|Articles about Biomaterials|
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| Drug eluting coronary stent: in vitro evaluation of magnet resonance safety at 3 Tesla
Shellock, F. G. and J. R. Forder (2005), J Cardiovasc Magn Reson 7(2): 415-9.
Abstract: PURPOSE: To evaluate MR safety at 3 Tesla for a drug eluting coronary stent. METHODS: A drug eluting coronary stent (Endeavor, cobalt alloy, Medtronic Vascular, Santa Rosa, CA) was evaluated for magnetic field interactions, heating, and artifacts at 3 Tesla. MRI-related heating was assessed with the stent in a gelled saline-filled phantom using a transmit/received RF body coil with a whole body averaged SAR of 2.0 W/kg. Artifacts were characterized using T1-weighted, spin echo, and gradient echo pulse sequences. RESULTS: The stent exhibited minor magnetic field interactions that will not cause migration. Heating was not substantial (+0.5 degrees C). Artifacts may create a problem if the area of interest is in the same area or close to the stent (e.g., for a T1-weighted, spin echo pulse sequence, within approximately 16 mm; for a gradient echo pulse sequence, within approximately 23 mm). Conclusion. The findings indicated that it would be safe for a patient with this cobalt alloy-based, drug-eluting coronary stent to undergo MRI at 3 Tesla or less. Importantly, because of the relative lack of magnetic field interactions, MRI may be performed immediately after implantation.
| Drug release from cast films of ethylene vinyl acetate (EVA) copolymer: Stability of drugs by 1H NMR and solid state 13C CP/MAS NMR
Kalachandra, S., D. M. Lin, et al. (2005), J Mater Sci Mater Med 16(7): 597-605.
Abstract: The study utilizes an oral biocompatible material based on ethylene vinyl acetate copolymer (EVA) designed to release drugs in vitro at therapeutic levels over several days. We examined the drug stability during film casting process using proton and solid state NMR techniques. The drug-loaded EVA films were prepared from the dry sheet obtained by solvent (dichloromethane) evaporation of polymer casting solutions. Drugs tested include chlorhexidine diacetate (CDA), doxycycline hydrochloride (DOH), tetracycline hydrochloride (TTH) and nystatin (NST). Drug release from the films was examined for at least 14 days in 10 ml ddH2O (NST in water/ethanol (4:1)) which was replaced daily. Changes in optical density were followed spectraphotometrically. Effect of temperature on rate measurements was studied and the energies of activation (E*) were calculated using Arrhenius plots. Effect of EVA copolymer composition on CDA release rate was also investigated. The enhanced rates with temperature increase may be attributed to the formation of channels with increased geometry in the polymer. The highest E* observed for CDA compared to DOH and TTH may be related to their average molecular weights. Spectral analyses for CDA and NST revealed that the chemical and physical structures of the drugs remained unaffected during the film casting process.
| Drug targeting with nano-sized carrier systems
Yokoyama, M. (2005), J Artif Organs 8(2): 77-84.
Abstract: This paper discusses the present status of, and future perspectives on, drug targeting through the bloodstream by describing the drug targeting concept, its methodologies, types of drug carriers, and recent clinical examples. This explanation and discussion is made from the viewpoint of possible correlations with studies on artificial organs, implants, and biomaterials. Two targeting methodologies (active and passive targeting), two targeting strategies (the magic bullet and the enhanced permeability and retention effect), and five types of drug carriers are explained. In addition, the clinical status of the five carrier systems is discussed.
| Drug-eluting biodegradable poly-D/L-lactic acid vascular stents: an experimental pilot study
Uurto, I., J. Mikkonen, et al. (2005), J Endovasc Ther 12(3): 371-9.
