Osteoclasts in the interface with electrospun hydroxyapatite.
Electrospinning is a method to produce lightweight, resorbable and bioinspired scaffolds for tissue engineering. Here we investigated the influence of electrospun hydroxyapatite fibers (HA) on macrophages and osteoclasts. A mouse macrophage cell line (RAW 264.7) and human bone marrow derived primary osteoclasts (hOC) were cultured with electrospun HA fibers embedded in Matrigel. Cell morphology and the secretion of pro-inflammatory cytokines (IL-6 and TNF-α) were analyzed using macrophages. Both fluorescent microscopy and scanning electron microscopy indicated that the cell morphology differed on the various materials (HA fibers on Matrigel, pure Matrigel and a glass control). Control macrophages were activated with bacterial lipopolysaccharide (LPS) but electrospun HA did not provoke an inflammatory response. Cytokine secretion detected with enzyme-linked immunosorbent assay (ELISA) also supported this observation. LPS, but not HA fibers, stimulated TNF-α and IL-6 secretion by macrophages at the 2 day time point. After 4 days in culture there was an increasing trend in cytokine secretion in the HA fiber samples. Human bone marrow myeloid precursor cells were able to fuse and differentiate on the fibrous mineral scaffold to form functional multinuclear osteoclasts that were able to resorb the HA nanofibers. This indicates that osteoclasts do not necessarily need a continuous bone surface but osteoclast ruffled border membranes can form a resorption interface with a fibrous mineral scaffold.
Department of Anatomy and Cell Biology and MRC Oulu, P.O. Box 5000, FI-90014, University of Oulu, Finland.
Jenni
J
Pasuri
Laboratory of Inorganic Chemistry, Department of Chemistry, P.O. Box 55, FI-00014, University of Helsinki, Finland.
Jani
J
Holopainen
Department of Anatomy and Cell Biology and MRC Oulu, P.O. Box 5000, FI-90014, University of Oulu, Finland.
Hanna
H
Kokkonen
Department of Anatomy and Cell Biology and MRC Oulu, P.O. Box 5000, FI-90014, University of Oulu, Finland.
Maria
M
Persson
Department of Anatomy and Cell Biology and MRC Oulu, P.O. Box 5000, FI-90014, University of Oulu, Finland.
Kyösti
K
Kauppinen
Department of Anatomy and Cell Biology and MRC Oulu, P.O. Box 5000, FI-90014, University of Oulu, Finland.
Petri
P
Lehenkari
Laboratory of Inorganic Chemistry, Department of Chemistry, P.O. Box 55, FI-00014, University of Helsinki, Finland.
Eero
E
Santala
Laboratory of Inorganic Chemistry, Department of Chemistry, P.O. Box 55, FI-00014, University of Helsinki, Finland.
Mikko
M
Ritala
Department of Anatomy and Cell Biology and MRC Oulu, P.O. Box 5000, FI-90014, University of Oulu, Finland. Electronic address: Juha.Tuukkanen@oulu.fi.
Juha
J
Tuukkanen
D000818:Animals; D002460:Cell Line; D017886:Durapatite / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D010010:Osteoclasts / Q000166:cytology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014961:X-Ray Diffraction
D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D017886:Durapatite
Bone tissue engineering; Carbonated hydroxyapatite; Inflammation; Nanofiber; Nanoparticle