a vertebral-fusion large-animal model was pursued [22].…”