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Record 4021 to 4040

The economics of advanced biomaterials
Williams, D. F. (1993), Med Device Technol 4(9): 8-10.
Abstract: A patient who has previously lost an eye through trauma develops a cataract in his remaining eye. Two types of intraocular lens are available for his treatment, one of modest cost, which is effective in all but a few high-risk patients, the other much more expensive, which gives marginally better results on average, but better performance in those with diabetes or glaucoma. Should the higher-cost lens be used even if there is no direct evidence that it will do better in this patient who does not have these conditions, or is it ethically justified to use the lower-cost lens even though failure would result in the total loss of sight? This case is used as the basis of a discussion on the use of high-cost materials and medical devices.

The effect of 6-mercaptopurine on early human placental explants
Matalon, S. T., A. Ornoy, et al. (2005), Hum Reprod 20(5): 1390-7.
Abstract: BACKGROUND: 6-mercaptopurine (6-MP) is an antineoplastic and immunosuppressive drug. Recently, more women have received this drug during pregnancy. Animal studies have shown that 6-MP has deleterious effects on the fetus, while human data include prematurity, intrauterine growth restriction, low birth weight and malformations that occur especially when the drug is administered in the first trimester of pregnancy. OBJECTIVES: To study the effects of 6-MP on cellular functions of human trophoblast explants. METHODS: Human placental explants (5.5-9 weeks gestational age), that were grown on matrigel, were exposed to medium containing 6-MP for 5 days. Medium alone served as control. Extravillous trophoblast (EVT) cell migration assessment was performed by visual observation. Analysis of proliferating events of the trophoblast cells was assessed by immunohistochemical examination. Apoptosis was analyzed by Tunnel procedure and by anti-caspase 3 staining and hormone level by enzyme-linked immunosorbent assay. RESULTS: 6-MP inhibited migration of EVT cells from the villi to the matrigel with a lower proliferation rate and increased apoptosis of cytotrophoblast cells compared to controls. However, no significant effect of 6-MP on hormone levels was observed. CONCLUSIONS: 6-MP inhibited migration and proliferation of trophoblast cells in first-trimester human placental explant culture.

The effect of alginate, hyaluronate and hyaluronate derivatives biomaterials on synthesis of non-articular chondrocyte extracellular matrix
Gerard, C., C. Catuogno, et al. (2005), J Mater Sci Mater Med 16(6): 541-51.
Abstract: Cartilage engineering consists of re-constructing functional cartilage by seeding chondrocytes in suitable biomaterials in vitro. The characteristics of neocartilage differ upon the type of biomaterial chosen. This study aims at determining the appropriate scaffold material for articular cartilage reconstruction using non articular chondrocytes harvested from rat sternum. For this purpose, the use of polysaccharide hydrogels such as alginate (AA) and hyaluronic acid (HA) was investigated. Several ratios of AA/HA were used as well as three derivatives obtained by chemical modification of HA (HA-C18, HA-C12(2.3), HA-C12(2.5)-TEG0.5). Sternal chondrocytes were successfully cultured in 3D alginate and alginate/HA scaffolds. HA retention in alginate beads was found to be higher in beads seeded with cells than in beads without cells. HA-C18 improved HA retention in beads but inhibited the chondrocyte synthesis process. Cell proliferation and metabolism were enhanced in all biomaterials when beads were mechanically agitated. Preliminary results have shown that the chondrocyte neo-synthesised matrix had acquired articular characteristics after 21 days culture.

The effect of apo-transferrin on bacterial adhesion to biomaterials
Ardehali, R., L. Shi, et al. (2002), Artif Organs 26(6): 512-20.
Abstract: Apo-transferrin (apo-Tf), the iron deficient form of Tf, has been identified previously as a potent inhibitor of Staphylococcus epidermidis adhesion to polyurethane surfaces. In this study, the ability of apo-Tf to suppress the adhesion of two other strains of bacteria, namely a Gram-positive Staphylococcus aureus and a Gram-negative Pseudomonas aeruginosa to several biomaterials, including polystyrene, polymethylmethacrylate, and silicone, is documented. The presence of apo-Tf in the medium at 20 microg/ml lowered bacterial adhesion to all tested biomaterials more than fourfold. Moreover, apo-Tf exerted its inhibitory activity even when protein coated surfaces were used as substrates for bacterial adhesion. To emphasize the importance of apo-Tf in the prevention of bacterial adhesion, human serum was depleted of Tf, employing affinity chromatography, and was shown to lose its inhibitory activity toward bacterial adhesion. Upon addition of apo-Tf to Tf-depleted serum, the activity was reestablished, resulting in a marked reduction in the number of bacteria adhered to the surfaces. Following the enzymatic deglycosylation, apo-Tf retained its ability to prevent bacterial adhesion. These results indicate that the carbohydrate moiety does not seem to play a role in this activity. The presented data provide the evidence that the inhibitory activity of apo-Tf is not bacterial strain specific and that the presence of apo-Tf in the medium results in a significant reduction of bacterial adhesion to a variety of neat and/or protein coated surfaces.

