151
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Fukushima T, Ohno J, Hayakawa T, Imayoshi R, Kawaguchi M, Doi Y, Kanaya K, Mitarai M. Polycationic protamine for water-insoluble complex formation with DNA. Dent Mater J 2010; 29:529-35. [PMID: 20733264 DOI: 10.4012/dmj.2009-131] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The DNA/protamine complex was prepared by a reaction between DNA and protamine sulfate solutions with stirring, and its cell viability, antibacterial effect and histopathological responses were examined. A water-insoluble white powder, DNA/protamine complex, with a porous structure was obtained. The molar binding ratio of the complex prepared from a solution containing equal amounts of DNA and protamine sulfate by weight was 0.038 and the efficiency of complex formation was 61%. In a cell culture test using MC-3T3-E1 mouse osteoblast cells, the complex showed less cytotoxicity than protamine sulfate alone and cell viabilities were more than 98%. A porous disk could be prepared easily and showed an antibacterial effect against Staphyrococcus aureus, Porphyromonas gingivalis and Prevotella intermedia in an antibacterial sensitivity test and a mild tissue response in vivo test. These results suggested that the DNA/protamine complex could be a useful biodegradable biomaterial with antibacterial effects.
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Affiliation(s)
- Tadao Fukushima
- Department of Dental Engineering, Bioengineering section, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan.
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152
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Sponer P, Strnadová M, Urban K. In vivo behaviour of low-temperature calcium-deficient hydroxyapatite: comparison with deproteinised bovine bone. INTERNATIONAL ORTHOPAEDICS 2010; 35:1553-60. [PMID: 20721552 DOI: 10.1007/s00264-010-1113-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/31/2010] [Accepted: 07/31/2010] [Indexed: 12/28/2022]
Abstract
This study aims to evaluate in detail the biological osteoconductive properties of the low-temperature synthetic porous calcium-deficient hydroxyapatite and to compare it with the biological apatite. Bone reactions to granules of similar sizes of the low-temperature hydroxyapatite and commercially available non-sintered deproteinized bovine bone were compared. Two different temperatures were used to fabricate two batches of newly developed porous hydroxyapatite with different carbonate groups content and specific surface area. The histological analysis of specimens with histomorphometry was performed at different time after in vivo implantation. Based on histological analysis, the level of bone formation in the spaces between the implanted granules and through the interconnected pores of all implanted materials within a cortical region (bone area ingrowth 72-85 %) was several-fold higher than within a cancellous bone site (bone area ingrowth 16-28 %) at three and six months after implantation. Within the cancellous bone site, bone coverage of the implanted material at six months was significantly higher in hydroxyapatite material fabricated using low-temperature synthesis and subsequent processing at 150°C than in hydroxyapatite scaffold developed using low-temperature synthesis with subsequent processing at 700°C or deproteinized bovine bone. According to our study, the bioactive properties of the low-temperature calcium-deficient hydroxyapatite are comparable with the biological apatite. The favourable influence of a high specific surface area of a low-temperature calcium-deficient hydroxyapatite on in vivo bone formation was emphasized.
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Affiliation(s)
- Pavel Sponer
- Department of Orthopaedic Surgery, Faculty of Medicine and University Hospital in Hradec Králové, Charles University in Prague, Sokolská 581, 500 05, Hradec Králové, Czech Republic.
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153
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Lan Levengood SK, Polak SJ, Poellmann MJ, Hoelzle DJ, Maki AJ, Clark SG, Wheeler MB, Wagoner Johnson AJ. The effect of BMP-2 on micro- and macroscale osteointegration of biphasic calcium phosphate scaffolds with multiscale porosity. Acta Biomater 2010; 6:3283-91. [PMID: 20176148 DOI: 10.1016/j.actbio.2010.02.026] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 02/16/2010] [Indexed: 12/20/2022]
Abstract
It is well established that scaffolds for applications in bone tissue engineering require interconnected pores on the order of 100 microm for bone in growth and nutrient and waste transport. As a result, most studies have focused on scaffold macroporosity (>100 microm). More recently researchers have investigated the role of microporosity in calcium phosphate -based scaffolds. Osteointegration into macropores improves when scaffold rods or struts contain micropores, typically defined as pores less than approximately 50 microm. We recently demonstrated multiscale osteointegration, or growth into both macropores and intra-red micropores (<10 microm), of biphasic calcium phosphate (BCP) scaffolds. The combined effect of BMP-2, a potent osteoinductive growth factor, and multiscale porosity has yet to be investigated. In this study we implanted BCP scaffolds into porcine mandibular defects for 3, 6, 12 and 24 weeks and evaluated the effect of BMP-2 on multiscale osteointegration. The results showed that given this in vivo model BMP-2 influences osteointegration at the microscale, but not at the macroscale, but not at the macroscale. Cell density was higher in the rod micropores for scaffolds containing BMP-2 compared with controls at all time points, but BMP-2 was not required for bone formation in micropores. In contrast, there was essentially no difference in the fraction of bone in macropores for scaffolds with BMP-2 compared with controls. Additionally, bone in macropores seemed to have reached steady-state by 3 weeks. Multiscale osteointegration results in bone-scaffold composites that are fully osteointegrated, with no 'dead space'. These composites are likely to contain a continuous cell network as well as the potential for enhanced load transfer and improved mechanical properties.
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Affiliation(s)
- Sheeny K Lan Levengood
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 West Green Street, Urbana, IL 61801, USA
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154
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Habraken W, Liao H, Zhang Z, Wolke J, Grijpma D, Mikos A, Feijen J, Jansen J. In vivo degradation of calcium phosphate cement incorporated into biodegradable microspheres. Acta Biomater 2010; 6:2200-11. [PMID: 20026289 DOI: 10.1016/j.actbio.2009.12.028] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 12/11/2009] [Accepted: 12/14/2009] [Indexed: 10/20/2022]
Abstract
In this study we have investigated the influence of the mechanism of microsphere degradation or erosion on the in vivo degradation of microsphere/calcium phosphate cement composites (microsphere CPCs) used in tissue engineering. Microspheres composed of poly(lactic-co-glycolic acid) (PLGA), gelatin and poly(trimethylene carbonate) (PTMC) were used as the model and the resulting microsphere CPCs were implanted subcutaneously for 4, 8 or 12weeks in the back of New Zealand white rabbits. Besides degradation, the soft tissue response to these formulations was evaluated. After retrieval, specimens were analyzed by physicochemical characterization and histological analysis. The results showed that all microsphere CPCs exhibited microsphere degradation after 12weeks of subcutaneous implantation, which was accompanied by decreasing compression strength. The PLGA microspheres exhibited bulk erosion simultaneously throughout the whole composite, whereas the gelatin type B microspheres were degradated from the outside to the center of the composite. High molecular weight PTMC microspheres exhibited surface erosion resulting in decreasing microsphere size. Furthermore, all composites showed a similar tissue response, with decreasing capsule thickness over time and a persistent moderate inflammatory response at the implant interface. In conclusion, microsphere CPCs can be used to generate porous scaffolds in an in vivo environment after degradation of microspheres by various degradation/erosion mechanisms.
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155
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Mour M, Das D, Winkler T, Hoenig E, Mielke G, Morlock MM, Schilling AF. Advances in Porous Biomaterials for Dental and Orthopaedic Applications. MATERIALS 2010. [PMCID: PMC5445918 DOI: 10.3390/ma3052947] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The connective hard tissues bone and teeth are highly porous on a micrometer scale, but show high values of compression strength at a relatively low weight. The fabrication of porous materials has been actively researched and different processes have been developed that vary in preparation complexity and also in the type of porous material that they produce. Methodologies are available for determination of pore properties. The purpose of the paper is to give an overview of these methods, the role of porosity in natural porous materials and the effect of pore properties on the living tissues. The minimum pore size required to allow the ingrowth of mineralized tissue seems to be in the order of 50 µm: larger pore sizes seem to improve speed and depth of penetration of mineralized tissues into the biomaterial, but on the other hand impair the mechanical properties. The optimal pore size is therefore dependent on the application and the used material.
