Evžen Amler

Czech Technical University in Prague, Praha, Praha, Czech Republic

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Publications (10)27.22 Total impact

  • Evžen Amler, Andrea Mickova, Matej Buzgo
    Nanomedicine 04/2013; 8(4):509-12. · 5.26 Impact Factor
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    ABSTRACT: The aim of the study was to evaluate the effect of a cell-free hyaluronate/type I collagen/fibrin composite scaffold containing polyvinyl alcohol (PVA) nanofibers enriched with liposomes, basic fibroblast growth factor (bFGF) and insulin on the regeneration of osteochondral defects. A novel drug delivery system was developed on the basis of the intake effect of liposomes encapsulated in PVA nanofibers. Time-controlled release of insulin and bFGF improved MSC viability in vitro. Nanofibers functionalized with liposomes also improved the mechanical characteristics of the composite gel scaffold. In addition, time-controlled release of insulin and bFGF stimulated MSC recruitment from bone marrow in vivo. Cell-free composite scaffolds containing PVA nanofibers enriched with liposomes, bFGF, and insulin were implanted into seven osteochondral defects of miniature pigs. Control defects were left untreated. After 12 weeks, the composite scaffold had enhanced osteochondral regeneration towards hyaline cartilage and/or fibrocartilage compared with untreated defects that were filled predominantly with fibrous tissue. The cell-free composite scaffold containing PVA nanofibers, liposomes and growth factors enhanced migration of the cells into the defect, and their differentiation into chondrocytes; the scaffold was able to enhance the regeneration of osteochondral defects in minipigs.
    International journal of pharmaceutics 03/2013; · 2.96 Impact Factor
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    ABSTRACT: Cell infiltration is a critical parameter for the successful development of 3D matrices for tissue engineering. Application of electrospun nanofibers in tissue engineering has recently attracted much attention. Notwithstanding several of their advantages, small pore size and small thickness of the electrospun layer limit their application for development of 3D scaffolds. Several methods for the pore size and/or electrospun layer thickness increase have been recently developed. Nevertheless, tissue engineering still needs emerging of either novel nanofiber-enriched composites or new techniques for 3D nanofiber fabrication. Forcespinning® seems to be a promising alternative. The potential of the Forcespinning® method is illustrated in preliminary experiment with mesenchymal stem cells.
    Cell adhesion & migration 01/2013; 8(1). · 2.34 Impact Factor
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    ABSTRACT: Aim: Platelet derivatives serve as an efficient source of natural growth factors. In the current study, α-granules were incorporated into coaxial nanofibers. Materials & methods: A nanofiber scaffold containing α-granules was prepared by coaxial electrospinning. The biological potential of the nanofiber scaffold was evaluated in chondrocyte and mesenchymal stem cell cultivation studies. Additionally, the concentration of TGF-β1 was determined. Results: Microscopy studies showed that intact α-granules were incorporated into the coaxial nanofibers. The cultivation tests showed that the novel scaffold stimulated viability and extracellular matrix production of chondrocytes and mesenchymal stem cells. In addition, the concentration of growth factors necessary for the induction of cell proliferation significantly decreased. Conclusion: The system preserved α-granule bioactivity and stimulated cell viability and chondrogenic differentiation of mesenchymal stem cells. Core/shell nanofibers incorporating α-granules are a promising system for tissue engineering, particularly cartilage engineering. Original submitted 21 March 2012; Revised submitted 8 August 2012.
    Nanomedicine 12/2012; · 5.26 Impact Factor
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    ABSTRACT: The structural properties of microfiber meshes made from poly(2-hydroxyethyl methacrylate) (PHEMA) were found to significantly depend on the chemical composition and subsequent cross-linking and nebulization processes. PHEMA microfibres showed promise as scaffolds for chondrocyte seeding and proliferation. Moreover, the peak liposome adhesion to PHEMA microfiber scaffolds observed in our study resulted in the development of a simple drug anchoring system. Attached foetal bovine serum-loaded liposomes significantly improved both chondrocyte adhesion and proliferation. In conclusion, fibrous scaffolds from PHEMA are promising materials for tissue engineering and, in combination with liposomes, can serve as a simple drug delivery tool.
    Journal of Materials Science Materials in Medicine 02/2012; 23(2):555-63. · 2.14 Impact Factor
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    ABSTRACT: Pulsed laser deposition was proved as a suitable method for hydroxyapatite (HA) coating of coaxial poly-ɛ-caprolactone/polyvinylalcohol (PCL/PVA) nanofibers. The fibrous morphology of PCL/PVA nanofibers was preserved, if the nanofiber scaffold was coated with thin layers of HA (200 nm and 400 nm). Increasing thickness of HA, however, resulted in a gradual loss of fibrous character. In addition, biomechanical properties were improved after HA deposition on PCL/PVA nanofibers as the value of Young's moduli of elasticity significantly increased. Clearly, thin-layer hydroxyapatite deposition on a nanofiber surface stimulated mesenchymal stem cell viability and their differentiation into osteoblasts. The optimal depth of HA was 800 nm.
    BioMed Research International 01/2012; 2012:428503. · 2.88 Impact Factor