Abstract: PURPOSE: To evaluate in vivo a new drug-eluting biodegradable vascular stent with respect to biocompatibility, neointimal hyperplasia formation, and reliability. METHODS: Self-expanding biodegradable poly-96L/4D-lactic acid (PLA) stents with 2 drugs (PLA + dexamethasone [DEX] and PLA + simvastatin [SIM]) and 2 different coatings (PLA + P(D,L)LA and PLA + polycaprolactone [PCL]) were compared with a self-expanding stainless steel Wallstent. The stents were implanted in both common iliac arteries of 8 pigs. Prior to sacrifice at 1 month, angiography was performed to determine patency. Specimens were harvested for quantitative histomorphometry; vascular injury and inflammation scores were assigned to the stented iliac segments. RESULTS: All stented arteries were angiographically patent. The mean luminal diameter (3.05 mm) and area (30.36 mm2) of DEX-eluting PLA stents were decreased compared to other stents (PLA + P(D,L)LA: 3.66 mm and 43.92 mm2; PLA + SIM: 4.21 mm and 56.48 mm2; PLA + PCL: 4.19 mm and 54.64 mm2; Wallstent: 5.01 mm and 81.19 mm2). Wallstents and DEX-eluting PLA stents induced minimal intimal hyperplasia: PLA + DEX: 0.16 mm, PLA + P(D,L)LA: 0.35 mm, PLA + SIM: 0.33 mm, PLA + PCL: 0.29 mm, and Wallstent: 0.18 mm. The vascular injury scores demonstrated only mild vascular trauma for all stents. Only mild to moderate inflammatory reaction was noted around stent struts with a vascular inflammation score. CONCLUSIONS: Biodegradable polymer stents appear to be biocompatible and reliable, causing minimal neointimal hyperplasia. Furthermore, the new biodegradable poly-D/L-lactic acid stent can be used as a local drug delivery vehicle. The DEX-eluting PLA stent reduces neointimal hyperplasia. The findings show a need for further investigation to prove the efficacy and safety of this new biodegradable drug-eluting stent.
| Drug-eluting biomaterials in urology: the time is ripe
Knudsen, B. E., B. H. Chew, et al. (2005), BJU Int 95(6): 726-7.
| Drug-eluting stent thrombosis: results from a pooled analysis including 10 randomized studies
Moreno, R., C. Fernandez, et al. (2005), J Am Coll Cardiol 45(6): 954-9.
Abstract: OBJECTIVES: We compared the risk of stent thrombosis (ST) after drug-eluting stents (DES) versus bare-metal stents (BMS), and tested the hypothesis that the risk of DES thrombosis is related to stent length. BACKGROUND: Whether DES increase the risk of ST remains unclear. Given the very low restenosis rate after drug-eluting stenting, longer stents are frequently implanted for the same lesion length in comparison to BMS. METHODS: We included in a meta-analysis 10 randomized studies comparing DES and BMS. Overall, 5,030 patients were included (2,602 were allocated to DES and 2,428 to BMS). The risk of thrombosis after DES versus BMS was compared, and the relationship between the rate of DES thrombosis and stent length was evaluated. RESULTS: Incidence of ST was not increased in patients receiving DES (0.58% vs. 0.54% for BMS; odds ratio: 1.05; 95% confidence interval [CI]: 0.51 to 2.15; p = 1.000). The overall rate of ST did not differ significantly between patients receiving sirolimus- or paclitaxel-eluting stents (0.57% vs. 0.58%; p = 1.000). We found a significant relation between the rate of ST and the stented length (Y = -1.455 + 0.121 X; 95% CI for beta: 0.014 to 0.227; R = 0.716; p = 0.031). In patients with DES, mean stented length was longer in those suffering ST (23.4 +/- 8.1 mm vs. 21.3 +/- 4.1 mm, p = 0.025). CONCLUSIONS: Drug-eluting stents do not increase the risk of ST, at least under appropriate anti-platelet therapy. The risk of ST after DES implantation is related to stent length.
| Drug-eluting stents. The third revolution in percutaneous coronary intervention
Saia, F., A. Marzocchi, et al. (2005), Ital Heart J 6(4): 289-303.
Abstract: Local stent-based drug delivery (drug-eluting stent - DES) is a new technology aimed to prevent the development of neointimal hyperplasia and restenosis following percutaneous coronary interventions. A number of DESs have been developed using different carrier stents, different kind of coatings, and different drugs. However, to date only two polymer-coated DESs (the Cypher sirolimus-eluting stent from Cordis, Johnson & Johnson, Miami Lake, FL, USA; and the Taxus paclitaxel-eluting stent, Boston Scientific, Natick, MA, USA) have become commercially available after a number of randomized trials showed their ability to reduce late luminal loss, binary restenosis and the need for repeat revascularization when compared to bare metal stents. This review describes the general concept of DES and summarizes the results of the principal clinical trials on DESs, both approved for clinical use or under development. For the marketed stents, we also report the results of the first clinical evaluations in real life and a few insights into the most controversial issues.
| Dual role of VEGF in pretreated experimental ePTFE arterial grafts
Randone, B., G. Cavallaro, et al. (2005), J Surg Res 127(2): 70-9.
