Autologous bone graft substitute containing rhBMP6 within autologous blood coagulum and synthetic ceramics of different particle size determines the quantity and structural pattern of bone formed in a rat subcutaneous assay

Stokovic, Nikola; Ivanjko, Natalia; Erjavec, Igor; Milosevic, Milan; Oppermann, Hermann; Shimp, Larry; Sampath, Kuber T.; Vukicevic, Slobodan

Affiliations

¹Laboratory for Mineralized Tissues, School of Medicine, University of Zagreb, Zagreb, Croatia

²Scientific Center of Excellence for Reproductive and Regenerative Medicine, Croatia

³Department for Environmental Health, Occupational and Sports Medicine, Andrija Štampar School of Public Health, School of Medicine, University of Zagreb, Zagreb, Croatia

⁴Genera Research, Kalinovica, Sveta Nedelja, Croatia

⁵CaP Biomaterials, East Troy, WI, USA

⁶perForm Biologics Inc, Holliston, MA, USA

Abstract and keywords

Bone morphogenetic proteins (BMPs) are potent osteoinductive agents for bone tissue engineering. In order to define optimal properties of a novel autologous bone graft substitute (ABGS) containing rhBMP6 within the autologous blood coagulum (ABC) and ceramic particles as a compression resistant matrix (CRM), we explored the influence of their amount, chemical composition and particle size on the quantity and quality of bone formation in the rat subcutaneous assay. Tested ceramic particles included tricalcium phosphate (TCP), hydroxyapatite (HA) and biphasic calcium phosphate ceramic (BCP), containing TCP and HA in 80/20 ratio of different particle sizes (small 74–420 μm, medium 500–1700 μm and large 1000–4000 μm). RhBMP6 was either mixed with ABC or lyophilized on CRM prior to use with ABC. The experiments were terminated on day 21 and implants were analysed by microCT, histology and histomorphometry. Addition of CRM to ABGS containing rhBMP6 in ABC significantly increased the amount of newly formed bone and the optimal CRM/ABC ratio was found to be around 100 mg/500 μL. MicroCT analyses revealed that all tested ABGS formulations induced an extensive new bone formation and there were no differences between the two methods of rhBMP6 application as determined by the bone volume. However, the particle size played a significant role in the quantity and quality of newly formed bone. ABGS containing small particles induced new bone forming a dense trabecular network, cortical bone at the rim, bone and bone marrow in apposition to and in between ceramic particles. ABGS containing medium and large particles also resulted in new bone on the surface of particles as well as inside the pores. Histomorphometric analysis revealed that the ceramics particle size correlated with the quality of trabecular pattern of newly formed bone, bone/bone marrow ratio as observed in apposition and between particles, and the ratio between the cortical and trabecular bone. By employing rat subcutaneous implant assay, we showed for the first time that the size of synthetic ceramics particles affected the osteogenesis as defined by both the quantity and quality of ectopic bone.

Keywords: Bone morphogenetic proteins; BMP; BMP carrier; Bone regeneration; Tissue engineering; TCP; HA

Links

DOI: 10.1016/j.bone.2020.115654

PubMed: 32977068

WoS: 000601334100005

History

Received: 2020-07-7

Revised: 2020-09-16

Accepted: 2020-09-16

Online: 2020-09-23

Cited Works (3)

Year	Entry
2020	Štoković N, Ivanjko N, Pećin M, Erjavec I, Karlović S, Smajlović A, Capak H, Milošević M, Bubić Špoljar J, Vnuk D, Matičić D, Oppermann H, Sampath TK, Vukičević S. Evaluation of synthetic ceramics as compression resistant matrix to promote osteogenesis of autologous blood coagulum containing recombinant human bone morphogenetic protein 6 in rabbit posterolateral lumbar fusion model. Bone. November 2020;140:115544.
2020	Walker EC, Truong K, McGregor NE, Poulton IJ, Isojima T, Gooi JH, Martin TJ, Sims NA. Cortical bone maturation in mice requires SOCS3 suppression of gp130/STAT3 signalling in osteocytes. eLife. 2020;9:e56666.
2020	Chiari C, Grgurevic L, Bordukalo‐Niksic T, Oppermann H, Valentinitsch A, Nemecek E, Staats K, Schreiner M, Trost C, Kolb A, Kainberger F, Pehar S, Milosevic M, Martinovic S, Peric M, Sampath TK, Vukicevic S, Windhager R. Recombinant human BMP6 applied within autologous blood coagulum accelerates bone healing: randomized controlled trial in high tibial osteotomy patients. J Bone Miner Res. October 2020;35(10):1893-1903.

Cited By (1)

Year	Entry
2020	Vukicevic S, Sampath KT, Luyten FP. Editorial - "The role of bone morphogenetic proteins (BMPs) in musculoskeletal biology". Bone. December 2020;141:115622.