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Affiliation(s)
- Meenakshi Mour
- Department of Mechanical Engineering, National Institute of Technology, Durgapur 713209, India; E-Mails: (M.M.); (D.D.)
| | - Debarun Das
- Department of Mechanical Engineering, National Institute of Technology, Durgapur 713209, India; E-Mails: (M.M.); (D.D.)
| | - Thomas Winkler
- Biomechanics Section, Hamburg University of Technology, Hamburg D-21073, Germany; E-Mails: (T.W.); (E.H.); (G.M.); (M.M.M.)
| | - Elisa Hoenig
- Biomechanics Section, Hamburg University of Technology, Hamburg D-21073, Germany; E-Mails: (T.W.); (E.H.); (G.M.); (M.M.M.)
| | - Gabriela Mielke
- Biomechanics Section, Hamburg University of Technology, Hamburg D-21073, Germany; E-Mails: (T.W.); (E.H.); (G.M.); (M.M.M.)
| | - Michael M. Morlock
- Biomechanics Section, Hamburg University of Technology, Hamburg D-21073, Germany; E-Mails: (T.W.); (E.H.); (G.M.); (M.M.M.)
| | - Arndt F. Schilling
- Biomechanics Section, Hamburg University of Technology, Hamburg D-21073, Germany; E-Mails: (T.W.); (E.H.); (G.M.); (M.M.M.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel: +49-(0)40-42878-4361; Fax: +49-(0)40-42878-2996
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156
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Roosa SMM, Kemppainen JM, Moffitt EN, Krebsbach PH, Hollister SJ. The pore size of polycaprolactone scaffolds has limited influence on bone regeneration in an in vivo model. J Biomed Mater Res A 2010; 92:359-68. [PMID: 19189391 DOI: 10.1002/jbm.a.32381] [Citation(s) in RCA: 157] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Bone tissue engineering scaffolds should be designed to optimize mass transport, cell migration, and mechanical integrity to facilitate and enhance new bone growth. Although many scaffold parameters could be modified to fulfill these requirements, pore size is an important scaffold characteristic that can be rigorously controlled with indirect solid freeform fabrication. We explored the effect of pore size on bone regeneration and scaffold mechanical properties using polycaprolactone (PCL) scaffolds designed with interconnected, cylindrical orthogonal pores. Three scaffold designs with unique microarchitectures were fabricated, having pore sizes of 350, 550, or 800 microm. Bone morphogenetic protein-7 transduced human gingival fibroblasts were suspended in fibrin gel, seeded into scaffolds, and implanted subcutaneously in immuno-compromised mice for 4 or 8 weeks. We found that (1) modulus and peak stress of the scaffold/bone constructs depended on pore size and porosity at 4 weeks but not at 8 weeks, (2) bone growth inside pores depended on pore size at 4 weeks but not at 8 weeks, and (3) the length of implantation time had a limited effect on scaffold/bone construct properties. In conclusion, pore sizes between 350 and 800 microm play a limited role in bone regeneration in this tissue engineering model. Therefore, it may be advantageous to explore the effects of other scaffold structural properties, such as pore shape, pore interconnectivity, or scaffold permeability, on bone regeneration when designing PCL scaffolds for bone tissue engineering.
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Affiliation(s)
- Sara M Mantila Roosa
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2099, USA
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157
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Ryu YM, Hah YS, Park BW, Kim DR, Roh GS, Kim JR, Kim UK, Rho GJ, Maeng GH, Byun JH. Osteogenic differentiation of human periosteal-derived cells in a three-dimensional collagen scaffold. Mol Biol Rep 2010; 38:2887-94. [PMID: 20107909 DOI: 10.1007/s11033-010-9950-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 01/14/2010] [Indexed: 01/17/2023]
Abstract
This study examined the osteogenic differentiation of cultured human periosteal-derived cells grown in a three dimensional collagen-based scaffold. Periosteal explants with the appropriate dimensions were harvested from the mandible during surgical extraction of lower impacted third molar. Periosteal-derived cells were introduced into cell culture. After passage 3, the cells were divided into two groups and cultured for 28 days. In one group, the cells were cultured in two-dimensional culture dishes with osteogenic inductive medium containing dexamethasone, ascorbic acid, and β-glycerophosphate. In the other group, the cells were seeded onto a three-dimensional collagen scaffold and cultured under the same conditions. We examined the bioactivity of alkaline phosphatase (ALP), the RT-PCR analysis for ALP and osteocalcin, and measurements of the calcium content in the periosteal-derived cells of two groups. Periosteal-derived cells were successfully differentiated into osteoblasts in the collagen-based scaffold. The ALP activity in the periosteal-derived cells was appreciably higher in the three-dimensional collagen scaffolds than in the two-dimensional culture dishes. The levels of ALP and osteocalcin mRNA in the periosteal-derived cells was also higher in the three-dimensional collagen scaffolds than in the two-dimensional culture dishes. The calcium level in the periosteal-derived cells seeded onto three-dimensional collagen scaffolds showed a 5.92-fold increase on day 7, 3.28-fold increase on day 14, 4.15-fold increase on day 21, and 2.91-fold increase on day 28, respectively, compared with that observed in two-dimensional culture dishes. These results suggest that periosteal-derived cells have good osteogenic capacity in a three-dimensional collagen scaffold, which provides a suitable environment for the osteoblastic differentiation of these cells.
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Affiliation(s)
- Young-Mo Ryu
- Department of Oral and Maxillofacial Surgery, Institute of Health Sciences, Biomedical Center (BK21), Gyeongsang National University School of Medicine, Jinju 660-702, Republic of Korea
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158
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Haaparanta AM, Haimi S, Ellä V, Hopper N, Miettinen S, Suuronen R, Kellomäki M. Porous polylactide/β-tricalcium phosphate composite scaffolds for tissue engineering applications. J Tissue Eng Regen Med 2010; 4:366-73. [DOI: 10.1002/term.249] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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159
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Bodde EWH, Habraken WJEM, Mikos AG, Spauwen PHM, Jansen JA. Effect of polymer molecular weight on the bone biological activity of biodegradable polymer/calcium phosphate cement composites. Tissue Eng Part A 2009; 15:3183-91. [PMID: 19364281 DOI: 10.1089/ten.tea.2008.0694] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Previous studies demonstrated that the addition of biodegradable polymer microparticles to calcium phosphate (CaP) cement improves the cement's degradative behavior without affecting its handling characteristics, especially its injectability and moldability. We investigated the influence of molecular weight of polymeric microparticles included in CaP cement on implant degradation and bone formation in critical-sized defects. Forty rats received cranial defects filled with formulations of CaP cement and poly(DL-lactic-co-glycolic acid) (PLGA) microparticles. Microparticles consisted of 100% high- (HMW) or low-molecular-weight (LMW) PLGA or mixtures of these (25%, 50%, or 75%). Implantation time was 12 weeks. Porosity measurements showed that the 100% HMW group was significantly less porous than the other groups. Histology and histomorphometry revealed significantly greater implant degradation in the 100% LMW group. Defect bridging was mainly seen in the 75% and 100% LMW groups, with the highest amount of bone in the 100% LMW formulation. These results suggest that LMW PLGA microparticles are associated with better bone formation than HMW PLGA, which is most likely explained by the greater degradation of LMW PLGA microparticles. In conclusion, CaP cement composites with high percentages of LMW PLGA microparticles show good bone transductive behavior, with complete defect bridging. The 100% LMW group turned out to be the best formulation.
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Affiliation(s)
- Esther W H Bodde
- Department of Periodontology and Biomaterials, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
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160
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Fukushima T, Ohno J, Hayakawa T, Kawaguchi M, Inoue Y, Takeda S, Toyoda M, Okahata Y. Mold fabrication and biological assessment of porous DNA-chitosan complexes. J Biomed Mater Res B Appl Biomater 2009; 91:746-754. [PMID: 19582845 DOI: 10.1002/jbm.b.31451] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A previous study revealed that DNA-chitosan complex prepared from the reaction between native DNA and chitosan in aqueous solution has suitable porosity for cell seeding, is nontoxic, and causes only a mild soft-tissue response. This simple and easy fabrication method for porous DNA-chitosan complex provides for a wide variety of applications as a scaffold material. The present study evaluated whether rinsing with PBS solution can fabricate DNA-chitosan complex in a mold and the histopathological responses of rat soft tissues to fabricated DNA-chitosan complexes. DNA-chitosan complex paste was prepared by mixing distilled water and freeze-dried water-rinsed DNA-chitosan complex powder. A DNA-chitosan complex disk could be fabricated by rinsing with PBS buffer and subsequently freeze-drying the DNA-chitosan complex paste in the mold. Thus, a wide range of applications of DNA-chitosan complex for tissue engineering can be anticipated using the present easy fabrication method. The porosity of the disk was 85%, and many pores were visible in the DNA-chitosan complex (before fabrication) and in the fabricated DNA-chitosan disk. The values of the complex disks gradually reduced in the tissues although 60% of disks remained in the tissues. In conclusion, an easy fabrication method for making porous DNA-chitosan complex disks was developed. It was found that the fabrication method can delay the biodegradation of the DNA-chitosan complex disk without serious tissue responses in vivo. DNA-chitosan complex is promising as a scaffold material, and a wide range of applications of DNA-chitosan complex for tissue engineering are anticipated.