Abstract: BACKGROUND: Lack of endothelialization and abnormal smooth muscle cell (SMC) growth adversely affect the outcome of vascular synthetic grafts. The aims of our study were to investigate how a coating of extracellular matrix (ECM) and vascular endothelial growth factor (VEGF) might affect the endothelialization rate, smooth muscle cells (SMC) proliferation, and myointimal hyperplasia in experimental arterial ePTFE grafts. METHODS: In each of 30 male Lewis rats, a 1-cm-long ePTFE graft was inserted at the level of the abdominal aorta. Animals were randomized in five groups (six animals each): groups A and A1 received ePTFE grafts coated with a synthetic extracellular matrix (growth factor-reduced matrigel) containing VEGF; groups B and B1 received ePTFE grafts coated with synthetic ECM; and group C received ePTFE grafts alone. The grafts were explanted at 30 days from surgery for immunohistochemical analysis. RESULTS: Both endothelialization rate and myointimal hyperplasia were augmented in group A versus groups B and C, and these findings were statistically significant. SMC density resulted significantly higher in group A versus groups B and C, and this was associated with an altered expression of bFGF and TGFbeta. CONCLUSIONS: Pretreating ePTFE grafts with synthetic ECM and VEGF results in better endothelialization, but also in undesired higher SMC density and myointimal hyperplasia.
| Dynamic blood cell contact with biomaterials: validation of a flow chamber system according to international standards
Otto, M., C. L. Klein, et al. (1997), J Mater Sci Mater Med 8(3): 119-29.
Abstract: The increasing number of patients requiring prosthetic substitution of segments of the vascular system strongly supports the need to optimize a relevant, standardized testing panel for new materials designed for synthetic vascular prostheses. The ISO gives the standard requirements for testing biomaterials provided for implantation. Our primary interest was the establishment of a reliable in vitro panel as a useful and relevant screening system for vascular implant devices to evaluate blood/device interactions under flow conditions. The aim of the present study was to evaluate influences of different flow conditions on blood cell-biomaterial interactions with special emphasis on the interactions of human granulocytes (PMN) and polymeric surfaces. PMN were isolated and vital cells were quantified by flow cytometrical analysis directly before, as well as immediately after the experiments. The viscosity of the final cellular suspension was analysed by using a computerized cone-plate rheometer. As reference materials we used FEP-teflon, PVC-DEHD, PU, PP and PE. Dacron and ePTFE synthetic vascular protheses were tested in a comparative way to those references. The adhesion processes were observed over a period of 40 minutes under arterial (shear stress 0.74 Pa) and venous (shear stress 0.16 Pa) flow conditions in a parallel plate flow chamber system under highly standardized conditions and laminar flow. The cells were observed with the help of inverse light microscopy. Cell behaviour was recorded and analysed in both analogue (video) and digital (imaging system) modes. Samples of the cell suspensions were obtained at regular time intervals and analysed by enzyme linked immuno sorbent assay (ELISA) to quantify LTB4 release. Irrespective of the material, approximately 3 to 4 times more PMN adhered to the biomaterial surfaces under venous flow conditions compared to the arterial. Shear intensity did not influence the running order of biomaterials with respect to cell numbers. This response in descending order at the end of the experiments was as follows: PU, PVC-DEHD, PP, PE and ePTFE. The biochemical analyses indicate that in the system used only a weak effect on LTB4 release induced by the different materials could be determined. A significant effect caused by flow conditions was not observed. Further experiments, both static as well as dynamic, must be performed for multiple, relevant parameters of haemocompatibility, for potential biomaterials as well as those currently in use in vascular prostheses.
| Dynamic heterodimer-functionalized surfaces for endothelial cell adhesion
Willcox, P. J., C. A. Reinhart-King, et al. (2005), Biomaterials 26(23): 4757-66.