The effect of bisphosphonates and titanium particles on osteoblasts: an in vitro study
Peter, B., P. Y. Zambelli, et al. (2005), J Bone Joint Surg Br 87(8): 1157-63.
Abstract: In an attempt to increase the life of cementless prostheses, an hydroxyapatite-coated implant which releases a bisphosphonate has been suggested as a drug-delivery system. Our in vitro study was designed to determine the maximum dose to which osteoblasts could be safely exposed.Our findings demonstrated that zoledronate did not impair the proliferation of human osteoblasts when used at concentrations below 1 microm. Murine cells can be exposed to concentrations as high as 10 microm.A concentration of 0.01% of titanium particles did not impair the proliferation of either cell line. Zoledronate affected the alkaline phosphatase activity of murine osteoblasts through a chelation phenomenon. The presence of titanium particles strongly decreased the alkaline phosphatase activity of murine osteoblasts. We did not detect any synergic effect of zoledronate and titanium particles on the behaviour of both human and murine osteoblasts.

The effect of calcium ion concentration on osteoblast viability, proliferation and differentiation in monolayer and 3D culture
Maeno, S., Y. Niki, et al. (2005), Biomaterials 26(23): 4847-55.
Abstract: Our research group aims to develop an osteochondral composite using type II collagen gel with hydroxyapatite (HAp) deposited on one side. Soaking gels in Ca2+ and phosphate solution is indispensable to HAp deposition, so relationships between cell behavior and Ca2+ concentration were examined in two- and three-dimensional cultures. The present results indicate that 2-4 mM Ca2+ is suitable for proliferation and survival of osteoblasts, whereas slightly higher concentrations (6-8 mM) favor osteoblast differentiation and matrix mineralization in both 2- and 3-dimensional cultures. Higher concentrations (>10 mM) are cytotoxic. Purely from the perspective of calcium deposition, higher concentrations lead to increased accumulation of Ca2+. Culturing cells in phosphate-containing gel in media with Ca2+ also leads to time-dependent formation of HAp in the gel. Considering the viability of embedded cells, culturing scaffolds in media with Ca2+ concentrations around 5mM is useful for both HAp deposition and osteoblast behavior.

The effect of cells on biomaterial calcification: experiments with in vivo diffusion chambers
Rosanova, I. B., B. P. Mischenko, et al. (1991), J Biomed Mater Res 25(2): 277-80.
Abstract: The results of these in vivo experiments show that bovine pericardium can undergo calcification without direct contact with tissue. It is clear that the direct interaction of cells with implanted samples both promotes and accelerates the process of calcification. Moreover, dietary calcium supplements, calcium chloride and vitamin D can intensify the rate and extent of this process.

The effect of charged groups on protein interactions with poly(HEMA) hydrogels
Lord, M. S., M. H. Stenzel, et al. (2006), Biomaterials 27(4): 567-75.
Abstract: Proteins, lipids and other biomolecules interact strongly with the acrylic-based biomaterials used for contact lenses. Although hydrogels are nominally resistant to protein fouling, many studies have reported considerable amounts of protein bound to poly(2-hydroxyethylmethacrylate) (PHEMA) lenses. This study examined the binding of a series of biomolecules (tear protein analogues, mucin and cholesterol) to poly(methylmethacrylate) (PMMA) and three HEMA-based hydrogels (PHEMA, HEMA plus methacrylic acid (P(HEMA-MAA)), HEMA plus methacrylic acid plus N-vinylpyrrolidone (P(HEMA-MAA-NVP))) by use of a quartz crystal microbalance with dissipation (QCM-D) monitoring. The QCM-D estimates changes in the mass and viscous constant for the adsorbed layer through measurements of frequency and dissipation. Protein interaction with each of the test materials caused a net increase in mass of the material indicating protein binding except for lysozyme interacting with P(HEMA-MAA). A net decrease in mass was observed for lysozyme interacting with P(HEMA-MAA) which may be ascribed to lysozyme collapsing the hydrogel by expelling water. A net mass decrease was observed for cholesterol interacting with each of the hydrogel materials, while a mass increase was observed on PMMA.

