| 1. |
- Carville, N. Craig, et al.
(author)
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Biocompatibility of ferroelectric lithium niobate and the influence of polarization charge on osteoblast proliferation and function
- 2015
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In: Journal of Biomedical Materials Research. Part A. - : John Wiley and Sons. - 1549-3296 .- 1552-4965. ; 103:8, s. 2540-2548
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Journal article (peer-reviewed)abstract
- In this work, the influence of substrate surface charge on in vitro osteoblast cell proliferation on ferroelectric lithium niobate (LN) crystal surfaces is investigated. LN has a spontaneous polarization along the z-axis and is thus characterized by positive and negative bound polarization charge at the +z and -z surfaces. Biocompatibility of LN was demonstrated via culturing and fluorescence imaging of MC3T3 osteoblast cells for up to 11 days. The cells showed enhanced proliferation rates and improved osteoblast function through mineral formation on the positively and negatively charged LN surfaces compared to electrostatically neutral x-cut LN and a glass cover slip control. These results highlight the potential of LN as a template for investigating the role of charge on cellular processes.
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| 2. |
- Idris, Shaza Bushra, et al.
(author)
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Polyester copolymer scaffolds enhance expression of bone markers in osteoblast-like cells
- 2010
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In: J BIOMED MATER RES PART A. - : Wiley. - 1549-3296. ; 94A:2, s. 631-639
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Journal article (peer-reviewed)abstract
- In tissue engineering, the resorbable aliphatic polyester poly(L-lactide) (PLLA) is used as scaffolds in bone regeneration. Copolymers of poly(L-lactide)-co-(epsilon-caprolactone) [poly(LLA-co-CL)] and poly(L-lactide)-co-(1,5-dioxepan-2-one) [poly(LLA-co-DXO)], with superior mechanical properties to PLLA, have been developed to be used as scaffolds, but the influence on the osteogenic potential is unclear. This in vitro study of test scaffolds of poly(LLA-co-CL) and poly(LLA-co-DXO) using PLLA scaffolds as a control demonstrates the attachment and proliferation of human osteoblast-like cells (HOB) as measured by SEM and a methylthiazol tetrazolium (MTT) colorimetric assay, and the progression of HOB osteogenesis for up to 3 weeks; expressed as synthesis of the osteoblast differentiation markers: collagen type 1 (Col 1), alkaline phosphatase, bone sialoprotein, osteocalcin (OC), osteopontin and runt related gene 2 (Runx2). Surface analysis disclosed excellent surface attachment, spread and penetration of the cells into the pores of the test scaffolds compared to the PLLA. MTT results indicated that test scaffolds enhanced the proliferation of HOBs. Cells grown on the test scaffolds demonstrated higher synthesis of Col 1 and OC and also increased bone markers mRNA expression. Compared to scaffolds of PLLA, the poly(LLA-co-CL) and poly(LLA-co-DXO) scaffolds enhanced attachment, proliferation, and expression of osteogenic markers by HOBs in vitro. Therefore, these scaffolds might be appropriate carriers for bone engineering. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 94A: 631-639, 2010
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| 3. |
- Jedenmalm, Anneli, et al.
(author)
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Effect of head surface roughness and sterilization on wear of UHMWPE acetabular cups
- 2009
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In: Journal of Biomedical Materials Research. - : Wiley. - 0021-9304 .- 1097-4636 .- 1549-3296 .- 1552-4965. ; 90:4, s. 1032-1042
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Journal article (peer-reviewed)abstract
- The impact of femoral head surface roughness on wear of gamma-irradiation sterilized (3 MRad in nitrogen, crosslinked) and nonsterilized (not crosshnked) UHMWPE acetabular cups has been evaluated. Gravimetric wear testing was performed in a hip joint simulator for 2 x 10(6) cycles. CoCrMo heads were used with different surface roughness (R-a = 15 nm and R-a = 400 rim). The surface roughness after wear test was unchanged for the roughened heads, whereas the initially smooth heads showed a few scratches. The roughened heads increased the wear of the acetabular cups 2-fold. The gamma-irradiated cups tested against rough heads underwent the highest wear. The absorption of water was highest for the gamma-irradiated cups (0.0204% compared to 0.0031% after 85 days). Raman spectroscopy showed small but significant crystallinity changes in the wear zone, where the gamma-irradiated cups with the most extensive abrasion increased in crystallinity, whereas the nonsterilized cups underwent a crystallinity decrease.
