Autologous blood coagulum is a physiological carrier for BMP6 to induce new bone formation and promote posterolateral lumbar spine fusion in rabbits

Abstract

In the present study, we describe autologous blood coagulum (ABC) as a physiological carrier for BMP6 to induce new bone formation. Recombinant human BMP6 (rhBMP6), dispersed within ABC and formed as an autologous bone graft substitute (ABGS), was evaluated either with or without allograft bone particles (ALLO) in rat subcutaneous implants and in a posterolateral lumbar fusion (PLF) model in rabbits. ABGS induced endochondral bone differentiation in rat subcutaneous implants. Coating ALLO by ABC significantly decreased the formation of multinucleated foreign body giant cells (FBGCs) in implants, as compared with ALLO alone. However, addition of rhBMP6 to ABC/ALLO induced a robust endochondral bone formation with little or no FBGCs in the implant. In rabbit PLF model, ABGS induced new bone formation uniformly within the implant resulting in a complete fusion when placed between two lumbar transverse processes in the posterolateral gutter with an optimum dose of 100-μg rhBMP6 per ml of ABC. ABGS containing ALLO also resulted in a fusion where the ALLO was replaced by the newly formed bone via creeping substitution. Our findings demonstrate for the first time that rhBMP6, with ABC as a carrier, induced a robust bone formation with a complete spinal fusion in a rabbit PLF model. RhBMP6 was effective at low doses with ABC serving as a physiological substratum providing a permissive environment by protecting against foreign body reaction elicited by ALLO. KEYWORDS allograft (ALLO), autologous blood coagulum (ABC), autologous bone graft substitute (ABGS), foreign body giant cells, posterolateral lumbar fusion (PLF), recombinant human BMP6 (rhBMP6)This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

A novel autologous bone graft substitute containing rhBMP6 in autologous blood coagulum with synthetic ceramics for reconstruction of a large humerus segmental gunshot defect in a dog: The first veterinary patient to receive a novel osteoinductive therapy

“…The efficacy and safety of this ABGS device for the treatment of critical size bone defects has been previously demonstrated in rabbits ( Grgurevic et al, 2019 ). To improve the implant biomechanical properties, we supplemented ABGS with allograft as a compression resistant matrix ( Vukicevic et al, 2020a ). Next, we tested synthetic ceramics of various chemical compositions (TCP, HA, BCP) formulated either as particles ( Stokovic et al, 2020a ) or blocks ( Stokovic et al, 2020b ) and demonstrated superior osteoconductive properties to support bone formation by rhBMP6 in ABC.…”

“…Bone morphogenetic proteins (BMPs) are potent osteoinductive agents that recruit mesenchymal stem cells and promote their proliferation and differentiation into bone and cartilage during embryonic development ( Sampath and Vukicevic, 2020 ; Vukicevic and Grgurevic, 2009 ). Autologous blood coagulum (ABC) is a novel physiological BMP carrier that supports tight BMP binding to plasma proteins within the fibrin meshwork, suppresses foreign body response, and allows a sustained in vitro release of rhBMP6 ( Vukicevic et al, 2014 ; Grgurevic et al, 2019 ; Vukicevic et al, 2020a ; Vukicevic et al, 2020b ). To improve biomechanical properties of implants, compression resistant matrix (CRM) could be added to implants in selected indications ( Vukicevic et al, 2020a ).…”

“…Autologous blood coagulum (ABC) is a novel physiological BMP carrier that supports tight BMP binding to plasma proteins within the fibrin meshwork, suppresses foreign body response, and allows a sustained in vitro release of rhBMP6 ( Vukicevic et al, 2014 ; Grgurevic et al, 2019 ; Vukicevic et al, 2020a ; Vukicevic et al, 2020b ). To improve biomechanical properties of implants, compression resistant matrix (CRM) could be added to implants in selected indications ( Vukicevic et al, 2020a ). Therefore, different bone graft substitutes with various scaffolds and growth factor combinations have been tested with and without cells, but the efficacy of bone formation remained unpredictable ( Wang and Yeung, 2017 ; Palombella et al, 2019 ; Ho-Shui-Ling et al, 2018 ; Vukicevic et al, 2019 ; Kuroiwa et al, 2019 ).…”

“…We have recently demonstrated that an autologous bone graft substitute (ABGS) containing recombinant human bone morphogenetic protein 6 (rhBMP6) within ABC with and without allograft as a CRM was safe and efficacious in the rabbit ulnar segmental defect model ( Grgurevic et al, 2019 ), rabbit and ovine posterolateral spinal fusion (PLF) and sheep anterior lumbar interbody fusion (ALIF) models ( Vukicevic et al, 2020a ; Grgurevic et al, 2020 ). In continuation, the ABGS was tested in Phase I clinical trials in patients with distal radial fracture ( Durdevic et al, 2020 ), and Phase I/II trial in patients undergoing high tibial osteotomy ( Chiari et al, 2020 ) and was proven safe and efficacious as compared to placebo and standard of care treated patients.…”

Recombinant Human BMP6 Applied Within Autologous Blood Coagulum Accelerates Bone Healing: Randomized Controlled Trial in High Tibial Osteotomy Patients

“…(9) ABGS induced new bone formation at 20 to 100 μg rhBMP6/mL coagulum in rat subcutaneous implants and restored the diaphyseal segmental defects in preclinical models. (9,10) ABC serves as a non-immunogenic physiological carrier. Furthermore, BMP6 has higher specific osteogenic activity than BMP2 and BMP7 presumably because it does not bind irreversibly to Noggin, a BMP antagonist, abundant in bone, compared with BMP2 and BMP7.…”