The effect of crystallinity on the deformation mechanism and bulk mechanical properties of PLLA
Renouf-Glauser, A. C., J. Rose, et al. (2005), Biomaterials 26(29): 5771-82.
Abstract: Poly (l-lactide) is a widely studied biomaterial, currently approved for use in a range of medical devices, however, most in vitro studies have so far focussed upon either the bulk properties during degradation and/or deformation, or on the microstructure of the unloaded material during degradation. This study aimed to combine these approaches through the technique of simultaneous small-angle X-ray scattering and tensile testing at various stages of degradation up to 8 months, on material with a range of induced microstructures. Results showed that the amorphous material deformed by crazing in the dry, wet and degraded states, however, the mechanism by which the craze developed changed significantly on hydration. Despite this difference, there was little change in the bulk mechanical properties. Crystalline materials deformed through crystal-mediated deformation, with contributions from both cavitation and fibrillated shear, but surprisingly, differences in the length scales within the spherulitic structure caused by annealing at different temperatures had very little effect on the mechanism of deformation, though differences were seen in the bulk properties. Furthermore, hydration had little effect on the crystalline materials, though degradation over 8 months resulted in loss of mechanical properties for samples produced at higher annealing temperatures. In conclusion, the introduction of crystallinity had a huge effect on both bulk and microscopic properties of PLLA, but the spherulitic structure of the crystalline material affected the bulk properties significantly more than it did the micromechanism of deformation.

The effect of cyclo-DfKRG peptide immobilization on titanium on the adhesion and differentiation of human osteoprogenitor cells
Pallu, S., C. Bourget, et al. (2005), Biomaterials 26(34): 6932-40.
Abstract: This study takes place in the field of development of a bioactive surface of titanium alloys. In this paper, titanium was functionalized with cyclo-DfKRG peptide by coating or grafting using different anchors (thiol or phosphonate) as spacers between the surface and the peptide. Cell adhesion, and differentiation of human osteoprogenitor (HOP) cells arising from human bone marrow were investigated. Our results seem to demonstrate that cyclo-DfKRG peptide coating with a phosphonate anchor and grafting procedure contributes to higher cell adhesion and a strong ALP and Cbfa1 mRNA expression, after 10 days of cell seeding. At the contrary, this peptide coated with a thiol anchor stimulates differentiation of HOP within 3 days of culture.

The effect of Emdogain on ectopic bone formation in tubes of rat demineralized dentin matrix
Koike, Y., S. Murakami, et al. (2005), J Periodontal Res 40(5): 385-94.
Abstract: BACKGROUND: Emdogain (EMD) is made from enamel matrix proteins (EMPs) from the tooth germ of swine and propylene glycol alginate (PGA) as a matrix. The function of EMD is known to differentiate cells of the dental follicle into cementoblasts. However, little is known about the effect of EMD on mesenchymal cells in other tissue. OBJECTIVE: The purpose of this study was to investigate whether EMD has the ability to induce hard tissue when applied with or without demineralized dentin matrix. METHODS: Half of the dentin tubes prepared from rat incisors were demineralized by treatment with 0.6 N hydrochloric acid for 3 h. EMD or PGA was injected into the demineralized or non-demineralized dentin tubes, which were then transplanted into rectus abdominis muscles. Untreated dentin tubes were also transplanted as a control. Animals were killed at 7, 14 and 21 days after the implantation. RESULTS: Non-demineralized dentin tubes with or without EMD or PGA did not form any hard tissue. In the demineralized group, chondrogenesis in the PGA groups occurred earlier than in the EMD groups. The expression of vascular endothelial growth factor (VEGF) mRNA in the demineralized group with PGA at day 14 was the highest. The expression of osteopontin and osteocalcin mRNAs was higher in all groups at 21 days compared with 7 or 14 days. CONCLUSION: These results suggest that neither EMD nor PGA has the ability to induce hard tissue and that EMPs contained within EMD might aggregate on the dentin surface and inhibit the effect of the demineralized dentin matrix.

