Presence of a fatty acid-binding protein in the armadillo Harderian gland

Clinical measurements on gingival indices and morphologic observations were performed in this study to verify the defending mechanism of gingival soft tissue against foreign invasions from the perspective of epithelial adhesion/attachment to implant surfaces in the monkey mandible. The following zones were observed using scanning electron microscopy: (1) plaque zone, suggesting susceptibility of the gingival tissue to bacterial invasion; (2) nude zone, demonstrating indirect adhesion of epithelial cells to the implant surface through the mucous layer and preventing bacterial invasion; and (3) epithelial cell attached zone, having greater bond strength of epithelial cells at the cell-implant interface as compared to cell-cell bonding within the epithelial cell layer. This study suggested that epithelial cell attachment/adhesion may play a dominant role in retaining the successful condition of a dental implant.     

Cytokeratin expression in human oral gingival epithelial cells: in vitro regulation by titanium-based implant materials

To evaluate whether cytokeratin expression in human oral epithelial cells could be influenced by implant materials used in dental surgery, passaged human oral gingival epithelial cells were seeded on commercially pure titanium (CP-Ti) or on Ti6Al4V titanium alloy. Confluence was achieved after about 15 days on both substrates. Cells formed at that time, an organized layer of densely packed polygonal cells, and harbored a filamentous cytokeratin network typical of epithelial cells. Immunochemistry and immunoblot analysis were used to detect modifications of the amount of individual CK polypeptides (CK7, 8, 13, 18 and 19) in function of the culture substrate. Results showed that the level of CK8, CK18 and CK19 expression was not altered whatever the culture substrate used. The expression of CK13 was reduced in epithelial cells cultured on the titanium alloy, as compared with commercially pure titanium. Conversely, the level of CK7 was higher on the Ti6Al4V alloy than on commercially pure titanium. This study suggests that titanium-based implant materials could influence differently the phenotype of oral gingival epithelial cells.     

Effects of titanium on transcriptional and post-transcriptional regulation of fibronectin in human fibroblasts

The effects of commercially pure titanium (Ti) on the regulation of fibronectin gene expression and synthesis were investigated in early-passage human gingival fibroblasts. The fibroblasts were cultured on 50 nm Ti-coated silicon wafers treated with radio-frequency glow discharge prior to use and on Falcon tissue culture plastic (TCP) dishes as a control. Northern hybridization analysis revealed that fibroblasts cultured on Ti reduced the fibronectin mRNA level by 58% at 16 h, but increased it by 2.6-fold at 90 h, although the cell numbers and house-keeping gene GAPD mRNA levels on these two surfaces were essentially the same. The amount of total RNA was slightly less on the Ti surface. While the total [35S]methionine incorporation was essentially unaltered, the amount of [35S]methionine-labeled fibronectin was significantly increased in cells cultured on a Ti surface in early cultures but decreased in the late cultures. The apparent discrepancy between the increased fibronectin mRNA levels and decreased translation could be explained by a 30% reduction in fibronectin mRNA half life in cells cultured on Ti. The distribution of fibronectin between the medium and the cell layer also was altered on Ti surfaces, with a approximately 100-fold increase of fibronectin assembled in extracellular matrix at 16 h, but a 36% reduction at 90 h. In contrast, the amount of fibronectin recovered in the medium was essentially unchanged. The total amount of protein assembled into the extracellular matrix by cells on Ti increased 2.1-fold at 16 h but decreased by 19% in 90-h cultures. These significant changes in fibronectin gene activity and gene product distribution by cells cultured on Ti surfaces demonstrate that the surface chemistry of biomaterials can selectively regulate the cellular behavior at the molecular level and, conversely, that molecular biological techniques provide sensitive indicators of the molecular biocompatibility of implant materials.     

