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31	A Comparative Analysis of the Biomechanics and Biochemistry of Cell-Derived and Cell-Remodeled Matrices: Implications for Wound Healing and Regenerative Medicine Ahlfors, Jan-Eric Wilhelm 03 May 2004 (has links) The purpose of this research was to study the synthesis and remodeling of extracellular matrix (ECM) by fibroblasts with special emphasis on the culture environment (media composition and initial ECM composition) and the resulting mechanical integrity of the ECM. This was investigated by culturing fibroblasts for 3 weeks in a variety of culture conditions consisting of collagen gels, fibrin gels, or media permissive to the self-production of ECM (Cell-Derived Matrix), and quantifying the mechanics of the resulting ECM. The mechanical characteristics were related to the biochemistry of the resulting ECM, notably in terms of collagen accumulation and collagen fibril diameters. The ultimate tensile strength (UTS) of the collagen gels and fibrin gels at the end of the 3-week period was 168.5 ± 43.1 kPa and 133.2 ± 10.6 kPa, respectively. The ultimate tensile strength of the cell-derived matrices was 223.2 ± 9 kPa, and up to 697.1 ± 36.1 kPa when cultured in a chemically-defined medium that was developed for the rapid growth of matrix in a more defined environment. Normalizing the strength to collagen density resulted in a UTS / Collagen Density in these groups of 6.4 ± 1.9 kPa/mg/cm3, 25.9 ± 2.4 kPa/mg/cm3, 14.5 ± 1.1 kPa/mg/cm3, and 40.0 ± 1.9 kPa/mg/cm3, respectively. Cells were synthetically more active when they produced their own matrix than when they were placed within gels. The resulting matrix was also significantly stronger when it was self-produced than when the cells rearranged the matrix within gels that corresponded to a significantly larger fraction of non-acid and pepsin extractable collagen. These studies indicate that cell-derived matrices have potential both as in vitro wound healing models and as soft connective tissue substitutes. tension failure strain mechanics fibroblasts regenerative medicine serum-free UTS proteoglycans thickness glycosaminoglycans extensibility collagen wound-healing model cell-remodeled matrix cell-derived matrix fibroblast-populated collagen gel biomechanical characterization fibrin gel strength chemically-defined medium growth factors tissue growth tissue regeneration total protein content human tissue formation biochemical characterization Extracellular matrix Fibroblasts Biomechanics Biochemistry Wound healing
32	An Assessment of Novel Biodegradable Magnesium Alloys for Endovascular Biomaterial Applications Persaud-Sharma, Dharam 10 June 2013 (has links) Magnesium alloys have been widely explored as potential biomaterials, but several limitations to using these materials have prevented their widespread use, such as uncontrollable degradation kinetics which alter their mechanical properties. In an attempt to further the applicability of magnesium and its alloys for biomedical purposes, two novel magnesium alloys Mg-Zn-Cu and Mg-Zn-Se were developed with the expectation of improving upon the unfavorable qualities shown by similar magnesium based materials that have previously been explored. The overall performance of these novel magnesium alloys has been assessesed in three distinct phases of research: 1) analysing the mechanical properties of the as-cast magnesium alloys, 2) evaluating the biocompatibility of the as-cast magnesium alloys through the use of in-vitro cellular studies, and 3) profiling the degradation kinetics of the as-cast magnesium alloys through the use of electrochemical potentiodynamic polarization techqnique as well as gravimetric weight-loss methods. As compared to currently available shape memory alloys and degradable as-cast alloys, these experimental alloys possess superior as-cast mechanical properties with elongation at failure values of 12% and 13% for the Mg-Zn-Se and Mg-Zn-Se alloys, respectively. This is substantially higher than other as-cast magnesium alloys that have elongation at failure values that range from 7-10%. Biocompatibility tests revealed that both the Mg-Zn-Se and Mg-Zn-Cu alloys exhibit low cytotoxicity levels which are suitable for biomaterial applications. Gravimetric and electrochemical testing was indicative of the weight loss and initial corrosion behavior of the alloys once immersed within a simulated body fluid. The development of these novel as-cast magnesium alloys provide an advancement to the field of degradable metallic materials, while experimental results indicate their potential as cost-effective medical devices. Magnesium Alloys Biodegradable Stents Corrosion Corrosion Science Mg-Zn-Cu Mg-Zn-Se Mg-Zn Biocompatibility Mechanical Properties Absorption Multi-Vitamin Effect Tissue Growth Magnesium Corrosion Control Magnesium Stents Biodegradable Stents Cardiovascular Endovascular Medical Devices Medical Device Minimally Invasive Endovascular Device Dharam Persaud Dharam Persaud-Sharma Biomaterials Biomedical Devices and Instrumentation Equipment and Supplies Surgical Procedures, Operative Therapeutics

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A Comparative Analysis of the Biomechanics and Biochemistry of Cell-Derived and Cell-Remodeled Matrices: Implications for Wound Healing and Regenerative Medicine

An Assessment of Novel Biodegradable Magnesium Alloys for Endovascular Biomaterial Applications