The effect of fibrinogen sialic acid residues on ex vivo platelet deposition on biomaterials
Park, K., S. J. Gerndt, et al. (1986), Thromb Res 43(3): 293-302.
Abstract: The effect of fibrinogen sialic acid residues on platelet deposition onto polymer surfaces was examined using a canine ex vivo shunt model. To test the hypothesis that desialylated fibrinogen may enhance platelet deposition when precoated on biomaterials, canine fibrinogen was desialylated and precoated on polyvinyl chloride (PVC) shunts. When protein-coated PVC shunts were exposed to flowing whole blood, both the native and the desialylated fibrinogen elicited the same profile of platelet deposition. This study indicates that platelet deposition and thrombus formation on biomaterial surfaces is not mediated by a mechanism which involves the sialic acid residues of fibrinogen.

The effect of freeze-drying with different cryoprotectants and gamma-irradiation sterilization on the characteristics of ciprofloxacin HCl-loaded poly(D,L-lactide-glycolide) nanoparticles
Bozdag, S., K. Dillen, et al. (2005), J Pharm Pharmacol 57(6): 699-707.
Abstract: In the present study, the influence of freeze-drying with several cryoprotective agents and gamma (gamma)-irradiation sterilization on the physicochemical characteristics of ciprofloxacin HCl-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles was evaluated. Nanoparticles were prepared by W/O/W emulsification solvent evaporation followed by high-pressure homogenization. They were freeze-dried in the presence of 5.0% (w/v) mannitol, trehalose or glucose, with 5.0% (w/v) or 15.0% (w/v) dextran as cryoprotectants. The nanoparticles were irradiated at a dose of 25 kGy using a 60Co source. The following physicochemical properties of the formulations were investigated: the ratio of particle size before (initial) and after freeze-drying, the ease of reconstitution of the nanoparticle suspensions and the drug-release profiles of irradiated and non-irradiated nanoparticles. The antibacterial activity against Pseudomonas aeruginosa was measured. The freeze-drying process induced a significant increase in particle size when no cryoprotectant was employed. Similar results were observed when cryoprotectants were added to the formulation. Only when mannitol was used was no significant size increase measured. Moreover, for formulations with dextran, reconstitution after freeze-drying was difficult by manual agitation and particle size could not be determined because of aggregation. After gamma-sterilization no significant difference in mean particle size was observed, but reconstitution was more difficult and drug release was influenced negatively. Ciprofloxacin HCl incorporated in the nanoparticles was still effective against the micro-organism selected after freeze-drying and gamma-sterilization.

The effect of gamma-irradiation on PLGA/PEG microspheres containing ovalbumin
Dorati, R., I. Genta, et al. (2005), J Control Release 107(1): 78-90.
Abstract: Poly(ethylene glycol) (PEG) and sodium chloride (NaCl) are excipients used in PLGA microsphere preparation to stabilize proteins and reduce their burst release. No information is till now available in the literature on the effect due to the use of such excipients on the biopharmaceutical performance of gamma-irradiated microparticulate systems. On this purpose, different batches of microspheres containing ovalbumin (OVA) were prepared by using a PLGA 50:50 (average Mr: 13000), different amounts of PEG (Mr: 400 or 4000) and/or sodium chloride. The non-irradiated and irradiated microspheres were characterized in terms of morphology (SEM, particle size distribution), OVA and PEG content and in vitro OVA release. Radiolysis mechanisms of OVA and OVA loaded microspheres were investigated by EPR analysis. Gamma irradiation affects either microsphere morphology or the release of OVA as a function of the amount of PEG, and the use of NaCl. Irradiation significantly reduces release rate of protein from the microspheres containing 15% and 30% of PEG and from controls (microspheres without additives), while no significative effect on protein release rate is highlighted on microspheres containing lower amounts of PEG. EPR investigation shows that increasing amounts of PEG up to 30% have a perturbation effect on OVA radiolysis path.