Abstract: The functionalization of hydrogels for receptor-mediated cell adhesion is one approach for targeted cell and tissue engineering applications. In this study, polyacrylamide gel surfaces were functionalized with specific cell adhesion ligands via the self-assembly of a peptide-based heterodimer. The system was comprised of a cysteine-terminated monomer, A (MW approximately 5400), grafted to the polyacrylamide gels and a complementary ligand presenting monomer, B(X) (MW approximately 5800) that was designed to heterodimerize with A. Two ligand presenting monomers were synthesized: one presenting the RGDS ligand, B(D), for receptor-mediated cell adhesion, and the other, a control monomer presenting the nonadhesive RGES ligand, B(E). Assembly of the peptide pair A-B(X) by association of the monomers into a coiled coil was verified by circular dichroism in solution. Binding studies were conducted to determine the dissociation constant of the pair A-B(X), which was found to be K(D) approximately 10(-8) m. Polyacrylamide gels functionalized with A-B(X) heterodimers were evaluated for cell adhesion using bovine aortic endothelial cells (BAECs). Endothelial cells cultured on the A-B(D) functionalized surfaces demonstrated typical cell morphologies and expected spreading behavior as a function of the density of RGDS ligand, calculated as the amount of B(D) associated with grafted A on the surface of the gels. In contrast, A-B(E) linked surfaces supported no cell adhesion. The adhesion of the substrate was dynamically altered through the reassembly of A-B(X) dimers as B(D) molecules in the solution replaced B(E) molecules at the substrate. The molecular constructs described here demonstrate the potential to design a broad family of switchable peptides that impart the dynamic control of biofunctionality at an interface, which would be useful for precise manipulation of cell physiology.
| Dynamic mechanical analysis of provisional resin materials reinforced by metal oxides
Korkmaz, T., A. Dogan, et al. (2005), Biomed Mater Eng 15(3): 179-88.
Abstract: In this study, several provisional resin materials were investigated by dynamic mechanical analysis (DMA). The materials were autopolymerized PMMA and PEMA, light cured PMMA. Autopolymerized PMMA has the highest T(g) (131 degrees C) compared to that of the autopolymerized PEMA (102 degrees C) and light cured PMMA (120 degrees C). The storage moduli for autopolymerized PMMA, autopolymerized PEMA and light cured PMMA are 2.9, 1.8 and 2.3 GPa, respectively. The loss moduli of the same resins are 330, 300 and 350 MPa, respectively. Each of these resins were reinforced with 1%, 3% and 5% of each of metal oxides of MgO, ZrO2 and Al2O3 and then studied with DMA. Small changes were observed for dynamic mechanical properties tested. However, the changes are not systematic and noticeable. This is most probably due to smaller size of metal oxides particles compared to that of polymer particle size.
| Dynamic mechanical properties of hydroxyapatite-reinforced and porous starch-based degradable biomaterials
Mano, J. F., C. M. Vaz, et al. (1999), J Mater Sci Mater Med 10(12): 857-62.
Abstract: It has been shown that blends of starch with a poly(ethylene-vinyl-alcohol) copolymer, EVOH, designated as SEVA-C, present an interesting combination of mechanical, degradation and biocompatible properties, specially when filled with hydroxyapatite (HA). Consequently, they may find a range of applications in the biomaterials field. This work evaluated the influence of HA fillers and of blowing agents (used to produce porous architectures) over the viscoelastic properties of SEVA-C polymers, as seen by dynamic mechanical analysis (DMA), in order to speculate on their performances when withstanding cyclic loading in the body. The composite materials presented a promising performance under dynamic mechanical solicitation conditions. Two relaxations were found being attributed to the starch and EVOH phases. The EVOH relaxation process may be very useful in vivo improving the implants performance under cyclic loading. DMA results also showed that it is possible to produce SEVA-C compact surface/porous core architectures with a mechanical performance similar to that of SEVA-C dense materials. This may allow for the use of these materials as bone replacements or scaffolds that must withstand loads when implanted.
| Dynamic study of calcium phosphate formation on porous HA/TCP ceramics
Duan, Y. R., Z. R. Zhang, et al. (2004), J Mater Sci Mater Med 15(11): 1205-11.
Abstract: Bone-like apatite formation on porous calcium phosphate ceramics was investigated in static simulated body fluid (SBF) and dynamic SBF at different flowing rates. The results of a 14-day immersion in static SBF showed that the formation of bone-like apatite occurred both on the surface and in the pores of the samples. When SBF flow at the physiological flow rate in muscle (2 ml/100 ml min1), bone-like apatite could be detected only in internal surface of the pores of samples. The result that bone-like apatite formation could only be found in the pores when SBF flown at physiological flow rate was consistent with that of porous calcium phosphate ceramics implanted in vivo: osteoinduction was only detected inside the pores of the porous calcium phosphate ceramics. This result implicates that the bone-like apatite may play an important role in the osteoinduction of Ca-P materials. The dynamic model used in this study may be better than usually used static immersion model in imitating the physiological condition of bone-like apatite formation. Dynamic SBF method is very useful to understand bone-like apatite formation in vivo and the mechanism of ectopic bone formation in calcium phosphate ceramics.
| Early apatite deposition and osteoblast growth on plasma-sprayed dicalcium silicate coating
Liu, X., Y. Xie, et al. (2005), J Biomed Mater Res A 74(3): 356-65.
