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Evaluation of protein-modulated macrophage behavior on biomaterials: designing biomimetic materials for cellular engineering
Kao, W. J. (1999), Biomaterials 20(23-24): 2213-21.
Abstract: Macrophage is a central cell type in directing host inflammatory and immune processes; hence, its response to biomaterials (i.e. adhesion and giant cell formation) has a direct impact on material biostability and biocompatibility. In this paper, several in vitro and in vivo techniques from previously published results and current investigations are highlighted and presented to demonstrate means of delineating a part of the complex molecular mechanisms involved in the interaction between biomaterials and macrophages. Complement component C3 was found critical in mediating the initial adhesion of human macrophages on medical-grade polyetherurethaneureas. From radioimmunoassay studies, the presence of a diphenolic antioxidant additive in polyetherurethaneureas increased the propensity for complement upregulation but did not affect adherent macrophage density. The subcutaneous cage-implant system was utilized to confirm the role of interleukin-4 in the fusion of adherent macrophages to form foreign body giant cells on polyurethanes in vivo. To probe the function-structural relationship of macrophage-active proteins, fibronectin was employed as a model in the formulation of synthetic oligopeptide mimetics. Peptides were grafted onto previously developed, non-cell adhesive polyethyleneglycol-based networks. The results indicate that grafted tripeptide RGD sequence supported higher adherent macrophage density than surfaces grafted with other peptides such as PHSRN and PRRARV sequences. However, the formation of foreign body giant cells on peptide-grafted networks was highly dependent on the relative orientation between PHSRN and RGD sequences located in a single peptide.

Evaluation of recombinant human bone morphogenetic protein-2 on the repair of alveolar ridge defects in baboons
Miranda, D. A., N. M. Blumenthal, et al. (2005), J Periodontol 76(2): 210-20.
Abstract: BACKGROUND: The objective of this study was to evaluate alveolar ridge augmentation following surgical implantation of recombinant human bone morphogenetic protein-2 (rhBMP-2) using two novel space-providing carrier technologies in the baboon (Papio anubis) model. METHODS: Standardized alveolar ridge defects (approximately 15 x 8 x 5 mm) were surgically produced in maxillary and mandibular edentulous areas in four baboons. The defect sites were implanted with rhBMP-2 (0.4 mg/mL) in a tricalcium phosphate/hydroxyapatite/ absorbable collagen sponge composite (TCP/HA/ACS) or calcium phosphate cement (alpha-BSM). Control treatments were TCP/HA/ACS and?-BSM without rhBMP-2 and sham surgery. Stainless steel pins were placed at the mid-apical and coronal level of the defect sites to provide landmarks for clinical measurements pre- and post-implantation. Impressions were obtained pre- and postimplantation to determine changes in alveolar ridge volume. Radiographic registrations were obtained pre- and post-implantation. Block sections of the defect sites were harvested at week 16 postimplantation and processed for histometric analysis including new bone area and bone density. Statistical comparisons between treatments were made using a mixed effect generalized linear model using least squares estimation. RESULTS: The carrier systems without rhBMP-2 provided a modest ridge augmentation. The addition of rhBMP-2 resulted in an almost 2-fold increase in alveolar ridge width, including a greater percentage of trabecular bone and a higher bone density compared to controls (P < or =0.05) without significant differences between the two rhBMP-2 protocols. CONCLUSIONS: TCP/HA/ACS and alphaBSM appear to be suitable carrier technologies for rhBMP-2. Alveolar augmentation procedures using either technology combined with rhBMP-2, rather than stand-alone therapies, may provide clinically relevant augmentation of alveolar ridge defects for placement of endosseous dental implants.

Evaluation of the acute scarring response to the implant of different types of biomaterial in the abdominal wall
Bellon, J. M., L. A. Contreras, et al. (2000), J Mater Sci Mater Med 11(1): 25-9.
Abstract: Since the short-term, acute scarring process induced by a biomaterial may condition the evolution of the repair process, the present investigation evaluates the behavior of polytetrafluoroethylene (PTFE) and polypropylene (PL) biomaterials in the initial stages of repair. Three PTFE biomaterials (Mycro Mesh, Dual Mesh and Soft Tissue Patch) and one PL biomaterial (Marlex) were employed to repair defects created in the abdominal wall of New Zealand rabbits. Animals were sacrificed at 3 or 7 days. Specimens were obtained for light and scanning electron microscopy, and immunohistochemical analysis using the RAM-11 monoclonal antibody for rabbit macrophages. The PL implants showed substantial adhesion formation with viscera. Lower adhesion formation was detected in the PTFE implants. The evolution of the acute phase of the repair process was similar for each PTFE biomaterial. At 3 days post implant, an incipient neoperitoneum was detected which was fully established after 7 days. The behavior of the PL implant was similar, although a greater amount of reticular granulation was detected. The neoformed peritoneum was irregular. Few RAM-11-labeled macrophages were detected in all cases. The acute phase of the tissue repair process induced by the implant of PTFE and PL biomaterials generally proceeds along similar lines to a normal repair process. However, the use of microporous, laminar materials seems to favor the early establishment of a well-defined neoperitoneal layer.

