Active and Passive Mineralization of Bio-Gide® Membranes in Rat Calvaria Defects

Abstract

Bio-Gide® is a collagen membrane routinely used in guided bone regeneration. Recent studies have shown that this collagen membrane has osteoconductive properties, meaning that it can support the growth of new bone. However, it has also been observed that the collagen membrane has areas of mineralized fibers which can occur spontaneously and independently of osteoblasts. To better understand how this works, we established a model using minced collagen membranes to reduce the active mineralization of intact collagen membranes in favor of passive mineralization. We thus compared the original intact membrane with a minced collagen membrane in a 5 mm calvarial defect model in Sprague Dawley rats. After three weeks of healing, histology and microcomputed tomography (μCT) were performed. Histological analysis confirmed the osteoconductive properties, with new bone growing inside the intact collagen membrane. However, in minced collagen membranes, the osteoconductive properties were restricted to the defect margins. Interestingly, histology revealed large mineralized areas indicating passive mineralization with no signs of bone formation. In the μCT analysis, the intact collagen membranes caused a higher median mineralized volume (1.5 mm3) compared with the minced group (0.4 mm3), but this lacked significance (p = 0.09). The μCT analysis needs to be interpreted carefully, particularly in defects filled with minced membranes, considering that the mineralized tissue may not necessarily be bone but also the result of passive mineralization. Taken together, the findings suggest that Bio-Gide® collagen membranes support bone formation while also exhibiting potential for passive mineralization.

Human versus Rat PRF on Collagen Membranes: A Pilot Study of Mineralization in Rat Calvaria Defect Model

“…PRF research is designed to optimize human PRF based on in vitro studies; however, preclinical testing using human PRF may have drawbacks. Therefore, this study was driven by the overall question of whether the preparation of human PRF can be tested using the established model of rat calvaria defects-in particular, a variation of the model where the defect is covered by a collagen membrane [25][26][27][28][29][30][31]. This collagen membrane allowed for active and passive mineralization [28,29], which was ideal for studying the impact of its functionalization in the present study with human PRF and rat PRF.…”

“…Therefore, this study was driven by the overall question of whether the preparation of human PRF can be tested using the established model of rat calvaria defects-in particular, a variation of the model where the defect is covered by a collagen membrane [25][26][27][28][29][30][31]. This collagen membrane allowed for active and passive mineralization [28,29], which was ideal for studying the impact of its functionalization in the present study with human PRF and rat PRF. The main finding was that, compared to rat PRF, coating the collagen membrane with human PRF reduces new bone formation and passive mineralization within the spongy part of the biomaterial.…”

“…PRF was also combined with a bone substitute material, allowing for bridging of the defects in the rat calvaria defect model [23,24]. Thus, PRF cannot replace a scaffold guiding the new bone towards the center of the defect, but collagen membranes can [25][26][27][28][29][30][31]. Preclinical research revealed that collagen-based scaffolds were functionalized with platelet-rich plasma for enhanced skin wound healing [32].…”

“…Bio-Gide ® collagen membranes have a long history of guided bone regeneration [37] and have recently been reported to possess osteoconductive properties, at least in a rat calvaria defect model [25][26][27][28][29][30][31]. Histology revealed new bone formation and areas of mineralized matrix inside the spongy part of the collagen membrane, and this model was appropriate to study the impact of acid bone [27] and dentine lysate [26] as well as boneconditioned media [28] on bone regeneration.…”