The use of mesenchymal stromal cell secretome to enhance guided bone regeneration in comparison with leukocyte and platelet‐rich fibrin

Abstract

ObjectivesSecretomes of mesenchymal stromal cells (MSC) represent a novel strategy for growth‐factor delivery for tissue regeneration. The objective of this study was to compare the efficacy of adjunctive use of conditioned media of bone‐marrow MSC (MSC‐CM) with collagen barrier membranes vs. adjunctive use of conditioned media of leukocyte‐ and platelet‐rich fibrin (PRF‐CM), a current growth‐factor therapy, for guided bone regeneration (GBR).MethodsMSC‐CM and PRF‐CM prepared from healthy human donors were subjected to proteomic analysis using mass spectrometry and multiplex immunoassay. Collagen membranes functionalized with MSC‐CM or PRF‐CM were applied on critical‐size rat calvaria defects and new bone formation was assessed via three‐dimensional (3D) micro‐CT analysis of total defect volume (2 and 4 weeks) and 2D histomorphometric analysis of central defect regions (4 weeks).ResultsWhile both MSC‐CM and PRF‐CM revealed several bone‐related proteins, differentially expressed proteins, especially extracellular matrix components, were increased in MSC‐CM. In rat calvaria defects, micro‐CT revealed greater total bone coverage in the MSC‐CM group after 2 and 4 weeks. Histologically, both groups showed a combination of regular new bone and ‘hybrid’ new bone, which was formed within the membrane compartment and characterized by incorporation of mineralized collagen fibers. Histomorphometry in central defect sections revealed greater hybrid bone area in the MSC‐CM group, while the total new bone area was similar between groups.ConclusionBased on the in vitro and in vivo investigations herein, functionalization of membranes with MSC‐CM represents a promising strategy to enhance GBR.

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.…”

“…In contrast to the two wound healing studies [35,43], we show that rat (but not human) PRF supports the osteoconductive properties of a collagen membrane when placed in a rat calvaria defect. The underlying reason remains unclear, but we know that collagen membranes functionalized with the conditioned medium of human PRF-thus, not containing the cells and the fibrin-rich matrix of the PRF membranes-result in around 50% defect coverage after four weeks [30]. Thus, mainly human cells and the fibrin-rich matrix hinder rat tissues from consolidating and forming new bone tissue.…”

“…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.…”