Evaluation of the biomaterial-interface of screw threads in patients having clinical pain
Johnson, D., M. Tucci, et al. (1996), Biomed Sci Instrum 32: 127-33.
Abstract: Fixation devices are normally anchored and stabilized with the use of metallic screws. Under normal circumstances, the patient has no adverse response to the fixation device. However, there are some patients that experience a significant amount of pain and the hardware needs to removed. Removal of the hardware, alleviates the pain. The tissues adjacent to the implanted devices were harvested and analyzed histochemically for cellular detail and immunochemically for the presence of PGE2. These tissues were compared with tissues retrieved from nonpainful stable fixation devices that were removed when they no longer were needed for stabilization. The results showed radiographically the presence of osteolysis in the area of the screw thread in patients with clinical pain. Also, histologically there was a presence of synovial-like granuloma tissue possibly produced by the micromotion of the loosened screw. When the tissues were analysed qualitatively by ELISA for PGE2 they had a statistically significant amount in comparison with tissue retrieved from patients with no clinical pain. The presence of PGE2 in the tissues suggest that this inflammatory mediator is produced in tissues adjacent to unstable devices and may mediate the osteolysis associated with the late implant failure and clinical pain.

Evaluation of the capacity of the SCGE assay to assess the genotoxicity of biomaterials
Chauvel-Lebret, D. J., P. Auroy, et al. (2001), Biomaterials 22(13): 1795-801.
Abstract: The comet test or SCGE assay, which is already widely used in other areas, has never been used to evaluate the mutagenic potential of medical biomaterials in the final form. The purpose of our study was thus to assess the comet test as a means of assessing the genotoxic potential of finished medical biomaterials. We used silicone elastomers with increasing concentrations of 4-nitroquinoline oxide, a genotoxic agent. Hydrogen peroxide was used as the positive control, and tissue culture polystyrene as the negative control. In our study, the comet test did not detect a significant difference in genotoxicity between the pure elastomer and the same elastomer containing 0.01 mg/ml 4-nitroquinoline oxide, but did detect a significant difference between two elastomers containing 0.01 and 0.3 mg/ml of 4-nitroquinoline oxide, respectively. Since, the surface properties of the samples were identical, only the chemical composition may have caused significant differences in mutagenicity. Whatever the cause of the genotoxicity detected by the SCGE assay, testing finished biomaterials using the comet assay makes it possible to evaluate interactions between biomaterials and living tissues that are much closer to actual application conditions.

Evaluation of the Coroflex Theca-Stent for reduction of restenosis (ECORI)
Unverdorben, M., R. Degenhardt, et al. (2005), J Invasive Cardiol 17(4): 199-202.
Abstract: BACKGROUND: Various stent coatings have been shown to significantly reduce restenosis rates in comparison to non-coated devices. Therefore, the short- and mid-term performance of the new polyphosphazene-coated Coroflex Theca-Stent was investigated. METHODS: 103 patients [63.9 +/- 11 yrs, 5/103 (4.9%) lesion type A, 52/103 (50.5%) type B1, and 46 of 103 (44.6%) type B2] were enrolled for elective single stent deployment into de-novo coronary lesions (stenoses: greater than or equal to 70%, < 100%; reference diameter greater than or equal to 2.75 mm, less than or equal to 4 mm; lesion length: < 16 mm). RESULTS: Deployment and procedural success were 100%, in 57/103 (55.3%) patients without pre-dilatation. 3/103 (2.9%) patients were lost to follow-up. During the 7.1 +/- 2.3 months clinical follow-up, 3 of 100 (3.0%) patients underwent premature target lesion revascularizations, 4 /100 (4%) had non-target lesion-related deaths, and 1 of 100 (1%) suffered myocardial infarction. Among the 77 of 100 (77.0%) patients who underwent angiographic follow-up, the initial stenosis declined from 87.3 +/- 5.7% to 14.2 +/- 8.3% after stenting, and increased to 32.8 +/- 22.7% after 6.4 +/- 1.3 months. The late loss and late loss index were 0.6 +/- 0.7 mm and 0.2 +/- 0.4, respectively; the recurrence rate was 12 of 77 (15.6%), with reintervention required in 11 of 77 (14.3%) of these patients. CONCLUSION: The Coroflex Theca-Stent provides excellent procedural results and a low restenosis rate. Further development of this polymer as the final coating and as the basis for drug-eluting stents seems justified.