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Affiliation(s)
- Tadao Fukushima
- Department of Dental Engineering, Bioengineering Section, Fukuoka Dental College, Sawara-ku, Fukuoka 814-0193, Japan
| | - Jun Ohno
- Department of Morphological Biology, Pathology Section, Fukuoka Dental College, Sawara-ku, Fukuoka 814-0193, Japan
| | - Tohru Hayakawa
- Department of Dental Biomaterials, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan
| | - Minoru Kawaguchi
- Department of Dental Engineering, Bioengineering Section, Fukuoka Dental College, Sawara-ku, Fukuoka 814-0193, Japan
| | - Yusuke Inoue
- Fukuoka College of Health Sciences, Sawara-ku, Fukuoka 814-0193, Japan
| | - Shoji Takeda
- Department of Biomaterials, Osaka Dental University, Hirakata, Osaka 573-1121, Japan
| | - Mika Toyoda
- Department of Functional Bioscience, Section of Infection Biology, Fukuoka Dental College, Sawara-ku, Fukuoka 814-0193, Japan
| | - Yoshio Okahata
- Department of Biomolecular Engineering, Tokyo Institute of Technology, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
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161
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Fuji T, Anada T, Honda Y, Shiwaku Y, Koike H, Kamakura S, Sasaki K, Suzuki O. Octacalcium Phosphate–Precipitated Alginate Scaffold for Bone Regeneration. Tissue Eng Part A 2009; 15:3525-35. [DOI: 10.1089/ten.tea.2009.0048] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Takeshi Fuji
- Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, Sendai, Japan
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Takahisa Anada
- Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Yoshitomo Honda
- Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Yukari Shiwaku
- Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, Sendai, Japan
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Hiroko Koike
- Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, Sendai, Japan
- Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Shinji Kamakura
- Division of Bone Regenerative Engineering, Department of Regenerative Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Keiichi Sasaki
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Osamu Suzuki
- Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, Sendai, Japan
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162
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Rong M, Zhou L, Gou Z, Zhu A, Zhou D. The early osseointegration of the laser-treated and acid-etched dental implants surface: an experimental study in rabbits. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2009; 20:1721-1728. [PMID: 19291368 DOI: 10.1007/s10856-009-3730-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 03/03/2009] [Indexed: 05/27/2023]
Abstract
The aim of the study was to evaluate early osseointegration of the laser-treated and acid-etched implant surface after the installation in rabbit tibias for 4 weeks. A total of 56 screw-shaped implants were grouped as follows: group A: implants were turned surface; group B: implants were laser-treated surface; group C: implants were acid-etched; group D: Implants were laser-treated and acid-etched surface. After 4 weeks, the removal torques were: group A: 13.21 +/- 11.30 Ncm; group B: 29.73 +/- 8.32 Ncm; group C: 30.31 +/- 9.45 Ncm; group D: 35.76 +/- 7.58 Ncm; The averages of bone-to-implant contact (BIC) were as follows: group A: 27.30 +/- 6.55%; group B: 38.00 +/- 8.56%; group C: 42.71 +/- 8.48%; group D: 49.71 +/- 9.21%. The removal torque and bone-to-implant contact measurements yielded statistically significant differences between the treated groups and turned group (P < 0.05); The laser-treated and acid-etched surface achieved higher Bone-to-Implant Contact than the laser-treated surface (P < 0.05), but there was no statistically significant difference between the laser-treated and acid-etched surface and the acid-etched surface in bone-to-implant contact (P > 0.05). In the present study, it was concluded that the laser-treated and acid-etched implants had good osteoconductivity and was a potential material for dental implantation.
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Affiliation(s)
- Mingdeng Rong
- Department of Oral and Maxillofacial Surgery, Guangdong Provincial Stomatological Hospital, Southern Medical University, Guangzhou, China
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163
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Honda Y, Anada T, Kamakura S, Morimoto S, Kuriyagawa T, Suzuki O. The Effect of Microstructure of Octacalcium Phosphate on the Bone Regenerative Property. Tissue Eng Part A 2009; 15:1965-73. [DOI: 10.1089/ten.tea.2008.0300] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Yoshitomo Honda
- Division of Craniofacial Function Engineering (CFE), Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Takahisa Anada
- Division of Craniofacial Function Engineering (CFE), Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Shinji Kamakura
- Division of Bone Regenerative Engineering, Department of Regenerative Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Shinji Morimoto
- Division of Craniofacial Function Engineering (CFE), Tohoku University Graduate School of Dentistry, Sendai, Japan
- Research & Development Laboratory, NIPRO, Kusatsu, Shiga, Japan
| | - Tsunemoto Kuriyagawa
- Department of Nanomechanics Center for Micro/Nano Design and Processing Engineering, Tohoku University Graduate School of Engineering, Sendai, Japan
| | - Osamu Suzuki
- Division of Craniofacial Function Engineering (CFE), Tohoku University Graduate School of Dentistry, Sendai, Japan
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164
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Blecha LD, Rakotomanana L, Razafimahery F, Terrier A, Pioletti DP. Targeted mechanical properties for optimal fluid motion inside artificial bone substitutes. J Orthop Res 2009; 27:1082-7. [PMID: 19180634 DOI: 10.1002/jor.20836] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Our goal was to develop a method to identify the optimal elastic modulus, Poisson's ratio, porosity, and permeability values for a mechanically stressed bone substitute. We hypothesized that a porous bone substitute that favors the transport of nutriments, wastes, biochemical signals, and cells, while keeping the fluid-induced shear stress within a range that stimulates osteoblasts, would likely promote osteointegration. Two optimization criteria were used: (i) the fluid volume exchange between the artificial bone substitute and its environment must be maximal and (ii) the fluid-induced shear stress must be between 0.03 and 3 Pa. Biot's poroelastic theory was used to compute the fluid motion due to mechanical stresses. The impact of the elastic modulus, Poisson's ratio, porosity, and permeability on the fluid motion were determined in general and for three different bone substitute sizes used in high tibial osteotomy. We found that fluid motion was optimized in two independent steps. First, fluid transport was maximized by minimizing the elastic modulus, Poisson's ratio, and porosity. Second, the fluid-induced shear stress could be adjusted by tuning the bone substitute permeability so that it stayed within the favorable range of 0.03 to 3 Pa. Such method provides clear guidelines to bone substitute developers and to orthopedic surgeons for using bone substitute materials according to their mechanical environment.
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Affiliation(s)
- L D Blecha
- Laboratory of Biomechanical Orthopedics EPFL-HOSR, 1005 Lausanne, Switzerland
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165
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Kubinová S, Horák D, Syková E. Cholesterol-modified superporous poly(2-hydroxyethyl methacrylate) scaffolds for tissue engineering. Biomaterials 2009; 30:4601-9. [PMID: 19500833 DOI: 10.1016/j.biomaterials.2009.05.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 05/10/2009] [Indexed: 01/15/2023]
Abstract
Modifications of poly(2-hydroxyethyl methacrylate) (PHEMA) with cholesterol and laminin have been developed to design scaffolds that promote cell-surface interaction. Cholesterol-modified superporous PHEMA scaffolds have been prepared by the bulk radical copolymerization of 2-hydroxyethyl methacrylate (HEMA), cholesterol methacrylate (CHLMA) and the cross-linking agent ethylene dimethacrylate (EDMA) in the presence of ammonium oxalate crystals to introduce interconnected superpores in the matrix. With the aim of immobilizing laminin (LN), carboxyl groups were also introduced to the scaffold by the copolymerization of the above monomers with 2-[(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA). Subsequently, the MCMEMA moiety in the resulting hydrogel was hydrolyzed to [2-(methacryloyloxy)ethoxy]acetic acid (MOEAA), and laminin was immobilized via carbodiimide and N-hydroxysulfosuccinimide chemistry. The attachment, viability and morphology of mesenchymal stem cells (MSCs) were evaluated on both nonporous and superporous laminin-modified as well as laminin-unmodified PHEMA and poly(2-hydroxyethyl methacrylate-co-cholesterol methacrylate) P(HEMA-CHLMA) hydrogels. Neat PHEMA and laminin-modified PHEMA (LN-PHEMA) scaffolds facilitated MSC attachment, but did not support cell spreading and proliferation; the viability of the attached cells decreased with time of cultivation. In contrast, MSCs spread and proliferated on P(HEMA-CHLMA) and LN-P(HEMA-CHLMA) hydrogels.