Abstract: Dicalcium silicate coating was deposited onto a Ti-6Al-4V substrate using plasma-spraying technology. The coating was immersed in simulated body fluid (SBF) for 1, 3, 6, 12, 24, and 48 h to investigate early apatite formation on the coating. Osteoblasts were also seeded onto the surface of the dicalcium silicate coating to evaluate its biocompatibility. Cold field-emission scanning electron microscopy and energy-dispersive X-ray spectrometry were used to evaluate the morphologies and determine the chemical composition of the coatings. The surface structural changes caused by immersion in SBF were analyzed using thin-film X-ray diffraction. After the dicalcium silicate coating was soaked in SBF solution 1-6 h, two types of particles containing calcium and phosphorus were formed on the surface. One type consisted of relatively larger particles (P1) precipitated on the surface of the coating from the precursor cluster formed in the SBF solution. The second type was composed of particles (P2) nucleated on the surface of the coating. With increasing immersion time, the particles coalesced to form a surface Ca-P layer. The Ca-P layer was composed of amorphous calcium phosphate that was not transformed to crystalline apatite until the immersion time in SBF exceeded 24 h. The formation mechanism of the Ca-P layer and apatite on the surface of the coating is believed to be involved in the formation of the Si 3-ring active surface site with negative charge. The cell-seeding test revealed that osteoblasts grew and proliferated very well on the surface of the dicalcium silicate coating.
| Ecosystem collapse in Pleistocene Australia and a human role in megafaunal extinction
Miller, G. H., M. L. Fogel, et al. (2005), Science 309(5732): 287-90.
Abstract: Most of Australia's largest mammals became extinct 50,000 to 45,000 years ago, shortly after humans colonized the continent. Without exceptional climate change at that time, a human cause is inferred, but a mechanism remains elusive. A 140,000-year record of dietary delta(13)C documents a permanent reduction in food sources available to the Australian emu, beginning about the time of human colonization; a change replicated at three widely separated sites and in the marsupial wombat. We speculate that human firing of landscapes rapidly converted a drought-adapted mosaic of trees, shrubs, and nutritious grasslands to the modern fire-adapted desert scrub. Animals that could adapt survived; those that could not, became extinct.
| Ectopic bone formation associated with mesenchymal stem cells in a resorbable calcium deficient hydroxyapatite carrier
Kasten, P., J. Vogel, et al. (2005), Biomaterials 26(29): 5879-89.
Abstract: Bone substitute materials can induce bone formation in combination with mesenchymal stem cells (MSC). The aim of the current study was to examine ectopic in vivo bone formation with and without MSC on a new resorbable ceramic, called calcium deficient hydroxyapatite (CDHA). Ceramic blocks characterized by a large surface (48 m2/g) were compared with beta-tricalcium phosphate (beta-TCP), hydroxyapatite (HA) ceramics (both ca. 0.5 m2/g surface) and demineralized bone matrix (DBM). Before implantation in the back of SCID mice carriers were freshly loaded with 2x10(5) expanded human MSC or loaded with cells and kept under osteogenic conditions for two weeks in vitro. Culture conditions were kept free of xenogenic supplements. Deposits of osteoid at the margins of ceramic pores occurred independent of osteogenic pre-induction, contained human cells, and appeared in 416 MSC/CDHA composites compared to 216 MSC/beta-TCP composites. ALP activity was significantly higher in samples with MSC versus empty controls (p<0.001). Furthermore, ALP was significantly (p<0.05) higher for all ceramics when compared to the DBM matrix. Compared to previous studies, overall bone formation appeared to be reduced possibly due to the strict human protocol. Ectopic bone formation in the novel biomaterial CDHA varied considerably with the cell pool and was at least equal to beta-TCP blocks.
| Ectopic bone formation by microporous calcium phosphate ceramic particles in sheep muscles
Le Nihouannen, D., G. Daculsi, et al. (2005), Bone 36(6): 1086-93.