Evaluation of the effects of different biomaterials on bone defects
Dalkyz, M., A. Ozcan, et al. (2000), Implant Dent 9(3): 226-35.
Abstract: Studies concerning natural and synthetic graft materials that have been used in different medical procedures have focused on freeze-dried bone, coral, hydroxylapatite, and tricalcium phosphate. This study histologically investigates the effects of these materials on the healing of bone defects. The experiments were performed on 30 albino rabbits. Cavities were drilled in the posterior right tibias of rabbits and were filled with coral, freeze-dried bone, hydroxylapatite, or calcium hydroxide. One cavity was left unfilled as a control. The bone in which the materials were implanted was excised at 7, 15, 30, 45, and 60 days. After the histological staining procedures, the prepared materials were observed using a light microscope. Although all materials showed good bone remodeling at the end of 60 days, coral and hydroxylapatite materials could be seen in the bone structure. The most effective materials within bone defect improvement were freeze-dried bone and calcium hydroxide.

Evaluation of the extraction method for the cytotoxicity testing of latex gloves
Baek, H. S., J. Y. Yoo, et al. (2005), Yonsei Med J 46(4): 579-83.
Abstract: In this study, the cytotoxicity of medical latex gloves to cultured L-929 cells was determined using various extraction conditions. According to the extraction time and temperature, three types of extraction conditions were used: 1) 24 h at 37 degrees C; 2) 72 h at 37 degrees C; 3) 72 h at 50 degrees C. Also, four different extraction vehicles were used, namely, distilled water (DW), 9 g/l sodium chloride (saline) in DW, and culture media with or without serum. Under the above-mentioned conditions, the samples were extracted and then 2-fold serially diluted in the concentration range 3.13 - 50%. When extracted with either DW or saline for 24 h or 72 h at 37 degrees C, only 50% diluted samples showed distinct cytotoxicity to L-929 cells. Moreover, no cytotoxic potentials were observed when gloves were extracted with DW or saline at 50 degrees C for 72 h. Cytotoxicity was markedly greater when gloves were extracted with culture medium, irrespective of the presence of serum in the medium. These results suggest that optimal extraction conditions should be established for the cytotoxicity evaluations of biomaterials and medical devices.

Evaluation of the haemocompatibility of titanium based biomaterials
Biehl, V., T. Wack, et al. (2002), Biomol Eng 19(2-6): 97-101.
Abstract: The increased use of metallic biomaterials in contact with blood e.g. for the application as coronary stents leads to the development of new biomaterials. The main requirements for stents are high flexibility, high cold deformability and sufficient mechanical strength (static and dynamic), which can be obtained by strain hardening, radio-opacity and haemocompatibility. In order to investigate the properties of the metallic biomaterials in contact with blood, a comparison of the haemocompatibility of newly developed materials with established materials has been performed. To evaluate haemocompatibility without the influence of the geometry of the material, spherical powders produced by rotating electrode process (REP) were used in a dynamic test system with full human blood under two different stress conditions. The high shear stress simulates the arterial and the low shear stress simulates the venous situation. The use of a dimensionless score point (SP) system where the parameters of the haemocompatibility are determined with and without a material exposition allows an objective comparison of the materials used.