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Affiliation(s)
- Sárka Kubinová
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic
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166
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Keeney M, Collin E, Pandit A. Multi-Channelled Collagen–Calcium Phosphate Scaffolds: Their Physical Properties and Human Cell Response. Tissue Eng Part C Methods 2009; 15:265-73. [DOI: 10.1089/ten.tec.2008.0365] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Michael Keeney
- National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland
| | - Estelle Collin
- National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland
| | - Abhay Pandit
- National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland
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167
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Meretoja VV, Malin M, Seppälä JV, Närhi TO. Osteoblast response to continuous phase macroporous scaffolds under static and dynamic culture conditions. J Biomed Mater Res A 2009; 89:317-25. [DOI: 10.1002/jbm.a.31980] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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168
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Li M, Liu X, Liu X, Ge B, Chen K. Creation of macroporous calcium phosphate cements as bone substitutes by using genipin-crosslinked gelatin microspheres. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2009; 20:925-934. [PMID: 19052846 DOI: 10.1007/s10856-008-3654-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 11/17/2008] [Indexed: 05/27/2023]
Abstract
Macroporous calcium phosphate cements (CPCs) were developed using genipin-crosslinked gelatin microspheres (GMs) with two weight ratios (2.5 wt% and 5 wt%). The initial setting time of the composite was prolonged by GMs. After GMs/CPCs were soaked in phosphate-buffered saline (PBS) for several weeks, macropores appeared as a result of the degradation of GMs. The presence of GMs accelerated the setting reaction and improved the structure of the composite. The compressive strength increased up to 12 MPa (2.5 wt% GMs/CPCs) and 14 MPa (5 wt% GMs/CPCs) after one week of PBS soaking, then gradually decreased to 9 MPa (2.5 wt% GMs/CPCs) and 7 MPa (5 wt% GMs/CPCs) after three weeks of soaking, and further to 6 MPa (2.5 wt% GMs/CPCs) and 2 MPa (5 wt% GMs/CPCs) after five weeks of soaking. CPCs with 2.5 wt% GMs were the most favorable composite in the tested samples. Cell experiments showed that rat osteoblasts displayed normal morphologies when exposed to the 2.5 wt% GMs/CPCs, and proliferation of the cells was also enhanced. An in vivo study showed that new bone tissue was able to grow into the pores that resulted from GM degradation. This study suggests that the new composite could be a promising candidate for use as a bone substitute under non-compression-loaded circumstances.
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Affiliation(s)
- Meng Li
- Orthopedic Institute of Chinese People's Liberation Army, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, People's Republic of China
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169
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Mangano C, Raspanti M, Traini T, Piattelli A, Sammons R. Stereo imaging and cytocompatibility of a model dental implant surface formed by direct laser fabrication. J Biomed Mater Res A 2009; 88:823-31. [PMID: 18481810 DOI: 10.1002/jbm.a.32033] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Direct laser fabrication (DLF) allows solids with complex geometry to be produced by sintering metal powder particles in a focused laser beam. In this study, 10 Ti6Al4V alloy model dental root implants were obtained by DLF, and surface characterization was carried out using stereo scanning electron microscopy to produce 3D reconstructions. The surfaces were extremely irregular, with approximately 100 microm deep, narrow intercommunicating crevices, shallow depressions and deep, rounded pits of widely variable shape and size, showing ample scope for interlocking with the host bone. Roughness parameters were as follows: R(t), 360.8 microm; R(z), 358.4 microm; R(a), 67.4 microm; and R(q), 78.0 microm. Disc specimens produced by DLF with an identically prepared surface were used for biocompatibility studies with rat calvarial osteoblasts: After 9 days, cells had attached and spread on the DLF surface, spanning across the crevices, and voids. Cell density was similar to that on a commercial rough microtextured surface but lower than on commercial smooth machined and smooth-textured grit-blasted, acid-etched surfaces. Human fibrin clot extension on the DLF surface was slightly improved by inorganic acid etching to increase the microroughness. With further refinements, DLF could be an economical means of manufacturing implants from titanium alloys.
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170
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Cuddihy MJ, Kotov NA. Poly(lactic-co-glycolic acid) bone scaffolds with inverted colloidal crystal geometry. Tissue Eng Part A 2009; 14:1639-49. [PMID: 18491955 DOI: 10.1089/ten.tea.2007.0142] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Controllability of scaffold architecture is essential to meet specific criteria for bone tissue engineering implants, including adequate porosity, interconnectivity, and mechanical properties to promote bone growth. Many current scaffold manufacturing techniques induce random porosity in bulk materials, requiring high porosities (>95%) to guarantee complete interconnectivity, but the high porosity sacrifices mechanical properties. Additionally, the stochastic arrangement of pores causes scaffold-to-scaffold variation. Here, we introduce a biodegradable poly(lactic-co-glycolic acid) (PLGA) scaffold with an inverted colloidal crystal (ICC) structure that provides a highly ordered arrangement of identical spherical cavities. Colloidal crystals (CCs) were constructed with soda lime beads of 100-, 200-, and 330-mum diameters. After the CCs were annealed, they were infiltrated with 85:15 PLGA. The method of construction and highly ordered structure allowed for ease of control over cavity and interconnecting channel diameters and for full interconnectivity at lower porosities. The scaffolds demonstrated high mechanical properties for PLGA alone (>50 MPa), in vitro biocompatibility, and maintenance of osteoblast phenotype, making them promising for a highly controllable bone tissue engineering scaffold.
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Affiliation(s)
- Meghan J Cuddihy
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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171
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Klein M, Goetz H, Pazen S, Al-Nawas B, Wagner W, Duschner H. Pore characteristics of bone substitute materials assessed by microcomputed tomography. Clin Oral Implants Res 2009; 20:67-74. [DOI: 10.1111/j.1600-0501.2008.01605.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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172
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Kasten P, Beyen I, Niemeyer P, Luginbühl R, Bohner M, Richter W. Porosity and pore size of beta-tricalcium phosphate scaffold can influence protein production and osteogenic differentiation of human mesenchymal stem cells: an in vitro and in vivo study. Acta Biomater 2008; 4:1904-15. [PMID: 18571999 DOI: 10.1016/j.actbio.2008.05.017] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 05/08/2008] [Accepted: 05/14/2008] [Indexed: 11/18/2022]
Abstract
The interaction of stem cells and ceramics in bone regeneration is still poorly understood. The aim of this study was to examine the influence of the porosity (25%, 65% and 75%) of beta-tricalcium phosphate (TCP) ceramics on osteogenic differentiation of mesenchymal stem cells (MSC) in vitro and in vivo. For the in vitro portion of the study, TCP scaffolds loaded with MSC were kept in osteogenic induction medium for 21 days. For the in vivo portion of the study, scaffolds loaded with undifferentiated MSC were implanted subcutaneously into SCID mice for 8 weeks and compared with similarly implanted controls that were not loaded with MSC. Measurements of total protein as well as specific alkaline phosphatase (ALP) activity were taken as indicators of growth/matrix production and osteogenic differentiation. An increase in the total protein concentration was noted from day 1 to day 21 on the in vitro TCP 65% and TCP 75% scaffolds (p<0.05) with no such increase noted in the TCP 25% specimens. However, the specific alkaline phosphatase activity increased from day 1 to day 21 in all three in vitro specimens (p<0.02) and reached similar levels in each specimen by day 21. In vivo, ALP activity of cell-loaded TCP 65% ceramics was higher when compared with both the TCP 25% and TCP 75% specimens (p<0.046), and higher in the TCP 75% than TCP 25% specimens (p=0.008). Histology revealed mineralization by human cells in the pores of the TCP ceramic scaffolds with a trend toward greater calcification in TCP 65% and 75%. In summary, a higher porosity of TCP scaffolds does not necessarily mean a higher ALP activity in vivo. The distribution and size of the pores, as well as the surface structure, might play an important role for osteogenic differentiation in vivo.
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Affiliation(s)
- Philip Kasten
- Orthopaedic University Hospital Heidelberg, Schlierbacher Landstr. 200a, 69118 Heidelberg, Germany.
