Fabrication of Vascularized Scaffold Containing Cardiac Tissue-derived Decellularized Extracellular Matrix Using Bioprinter

Panahi Velashedi, Behnam | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54706 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Mashayekhan, Shohreh
  7. Abstract:
  8. In this study, a new bioink was introduced for the production of tubular tissue structures for cardiac tissue engineering by bioprinter using the FRESH (Freeform Reversible Embedding of Suspended Hydrogels) method. The novel bioink that we used was a combination of cardiac extracellular matrix (cECM) and oxidized alginate. The cardiac extracellular matrix was used to increase the biomimetic of the printed structures to the actual tissue of the body, and also to create sites for cell adhesion, and to improve cell growth and survival. We used alginate oxide (oxidation degree: 5%) to increase the mechanical properties of the tissue. Alginate oxidation has been due to extracellular matrix (ECM) bonding and biodegradation control of the biological structure. In this research, comprehensive characterization and optimizations were performed to obtain the optimal values of bioink composition percentage. According to the reasons for using the extracellular matrix of the heart, 0.8% by weight-volume was selected for use in bio-ink. A range of 3 to 11% was selected to obtain the optimal amount of alginate oxide. During this period, the combination of alginate oxide with the extracellular matrix of can be used as a biological ink. To characterize and optimize the composition of alginate oxide percentage, mechanical and rheological properties test was taken from three biological inks with a combination of 3, 7 and 11 and 0.8% ECM. According to the results of these tests, bioink with 11% oxide Alginate was selected as the optimal sample. Then, the two parameters of the bioprinter, which include nozzle pressure and nozzle velocity, were optimized in two ways, qualitatively and quantitatively. In the qualitative method, according to the range that was considered for the independent variables of pressure and velocity, the parameters were optimized by observing the printed structure. In the quantitative optimization, using the RSM method, a mathematical model for the dependent variable changes, which here is the ratio of the produced diameter of filament to the designed diameter, was presented, based on the changes of the independent variables. Then the optimal parameters were obtained according to the results of the proposed model for bio-inks. The value of the optimal parameters of the bioprinter in this research and for our novel bioink was 100 kPa for nuzzle pressure and 10 mm/second for nuzzle speed. After characterization and mechanical optimization for bio-ink and obtaining optimal bio-printing parameters, structures with complex shapes were produced by FRESH method. In the last part of the research, a system was developed for dynamic cell culture. For this purpose, a mold consisting of two parts with Plexiglas and PDMS was made to place the produced structure and the hydrogel around it. The dynamic culture system was tested in the laboratory for sealing, leakage and destruction of the printed structure
  9. Keywords:
  10. Optimization ; Characterization ; Heart Tissue Engineering ; Extracellular Matrix ; Bioink ; Freeform Reversible Embedding of Suspended Hydrogels (FRESH)Method ; Bio-Printing

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