In vitro evaluation of a multifunctional bactericidal synthetic bone substitute

1. In vitro evaluation of a multifunctional bactericidal synthetic bone substitute D. Bollati, M. Morra, C. Cassinelli, G. Cascardo Nobil Bio Ricerche srl, Via Valcastellana 26, 14037 Portacomaro (AT) Italy www.nobilbio.it dbollati@nobilbio.it Baveno, SIB Conference, 3-5 June 2013

2. Outline • Introduction • Goal of the study • Materials and methods • Results • Comments and conclusions Baveno, SIB Conference, 3-5 June 2013

3. Introduction: bone substitutes Powder, granules or scaffolds used to fill up bone pits in different applications: - maxillofacial - dental - prosthetic surgery - spinal surgery • These materials could be synthetic or of animal/human source ; • a synthetic bone substitute should be biocompatible, osteoconductive and possibly osteoinductive; • often used in presence of infections antibiotic delivery in the implant site Baveno, SIB Conference, 3-5 June 2013

4. Bone formation at the interface with tissue Prevention of bacteria colonization Goal of the study Development of an innovative process of surfacemodification on a synthetic phosphatic bone substitute: ‘’Multifunctional’’ synthetic bone substitute Baveno, SIB Conference, 3-5 June 2013

5. 1 mm 10 µm Materials and methods Symbol Formula Ca/P - β-TCP 75% - nano HAP 25% HAP Ca10(PO4)6(OH)2 1,67 - Granules dimensions: 300 μm/ 2 mm Β-TCP Ca3(PO4)2 1,5 Baveno, SIB Conference, 3-5 June 2013

6. ~ 200 nm Materials and methods Surface modification ‘’CVHA’’ collagen 1. Collagen fibrillation with vancomycin and hyaluronic acid; vancomycin 2. covalent linking of hyaluronic acid; hyaluronic acid 3. interaction of vancomycin with HA and crosslinking. βTCP/HAP granules Baveno, SIB Conference, 3-5 June 2013

7. Ctrl “CVHA” Staph. Epidermidis growth is inhibited by vancomycin release from the granules Results: anti-bacterial effect ‘’Agar germ’’ experiments Baveno, SIB Conference, 3-5 June 2013

8. Most of antibiotic is released within 3 days Results: anti-bacterial effect Vancomycin release Baveno, SIB Conference, 3-5 June 2013

9. “Osteoimmunology: crosstalk between the immune and bone system” T. Nakashima, H. Takayanagi ; J Clin Immunol (2009) 29:555–567 Gene expression analysis of macrophages and osteoblasts Results: biological response • bone formation depends on the balancing between osteoblast and osteoclast activity • osteoclast differentiation is enhanced by several cytokines produced by inflammatory cells and by specific signal molecules produced by monocytes and osteoblasts Baveno, SIB Conference, 3-5 June 2013

10. - MCP-1 - IL-1β - IL-6 - IL-10 1) M.Rauner et al “Osteoimmunology” Int. Arch. Allergy Immunol. 2007,143, 31-48 2) K. Steeve et al. “IL-6, RANKL, TNF alpha/IL1: interrelations in bone resorption pathophysiology” Cytokine and Growth Factor Reviews, 15 (2004), 49-60 Results: biological response (macrophages) Gene expression of J774A.1 macrophages Expression of these genes at different timepoints Pro-inflammatory mediators, stimulate bone resorption, osteoclast formation, RANKL signaling and are involved in the response to bacteria and endotoxins Anti-inflammatory mediator Baveno, SIB Conference, 3-5 June 2013

11. 4h 24h Ctrl CVHA Results: biological response (macrophages) Gene expression of J774A.1 macrophages Baveno, SIB Conference, 3-5 June 2013

12. - ALP - OCN - BSP - RANKL - OPG 1) M.Rauner et al “Osteoimmunology” Int. Arch. Allergy Immunol. 2007,143, 31-48 2) K. Steeve et al. “IL-6, RANKL, TNF alpha/IL1: interrelations in bone resorption pathophysiology” Cytokine and Growth Factor Reviews, 15 (2004), 49-60 3) V. Pivodova et al. “Osteoblast and gingival fibroblast markers in dental implant studies” Biomed. Pap. Med. 2011, June, 155(2) 109-116 Results: biological response (osteoblasts) Gene expression of SaOs-2 osteoblasts Expression of these genes at different timepoints Pro-osteogenic markers, generate free phosphates, involved in bone mineralization and calcium binding action RANK receptor,induces differentitation of pre-osteoclasts to osteoclasts Soluble RANK, its interaction with RANKL inhibits osteoclast formation Baveno, SIB Conference, 3-5 June 2013

13. 24h 72h Ctrl CVHA Results: biological response (osteoblasts) Gene expression of SaOs-2 osteoblasts Baveno, SIB Conference, 3-5 June 2013

14. osteoblasts monocytes ALP, BSP IL-1, IL-6, MCP-1 RANKL IL-10 differentiation osteoclasts Results: biological response ‘’CVHA’’ surface modification could affect bone remodeling mechanisms Baveno, SIB Conference, 3-5 June 2013

15. Comments and conclusions • a synthetic biphasic bone substitute was developed • surface modification with collagen, vancomycin and hyaluronic acid (stable even after γ sterilization) • antibiotic release is immediate and effective to inhibit bacterial growth in vitro • the presence of collagen and hyaluronic acid seems to shift the balance of bone remodeling towards bone formation, instead of its resorption • this multifunctional product could help to meet several clinical needs Thank you for attention Baveno, SIB Conference, 3-5 June 2013