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173
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Asoda S, Arita T, Koshitomae H, Takakuda K. Mechanical attachment of soft fibrous tissues to implants by using mesh structures. Clin Oral Implants Res 2008; 19:1171-7. [DOI: 10.1111/j.1600-0501.2008.01562.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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174
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Shape-memory NiTi foams produced by replication of NaCl space-holders. Acta Biomater 2008; 4:1996-2007. [PMID: 18678532 DOI: 10.1016/j.actbio.2008.06.005] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 05/06/2008] [Accepted: 06/13/2008] [Indexed: 11/20/2022]
Abstract
NiTi foams were created with a structure (32-36% open pores 70-400 microm in size) and mechanical properties (4-25 GPa stiffness, >1000 MPa compressive strength, >42% compressive ductility, and shape-memory strains up to 4%) useful for bone implant applications. A mixture of NiTi and NaCl powders was hot-isostatically pressed at 950 and 1065 degrees C and the NaCl phase was then dissolved in water. The resulting NiTi foams show interconnected pores that replicate the shape and size of the NaCl powders, indicating that NiTi powders densified significantly before NaCl melted at 801 degrees C. Densifying NiTi or other metal powders above the melting point of the space-holder permits the use of NaCl, with the following advantages compared with higher-melting, solid space-holders such as oxides and fluorides used to date: (i) no temperature limit for densification; (ii) lower cost; (iii) greater flexibility in powder (and thus pore) shape; (iv) faster dissolution; (v) reduced metal corrosion during dissolution; (vi) lower toxicity if space-holder residues remain in the foam.
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175
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Klenke FM, Liu Y, Yuan H, Hunziker EB, Siebenrock KA, Hofstetter W. Impact of pore size on the vascularization and osseointegration of ceramic bone substitutes in vivo. J Biomed Mater Res A 2008; 85:777-86. [PMID: 17896777 DOI: 10.1002/jbm.a.31559] [Citation(s) in RCA: 166] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The repair of bone defects with biomaterials depends on a sufficient vascularization of the implantation site. We analyzed the effect of pore size on the vascularization and osseointegration of biphasic calcium phosphate particles, which were implanted into critical-sized cranial defects in Balb/c mice. Dense particles and particles with pore sizes in the ranges 40-70, 70-140, 140-210, and 210-280 microm were tested (n = 6 animals per group). Angiogenesis, vascularization, and leukocyte-endothelium interactions were monitored for 28 days by intravital microscopy. The formation of new bone and the bone-interface contact (BIC) were determined histomorphometrically. Twenty-eight days after implantation, the functional capillary density was significantly higher with ceramic particles whose pore sizes exceeded 140 microm [140-210 microm: 6.6 (+/-0.8) mm/mm(2); 210-280 microm: 7.3 (+/-0.6) mm/mm(2)] than with those whose pore sizes were lesser than 140 microm [40-70 microm: 5.3 (+/-0.4) mm/mm(2); 70-140 microm: 5.6 (+/-0.3) mm/mm(2)] or with dense particles [5.7 (+/-0.8) mm/mm(2)]. The volume of newly-formed bone deposited within the implants increased as the pore size increased [40-70 microm: 0.07 (+/-0.02) mm(3); 70-140 microm: 0.10 (+/-0.06) mm(3); 140-210 microm: 0.13 (+/-0.05) mm(3); 210-280 microm: 0.15 (+/-0.06) mm(3)]. Similar results were observed for the BIC. The data demonstrates pore size to be a critical parameter governing the dynamic processes of vascularization and osseointegration of bone substitutes.
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Affiliation(s)
- Frank M Klenke
- Department Clinical Research, Group for Bone Biology and Orthopedic Research, University of Berne, CH-3010 Berne, Switzerland.
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176
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Abstract
Autologous bone grafting remains the gold standard for bone grafting in clinical practice. Although it has withstood the test of time, it remains associated with multiple comorbidities. The search for an alternative bone graft substitute harnessing bone's osteoconductive, osteoinductive, and osteogenic properties remains a challenge. This article examines the various bone grafting materials currently in use and highlights the current properties and uses of silicon-substituted calcium phosphates as a competitive substitute for high cost materials used today.
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Affiliation(s)
- Walid Waked
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT 06520-8071, USA
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177
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Bottino MC, Coelho PG, Henriques VAR, Higa OZ, Bressiani AHA, Bressiani JC. Processing, characterization, and
in vitro
/
in vivo
evaluations of powder metallurgy processed Ti‐13Nb‐13Zr alloys. J Biomed Mater Res A 2008; 88:689-96. [DOI: 10.1002/jbm.a.31912] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Marco C. Bottino
- Materials Science and Technology Center, Institute for Energy and Nuclear Research, São Paulo, São Paulo 05508‐000, Brazil
- Department of Materials Science and Engineering, University of Alabama at Birmingham, Alabama, 35294
| | - Paulo G. Coelho
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, New York 10100
| | - Vinicius A. R. Henriques
- Materials Division (AMR/IAE), Brazilian Aerospace Technical Center, São José dos Campos, São Paulo 12228‐904, Brazil
| | - Olga Z. Higa
- Materials Science and Technology Center, Institute for Energy and Nuclear Research, São Paulo, São Paulo 05508‐000, Brazil
| | - Ana H. A. Bressiani
- Materials Science and Technology Center, Institute for Energy and Nuclear Research, São Paulo, São Paulo 05508‐000, Brazil
| | - José C. Bressiani
- Materials Science and Technology Center, Institute for Energy and Nuclear Research, São Paulo, São Paulo 05508‐000, Brazil
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178
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Endres S, Wilke M, Knöll P, Frank H, Kratz M, Wilke A. Correlation of in vitro and in vivo results of vacuum plasma sprayed titanium implants with different surface topography. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2008; 19:1117-25. [PMID: 17701309 DOI: 10.1007/s10856-007-3086-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Accepted: 05/02/2007] [Indexed: 05/16/2023]
Abstract
Research has proven that rough surfaces improve both biologic and biomechanical responses to titanium (Ti) implants. The purpose of this study was to evaluate the correlation between the expression of bone cell-associated proteins to Vacuum Plasma-Sprayed Titanium implants (VPS-Ti) with different surface textures in vitro and the bone integration in vivo. The biological performances of the surfaces were evaluated over a period of 8 weeks using human bone marrow cell cultures and Göttinger mini pigs. Cells were cultured on VPS-Ti with two respectively different surface-roughnesses (Ra). The level of Osteoprotegerin (OPG), Osteocalcin (OC) and alkaline phosphatase activity (ALP) were evaluated. The bone integration in vivo was evaluated by histomorphological analyses. A cancellous structured titanium (CS-Ti) construct was used as reference material in both study designs. Comparison of data was conducted using the Scheffé tests and the paired t-test with Bonferroni's correction. A comparative analysis was done to measure the degree of association between the in vitro and in vivo data. A total amount of OC was significantly increased for VPS-Ti for cells cultured on both VPS-Ti and CS-Ti, while OPG was only detectable after 8 weeks without any significant differences. The ALP activity on all surfaces was not statistically increased. For VPS-Ti with Ra ranging from 0.025 mm up to 0.059 mm, bone integration response was increased, but there was no statistical difference between the VPS-Ti. Expression of OPG, OC and ALP correlated with the histomorphological data over the 8-week period. The in vitro data suggest the superiority of VPS-Ti over CS-Ti, but more importantly, the biocompatibility of testing an in vitro model to predict the outcome and possible integration of implants in vivo.
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Affiliation(s)
- Stefan Endres
- Department of Orthopaedic Surgery, Elisabeth-Klinik GmbH Bigge/Olsberg, Heinrich-Sommer-Str. 4, 59939, Olsberg, Germany.
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179
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Histomorphologic evaluation of Ti–13Nb–13Zr alloys processed via powder metallurgy. A study in rabbits. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2008. [DOI: 10.1016/j.msec.2006.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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180
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Abstract
The use of bone grafts in the repair of defects has a long history of success, primarily with the use of autologous bone. With increasing technologic advances, researchers have been able to broaden the spectrum of grafting materials to allografts, xenografts, and synthetic materials, which provide the surgeon and patient with options, each with unique advantages. It is with the knowledge of each material that the clinician can present and suggest the best material and tailor treatment plans to fit each individual. In this article, we present an overview of the principles of bone grafting, the types of graft materials available, and an outlook to what the future holds in this area of medicine and dentistry.
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Affiliation(s)
- Solon T Kao
- Oral and Maxillofacial Surgery, Medical College of Georgia School of Dentistry, Augusta, GA 30912, USA.
