Abstract
ABSTRACT Hydroxyapatite (HA) is widely used as a biomaterial for bone repair and metallic prostheses coating. The main limitations of the current commercial synthetic hydroxyapatite compounds include high cost and decreased availability, especially for veterinary medicine purposes. Additionally, it is thought that HA biocompatibility and bioactivity could be enhanced by the addition of metal compounds. The objective of this work was to compare the subcutaneous tissue response of commercial and engineered hydroxyapatite obtained from the bovine femur diaphysis mixed with different concentrations of hexa-hydrated Zinc Nitrate in rabbits. Twenty-Five New Zealand female rabbits were used. Five treatments were done according to HA composition (commercial HA, no Zn-HA, 0.1M Zn, 0.2M Zn, and 0.3M Zn). Each treatment was evaluated at five time-points (8, 15, 30, 60 and 90 days post-implantation). Histopathologic analysis was performed to assess inflammation by polymorphonuclear cells infiltration, neovascularization, and fibrosis. Results obtained in this work suggest that general inflammation decreased after 60 days of implantation regardless of Zn concentration. Fibrosis score was increased in the commercial HP compared to control and Zn-hydrated HA. This paper shows that bovine hydroxyapatite is a biocompatible material regardless of nitrate Zinc concentration and has the same properties of commercial hydroxyapatite.
Highlights
Musculoskeletal trauma is a common source of bone loss, mainly associated with open fractures (Keating et al, 2005)
Present results show that addition of 0.1M of Zn nitrate lead to a higher polymorphonuclear cells infiltration (PMN) cells infiltration the first 8 days after implantation compared to the other treatments (Figure 5A)
PMN counts show similar results compared to commercial HA on day 15 (Figure 5B)
Summary
Musculoskeletal trauma is a common source of bone loss, mainly associated with open fractures (Keating et al, 2005). Lower limb fractures are common among active men and women (Hootman et al, 2002). Therapeutic intervention often includes the use of autografts and allografts; donor site morbidity and adverse immune response are common weaknesses of these methods (Hootman et al, 2002; Keating et al, 2005; Mauffrey et al, 2012). It has been shown that hydroxyapatite (HA) improves bone tissue regeneration (Swetha et al, 2010). It is hypothesized that the incorporation of Zn into HA matrix would increase osteoblast bioactivity, leading to improved bone formation and higher biological properties (Thian et al, 2013)
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