Evaluation of the osteogenic potential of biomaterials implanted in the palatal connective tissue of miniature pigs using undecalcified sections
Naaman Bou-Abboud, N., J. L. Patat, et al. (1994), Biomaterials 15(3): 201-7.
Abstract: Calcium phosphate or calcium carbonate biomaterials are widely used as bone substitutes in periodontal surgery. This study evaluates the osteogenic potential of five different alloplastic biomaterials implanted in the connective tissue of the palatal papilla in miniature pigs. A porous hydroxyapatite (PHA), a dense hydroxyapatite (DHA), a semi-porous hydroxyapatite (SPHA), a tricalcium phosphate (TCP) and a calcium carbonate natural coral (NC) were implanted in a tunnel in the palatal papillae of seven miniature pigs. Undecalcified sections were examined histologically at 1, 2, 3, 4, 8, 12 and 24 wk intervals. Resorbable materials (TCP and NC) were totally resorbed by 24 wk. DHA, PHA and HA showed very limited resorption, although there were multinucleated giant cells in contact with PHA and SPHA. There was no histologically detectable bone formation in contact with or near any of the biomaterials tested. However, several particles of NC, and sometimes of PHA, were surrounded by a dense, mineralized matrix. It is concluded that none of these biomaterials, in their presently available forms, has any bone inducing capacity.

Evaluation of the porcine intestinal collagen layer as a biomaterial
Abraham, G. A., J. Murray, et al. (2000), J Biomed Mater Res 51(3): 442-52.
Abstract: The submucosal layer of the small intestine has been investigated as a source of collagenous tissue with the potential to be used as a biomaterial because of its inherent strength and biocompatibility. In this study we utilized a novel method for processing the tissue to generate an acellular intestinal collagen layer (ICL). This nondetergent, nonenzymatic chemical cleaning protocol removes cells and cellular debris without damaging the native collagen structure. Multilayer laminates of ICL crosslinked with a water-soluble carbodiimide (EDC) were evaluated as a tissue repair material in a rabbit abdominal hernia model. The ICL laminates provided the requisite physical properties and did not lead to adhesion formation. No immune response to the porcine collagen was detectable, and this material did not show any calcification in either the rabbit model or in the juvenile rat model.

Evaluation of the xerovac process for the preparation of heat tolerant contagious bovine pleuropneumonia (CBPP) vaccine
Litamoi, J. K., G. Ayelet, et al. (2005), Vaccine 23(20): 2573-9.
Abstract: The study was conducted with the aim of evaluating the xerovac process as a method for preparing contagious bovine pleuropneumonia (CBPP) vaccine with increased heat resistance. The thermo-protective effects of various concentrations of trehalose in mycoplasma growth medium, various concentrations of trehalose in the dehydration stabilizer and the importance of some divalent cations were assessed. The results obtained indicate that a rapid dehydration of CBPP vaccine following the xerovac method and in an excipient composed of a high concentration of trehalose, renders the product more heat tolerant than a similar vaccine prepared using a regular or an extended freeze drying regime. It was also demonstrated that the addition of chitosan as a mycoplasma precipitating agent conferred additional heat resistance to the vaccine. It is suggested that the application of the xerovac process in the dehydration of CBPP vaccine offers the advantages of a faster, cheaper and easier process over the conventional dehydration methods like freeze drying.

Evaluation of thrombus deposition onto polymeric biomaterials in a new subhuman primate ex vivo series shunt model
Lambrecht, L. K., M. D. Lelah, et al. (1983), Trans Am Soc Artif Intern Organs 29: 194-9.

Evaluation of titanium dioxide as a pharmaceutical excipient for preformulation of a photo-labile drug: effect of physicochemical properties on the photostability of solid-state nisoldipine
Kakinoki, K., K. Yamane, et al. (2005), Chem Pharm Bull (Tokyo) 53(7): 811-5.
Abstract: To characterize the photocatalytic activity of TiO2 via solid-state reaction, the relationship between the physicochemical properties and photocatalytic activity of TiO2 was investigated and estimated from the results of photodegradation of nisoldipine. The photodegradation of nisoldipine was significantly enhanced by addition of TiO2. Two degradation products, nitroso-phenylpyridine derivative and nitro-phenylpyridine derivative, were formed. The degree of photocatalytic activity of TiO2 was quite different between the various types of TiO2 investigated, even when the crystalline phase was the same. As a result of the investigations into the relationship between the photocatalytic activity and physicochemical properties of TiO2, it was found that for the rutile form the photocatalytic activity has good correlation with specific surface area of TiO2, but poor correlation with water loss on drying of TiO2. However, for the anatase form, the photocatalytic activity has good correlation with water loss on drying of TiO2, but poor correlation with specific surface area. Moreover, it was found that the crystallinity of TiO2 has a moderate correlation with the photocatalytic activity of both crystal forms of TiO2. These results suggest that a degree of photocatalytic activity of TiO2 depends on the various physicochemical properties of each type of TiO2 investigated.