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181
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Turgut G, Eksilioglu A, Gencay N, Gonen E, Hekim N, Yardim MF, Sakiz D, Ekinci E. Pore structure engineering for carbon foams as possible bone implant material. J Biomed Mater Res A 2008; 85:588-96. [PMID: 17806113 DOI: 10.1002/jbm.a.31489] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In this study authors aim to produce carbon foams with controllable pore size and distribution with high ratio of open porosity and to determine the cytotoxicity, and the bio-compatibility of the carbon foams by controlled experiments on the Dawley rats. Carbon foams are produced from Mitsubishi AR pitch at different pressures, temperatures, pressure release times, and additives for the purpose of using it as a bone implant material. Carbon foams with controllable range of pore sizes and distribution by using temperatures between 283 and 300 degrees C, pressures between 38 and 78 bar, and pressure release times between 5 and 600 s. The highest total porosity was found to be 86%. This porosity level was also complemented by the highest density, and compressive strength. Addition of isotropic pitch, graphite powder and THF, toluene and xylene solvents resulted in higher pore volumes compared with no additives. In the case of exploiting this result, it should be noted that higher pore volumes are realized with drastic drop in porosity and strength. The ability of porous foam to provide scaffold to tissue in vivo was finally investigated after 3 months of implantation in adequate pockets in the nude mice for insertion. Histological examination of the engineered constructs revealed that the tissue adaptation and bone compatibility of the carbon foam material studies on rats was found to be satisfactory. Progression of connective tissue formation into the carbon implant was observed without any sign of cytotoxicity and incompatibility during the postoperative follow-ups.
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Affiliation(s)
- Gursel Turgut
- Department of Plastic Reconstructive Surgery, Sisli Etfal Research Hospital, Istanbul, Turkey
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182
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Aparecida AH, Guastaldi AC, Fook MVL. Desenvolvimento e caracterização de suportes porosos de polietileno de ultra alto peso molecular (PEUAPM) para utilização como biomaterial para reposição e regeneração óssea. POLIMEROS 2008. [DOI: 10.1590/s0104-14282008000400004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
O uso de polímeros como biomateriais tem crescido nos últimos anos, principalmente como suportes poliméricos para regeneração tridimensional e substituição de tecidos. Embora o polietileno de ultra alto peso molecular (PEUAPM) apresente vantagens na sua utilização como biomaterial, principalmente como implante ortopédico, sua baixa reatividade química constitui-se como fator limitante para sua interação com o tecido ósseo. Neste contexto, a modificação morfológica deste polímero, tornando-o um material poroso, e sua associação com um material bioativo pode proporcionar a obtenção de um biomaterial adequado para a regeneração e reposição do tecido ósseo. Neste trabalho, foram preparados e caracterizados suportes porosos de PEUAPM, pela combinação das técnicas de lixiviação de sal e moldagem por compressão com a aplicação de diferentes pressões de compactação, visando a sua utilização como biomaterial para reposição e regeneração óssea. Os suportes poliméricos apresentaram porosidade interconectada com diâmetro médio de poros entre 34 e 49 mm e porosidade entre 39 e 53%, podendo ser classificados adequados para a utilização como biomaterial poroso.
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183
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Jou CH, Chen WC, Yang MC, Hwang MC, Chou WL, Lin SM, Hsu CY. In vitro biocompatibility of three-dimensional chitosan scaffolds immobilized with chondroitin-6-sulfate. POLYM ADVAN TECHNOL 2008. [DOI: 10.1002/pat.1020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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184
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185
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Sargeant TD, Guler MO, Oppenheimer SM, Mata A, Satcher RL, Dunand DC, Stupp SI. Hybrid bone implants: self-assembly of peptide amphiphile nanofibers within porous titanium. Biomaterials 2007; 29:161-71. [PMID: 17936353 DOI: 10.1016/j.biomaterials.2007.09.012] [Citation(s) in RCA: 195] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Accepted: 09/17/2007] [Indexed: 11/29/2022]
Abstract
Over the past few decades there has been great interest in the use of orthopedic and dental implants that integrate into tissue by promoting bone ingrowth or bone adhesion, thereby eliminating the need for cement fixation. However, strategies to create bioactive implant surfaces to direct cellular activity and mineralization leading to osteointegration are lacking. We report here on a method to prepare a hybrid bone implant material consisting of a Ti-6Al-4V foam, whose 52% porosity is filled with a peptide amphiphile (PA) nanofiber matrix. These PA nanofibers can be highly bioactive by molecular design, and are used here as a strategy to transform an inert titanium foam into a potentially bioactive implant. Using scanning electron microscopy (SEM) and confocal microscopy, we show that PA molecules self-assemble into a nanofiber matrix within the pores of the metallic foam, fully occupying the foam's interconnected porosity. Furthermore, the method allows the encapsulation of cells within the bioactive matrix, and under appropriate conditions the nanofibers can nucleate mineralization of calcium phosphate phases with a Ca:P ratio that corresponds to that of hydroxyapatite. Cell encapsulation was quantified using a DNA measuring assay and qualitatively verified by SEM and confocal microscopy. An in vivo experiment was performed using a bone plug model in the diaphysis of the hind femurs of a Sprague Dawley rat and examined by histology to evaluate the performance of these hybrid systems after 4 weeks of implantation. Preliminary results demonstrate de novo bone formation around and inside the implant, vascularization around the implant, as well as the absence of a cytotoxic response. The PA-Ti hybrid strategy could be potentially tailored to initiate mineralization and direct a cellular response from the host tissue into porous implants to form new bone and thereby improve fixation, osteointegration, and long term stability of implants.
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Affiliation(s)
- Timothy D Sargeant
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108, USA
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186
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Greiner A, Wendorff J. Elektrospinnen: eine faszinierende Methode zur Präparation ultradünner Fasern. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200604646] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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187
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Greiner A, Wendorff JH. Electrospinning: A Fascinating Method for the Preparation of Ultrathin Fibers. Angew Chem Int Ed Engl 2007; 46:5670-703. [PMID: 17585397 DOI: 10.1002/anie.200604646] [Citation(s) in RCA: 2146] [Impact Index Per Article: 126.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Electrospinning is a highly versatile method to process solutions or melts, mainly of polymers, into continuous fibers with diameters ranging from a few micrometers to a few nanometers. This technique is applicable to virtually every soluble or fusible polymer. The polymers can be chemically modified and can also be tailored with additives ranging from simple carbon-black particles to complex species such as enzymes, viruses, and bacteria. Electrospinning appears to be straightforward, but is a rather intricate process that depends on a multitude of molecular, process, and technical parameters. The method provides access to entirely new materials, which may have complex chemical structures. Electrospinning is not only a focus of intense academic investigation; the technique is already being applied in many technological areas.
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Affiliation(s)
- Andreas Greiner
- Department of Chemistry, Philipps-Universität Marburg, 35032 Marburg, Germany.
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188
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Arpornmaeklong P, Suwatwirote N, Pripatnanont P, Oungbho K. Growth and differentiation of mouse osteoblasts on chitosan–collagen sponges. Int J Oral Maxillofac Surg 2007; 36:328-37. [PMID: 17223012 DOI: 10.1016/j.ijom.2006.09.023] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2004] [Revised: 05/30/2006] [Accepted: 09/28/2006] [Indexed: 10/23/2022]
Abstract
The aim of this study was to investigate the effects of collagen on the microstructure and biocompatibility of chitosan-collagen composite sponges fabricated by a freezing and drying technique. The study was categorized into four groups: Group I: collagen; Group II: chitosan; Group III: 1:1 (by wt) chitosan-collagen and Group IV: 1:2 (by wt) chitosan-collagen sponges. A mouse osteoblast cell line, MC3T3-E1, was cultivated on the sponges in a mineralized culture medium for 21 days. Microstructure of scaffolds and growth of cells on the sponges were examined using scanning electron and confocal laser scanning electron microscopes. Pore size was analysed from scanning electron microscope images using Image-Pro Plus image analysis software. Cell viability (MTT assay), alkaline phosphatase activity and levels of osteocalcin and calcium were monitored every 3 days and on days 15 and 21, respectively. It was found that the sponges were porous with average pore sizes of 80-100 microm. A combination of chitosan and collagen matrixes created a well defined porous microstructure and biocompatible scaffolds. Chitosan-collagen composite sponges promoted growth and differentiation of osteoblasts into the mature stage. To optimize application of the composite sponges in bone regeneration, the fabrication process must be improved to increase the pore size of the scaffolds.
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Affiliation(s)
- P Arpornmaeklong
- Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Prince of Songkla University, Hat Yai, 90112 Songkhla, Thailand.