The effect of haemodilution on blood-biomaterial contact-mediated CD11b expression on neutrophils: ex vivo studies
Gourlay, T., I. Samartzis, et al. (2003), Perfusion 18(2): 87-93.
Abstract: Modern cardiopulmonary bypass (CPB) systems are getting smaller, both in terms of the exposed surface area of biomaterials and the priming volume. In a series of studies utilizing a rat recirculation model, we demonstrated that the magnitude of the inflammatory response seen under these conditions is proportional to the surface area of exposed material, a finding that supports the use of miniature systems in terms of moderating the inflammatory response. However, the second impact of miniature perfusion systems, the reduced priming volume with concomitant reduction in haemodilution, was not investigated with reference to inflammation. The present study was designed to determine whether this change in CPB haematocrit profile has any effect on the inflammatory response. In common with previous studies by this group, we employed the expression of the integrin CD11b on neutrophils as a marker of neutrophil activation, and hence the inflammatory response, in a rat recirculation biomaterial testing model, containing di-(2-ethyl-hexyl)-phthalate plasticized polyvinyl chloride of the type commonly employed in CPB circuits. The results demonstrated that neutrophil activation is influenced by haemodilution. We studied five groups of animals, each with different mean induced haematocrit: Group 1 (41.3 +/- 1.27%); Group 2 (30.93 +/- 2.85%); Group 3 (24.83 +/- 1.36%); Group 4 (20.60 +/- 3.47%); Group 5 (20.48 +/- 1.31%). Groups 1 and 5 animals were controls, neither of which underwent the period of recirculation. Rather, these controls were employed to isolate the noncontact effect of haemodilution on CD11b expression. We found that there were differences in per cent change in CD11b expression from start to end of the recirculation period between Group 1 (109.54 +/- 49.53%), Group 2 (189.1 +/- 18.68%), Group 3 (224.28 +/- 43.97), Group 4 (368.97 +/- 24.28%) and Group 5 (127 +/- 57.8%). There were intergroup statistically significant differences (p < 0.05). These results confirm that there is a relationship between haematocrit level and biomaterial contact-mediated activation of neutrophils. Furthermore, these studies confirm that haemodilution alone has no effect on neutrophil activation. One possible explanation for this outcome is that with higher levels of haemodilution, neutrophils have a greater opportunity to contact surface 'receptor' sites on the biomaterial, resulting in more neutrophil activation. Whatever the mechanism, these data tend to support the modern trend towards lower circuit surface area and higher haematocrit.

The effect of hemodialysis and dialyzer biocompatibility on erythrocyte glutathione-defense system in chronic hemodialysis patients
Alhamdani, M. S., A. F. Al-Najjar, et al. (2005), Int J Artif Organs 28(6): 576-82.
Abstract: BACKGROUND: Uremic patients, especially those receiving regular hemodialysis (HD) treatment, are at high risk of oxidative damage by noxious free radicals and reactive oxygen species (ROS). The erythrocyte glutathione-defense system (GSH-DS) is one of the major enzymatic means of scavenging and detoxifying ROS. This study aimed to elucidate the effect of HD and dialyzer biocompatibility on erythrocyte GSH-DS in uremic patients on maintenance HD treatment. METHODS: Twenty-five healthy volunteers and 42 HD patients were enrolled in this study. Blood samples were drawn immediately before and after HD session, and erythrocyte glutathione (GSH) level as well as the activities of the enzymes glucose-6-phosphate dehydrogenase (G6PD), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-Rd), and glutathione S-transferase (GST) were measured. To evaluate the effect of dialyzer type on the studied parameters the patients were were subdivided into two groups: those who had dialysis with cuprophane (CU) membranes (n=23) and those who received dialysis with the aid of polysulfone (PS) membranes (n=19). RESULTS: The activities of G6PD and GSH-Px as well as GSH level were significantly decreased in HD patients as compared with controls. On the other hand, the activities of GSSG-Rd and GST were significantly elevated among HD patients in comparison with control values. A single HD session, regardless of the type of dialyzer, did not induce any significant effect on any of the measured parameters, although G6PD activity increased significantly after dialysis. CU membrane did not result in any change in GSH or its metabolizing enzymes, while PS dialyzers exerted a minor but significant restoration in GSH-DS. CONCLUSION: The antioxidant pool, as represented by GSH-DS, is significantly affected by dialyzer type in HD patients being significantly corrected with polysulfone dialyzer.

The effect of hyaluronic acid on insulin secretion in HIT-T15 cells through the enhancement of gap-junctional intercellular communications
Li, Y., T. Nagira, et al. (2006), Biomaterials 27(8): 1437-43.
Abstract: The transplantation of bioartificial pancreas has the potential to restore endogenous insulin secretion in type I diabetes. The bioartificial pancreas is constructed in vitro from cells and a support matrix. Hyaluronic acid (HA) is an extremely ubiquitous polysaccharide of extracellular matrix in the body and plays various biological roles. It has been suggested that high molecular weight (HMW) HA increases in the function of gap-junctional intercellular communications (GJIC) and the expression of connexin-43 (Cx43). To determine whether the function of pancreatic beta-cells is affected by gap junctions after HMW HA-treatment, we exposed HIT-T15, a clonal pancreatic beta-cell line, in various concentrations of HA for 24h, and then detected the insulin secretion and content, using an insulin assay kit by ELISA technique. The cellular functions of GJIC were assayed by dye-transfer method using the dye solution of Lucifer yellow. HA-treatment resulted in the enhancement of GJIC function, the increase of insulin release and insulin content. The results obtained in this study suggest that HA-coating increases the insulin secretion of HIT-T15 cells by the enhancement of Cx43-mediated GJIC. The results give useful information on design biocompatibility of HA when is used as a biomaterial for bioartificial pancreas.

