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  • 1. Carville, N. Craig
    et al.
    Collins, Liam
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Lukasz, Bart I.
    McKayed, Katey K.
    Simpson, Jeremy C.
    Rodriguez, Brian J.
    Biocompatibility of ferroelectric lithium niobate and the influence of polarization charge on osteoblast proliferation and function2015In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 103, no 8, 2540-2548 p.Article in journal (Refereed)
    Abstract [en]

    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.

  • 2. Karlsson, Johan
    et al.
    Harmankaya, Necati
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Palmquist, Anders
    Atefyekta, Saba
    Omar, Omar
    Tengvall, Pentti
    Andersson, Martin
    Stem cell homing using local delivery of plerixafor and stromal derived growth factor-1alpha for improved bone regeneration around Ti-implants2016In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 104, no 10, 2466-2475 p.Article in journal (Refereed)
    Abstract [en]

    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-1/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-1, 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-1 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.

  • 3. Skodje, A.
    et al.
    Idris, S. B. M.
    Sun, Yang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Bartaula, S.
    Mustafa, K.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wikesjö, U. M. E.
    Leknes, K. N.
    Biodegradable polymer scaffolds loaded with low-dose BMP-2 stimulate periodontal ligament cell differentiation2015In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 103, no 6, 1991-1998 p.Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Sun, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Xing, Zhe
    Dept. of Clinical Dentistry-Center for Clinical Dental Research, Faculty of Medicine and Dentistry, University of Bergen, Norway.
    Mustafa, Kamal
    Dept. of Clinical Dentistry-Center for Clinical Dental Research, Faculty of Medicine and Dentistry, University of Bergen, Norway.
    Hendrikson, Wim J.
    Department of Tissue Regeneration, University of Twente, The Netherlands.
    Grijpma, Dirk W.
    Dept. of Biomaterials Science and Technology, MIRA Institute for Biomedical Technology and Technical Medicine, Enschede, The Netherlands.
    Moroni, Lorenzo
    Department of Tissue Regeneration, University of Twente, The Netherlands.
    Degradable amorphous scaffolds with enhanced mechanical properties and homogeneous cell distribution produced by a three-dimensional fiber deposition method2012In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 100A, no 10, 2739-2749 p.Article in journal (Refereed)
    Abstract [en]

    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.

  • 5. Xing, Zhe
    et al.
    Xue, Ying
    Dånmark, Staffan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Schander, Kerstin
    Ostvold, Siren
    Arvidson, Kristina
    Hellem, Solve
    Finne Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mustafa, Kamal
    Effect of endothelial cells on bone regeneration using poly(L-lactide-co-1,5-dioxepan-2-one) scaffolds2011In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 96A, no 2, 349-357 p.Article in journal (Refereed)
    Abstract [en]

    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.

  • 6. Xing, Zhe
    et al.
    Xue, Ying
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Yang, Zhuang-Qun
    Mustafa, Kamal
    Copolymer cell/scaffold constructs for bone tissue engineering: Co-culture of low ratios of human endothelial and osteoblast-like cells in a dynamic culture system2013In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 101A, no 4, 1113-1120 p.Article in journal (Refereed)
    Abstract [en]

    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.

  • 7. Yassin, M. A.
    et al.
    Leknes, K. N.
    Sun, Yang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lie, S. A.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mustafa, K.
    Surfactant tuning of hydrophilicity of porous degradable copolymer scaffolds promotes cellular proliferation and enhances bone formation2016In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965Article in journal (Refereed)
    Abstract [en]

    Poly(l-lactide-co-e(open)-caprolactone) (poly(LLA-co-CL)) has been blended with Tween 80 to tune the material properties and optimize cell-material interactions. Accordingly, the aims of this study were fourfold: to evaluate the effect of low concentrations of Tween 80 on the surface microstructure of 3D poly(LLA-co-CL) porous scaffolds: to determine the effect of different concentrations of Tween 80 on proliferation of bone marrow stromal cells (BMSCs) in vitro under dynamic cell culture at 7 and 21 days; to assess the influence of Tween 80 on the degradation rate of poly(LLA-co-CL) at 7 and 21 days; and in a subcutaneous rat model, to evaluate the effect on bone formation of porous scaffolds modified with 3% Tween 80 at 2 and 8 weeks. Blending 3% (w/w) Tween 80 with poly(LLA-co-CL) improves the surface wettability (p<0.001). Poly(LLA-co-CL)/3% Tween 80 shows significantly increased cellular proliferation at days 7 and 21 (p<0.001). Moreover, the presence of Tween 80 facilitates the degradation of poly(LLA-co-CL). Two weeks post-implantation, the poly(LLA-co-CL)/3% Tween 80 scaffolds exhibit significant mRNA expression of Runx2 (p=0.004). After 8 weeks, poly(LLA-co-CL)/3% Tween 80 scaffolds show significantly increased de novo bone formation, demonstrated by μ-CT (p=0.0133) and confirmed histologically. It can be concluded that blending 3% (w/w) Tween 80 with poly (LLA-co-CL) improves the hydrophilicity and osteogenic potential of the scaffolds.

  • 8. Yassin, Mohammed A.
    et al.
    Leknes, Knut N.
    Pedersen, Torbjorn O.
    Xing, Zhe
    Sun, Yang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lie, Stein A.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mustafa, Kamal
    Cell seeding density is a critical determinant for copolymer scaffolds-induced bone regeneration2015In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 103, no 11, 3649-3658 p.Article in journal (Refereed)
    Abstract [en]

    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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