The influence of calcium phosphate biomaterials on human bone cell activities. An in vitro approach

Over the past decade, a large number of biomaterials have been proposed as artificial bone fillers for repairing bone defects. The material most widely used in clinical medicine is hydroxyapatite. The aim of our investigation was to study the effect of hydroxyapatite size mechanism on osteoblasts. The osteoblasts were cultured in vitro with 0.1% (1 mg/mL) of various sized hydroxyapatite particles (0.5-3.0, 37-63, 177-250, and 420-841 microm) for 1 h, 3 h, 1 day, 3 days, and 7 days. The results showed that adding hydroxyapatite particles to osteoblast cultures can significantly affect osteoblast cell count. Osteoblast populations decreased significantly. Osteoblast mean surface areas also changed significantly. Transforming growth factor-beta1 (TGF-beta1) concentrations in culture medium decreased significantly with the addition of hydroxyapatite particles. Prostaglandin E2 (PGE2) concentrations in medium increased significantly. The changes in TGF-beta1 and PGE2 concentration were more significant and persisted longer in smaller-particle groups. The inhibitory effects of hydroxyapatite particles on osteoblast cell cultures were mediated by the increased synthesis of PGE2. Caution should be exercised before using a hydroxyapatite product which could easily break down into fine particles.

Section: Discussionmentioning

confidence: 99%

Influence of hydroxyapatite particle size on bone cell activities: Anin vitro study

Sun

Liu

Chang

et al. 1998

“…A similar layer has been described on HA implants in vivo 4,5 and in vitro. 14,15 This layer was evident as a thin electron-dense layer on the HA surfaces at about 8 days of culture. Its early deposition appeared to result from the fusion and emptying of small extracellular vesicles onto the HA surface.…”

Section: Discussionmentioning

confidence: 98%

“…Although electron microscopic studies have described the ultrastructure of the bone-hydroxyapatite interface in vivo [1][2][3][4][5] and in vitro, [13][14][15] the mechanisms that initiate bone formation at this interface are un- clear. Because of the difficulties in preparing in vivo and in vitro HA samples for morphological and biochemical analysis, the objective of this study was to develop an in vitro method that would facilitate retrieving and preparing intact bone-HA interface samples for the investigation of early bone formation.…”

Section: Discussionmentioning

confidence: 99%

“…12 It is only recently that in vitro studies have reported on the interaction of cultured osteoblasts with HA surfaces. [13][14][15] When osteogenic MC 3T3-E1 cells were cultured on HA or HA particles, they attached and spread on the substrate without apparent toxicity. 13,14 The nature of the attachment was not addressed.…”

Section: Introductionmentioning

confidence: 99%

“…[13][14][15] When osteogenic MC 3T3-E1 cells were cultured on HA or HA particles, they attached and spread on the substrate without apparent toxicity. 13,14 The nature of the attachment was not addressed. Studies describing the interface between mouse calvarial osteoblasts and porous HA particles in cell culture showed that osteoblasts formed globules of mineralized bone matrix adjacent to the porous HA particles.…”

Section: Introductionmentioning

confidence: 99%

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Anin vitro system for studying osteointegration of dental implants utilizing cells grown on dense hydroxyapatite disks

Layman

Ardoin

1998

A proposed in vitro system is described where chick osteoblasts are cultured on the flat surfaces of dense, nonporous HA disks to facilitate the study of bone formation at the cell-HA interface. During early bone formation cell-coated HA disks were retrieved, fixed with buffered 2% glutaraldehyde, and embedded in epon/araldite. The underlying HA disks were demineralized in diluted acid, and the intact cell-HA interfaces were re-embedded and thin sectioned for routine transmission electron microscopy. Morphologic studies indicated that osteoblasts proliferated and formed nodules of cells on the surfaces of HA disks. With increasing time in culture, they deposited orthogonally packed collagen fibrils between the cell layers that were enveloped by electron-dense mineralized globules. Eventually, small spicules of mineralized HA formed along collagen fibrils. An electron-dense layer about 50 nm thick was observed on the surface of the HA disks. Biochemical studies indicated that cell proliferation, as judged by 3H-thymidine uptake, increased rapidly during the first 3 days, reached a maximum around 6 days, and then declined by 12 days in culture. AP activity and collagen synthesis, as determined by 3H-hydroxyproline formation, increased as cellular proliferation declined. Mineralization, as judged by 45Ca uptake and spicule formation, occurred, as expected, following the increase in AP activity and deposition of densely packed collagen fibrils. Thus, all morphological and biochemical parameters studied indicate that the proposed in vitro system is reproducible and can facilitate the study of the osteointegration of HA-coated implants.

Differential effects of different forms of hydroxyapatite and hydroxyapatite/tricalcium phosphate particulates on human monocyte/macrophagesin vitro

Harada

Wang

Doppalapudi

et al. 1996

A possible complication associated with the use of hydroxyapatite (HA) or HA/tricalcium phosphate (HA/TCP) coating on the surfaces of prosthetic devices used for dental and orthopedic implants is their potential to fragment and thus exist as wear debris. In contrast to the so-called osteoconductive properties of HA or HA/TCP coatings, in particulate form these materials may lead to an adverse pattern of cellular and tissue responses at the bone-implant interface. We have established an in vitro cell culture system to characterize the biologic and biochemical effects of various particulate materials. The present study demonstrates that the HA/TCP particles derived from different sintering temperatures exhibit differential effects on cultured human monocyte/macrophages (M/M). The HA/TCP particles dried at 110 degrees C were the most biologically active, stimulating significant release of interleukin 1 beta (IL-1 beta), IL-6, tumor necrosis factor alpha, and prostaglandin E2 (PGE2), products implicated as important mediators of inflammation in diverse pathologic conditions. Other particles, sintered at either 900 or 1200 degrees C, did not stimulate production of cytokines or PGE2. HA/TCP particles from plasma-spray coatings also failed to release proinflammatory products. These results suggest that the biochemical and crystalline structural properties of particles markedly affects their capacity to modulate M/M function. This in vitro culture system should be useful in characterizing the specific physical and chemical properties of HA or HA/TCP particulates that are responsible for stimulating proinflammatory cell responses.