Titanium–hydroxyapatite composite biomaterial for dental implants

Abstract

The objective of the present study was to investigate high velocity compaction of titanium powder and to prepare a dense composite biomaterial of titanium and hydroxyapatite with the purpose of forming dental components with improved early healing properties. A high purity titanium powder was compacted using high velocity compaction to study the density distribution. Then, a titanium–hydroxyapatite composite was prepared by mixing titanium powders and hydroxyapatite grains. Dental implant components were formed from the high velocity compacted specimens, exposing the hydroxyapatite grains at the component surface. The green density reached more than 98·5% after more than one impact. The composite was heated to 500°C, enough to bind the titanium grains, but to avoid observable reactions. Compacted pure titanium could be sintered to full density. The heated composite material reached 99% density, no reaction was observed between titanium and hydroxyapatite, and the composite material could be formed into dental implants.     

Evidence for an impaired ability to determine semantic relations in Alzheimer''s disease patients

Gingival and periodontal ligament (PDL) fibroblasts are the major cellular components of periodontal soft connective tissues, but the precise differences between these cells are not yet known. In the present study, we have therefore examined the phenotypic and functional features of the cells obtained from gingival and PDL biopsy samples. Spindle-shaped cells characteristic of fibroblasts were the main cell type observed in vitro, although epithelial cells were also present in primary gingival cell cultures. Flow cytometry was used to measure the size and granularity of the cultured cells, and showed that the gingival fibroblasts were smaller and less granular compared with the PDL cells. The expression of certain key extracellular matrix (ECM) proteins, fibronectin, collagen type I, and tenascin was measured by flow cytometry. Analysis of the fluorescence profiles of these cultures showed that the majority of cells expressed fibronectin and that the average fluorescence intensity of this antigen in the PDL cells was higher than that in the gingival fibroblasts. Moreover, the fibronectin-positive PDL cells apparently comprised two subpopulations which expressed fibronectin at different levels, suggesting that the cells in the PDL cultures were functionally heterogeneous. The level of collagen type I was also found to be up-regulated in the PDL compared with the gingival cells and, as with fibronectin, was expressed at two different levels by subsets of the PDL cells. In contrast, tenascin was expressed at very similar levels by both the gingival fibroblasts and PDL cells. In addition, measurement of alkaline phosphatase, a marker enzyme for mineralized tissue-forming cells, showed that the PDL cells had higher activity than the gingival fibroblasts and that the alkaline phosphatase activity in the PDL cells was far more markedly up-regulated by dexamethasone. Our findings demonstrate that, despite their similar spindle-shaped appearance, fibroblasts derived from gingival and PDL tissues appear to display distinct functional activities which are likely to play a vital part in the maintenance of tissue integrity and regenerative processes.     

钛及钛合金人体植入材料研究进展

钛及其合金因其具有低密度、高比强度、低弹性模量、良好的生物相容性和耐蚀性等特点, 被认为是一种理想的人体植入金属材料, 广泛应用于骨关节替换、牙齿修复等方面, 且对其的需求量快速增长; 同时, 钛也存在骨整合率低、抗菌性差、耐磨性差等缺陷, 急需进一步研究和改进。本文介绍了钛及钛合金作为人体植入材料的优异特性, 概述了国内外关于新型β型钛合金、表面改性钛合金、多孔钛合金、钛-陶复合材料的研究进展, 总结了钛及钛合金材料存在的一些问题, 为新型钛及钛合金材料的设计研发, 钛及钛合金综合性能的优化, 钛及钛合金使用寿命的延长提供参考。     

Mechanism of initial attachment of corneal epithelial cells to polymeric surfaces