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    ABSTRACT: Improved staging of cartilage degeneration is required, particularly during the early stages. We correlated mechanical properties with histological and macroscopic findings. One hundred and twenty cartilage samples were obtained during total knee arthroplasty. Two adjacent plugs were harvested--one for histological classification and one for macroscopic and biomechanical purposes. Dynamic impact testing was performed; normal stress, dissipated energy (∆E), tangent modulus and stiffness were evaluated. Samples were classified according to six categories of the ICRS histological scale. Mechanical characteristics revealing significant differences between the groups (p < 0.01) were specific damping and related absolute ∆E. A significant correlation was found between the macroscopic score and specific damping, as well as absolute and relative ∆E (p < 0.01). A strong relation was revealed between relative ∆E and cartilage thickness (p < 0.001; R (2) = 0.69). Only ∆E correlated with the condition of the cartilage--the value increased with decreasing quality-and is the most suitable characteristic. This change appears substantial in initial stages of cartilage deterioration.
    International Orthopaedics 01/2011; 35(11):1733-9. · 2.32 Impact Factor
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    ABSTRACT: Hydrogels prepared from a mixture of fibrin and high-molecular weight (MW) hyaluronic acid (HA) were found to be suitable scaffolds for chondrocyte seeding and pig knee cartilage regeneration. Collagen in the hydrogels is not necessary for the formation of biomechanically stable tissue. Regenerated cartilage showed very good biomechanical and histological properties only 6 months after implantation. Notably, the quality of the healing process was dependent on the initial chondrocyte concentration of the scaffolds. These experiments were performed according to good laboratory practice (GLP).
    ASAIO journal (American Society for Artificial Internal Organs: 1992) 10/2010; 56(6):563-8. · 1.39 Impact Factor
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    ABSTRACT: This synoptic study gives a concise overview of current knowledge of bone healing, the role of mesenchymal stem cells in bone tissue regeneration and contemporary possibilities of supporting regeneration of damaged bone. Attention of research concerning the healing of fractures with extensive loss of bone tissue following trauma, the treatment of belatedly healing or non-healing fractures or the healing of segmental bone defects following tumour resection, is focused on development of three-dimensional scaffolds planted with mesenchymal stem cells that might be used for reconstruction of such large bone lesions. Presented are possibilities of transplantation of mesenchymal stem cells combined with biomaterials into bone defects, including the results of our own experimental studies dealing with the use of stem cells in the treatment of damaged tissues of the musculoskeletal system in animal models.
    Acta Veterinaria Brno - ACTA VET BRNO. 01/2009; 78(4):635-642.
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    ABSTRACT: The study is focused on the biomechanical aspects of the anterior cruciate ligament (ACL) reconstruction procedures with an emphasis on evaluating the dynamic strain of materials commonly used for this purpose. Separate and multiple, equally tensioned strands of hamstring grafts used for the reconstruction of the ACL were biomechanically tested and compared to original ACL and bone-patellar tendon-bone (BPTB) grafts, using tissue samples from cadavers. The study was focused on measuring such material properties as the strength, stiffness, maximum load, and elongation at maximum load of the original ACL, BPTB graft, and single tendon hamstring (gracilis and semitendinosus) grafts, continued by double strands and finally by four-strand graft (STG) evaluation. Fresh-frozen cadaveric knees were used, which had been clamped and tensioned equally. The measurement was performed by drop-weight testing, using a Laser Doppler Vibrometer as a basic sensor of the dynamic movements of the gripping clamps, with parallel correlation by a piezoelectric transducer. The grafts for experiments were obtained from 21-paired knees. The measurement was performed at room temperature (21°C) after 24h of thawing at 4°C. All the specimens were measured for their response to the dynamic tensile load. The maximum strength values were obtained and calculated for the appropriate section area of the specimen. The tensioned strands of the original ACL showed a maximum average load of 1,246±243N in the section area of about 30mm2 (max. stress 41.3MPa); the strands of BPTB grafts showed values of 3,855±550N in the section area of 80mm2 (max. stress 40.6MPa); the gracilis tendons showed 925±127N in the section area of 10mm2 (max. stress 95.1MPa) and the semitendinosuss yielded a result of 2,050±159N in the area of 20mm2 (max. stress 88.7MPa). Of all the materials, the original ACL have the lowest strength and stiffness in respect of their biomechanical properties. BPTB grafts showed a slightly higher value of maximum stress, while both the gracilis and semitendinosus tendons showed double the value of maximum load per section area—tensile stress. Two- and four- combined hamstring strands clamped together and equally tensioned with a drop-weight had the combined tensile strength properties of the individual strands within the estimated range of measurement errors. No significant changes in maximum loads/stresses were observed under impact loading conditions. The results of this study demonstrate that equally tensioned four-strand hamstring-tendon grafts have higher initial tensile properties than those in other varieties of samples. From a biomechanical point of view, they seem to be a reasonable alternative procedure for ACL reconstruction.
    Knee Surgery Sports Traumatology Arthroscopy 01/2007; 15(3):233-241. · 2.68 Impact Factor

Publication Stats

23 Citations
82 Downloads
472 Views
27.22 Total Impact Points

Institutions

  • 2013
    • Czech Technical University in Prague
      Praha, Praha, Czech Republic
  • 2007–2013
    • Charles University in Prague
      • Ústav biofyziky (2. LF)
      Praha, Hlavni mesto Praha, Czech Republic
  • 2010–2012
    • Academy of Sciences of the Czech Republic
      • • Ústav experimentální medicíny
      • • Laboratoř tkáňového inženýrství
      Praha, Hlavni mesto Praha, Czech Republic