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| 4. |
- Karlsson, Johan, 1984, et al.
(author)
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Stem cell homing using local delivery of plerixafor and stromal derived growth factor-1alpha for improved bone regeneration around Ti-implants
- 2016
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In: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 104:10, s. 2466-2475
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Journal article (peer-reviewed)abstract
- Triggering of the early healing events, including the recruitment of progenitor cells, has been suggested to promote bone regeneration. In implantology, local drug release technologies could provide an attractive approach to promote tissue regeneration. In this study, we targeted the chemotactic SDF-1a/CXCR4 axis that is responsible e.g. for the homing of stem cells to trauma sites. This was achieved by local delivery of plerixafor, an antagonist to CXCR4, and/or SDF-1a from titanium implants coated with mesoporous titania thin films with a pore size of 7.5 nm. In vitro drug delivery experiments demonstrated that the mesoporous coating provided a high drug loading capacity and controlled release. The subsequent in vivo study in rat tibia showed beneficial effects with respect to bone-implant anchorage and bone-formation along the surface of the implants when plerixafor and SDF-1a were delivered locally. The effect was most prominent by the finding that the combination of the drugs significantly improved the mechanical bone anchorage. These observations suggest that titanium implants with local delivery of drugs for enhanced local recruitment of progenitor cells have the ability to promote osseointegration. This approach may provide a potential strategy for the development of novel implant treatments.
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| 5. |
- Skodje, A., et al.
(author)
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Biodegradable polymer scaffolds loaded with low-dose BMP-2 stimulate periodontal ligament cell differentiation
- 2015
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In: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 103:6, s. 1991-1998
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Journal article (peer-reviewed)abstract
- Poly(l-lactide)-co-(epsilon-caprolactone) [poly(LLA-co-CL)] and poly(l-lactide)-co-(1,5-dioxepan-2-one) [poly(LLA-co-DXO)] are being considered candidate scaffolds for bone tissue engineering. We evaluated the bioactive potential of poly(LLA-co-CL) and poly(LLA-co-DXO) scaffolds loaded with low-dose bone morphogenetic protein-2 (BMP-2). Periodontal ligament (PDL) cells were cultured onto the various scaffolds loaded with 1 μg BMP-2 or without BMP-2 (control). Cell viability, attachment, and proliferation were determined using a methylthiazol tetrazolium (MTT) colorimetric assay at day 1, 3, and 7. Scanning electron microscopy was used to analyze cell morphology at day 7. Cell differentiation was evaluated assaying alkaline phosphatase (ALP) activity at day 7, 14, and 21. Real-time PCR was used to evaluate the mRNA expression of periostin, ALP, type I collagen, bone sialoprotein and BMP-2. A commercially available enzyme-linked immunosorbent assay was used to assess BMP-2 production. Surface analysis disclosed excellent cell attachment, spread, and penetration into the porous scaffolds. The MTT assay indicated that scaffolds loaded with low concentration of BMP-2 did not influence the viability of cells. Cells grown on the modified scaffolds expressed higher levels of osteogenic markers than the nonmodified scaffolds (p<0.05). Poly(LLA-co-CL) and poly(LLA-co-DXO) scaffolds loaded with low-dose BMP-2 exhibited a significant effect stimulating PDL differentiation suggesting a continued evaluation in relevant in vivo models.
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| 6. |
- Stjerndahl, Anna, et al.
