title: Bone formation on rough, but not polished, subcutaneously implanted Ti surfaces is preceded by macrophage accumulation.
abstract: Implanted rough surfaces have long been associated with the accumulation of macrophages and other cells of the monocytic lineage such as foreign body giant cells and osteoclasts. As cells of the moncytic lineage are part of the immune system, the response of this cell family to biomaterials has attracted wide concern. This study compared events at the interface of implant surface topographies with varied roughness in a rat subcutaneous model. Titanium-coated epoxy replicas of machined, etched, blasted, titanium-plasma-sprayed (TPS), sandblasted-and-etched (SLA), micromachined, and polished surfaces were implanted for up to 11 weeks, and processed for light or electron microscopy or immunohistochemistry for ED1, a marker for recruited macrophages. Initially, healing appeared similar among all surfaces, the frequency of mineralization followed the order of SLA, micromachined, TPS, machined, etched, blasted, and polished surfaces. On the SLA surface macrophages, as identified by both ultrastructural morphology and immunohistochemistry were the predominant cell type at 1 week and persisted until mineralization occurred as early as 2 weeks. On smoother surfaces collagenous matrix predominated at 2 weeks and subsequently increased with time. There, thus, appears to be two routes to bone-like tissue formation on Ti implants in this rat subcutaneous model; macrophage-mediated and macrophage-independent dense collagenous-matrix-associated.
authors.affiliation: Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, Canada V6T 1Z3. bchehrou@interchange.ubc.ca
authors.forename: Babak
authors.initials: B
authors.lastname: Chehroudi
authors.forename: Salem
authors.initials: S
authors.lastname: Ghrebi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Murakami
authors.forename: John Douglas
authors.initials: JD
authors.lastname: Waterfield
authors.forename: Gethin
authors.initials: G
authors.lastname: Owen
authors.forename: Donald Maxwell
authors.initials: DM
authors.lastname: Brunette
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism / Q000648:ultrastructure; D020007:Implants, Experimental; D008264:Macrophages / Q000276:immunology* / Q000648:ultrastructure; D008297:Male; D008422:Materials Testing; D010012:Osteogenesis / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D014025:Titanium