The initial attachment of cultured bovine corneal epithelial cells and stromal fibroblasts to two oxygen-containing synthetic polymers was studied. Cultured epithelial cells and stromal fibroblasts were seeded onto two oxygen-containing surfaces: 'tissue culture' polystyrene (TCPS) and a polymer film deposited by RF plasma deposition using a methylmethacrylate monomer (MMA/FEP). To establish the mechanism of cell attachment, the effect of the selective removal of the vitronectin and fibronectin from the serum used in the culture medium was tested. The attachment of cultured epithelial cells during the first 90 min of culture was reduced by 40% (TCPS)-80% (MMA/FEP) as a result of removing vitronectin from the medium. Attachment of these cells to TCPS was reduced by 85-95% when the serum was depleted of both fibronectin and vitronectin. However, depletion of fibronectin reduced cell attachment to TCPS by 20%, whilst on MMA/FEP cell attachment was equivalent, or higher, than that for intact serum. The attachment of cultured corneal stromal fibroblasts was similarly dependent on vitronectin but less dependent on fibronectin. Therefore, for the attachment of both cultured epithelial cells and fibroblasts to oxygen-containing surfaces in the presence of serum, there is a high requirement for serum vitronectin but a lesser requirement for fibronectin. The effects of the establishment of corneal epithelial cells in culture and the site of origin of the cells, were determined. Primary isolates of epithelial cells isolated from the limbal, central or peripheral regions of the cornea were less dependent on vitronectin for initial attachment to TCPS than were these cells after several passages in culture. Furthermore, the primary isolates were dramatically less responsive to vitronectin than the cultured cells. These results indicate that the mechanism of attachment of corneal epithelial cells to TCPS varies with the culture experience of the cells. Cells that are culture neophytes can employe endogenous mechanisms for the initial attachment to TCPS, whereas cells established in culture are dependent on exogenous vitronectin in order to attach.     

Cyclosporin A and hydroxycyclosporine (M-17) affect the secretory phenotype of human gingival fibroblasts

The responsiveness of human gingival fibroblast populations to cyclosporin A (CsA) and its principal metabolite, hydroxycyclosporine (M17), was evaluated in cell culture. Gingival fibroblasts exhibited a dose-dependent accumulation and bell-shaped distribution of dansylated CsA. A 100-fold excess of non-labeled CsA prevented the accumulation of the fluorescent probe in the fibroblasts. Both CsA (400 ng/ml) and M17 (100 ng/ml) stimulated mean gingival fibroblast cell number to 23.2% and 36.7% above controls, and reduced mean collagen production by 37.7% and 37.4% below controls, respectively; however, neither CsA nor M17 affected mean protein production in comparison to control cultures. Analyses of responses to CsA and M17 by ligand-accumulating and non-accumulating fibroblasts sorted out from the parent cultures did not provide consistent interstrain responses either by cells representing the upper quartile of fluorescence or cells representing the bottom quartiles of fluorescence. These data demonstrate that CsA is accumulated by gingival fibroblasts and that CsA and M17 are potent modulators of gingival fibroblast phenotype.     

Parallel involvement of perirhinal and lateral entorhinal cortex in the polysynaptic activation of hippocampus by olfactory inputs

BACKGROUND AND AIMS OF THE STUDY: There is a need for a replacement cardiac valve constructed from non-immunogenic materials but incorporating living, and preferably autologous, cells. The object of this study was to colonize freeze-dried porcine valve leaflets with human fibroblasts and vascular endothelial cells. METHODS: Porcine pulmonary valve leaflets were freeze-dried to produce a porous matrix having communicating cavities of appropriate dimensions for fibroblast repopulation. Cultured human fibroblasts and vascular endothelial cells that had been cryopreserved by standard methods were added to freeze-dried leaflets. Following culture at 37 degrees C, the leaflets were examined by confocal scanning microscopy and transmission electron microscopy. RESULTS: Mechanical perforation of the leaflet surface permitted colonization of the freeze-dried matrix by fibroblasts; under the conditions we studied, the cell density did not reach physiologic levels but those cells that were present were well attached and metabolically active. Gentle cotton abrasion of the surface of the freeze-dried leaflets provided a suitable substrate for endothelial cell attachment and confluence was achieved in 10 days. Leaflets were perforated, cultured with human fibroblasts for 10 days, then gently rubbed with a cotton bud and cultured for a further 10 days with human endothelial cells. The endothelial cells formed a confluent layer on the surface and viable fibroblasts were present within the substance of the leaflet. CONCLUSION: Although these results are preliminary, they demonstrate the basic feasibility of this approach to the production of xenogeneic valves that contain the patient's own cells.     