(author)
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Minimization of residual tin in the controlled Sn(II)octoate-catalyzed polymerization of ε-caprolactone
- 2008
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In: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87A:4, s. 1086-1091
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Journal article (peer-reviewed)abstract
- By using less catalyst in the ring-opening polymerization of epsilon-caprolactone, a residual tin content of 5 ppm was reached without the need for additional purification. The initial amount of tin (II) 2-ethylhexanoate [Sn(Oct)(2)] was varied using catalyst:monomer ratios of 1:1000, 1:10,000, and 1:20,000. The impact on the final conversion, reaction control, average molecular weight, and polydispersity was studied. The amount of Sn(Oct)(2) could be significantly, reduced without influencing the reaction results. The residual amount of tin was reduced from 176 ppm with a catalyst:monomer ratio of 1:1000 in the polymer, to 5 ppm with the ratio 1:10,000. It was thus concluded that a catalyst:monomer ratio of 1:10,000 or lower is required to achieve a polymer with tin content Suitable for biomedical applications. The materials were also tested in a proliferation study with mesenchymal stem cells from mouse. Porous scaffolds were fabricated from the polymers, using a salt leaching technique, and the cell growth on the porous scaffolds as well as on homogeneous films was determined by light absorbance measurements. In this study, the cell proliferation results showed that cells could grow on all polymers with ail efficiency equal to or better than that on normal tissue Culture plastic.
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| 7. |
- Sun, Yang, 1983-, et al.
(author)
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Degradable amorphous scaffolds with enhanced mechanical properties and homogeneous cell distribution produced by a three-dimensional fiber deposition method
- 2012
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In: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 100A:10, s. 2739-2749
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Journal article (peer-reviewed)abstract
- The mechanical properties of amorphous, degradable, and highly porous poly(lactide-co-caprolactone) structures have been improved by using a 3D fiber deposition (3DF) method. Two designs of 3DF scaffolds, with 45 degrees and 90 degrees layer rotation, were printed and compared with scaffolds produced by a salt-leaching method. The scaffolds had a porosity range from 64% to 82% and a high interconnectivity, measured by micro-computer tomography. The 3DF scaffolds had 89 times higher compressive stiffness and 35 times higher tensile stiffness than the salt-leached scaffolds. There was a distinct decrease in the molecular weight during printing as a consequence of the high temperature. The chain microstructure was, however, not affected; the glass transition temperature and the decomposition temperature were constant. Human OsteoBlast-like cells were cultured in vitro and the cell morphology and distribution were observed by scanning electron microscopy and fluorescence microscopy. The cell distribution on the 3DF scaffolds was more homogeneous than the salt-leached scaffolds, suggesting that 3DF scaffolds are more suitable as porous biomaterials for tissue engineering. These results show that it is possible to design and optimize the properties of amorphous polymer scaffolds. The 3DF method produce amorphous degradable poly(lactide-co-caprolactone) that are strong and particularly suitable for cell proliferation.
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| 8. |
- Xing, Zhe, et al.
(author)
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Copolymer cell/scaffold constructs for bone tissue engineering : Co-culture of low ratios of human endothelial and osteoblast-like cells in a dynamic culture system
- 2013
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In: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 101A:4, s. 1113-1120
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Journal article (peer-reviewed)abstract
- The aim of this study was to compare the effect of different ratios of human umbilical vein endothelial cells (HUVECs) on osteogenic activity of human osteoblast-like cells (HOB) and capillary-like structure (CLS), seeded into copolymer scaffolds in a dynamic culture system. HOB and HUVEC were co-cultured into poly(L-lactide)-co-(1,5-dioxepan-2-one) [poly(LLA-co-DXO)] scaffolds at ratios of 5:1 (5:1 group) and 2:1 (2:1 group). Samples were collected after 5, 15, and 25 days. Cross-sections were processed and the CLS from HUVEC was disclosed in both groups. Cell viability was determined by dsDNA assay. Cells seeded at the ratio of 5:1 had good viability. Total RNA was isolated and the reverse transcription reaction was performed. The influences on the expression of several osteogenic genes were various with regarding to different ratios of HUVEC demonstrated by the PCR array. The RT-PCR results was in consistent with the PCR array results that several osteogenesis related genes had higher expression in the 5:1 group than in the 2:1 group, especially at day 25, such as alkaline phosphatase, insulin-like growth factor 1 (IGF1), and so forth. ELISA showed that the production of IGF1 after 25 days of incubation were higher in cells co-cultured at the 5:1 ratio than at the 2:1 ratio. The results show that under dynamic culture conditions, co-culture of HOB with a low ratio of HUVEC in copolymer scaffolds results in CLS formation and significantly influenced the expression of osteogenic markers.