Evaluation of ultrasonic atomization as a new approach to prepare ionically cross-linked chitosan microparticles
Albertini, B., N. Passerini, et al. (2005), J Pharm Pharmacol 57(7): 821-9.
Abstract: Ultrasonic atomization was evaluated as a new approach for the preparation of ionically cross-linked controlled-release chitosan microparticles loaded with theophylline as the model drug, using tripolyphosphate (TPP) as counter-ion. It was possible to nebulize both 2% and 3% (w/v) chitosan solutions as a function of their viscosity, usually not processed by employing the conventional nebulizer. The results of the chitosan molecular characterization using the SEC-MALS analysis revealed that ultrasonic atomization caused a certain depolymerization, probably due to the main chain scission of the 1,4-glycosidic bond; however, Fourier transform-infrared spectroscopy revealed the absence of other chemical modifications. The ultrasonic atomization allowed preparation of TPP cross-linked chitosan microparticles mostly ranging between 50 and 200 mum. As regards manufacturing parameters, the linking time and washing medium were found to affect the properties of the microparticles, while the stirring rate of the TPP solution did not show any influence. The evaluation of the formulation variables revealed that chitosan concentration strongly affected both the feasibility of the ultrasonic atomization and the drug release. All the microparticles showed an encapsulation efficiency of > 50 % and, after an initial burst effect, a controlled release of drug for 48 h. In conclusion, the ultrasonic atomization could be proposed as a robust and innovative single-step procedure with scale-up potential to successfully prepare ionically cross-linked chitosan microparticles.

Evaluation of vacuum and dynamic cell seeding of polyglycolic acid and chitosan scaffolds for cartilage engineering
Griffon, D. J., M. R. Sedighi, et al. (2005), Am J Vet Res 66(4): 599-605.
Abstract: OBJECTIVES: To compare combined vacuum and rotation with the spinner flask technique for seeding chondrocytes on chitosan versus polyglycolic acid matrices. SAMPLE POPULATION: Porcine chondrocytes. PROCEDURE: A suspension containing 5 X 10(6) chondrocytes/scaffold was used to evaluate 2 seeding techniques, including a spinner flask and a custom-designed vacuum chamber used for 2 hours prior to transfer to a bioreactor. For each seeding technique, prewetted scaffolds were composed of polyglycolic acid (PGA) mesh or macroporous chitosan sponge. Constructs were collected at 48 hours for DNA quantification, measurement of water and gycosaminoglycan (GAG) content, and scanning electron microscopy. RESULTS: Yield of both seeding techniques was similar for each type of scaffold. Percentage of cells contained in the center of PGA constructs was increased with seeding in the bioreactor (43% of total cell number), compared with the spinner flask (18%).The DNA content and cell number per construct were 10 times greater for PGA constructs, compared with chitosan constructs. Chitosan scaffolds seeded in the bioreactor yielded a significantly higher GAG:DNA ratio than did PGA scaffolds. Whereas chondrones formed on chitosan scaffolds, cell distribution was more uniform on PGA scaffolds. CONCLUSIONS AND CLINICAL RELEVANCE: The vacuum-bioreactor technique allowed seeded chondrocytes to attach to PGA scaffolds within 48 hours and improved uniformity of cell distribution, compared with the spinner technique. Although formation of extracellular matrix may be stimulated by seeding chitosan scaffolds in the bioreactor, further evaluations of the seeding technique and characteristics of chitosan scaffolds are warranted.

Evidence for redifferentiation of human chondrocytes grown on a hyaluronan-based biomaterial (HYAff 11): molecular, immunohistochemical and ultrastructural analysis
Grigolo, B., G. Lisignoli, et al. (2002), Biomaterials 23(4): 1187-95.
Abstract: Association of biomaterials with autologous cells can provide a new generation of implantable devices for cartilage repair. Such scaffolds should provide a preformed three-dimensional shape and prevent cells from escaping into the articular cavity. Furthermore, these constructs should have sufficient mechanical strength to facilitate handling in a clinical setting and stimulate the uniform spreading of cells and their phenotype redifferentiation. The aim of this study was to verify the ability of HYAFF 11, a recently developed hyaluronic-acid-based biodegradable polymer, to support the growth of human chondrocytes and to maintain their original phenotype. This capability was assessed by the evaluation of collagen types I, II and aggrecan mRNA expression. Immunohistochemical analyses were also performed to evaluate collagen types I, II and proteoglycans synthesis. A field emission in lens scanning microscopy was utilized to verify the interactions between the cells and the biomaterial. Our data indicate that human chondrocytes seeded on HYAFF 11 express and produce collagen type II and aggrecan and downregulate the production of collagen type I. These results provide an in vitro demonstration for the therapeutic potential of HYAFF 11 as a delivery vehicle in a tissue-engineered approach towards the repair of articular cartilage defects.