Effects of extracellular matrix constituents on the attachment of human oral epithelial cells at the titanium surface

This in vitro study attempts to delineate the role of extracellular matrix (ECM) constituents at the epithelial tissue-implant interface. To know which ECM constituents have a beneficial influence on the behavior of epithelial cells, the attachment, proliferation, morphologic pattern, and differentiation or cytoskeletal organization of human oral epithelial cells on ECM-coated (type IV collagen, fibronectin, type I collagen, laminin, and vitronectin) and noncoated titanium surface have been evaluated and compared. In each experiment comparing commercially pure titanium and oxygen plasma-cleaned titanium, the same ECM constituents were used. In this study, type IV collagen could provide an excellent substratum for epithelial cell attachment on titanium surface, but vitronectin-coated titanium revealed lower effectiveness for attachment of epithelial cells than noncoated titanium. These results suggested that type IV collagen could be used as a means for obtaining good epithelial seal, whereas vitronectin could be used to restrain the attachment of epithelium to dental implants.     

Deficiency in collagen and fibronectin phagocytosis by human buccal mucosa fibroblasts in vitro as a possible mechanism for oral submucous fibrosis

Oral submucous fibrosis (OSF), a chronic oral mucosal condition commonly found in south Asians, is a disorder characterized by a quantitative as well as a qualitative alteration of collagen deposition within the subepithelial layer of the oral mucosa. Since degradation of collagen by fibroblast phagocytosis is an important pathway for physiological remodelling of soft connective tissues, we have investigated phagocytosis of collagen- and fibronectin-coated latex beads by fibroblast cultures with an in vitro model system. Coated fluorescent latex beads were incubated with human oral mucosa fibroblasts and the fluorescence associated with internalized beads was measured by flow cytometry. Cells from normal tissues that had been incubated with beads for 16 h contained a mean of 75% collagen phagocytic cells and 70% fibronectin phagocytic cells; however, about 15% and 10% of phagocytic cells individually contained more than twice the mean number of beads per cell. In contrast, cells from OSF tissues exhibited a 40% reduction of the proportions of collagen phagocytic cells (mean=35%) and a 48% decrease of the proportions of fibronectin phagocytic cells (mean=22%), none of the cells having a high number of beads as compared to normal fibroblasts. OSF lesions appear to contain fibroblasts with marked deficiencies in collagen and fibronectin phagocytosis. To investigate if inhibition of phagocytosis could be demonstrated in vitro, normal fibroblast cultures were incubated with areca nut alkaloids (arecoline, arecaidine). The cultures had a dose-dependent reduction in the proportions of phagocytic cells. On the other hand, corticosteroid used in the treatment of OSF exhibited a dose-dependent enhancement in the proportion of phagocytic cells. Therefore, our hypothesis for OSF, although oversimplified, is that betel nut alkaloids (arecoline, arecaidine) inhibit fibroblast phagocytosis and this provides a mechanism for the development of OSF. The benefit of a local intralesional injection of corticosteroid is also possibly, at least in part, through an enhancement of fibroblast collagen phagocytosis.     