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189
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Saiz E, Gremillard L, Menendez G, Miranda P, Gryn K, Tomsia A. Preparation of porous hydroxyapatite scaffolds. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2007. [DOI: 10.1016/j.msec.2006.05.038] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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190
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Wachiralarpphaithoon C, Iwasaki Y, Akiyoshi K. Enzyme-degradable phosphorylcholine porous hydrogels cross-linked with polyphosphoesters for cell matrices. Biomaterials 2007; 28:984-93. [PMID: 17107708 DOI: 10.1016/j.biomaterials.2006.10.024] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Accepted: 10/24/2006] [Indexed: 01/09/2023]
Abstract
Biodegradable highly porous hydrogels composed of poly [2-methacryloyloxyethyl phosphorylcholine (MPC)] cross-linked with polyphosphoesters have been prepared as novel cellular matrices. Well-controlled porous hydrogels were fabricated by using potassium hydrogen carbonate as a porogen salt for forming gas. This process enabled the homogeneous expansion of pores within the polymer hydrogel matrices, leading to well-interconnected high porosity. The mechanical properties of the hydrogels were influenced by the cross-linking density and porous structure. Hydrolysis and enzymatic digestion of the hydrogels were determined under basic conditions. The cross-linking density and porosity influenced the rate of degradation of the hydrogels. Acceleration of the degradation with alkaline phosphatase was also observed. Cultivation of mouse osteoblastic cell (MC3T3-E1) was performed in the highly porous hydrogels and cell viability was well maintained. The rate of cell proliferation also was relatively increased with an increase in the amount of polyphosphoesters in the hydrogel. Basic fibroblast growth factor (bFGF) was physically absorbed by the hydrogels and effectively induced cell proliferation. In conclusion, the porous hydrogels prepared in this study contributed a suitable environment for three-dimensional cell cultivation and may be useful for cell and tissue matrices.
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Affiliation(s)
- Chookaet Wachiralarpphaithoon
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062, Japan
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191
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Aho AJ, Rekola J, Matinlinna J, Gunn J, Tirri T, Viitaniemi P, Vallittu P. Natural composite of wood as replacement material for ostechondral bone defects. J Biomed Mater Res B Appl Biomater 2007; 83:64-71. [PMID: 17318823 DOI: 10.1002/jbm.b.30767] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Deciduous wood, birch, pretreated by a technique combining heat and water vapor was applied for the reconstruction of bone defects in the knee joint of rabbits. It was observed that wood showed characteristic properties to be incorporated by the host bone during observation time of 4, 8, and 20 weeks. The natural channel structure of wood served as a porous scaffold, allowing host bone growth as small islets into the wood implants. The other properties of heat-treated wood, such as bioactivity, good handling properties, and sufficient biomechanical properties, might be additional favorable factors for the application of wood as a natural composite material for bone and cartilage repair. At the interface of the surfaces of wood and living bone, bonding occurred. The Chemical Interface Model for bonding bone to wood consists of the reactive ions, such as hydroxyl groups --OH, and covalent bonding as well as hydrogen bonding, which originate from both wood and bone. The bone tissue trauma, with its reactive Ca(2+) and PO(4) (3-) ions, proteins, and collagen, available for interaction at ionic and nanolevel, are associated with the complicated chemistry in the cellular response of the early bone healing process. It was concluded that heat-treated wood acted like a porous biomaterial scaffold, allowing ongrowth and ingrowth of bone and cartilage differentiation on its surface, and demonstrating osteoconductive contact, bonding at the interface.
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Affiliation(s)
- Allan J Aho
- Department of Prosthetic Dentistry and Biomaterials Science, University of Turku, Turku, Finland.
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192
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Abstract
Bone grafting procedures are undergoing a major shift from autologous and allogeneic bone grafts to synthetic bone graft substitutes. Bioactive glasses are a group of synthetic silica-based bioactive materials with bone bonding properties first discovered by Larry Hench. They have several unique properties compared with other synthetic bioresorbable bioactive ceramics, such as calcium phosphates, hydroxyapatite (HA) and tricalcium phosphate (TCP). Bioactive glasses have different rates of bioactivity and resorption rates depending on their chemical compositions. The critical feature for the rate of bioactivity is a SiO2 content < 60% in weight. In vivo, the material is highly osteoconductive and it seems to promote the growth of new bone on its surface. In a recent study, the activity of the material was found even to overshadow the effect of BMP-2 gene therapy. In vivo, there is a dynamic balance between intramedullary bone formation and bioactive glass resorption. Recent studies of molecular biology have shown that bioactive glass induces a high local turnover of bone formation and resorption. Many osteoporotic fracture patients are candidates for concurrent treatment with bisphosphonates and bioceramic bone graft substitutes. Since osteopromotive silica-based bioactive glasses induce accelerated local bone turnover, adjunct antiresorptive agents may affect the process. However, a recent study showed that an adjunct antiresorptive therapy (zoledronic acid) is even beneficial for bone incorporation of bioactive glass. Based on these observations, bioactive glasses are a promising group of unique biomaterials to act as bone graft substitutes.
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Affiliation(s)
- V V Välimäki
- Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology University of Turku, Turku, Finland
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193
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Deville S, Saiz E, Tomsia AP. Freeze casting of hydroxyapatite scaffolds for bone tissue engineering. Biomaterials 2006; 27:5480-9. [PMID: 16857254 DOI: 10.1016/j.biomaterials.2006.06.028] [Citation(s) in RCA: 327] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Accepted: 06/29/2006] [Indexed: 12/01/2022]
Abstract
Although extensive efforts have been put into the development of porous scaffolds for bone regeneration, with encouraging results, all porous materials have a common limitation: the inherent lack of strength associated with porosity. Hence, the development of porous hydroxyapatite scaffolds has been hindered to non-load bearing applications. We report here how freeze casting can be applied to synthesize porous scaffolds exhibiting unusually high compressive strength, e.g. up to 145 MPa for 47% porosity and 65 MPa for 56% porosity. The materials are characterized by well-defined pore connectivity along with directional and completely open porosity. Various parameters affecting the porosity and compressive strength have been investigated, including initial slurry concentration, freezing rate, and sintering conditions. The implications and potential application as bone substitute are discussed. These results might open the way for hydroxyapatite-based materials designed for load-bearing applications. The biological response of these materials is yet to be tested.
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Affiliation(s)
- Sylvain Deville
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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194
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von Doernberg MC, von Rechenberg B, Bohner M, Grünenfelder S, van Lenthe GH, Müller R, Gasser B, Mathys R, Baroud G, Auer J. In vivo behavior of calcium phosphate scaffolds with four different pore sizes. Biomaterials 2006; 27:5186-98. [PMID: 16790273 DOI: 10.1016/j.biomaterials.2006.05.051] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Accepted: 05/18/2006] [Indexed: 10/24/2022]
Abstract
The goal of the present study was to assess the effect of macropore size on the in vivo behavior of ceramic scaffolds. For that purpose, beta-tricalcium phosphate (beta-TCP) cylinders with four different macropore sizes (150, 260, 510, and 1220 microm) were implanted into drill hole defects in cancellous bone of sheep and their resorption behavior was followed for 6, 12 and 24 weeks. The scaffolds were evaluated for biocompatibility, and new bone formation was observed macroscopically, histologically and histomorphometrically. Histomorphometrical measurements were performed for the whole defect area and for the area subdivided into three concentric rings (outer, medial, and inner ring). All implants were tolerated very well as evidenced by the low amount of inflammatory cells and the absence of macroscopic signs of inflammation. Resorption proceeded fast since less than 5% ceramic remained at 24-week implantation. Hardly any effect of macropore size was observed on the in vivo response. Samples with an intermediate macropore size (510 microm) were resorbed significantly faster than samples with smaller macropore sizes (150 and 260 microm). However, this fast resorption was associated with a lower bone content and a higher soft tissue content. At 12 and 24 weeks, the latter differences had disappeared. Bone was more abundant in the outer ring than in the rest of the blocks at 6 weeks, and in the outer and medial ring compared to the inner ring at 12 weeks.
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Affiliation(s)
- Marie-Cécile von Doernberg
- Musculoskeletal Research Unit (MSRU), Equine Hospital, University of Zurich, Winterthurerstrasse 260, CH 8057 Zurich, Switzerland
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195
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Otsuki B, Takemoto M, Fujibayashi S, Neo M, Kokubo T, Nakamura T. Pore throat size and connectivity determine bone and tissue ingrowth into porous implants: three-dimensional micro-CT based structural analyses of porous bioactive titanium implants. Biomaterials 2006; 27:5892-900. [PMID: 16945409 DOI: 10.1016/j.biomaterials.2006.08.013] [Citation(s) in RCA: 252] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2006] [Accepted: 08/07/2006] [Indexed: 11/23/2022]
Abstract
A porous structure comprises pores and pore throats with a complex three-dimensional (3D) network structure, and many investigators have described the relationship between average pore size and the amount of bone ingrowth. However, the influence of network structure or pore throats for tissue ingrowth has rarely been discussed. Four types of bioactive porous titanium implants with different pore sizes and porosities (6mm in diameter and 15 mm long) were analyzed using specific algorithms for 3D analysis of interconnectivity based on a micro focus X-ray computed tomography system. In vivo histomorphometric analysis was performed using the very same implants implanted into the femoral condyles of male rabbits for 6 and 12 weeks. This matching study revealed that more poorly differentiated pores tended to have narrow pore throats, especially in their shorter routes to the outside. In addition, for assessment of the entire implant, we proposed new two indices that represent the degree of bone and tissue ingrowth into an implant by considering the effect of narrow pore throats. Data obtained suggest that this sort of novel analysis is useful for evaluating bone and tissue ingrowth into porous biomaterials.