The effect of hydroxyapatite nanocrystals on microvascular endothelial cell viability and functions
Pezzatini, S., R. Solito, et al. (2005), J Biomed Mater Res A
Abstract: To favor bone reconstitution with biomaterials endothelial cells should maintain proper functions to drive angiogenesis. To this aim nanocrystals of hydroxyapatite (HA) have been synthesized and characterized on endothelial cells. Microvascular endothelial cells have been exposed to stoichiometric HA nanocrystals. Cell morphology and organization of cytoskeletal proteins have been monitored by SEM analysis and immunofluorescence. Biochemical markers of physiological and pathological responses of endothelial cells, endothelial constitutive nitric oxide synthase, and cycloxygenase-2 (ecNOS and COX-2, respectively) have been measured by immunofluorescence. Crystallized HA sustained endothelial survival without any cytotoxic effect. At the observation with SEM, endothelial cell morphology was maintained in the presence of HA. The localization and organization of beta-actin documented the formation of stress fibers, indicating an activation of endothelial cells induced by HA nanocrystals. Immunohistochemistry for biochemical key signaling pathways in endothelium demonstrated that nanocrystals of HA maintained the expression of ecNOS and did not increase COX-2 expression. In conclusion, the present findings indicate that HA nanocrystals exhibit high biocompatibility for microvascular endothelium. In the presence of HA nanocrystals endothelial cells maintain biochemical markers of healthy endothelium. They do not acquire a proinflammatory or thrombogenic phenotype, but express markers of functioning endothelium that might contribute to angiogenesis. (c) 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005.

The effect of incorporating RGD adhesive peptide in polyethylene glycol diacrylate hydrogel on osteogenesis of bone marrow stromal cells
Yang, F., C. G. Williams, et al. (2005), Biomaterials 26(30): 5991-8.
Abstract: Advances in tissue engineering require biofunctional scaffolds that can not only provide cells with structural support, but also interact with cells in a biological manner. To achieve this goal, a frequently used cell adhesion peptide Arg-Gly-Asp (RGD) was covalently incorporated into poly(ethylene glycol) diacrylate (PEODA) hydrogel and its dosage effect (0.025, 1.25 and 2.5 mm) on osteogenesis of marrow stromal cells in a three-dimensional environment was examined. Expression of bone-related markers, osteocalcin (OCN) and Alkaline phosphatase (ALP), increased significantly as the RGD concentration increased. Compared with no RGD, 2.5 mm RGD group showed a 1344% increase in ALP production and a 277% increase in OCN accumulation in the medium. RGD helped MSCs maintain cbfa-1 expression when shifted from a two-dimensional environment to a three-dimensional environment. Soluble RGD was found to completely block the mineralization of marrow stromal cells, as manifested by quantitative calcium assay, phosphorus elemental analysis and Von Kossa staining. In conclusion, we have demonstrated that RGD-conjugated PEODA hydrogel promotes the osteogenesis of MSCs in a dosage-dependent manner, with 2.5 mm being optimal concentration.

The effect of injection of powdered biomaterials on mouse peritoneal cell populations
Pizzoferrato, A., A. Vespucci, et al. (1987), J Biomed Mater Res 21(4): 419-28.
Abstract: The authors suggest an experimental model for the assaying, before implantation, of the tissue reaction that wear particles from artificial joints can cause in the human body. Mice were intraperitoneally injected with biomaterial powders in suspension in saline. The materials used were chromium, chromium oxide, nickel, nickel oxide, aluminum, alumina, alumina-titania, cobalt, molybdenum, titanium, silver, zirconium oxide, iron oxide, and stainless steel. Peritoneal lavage was performed a week after injection. A thorough morphological and quantitative analysis of the cell suspension thus obtained was made both immediately after collection and after a 24 h culture.

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