Site-directed mutagenesis of the arginine-glycine-aspartic acid sequence in osteopontin destroys cell adhesion and migration functions

Osteopontin (OPN) is a secreted calcium-binding phosphoprotein produced in a variety of normal and pathological contexts, including tissue mineralization and cancer. OPN contains a conserved RGD (arg-gly-asp) amino acid sequence that has been implicated in binding of OPN to cell surface integrins. To determine whether the RGD sequence in OPN is required for adhesive and chemotactic functions, we have introduced two site-directed mutations in the RGD site of the mouse OPN cDNA, in which the RGD sequence was either deleted or mutated to RGE (arg-gly-glu). In order to test the effect of these mutations on OPN function, we expressed control and mutated mouse OPN in E. coli as recombinant glutathione-S-transferase (GST)-OPN fusion proteins. Control mouse GST-OPN was functional in cell adhesion assays, supporting attachment and spreading of mouse (malignant PAP2 ras-transformed NIH 3T3, and, to a lesser extent, normal NIH 3T3 fibroblasts) and human (MDA-MB-435 breast cancer, and normal gingival fibroblast) cells. In contrast, neither of the RGD-mutated OPN proteins ("delRGD" or "RGE") supported adhesion of any of the cell lines, even when used at high concentrations or for long assay times. GRGDS (gly-arg-gly-asp-ser) peptides inhibited cell adhesion to intact GST-OPN, as well as to fibronectin and vitronectin. In chemotaxis assays, GST-OPN promoted directed cell migration of both malignant (PAP2, MDA-MB-435) and normal (gingival fibroblast, and NIH 3T3) cells, while RGD-mutated OPN proteins did not. Together these results suggest that the conserved RGD sequence in OPN is required for the majority of the protein's cell attachment and migration-stimulating functions.     

Response of human osteoblasts to implant materials: integrin-mediated adhesion

The initial interaction of the human osteoblast-like cell line Saos-2 with orthopaedic implant materials was analyzed to determine the mechanism by which these cells adhere to implant surfaces. Saos-2 cells were allowed to attach to disks composed of the orthopaedic implant materials Tivanium (Ti6A14V) and Zimaloy (CoCrMo) and to control disks of glass and plastic. Serum had no effect on the number of cells that attached to Tivanium and Zimaloy at 4 or 24 hours but did increase the number of cells that attached to glass at 24 hours. Collagen synthesis was determined by [3H]proline incorporation into collagenase-digestible protein and noncollagen protein. A significant increase of 19% was found for collagen synthesized in cells cultured on Zimaloy for 24 hours compared with glass, with no differences on Tivanium and plastic. However, collagenase-digestible protein and noncollagen protein were increased the most (204 and 198%, respectively) on Tivanium compared with glass. To determine if integrins were involved in cell attachment to implant materials, the peptide GRGDSP (Gly-Arg-Gly-Asp-Ser-Pro), which blocks integrin receptors through the Arg-Gly-Asp sequence, was added to the cells in serum-free medium. This peptide inhibited cell adhesion by 28% on Tivanium and 40% on Zimaloy but had no effect on glass and plastic. The control peptide GRADSP (Gly-Arg-Ala-Asp-Ser-Pro) had no effect on adhesion. Inhibition of protein synthesis and enzymatic removal of surface proteins did not affect the ability of Arg-Gly-Asp peptides to inhibit cell attachment to the implant materials. These results suggest that integrins are able to bind directly to Tivanium and Zimaloy. Western blot analysis of integrin protein demonstrated changes in many integrin subunits, depending on the substrate to which cells attached. In particular, the beta 1 integrin subunit was increased 3.8 to 9.5-fold at 24 hours. To determine specifically which integrins may be involved in adhesion, antibodies to integrins were added. An antibody to the fibronectin receptor, alpha 5 beta 1, significantly inhibited binding of cells to Tivanium by 63% and to Zimaloy by 49% and had no effect on glass. The vitronectin receptor antibody, alpha v beta 3/beta 5, did not alter cell adhesion. In conclusion, osteoblast-like cells appear to be capable of attaching directly to implant materials through integrins. The type of substrate determines which integrins and extracellular matrix proteins are expressed by osteoblasts. These data provide information on how implant materials may affect osteoblast differentiation and bone growth.     