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Affiliation(s)
- Bungo Otsuki
- Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Shogoin, Kyoto 606-8507, Japan.
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196
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Link DP, van den Dolder J, Jurgens WJFM, Wolke JGC, Jansen JA. Mechanical evaluation of implanted calcium phosphate cement incorporated with PLGA microparticles. Biomaterials 2006; 27:4941-7. [PMID: 16759694 DOI: 10.1016/j.biomaterials.2006.05.022] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Accepted: 05/14/2006] [Indexed: 10/24/2022]
Abstract
In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorporated with 20wt% poly (dl-lactic-co-glycolic acid) (PLGA) microparticles were investigated in a rat cranial defect. After 2, 4 and 8 weeks of implantation, implants were evaluated mechanically (push-out test) and morphologically (Scanning Electron Microscopy (SEM) and histology). The results of the push-out test showed that after 2 weeks the shear strength of the implants was 0.44+/-0.44MPa (average+/-sd), which increased to 1.34+/-1.05MPa at 4 weeks and finally resulted in 2.60+/-2.78MPa at 8 weeks. SEM examination showed a fracture plane at the bone-cement interface at 2 weeks, while the 4- and 8-week specimens created a fracture plane into the CaP/PLGA composites, indicating an increased strength of the bone-cement interface. Histological evaluation revealed that the two weeks implantation period resulted in minimal bone ingrowth, while at 4 weeks of implantation the peripheral PLGA microparticles were degraded and replaced by deposition of newly formed bone. Finally, after 8 weeks of implantation the degradation of the PLGA microparticles was almost completed, which was observed by the bone ingrowth throughout the CaP/PLGA composites. On basis of our results, we conclude that the shear strength of the bone-cement interface increased over time due to bone ingrowth into the CaP/PLGA composites. Although the bone-cement contact could be optimized with an injectable CaP cement to enhance bone ingrowth, still the mechanical properties of the composites after 8 weeks of implantation are insufficient for load-bearing purposes.
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Affiliation(s)
- Dennis P Link
- Radboud University Nijmegen Medical Centre, Department of Periodontology & Biomaterials, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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197
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Abstract
Generally, characterizations of pore structures of porous biomaterials are mainly based on 2-dimensional (2-D) analysis using cross sectional micrographs. However, interconnectivity of each pore may be more important factor, when tissue ingrowth into deeper pores is considered. In this paper, using micro-CT imaging with 3-D image processing software, analyses of porous material based on 3-demensional (3-D) geometrical considerations were successfully performed. Plasmasprayed porous titanium implant (PT) and four types of sintered porous titanium implants (ST50- 200, ST50-500, ST70-200, and ST70-500) that possess different porosities (50% and 70%) and pore sizes (200-500+m and 500-1500+m) were analyzed in this study. A micro focus X-ray computed
tomography system was employed to acquire microstructural information from the porous implants. Using 3-D image processing software, we performed three types of 3-D analysis including detection of the dead space (% dead pore), analysis of interconnectivity by blocking the narrow pore throat with caliber less than 52 +m (% pore with narrow throat) and analysis of material construct by
contracting thin strut with thickness less than 52 +m (% construct with thin strut). ST50S and ST50L possessed interconnected porous structure with thicker strut; however, pore throat was considered to be relatively narrow. On the other hand, PT implant possesses favorable interconnectivity despite its’ low porosity; however, relatively thin strut indicate the structural disadvantage for mechanical property. These results suggest that the 3-D analysis of pore and strut structure using micro focus X-ray computed tomography and 3-D image processing software will
provide effective information to develop porous implant.
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198
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St-Pierre JP, Gauthier M, Lefebvre LP, Tabrizian M. Three-dimensional growth of differentiating MC3T3-E1 pre-osteoblasts on porous titanium scaffolds. Biomaterials 2005; 26:7319-28. [PMID: 16000220 DOI: 10.1016/j.biomaterials.2005.05.046] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present work assesses the potential of three-dimensional porous titanium scaffolds produced by a novel powder metallurgy process for applications in bone engineering through in vitro experimentation. Mouse MC3T3-E1 pre-osteoblasts were used to investigate the proliferation (DNA content), differentiation (alkaline phosphatase activity and osteocalcin release) and mineralisation (calcium content) processes of cells on titanium scaffolds with average pore sizes ranging from 336 to 557 microm, using mirror-polished titanium as reference material. Scanning electron microscopy was employed to qualitatively corroborate the results. Cells proliferate on all materials before reaching a plateau at day 9, with proliferation rates being significantly higher on foams (ranging from 123 to 163 percent per day) than on the reference material (80% per day). Alkaline phosphatase activity is also significantly elevated on porous scaffolds following the proliferation stage. However, cells on polished titanium exhibit greater osteocalcin release toward the end of the differentiation process, resulting in earlier mineralisation of the extracellular matrix. Nevertheless, the calcium content is similar on all materials at the end of the experimental period. Average pore size of the porous structures does not have a major effect on cells as determined by the various analyses, affecting only the proliferation stage. Thus, the microstructured titanium scaffolds direct the behaviour of pre-osteoblasts toward a mature state capable of mineralising the extracellular matrix.
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Affiliation(s)
- Jean-Philippe St-Pierre
- Department of Biomedical Engineering and Faculty of Dentistry, McGill University, Montreal, Que., Canada H3A 2B4
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199
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Abstract
STUDY DESIGN Explant analysis for bone ingrowth of retrieved cervical disc prosthesis in chimpanzees and humans. OBJECTIVES To assess the bone ingrowth into retrieved Bryan Cervical Discs. SUMMARY OF BACKGROUND DATA Bone ingrowth in cervical disc prosthesis has not been documented in the literature. METHODS Chimpanzee: Two chimpanzees underwent placement of the Bryan disc at C3-C4 and 3 months later had explantation and interbody fusion. Human: Two patients had removal of their Bryan disc and interbody fusion for failure to resolve symptoms at 8 and 10 months. The explants were analyzed for bone ingrowth. RESULTS Chimpanzee: Histologic analysis showed bony ingrowth through the interstices of the porous coating and apposition ranging from 10% to 50% of toluidine blue-stained sections. New ingrowth, rather than bony impaction, was confirmed with fluorochrome-labeled sections Human: Bone ingrowth was a mean of 30.1% (12% SD). No difference was observed between peripheral, intermediate, or central locations. CONCLUSIONS Adequate bony apposition was found in all primate device-to-vertebral body interfaces. Human retrievals also demonstrated significant ingrowth in all four surfaces. This compares with hip and knee arthroplasty percent ingrowth rates of 10% to 30%. All implants had stable fixation judged by radiographs and at the time of implant removal.
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Affiliation(s)
- Wade K Jensen
- Department of Orthopedic Surgery and Rehabilitation, University of Wisconsin, Madison, WI 53792, USA
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200
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Karande TS, Ong JL, Agrawal CM. Diffusion in musculoskeletal tissue engineering scaffolds: design issues related to porosity, permeability, architecture, and nutrient mixing. Ann Biomed Eng 2005; 32:1728-43. [PMID: 15675684 DOI: 10.1007/s10439-004-7825-2] [Citation(s) in RCA: 281] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The field of tissue engineering continues to advance with the discovery of new biomaterials, growth factors and scaffold fabrication techniques. However, for the ultimate success of a tissue engineered construct the issue of nutrient transport to the scaffold interior needs to be addressed. Often, the requirements for adequate nutrient supply are at odds with other scaffold design parameters such as mechanical properties as well as scaffold fabrication techniques, leading to incongruities in finding optimal solutions. The goal of this review article is to provide an overview of the various engineering design factors that promote movement of nutrients, waste and other biomolecules in scaffolds for musculoskeletal tissue engineering applications. The importance of diffusion in scaffolds and how it is influenced by porosity, permeability, architecture, and nutrient mixing has been emphasized. Methods for measuring porosity and permeability have also been outlined. The different types of biomaterials used, scaffold fabrication techniques implemented and the pore sizes/porosities obtained over the past 5 years have also been addressed.
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Affiliation(s)
- Tejas S Karande
- Center for Clinical Bioengineering, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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