Abstract: Calcium phosphate ceramics are widely used in bone reconstructive surgery because of their osteconductive properties. However, these materials generally lack osteoinductive properties required to support bone healing in large defects. In this article, we study the osteoinductive potential of calcium phosphate ceramic particles implanted for 6 months into the dorsal muscles of eight adult female sheep. Microporous biphasic calcium phosphate (MBCP) granules of 1-2 mm composed of hydroxyapatite and beta-tricalcium phosphate (60/40) had macropores of 450 microm, micropores of 0.43 microm, and a specific surface area of 1.8 m(2)/g. After 6 months in the back muscles of sheep, the explants composed of MBCP granules were hard and encapsulated by normal muscle tissue. Ectopic bone formation with Haversian structures was observed in close contact with the MBCP granules in histological sections. Back-scattered electron microscopy and micro-computed tomography indicated that approximately 10% of well-mineralized bone with mature osteocytes had formed between or upon the granules. The ectopic bone showed trabeculae bridging the MBCP granules. Both the number and thickness of the trabeculae formed between the MBCP particles were comparable to those measured in spongious bone. The overall results therefore confirmed the presence of mature bone after intramuscular implantation of MBCP granules. The different hypotheses explaining ectopic bone formation induced by MBCP granules are discussed. Synthetic bone substitutes with osteoinductive properties could be used in bone reconstructive surgery.
| Ectopic bone formation in rat marrow stromal cell/titanium fiber mesh scaffold constructs: effect of initial cell phenotype
Holtorf, H. L., J. A. Jansen, et al. (2005), Biomaterials 26(31): 6208-16.
Abstract: Titanium fiber mesh scaffolds have been shown to be a suitable material for culture of primary marrow stromal cells in an effort to create tissue engineered constructs for bone tissue replacement. In native bone tissue, these cells are known to attach to extracellular matrix molecules via integrin receptors for specific peptide sequences, and these attachments can be a source of cell signaling, affecting cell behaviors such as differentiation. In this study, we examined the ability of primary rat marrow stromal cells at two different stages of osteoblastic differentiation to further differentiate into osteoblasts both in vitro and in vivo when seeded on titanium fiber mesh scaffolds either with or without RGD peptide tethered to the surface. In vitro, the tethered RGD peptide resulted in reduced initial cell proliferation. In vivo, there was no effect of tethered RGD peptide on ectopic bone formation in a rat subcutaneous implant model. Scaffold/cell constructs exposed to dexamethasone for 4 days prior to implantation (+dex constructs) resulted in significant bone formation whereas no bone formation was observed in--dex constructs. These results show that the osteoblastic differentiation of marrow stromal cells was not dependent on surface tethered RGD peptide, and that the initial differentiation stage of implanted cells plays an important role in bone formation in titanium fiber mesh bone tissue engineering constructs.
| Ectopic bone induction by partially purified bone extract alone or attached to biomaterials
Swoboda, H. F., F. M. Wimmer, et al. (1990), Biomater Artif Cells Artif Organs 18(3): 383-401.
Abstract: Formation of new bone is suggested to be caused by interaction of a set of chemical factors with mesenchymal target cells. A specific assembly of factors, i.e. chemotaxis-, adhesion-, proliferation- and differentiation-factors, as well as macromolecular structure components, essential for formation of large amounts of ectopic bone was termed "osteopoetin" (OP). In the present study a partially purified osteopoetin containing bovine bone extract (OCBE) was used to induce ectopic bone formation. In order to reduce the amount of OCBE necessary for bone induction, OCBE was seeded onto different commercially available collagens or poly-L-lactic acids (PL). Solid collagens in a sponge-like form were used for the first time to function as an attachment system for an osteoinductive substance. The test substances were implanted into abdominal muscle pouches of male Wistar rats. After 21 days the implants were harvested and evaluated histologically. OCBE resulted in the formation of large ossicles containing hematopoietic bone marrow. The minimal amount of OCBE to elicit ectopic bone formation can be reduced by a factor of 10 when attached to quickly resorbable collagens, but not when attached to slowly resorbable PL. These results suggest that collagens are suitable OCBE attachment systems and useful for clinical application.
| Educational goals for biomaterials science and engineering: prospective view
von Recum, A. F. and M. LaBerge (1995), J Appl Biomater 6(2): 137-44.
Abstract: The research field of biomaterials and surgical implants has matured to a point suggesting that a formal and comprehensive education is now required to handle all professional issues related to biomaterials and implant development. A professional curriculum is proposed for a discipline of biomaterials science and engineering on a graduate level. The curriculum includes the definition of an essential knowledge base and describes two track options for a study period of 3 years. Lists of prerequisites as well as required and suggested courses are presented and discussed. Continuing education courses are presented as examples. A quick vision of the immediate future of the field enforces the need for biomaterials professionals to take the lead in bringing the field into the next century.
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