Enhancement of cell interactions with collagen/glycosaminoglycan matrices by RGD derivatization

The interaction of three cell types important to the wound repair process with collagen/glycosaminoglycan (GAG) dermal regeneration matrices covalently modified with an Arg-Gly-Asp (RGD)-containing peptide was characterized. Function-blocking monoclonal antibodies directed against various integrin subunits were used to demonstrate that human fibroblasts attached to the unmodified matrix through the integrin, alpha2beta1. Human endothelial cells and human keratinocytes, however, attached minimally to the unmodified matrix. After modification of the collagen/GAG matrix with RGD-containing peptide, endothelial cells and keratinocytes attached and spread well on the matrix. This attachment was RGD dependent as evidenced by essentially complete inhibition with competing soluble peptide. In terms of overall cell number, fibroblast cell attachment remained unchanged on the RGD peptide-modified matrix compared to the unmodified material. Antibody and peptide inhibition studies demonstrate, however, that attachment to the modified matrix was mediated by both alpha2beta1 and RGD-binding integrins. We have successfully introduced a specific RGD receptor-mediated attachment site on collagen/GAG dermal regeneration matrices, resulting in enhanced cell interaction of important wound healing cell types. This modification could have important implications for the performance of these matrices in promoting dermal regeneration.     

Amyloid fibres of Sup35 support a prion-like mechanism of inheritance in yeast

Hydrogels were prepared from poly(vinyl alcohol) and chitosan in various blend ratios. The water contents of the hydrogels were in the range of 65 to 75 wt %. The attachment and growth of fibroblast cells (L-929) on the hydrogels were studied with a cell culture method. On the hydrogels with more than 15 wt % chitosan content, the attached cells were able not only to remain viable but also to proliferate. The relative cell attachment after incubation for 30 h increased with increasing chitosan content in the hydrogels. Cell attachment and growth on the hydrogel with 40 wt % chitosan content exceeded those on collagen, a widely-used mammalian cell culture substrate. The morphology of the cells attached onto the hydrogels with a lower chitosan content was spherical, but in hydrogels with more than 15 wt % chitosan content, the number of spindle-shaped cells increased with increasing chitosan content.     

Basic fibroblast growth factor promotes bone ingrowth in porous hydroxyapatite

The effect of basic fibroblast growth factor on tissue ingrowth and differentiation in porous hydroxyapatite of coralline origin was studied in a bone chamber model. The hydroxyapatite with or without basic fibroblast growth factor was placed in 22 mm3 titanium bone conduction chambers implanted bilaterally in rat tibiae. Ingrowing bone could enter the cylindrical interior of the chamber only at 1 end. It then penetrated the porous hydroxyapatite inside the chamber. The distance that the ingrown tissue had reached into the material then was measured on histologic slides. Because fibrous tissue always reached further into the material than did bone, both total tissue ingrowth and bone ingrowth distances were measured. In implants supplemented with 0.04 microg basic fibroblast growth factor in a hyaluronate gel carrier, the bone ingrowth distance was increased by 70% at 6 weeks, as compared with paired controls in the contralateral leg. The total tissue ingrowth distance also was increased by 58%. When the dose of basic fibroblast growth factor was increased to 1.0 microg, still using the hyaluronate carrier, there was no difference in bone ingrowth compared with controls, but this dose still increased the total tissue ingrowth. In hydroxyapatite with 1.5 microg basic fibroblast growth factor without hyaluronate gel at 4 weeks, no increase in bone ingrowth was shown, but total tissue ingrowth was increased. At 6 weeks, bone ingrowth and total tissue ingrowth were increased by 41% and 33%, respectively. With a lower dose of 0.15 microg without carrier, only the total ingrowth distance was increased. The results suggest that basic fibroblast growth factor may promote tissue ingrowth into porous hydroxyapatite and that bone ingrowth may be increased by appropriate doses. The hyaluronate gel carrier reduced the optimal dose.     