Evidence of chemical bonding at biomaterial-hard tissue interfaces
Yoshida, Y., B. Van Meerbeek, et al. (2000), J Dent Res 79(2): 709-14.
Abstract: For many years, glass-polyalkenoate cements have been described as possessing the unique properties of self-adherence to human hard tissues, such as bones or teeth. However, direct experimental evidence to prove the existence of chemical bonding has not been advanced. X-ray Photoelectron Spectroscopy (XPS) was used to analyze the chemical interaction of a synthesized polyalkenoic acid with enamel and synthetic hydroxyapatite. For both enamel and hydroxyapatite, the peak representing the carboxyl groups of the polyalkenoic acid was detected to have significantly shifted to a lower binding energy. De-convolution of this shifted peak disclosed two components with a peak representing unreacted carboxyl groups and a peak suggesting chemical bonding to hydroxyapatite. On average, 67.5% of the carboxyl groups of the polyalkenoic acid were measured to have bonded to hydroxyapatite. XPS of hydroxyapatite also disclosed its surface to be enriched in calcium and decreased in phosphorus, indicating that phosphorus was extracted at a relatively higher rate than calcium. Analysis of these data supports the mechanism in which carboxylic groups replace phosphate ions (PO4(3-)) of the substrate and make ionic bonds with calcium ions of hydroxyapatite. It is concluded that an ultrathin layer of a polyalkenoic acid can be prepared on a hydroxyapatite-based substrate by careful removal of non-bonded molecules. With this specimen-processing method, XPS not only provided direct evidence of chemical bonding, but also enabled us to quantify the percentages of functional groups of the polyalkenoic acids that bonded to calcium of hydroxyapatite.

Evidence of chemical bonding to hydroxyapatite by phosphoric acid esters
Fu, B., X. Sun, et al. (2005), Biomaterials 26(25): 5104-10.
Abstract: Phosphoric acid esters (PAEs) have been used as a self-etching primer for composite-to-enamel bonding in adhesive dentistry. However, the chemical mechanism of their interactions with hydroxyapatite (HA) is not clear. In the present study, HA particles were mixed with Resulcin AquaPrime (Merz Co.) priming agent that contains a mixture of PAEs, and dried. The primer, HA and the mixture of both were analyzed by FTIR. Primed and untreated HA discs were analyzed with attenuated total reflectance (ATR). After AquaPrime+D(2)O (1:1) was mixed with HA or Ca(OD)(2) for 48 h, the primer and both mixtures were analyzed with (31)P NMR in D(2)O. The solid and the liquid separated from both mixtures were analyzed with (31)P NMR in CDCl(3). The primer's characteristic bands (nu(CO), nu(CC)) were found on the primer-subtracted mixture's spectrum and the primed HA disc. (31)P NMR data indicated that the reactions of PAEs with HA produced PAEs-HA complexes, and were not a simple acid-base reaction like those with Ca(OD)(2), either in liquid or in solid. It is concluded that phosphoric acid esters can decalcify and adhere to hydroxyapatite simultaneously.

Evidence that HSP70 gene expression may be useful for assessing the cytocompatibility of dental biomaterials
Hashimoto, Y., A. Ueda, et al. (2004), Dent Mater J 23(2): 184-9.
Abstract: In the current studies, we examined the possibility of using HSP70 gene regulation as a cytocompatibility test for dental biomaterials. For this reason, we assessed the effects of three metal salts, HgCl2, CuSO4 and NiCl2 on HSP70 gene expression in HeLa S3 cells using real-time Taqman quantitative PCR. Incubation of the cells for 4 h in medium containing HgCl2 (20 or 40 microM), CuSO4 (157, 313, 625 or 1250 microM) or NiCl2 (5000 and 10000 microM) significantly induced HSP70 mRNA. The real-time Taqman quantitative PCR was able to detect HSP70 mRNA induction at 4-fold lower concentrations of HgCl2 and 8-fold lower concentrations of CuSO4 than the Neutral Red cell viability assay. These results indicate that real-time Taqman quantitative PCR, in combination with the monitoring of cell viability, may be a valuable tool for distinguishing between specific HSP70 mRNA induction and cytocompatibility of metals in dental biomaterials.

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