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Abstract

Hydroxyapatite (HA) coatings have been used to improve implant fixation by promoting bone formation around the prosthesis. A macrophage response to HA particulates has been noted around loosened HA-coated prostheses. As biomaterial wear particle-associated macrophages are known to be capable of differentiating into osteoclasts that are capable of bone resorption, we examined whether particulate HA could similarly induce macrophage-osteoclast differentiation. HA-associated macrophages were isolated from granulomas, formed by subcutaneous implantation of HA, and co-cultured with UMR 106 osteoblast-like cells in the presence of 1,25-dihydroxyvitamin D(3) for up to 14 days on glass coverslips and bone slices. HA-associated macrophage-osteoclast differentiation was evidenced by the formation of numerous multinucleated tartrate resistant acid phosphatase (TRAP)-positive cells which formed lacunar resorption pits on bone slices. Polymethylmethacrylate (PMMA) particle-associated macrophages, isolated from subcutaneous PMMA-containing granulomas, caused significantly more osteoclast formation and bone resorption than HA-associated macrophages. These results indicate that macrophages responding to HA particles are capable of osteoclast differentiation. They also suggest that particles derived from uncemented (HA-coated) implants are likely to induce less osteoclast formation and osteolysis than cemented implants.

https://microbiologyjournal.org/in-vitro-evaluation-of-chitosan-hydroxyapatite-nanocomposite-scaffolds-as-bone-substitutes-with-antibiofilm-properties/

“…HA shows excellent biocompatibility and osteoconductivity due to its similar chemical and crystal resemblance to the mineral component of bone. On the surface of implants, the HA induces bony apatite formation 5 . It was found to promote bone growth when tested on dogs, indicating osteoinductive characteristic of HA.…”

Preparation, characterization and antimicrobial activity of a bio-composite scaffold containing chitosan/nano-hydroxyapatite/nano-silver for bone tissue engineering

“…HA can promote the formation of bone-like apatite on its surface [9]. Polymers combined with HA are capable of promoting osteoblast adhesion, migration, differentiation and proliferation [10], especially useful for potential applications in bone repair and regeneration.…”

The influence of surface mineral and osteopontin on the formation and function of murine bone marrow-derived osteoclasts

“…Furthermore, studies of implant biomaterials have also suggested that attributes such as wear particle composition in prosthetic materials can modulate cellular activity by altering bonerelated gene profiles in vivo [23]. Recently, poly-methylmethacrylate (PMMA) particleassociated macrophages were shown to cause significantly more osteoclast formation and bone resorption than HA-associated macrophages, suggesting that particles derived from uncemented (HA-coated) implants are likely to induce less osteoclast formation and osteolysis than cemented implants [24]. These findings support the idea that a material compostion induced eefect on osteoclastic activity at the interface of prostheses may be a significant factor in the failure of orthopaedic implants.…”