The mucosal attachment at different abutments. An experimental study in dogs

The present experiment was performed to examine if the material used in the abutment part of an implant system influenced the quality of the mucosal barrier that formed following implant installation. 5 beagle dogs were included in the study. The mandibular premolars and the 1st, 2nd and 3rd maxillary premolars were extracted. Three fixtures of the Br?nemark System were installed in each mandibular quadrant (a total of 6 fixtures per animal). Abutment connection was performed after 3 months of healing. In each dog the following types of abutments were used: 2 "control abutments" (c.p. titanium), 2 "ceramic abutments" (highly sintered Al2O3), 1 "gold abutment", and 1 "short titanium abutment". This "short titanium abutment" was provided with an outer structure made of dental porcelain fused to gold. Following abutment connection a plaque control program was initiated and maintained for 6 months. The animals were sacrificed and perfused with a fixative. The mandibles were removed and each implant region was dissected, demineralized in EDTA and embedded in EPON. Semithin sections representing the mesial, distal, buccal and lingual aspects of the peri-implant tissues were produced and subjected to histological examination. The findings from the analysis demonstrated that the material used in the abutment portion of the implant influenced the location and the quality of the attachment that occurred between the periimplant mucosa and the implant. Abutments made of c.p. titanium or ceramic allowed the formation of a mucosal attachment which included one epithelial and one connective tissue portion that were about 2 mm and 1-1.5 mm high, respectively. At sites where abutments made of gold alloy or dental porcelain were used, no proper attachment formed at the abutment level, but the soft tissue margin receded and bone resorption occurred. The abutment fixture junction was hereby occasionally exposed and the mucosal barrier became established to the fixture portion of the implant. It was suggested that the observed differences were the result of varying adhesive properties of the materials studied or by variations in their resistance to corrosion.     

新型微弧氧化钛基种植材料的细胞毒性研究

采用四甲基偶氮唑盐微量酶反应比色法（MTT法）对微弧氧化处理的钛基种植材料的细胞毒性进行研究，并用相差显微镜对细胞形态进行了观察与分析。本研究采用原代培养鉴定后的成骨细胞，与不同材料三维培养，进行种植体材料的细胞毒性研究。结果表明：微弧氧化处理的材料表面细胞形态良好，生长旺盛，细胞计数及MTT测定结果与其它组比较，具有显著性差异，细胞毒性级别优于0级，具有良好的细胞相容性。     

Are rotors at the heart of all biological motors?

A cell culture system for biocompatibility testing of hip implant materials is described. Human bone marrow cells have been chosen because these cells are in direct contact with the biomaterial after implantation in situ. The sensitivity of this method is evaluated for materials which are already being used as implants in humans and animal, e.g., hydroxyapatite (HA) ceramic, pure titanium, and ultra-high-molecular-weight polyethylene (UHMWPE). As indicative parameters of biocompatibility primary cell adherence, cell number, cell proliferation, production of extracellular matrix, cell vitality, and cell differentiation are described. After 2 weeks in culture, obvious differences between the biomaterials with respect to the indicative parameters could be observed. Cell numbers were greatest on the HA specimens. In the case of titanium alloys, we observed a decreased number of cells. The production of extracellular matrix was high for the HA ceramics but reduced for titanium specimens. The polymers allowed only a few adherent cells and showed no signs of extracellular matrix production. The results can be correlated astonishingly well to animal experiments and clinical experiences. Therefore, we suggest that this cell culture system seems to be a useful tool for biocompatibility testing of bone implantation materials. It also helps reduce animal experiments. With the help of flow cytophotometry, we analyzed the influence of biomaterials on large numbers of cells with respect to differentiation. There were similar populations of T cells and monocytes on all specimens tested. Extended B-cell and granulocyte populations, however, were observed with titanium and UHMWPE. Most osteocalcin-containing cells adhered to the HA ceramics.