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| 9. |
- Xing, Zhe, et al.
(author)
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Effect of endothelial cells on bone regeneration using poly(L-lactide-co-1,5-dioxepan-2-one) scaffolds
- 2011
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In: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 96A:2, s. 349-357
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Journal article (peer-reviewed)abstract
- Our recent in vitro study demonstrated that endothelial cells (ECs) might influence the differentiation of bone marrow stromal cells (BMSCs). Therefore, the aim of this study was to describe this effect in vivo, using a rat calvarial bone defect model. BMSCs were isolated from femurs of two-donor Lewis rats and expanded in alpha-minimum essential medium containing 10% fetal bovine serum. One fifth of BMSCs were induced and differentiated into ECs in an Endothelial Cell Growth Medium-2 and then characterized by a flow cytometry. The remaining BMSCs were cultured in freshly prepared osteogenic stimulatory medium, containing dexamethasone, ascorbic acid and beta-glycerophosphate. Either BMSCs alone (BMSC-group) or co-cultured ECs/BMSCs (CO-group) were seeded into poly(L-lactide-co-1,5-dioxepan-2-one) [poly(LLA-co-DXO)] scaffolds, cultured in spinner flasks, and then implanted into symmetrical calvarial defects prepared in recipient rats. The animals were sacrificed after 2 months. The formation of new bone was evaluated by radiography and histology and by the expression of osteogenic markers using reverse transcriptase-polymerized chain reaction (RT-PCR). To investigate vessel formation, histological staining was performed with EC's markers. The radiographical and histological results showed more rapid bone formation in the CO-than in the BMSC-group. However, the expression of EC's marker was similar on both groups by histological analysis after 2 months postoperatively. Furthermore, the CO-group exhibited greater expression of osteogenic markers as demonstrated by RT-PCR. The results are consistent with the previous in vitro findings that poly(LLA-co-DXO) scaffold might be suitable candidate for bone tissue engineering. In vivo, bone regeneration was enhanced by a construct of the polymer scaffold loaded with co-cultured cells.
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| 10. |
- Yassin, Mohammed A., et al.
(author)
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Cell seeding density is a critical determinant for copolymer scaffolds-induced bone regeneration
- 2015
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In: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 103:11, s. 3649-3658
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Journal article (peer-reviewed)abstract
- Constructs intended for bone tissue engineering (TE) are influenced by the initial cell seeding density. Therefore, the objective of this study was to determine the effect of bone marrow stromal stem cells (BMSCs) density loaded onto copolymer scaffolds on bone regeneration. BMSCs were harvested from rat's bone marrow and cultured in media with or without osteogenic supplements. Cells were seeded onto poly(l-lactide-co-epsilon-caprolactone) [poly(LLA-co-CL)] scaffolds at two different densities: low density (1 x 10(6) cells/scaffold) or high density (2 x 10(6) cells/scaffold) using spinner modified flasks and examined after 1 and 3 weeks. Initial attachment and spread of BMSC onto the scaffolds was recorded by scanning electron microscopy. Cell proliferation was assessed by DNA quantification and cell differentiation by quantitative real-time reverse transcriptase-polymerized chain reaction analysis (qRT-PCR). Five-millimeter rat calvarial defects (24 defects in 12 rats) were implanted with scaffolds seeded with either low or high density expanded with or without osteogenic supplements. Osteogenic supplements significantly increased cell proliferation (p < 0.001). Scaffolds seeded at high cell density exhibited higher mRNA expressions of Runx2 p=0.001, Col1 p=0.001, BMP2 p<0.001, BSP p<0.001, and OC p=0.013. More bone was formed in response to high cell seeding density (p=0.023) and high seeding density with osteogenic medium (p=0.038). Poly (LLA-co-CL) scaffolds could be appropriate candidates for bone TE. The optimal number of cells to be loaded onto scaffolds is critical for promoting Extracellular matrix synthesis and bone formation. Cell seeding density and osteogenic supplements may have a synergistic effect on the induction of new bone.
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