Fabrication and Optimizing a Bilayer Scaffold with the Ability to Release Growth Factors in Aim to Treating Injuries in Tissue Engineering

Seifi, Saeed | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55518 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Shamloo, Amir; Hosseini, Vahid
  7. Abstract:
  8. Skin, as the largest organ of the body and the first protector against external injuries, plays an important role in maintaining human health. Therefore, providing a method for complete treatment of skin lesions is very important. In the last century, tissue engineering approaches, with the introduction of skin scaffolds, have been instrumental in the process of skin tissue regeneration and treatment. The aim of the present study is to construct an optimal bilayer scaffold to mimic the two outer layer of the skin (epidermis and dermis). Besides, the effects of placenta extract on acceleration of wound healing was investigated by an in-vivo test. both layer of scaffold are porous hydrogels, so that in the construction of the dermis substitute, a combination of chitosan and gelatin has been used. In the first phase of the research, the most suitable candidate has been selected by considering the different percentages of cross linkers. In the construction of the outer layer (epidermal mimic), a combination of carboxyl-methylcellulose and sodium alginate polymers has been used, which in this layer, considering parameters such as the percentage of cross linker addition and the ratio of the composition of the two polymers, are the most substantial parameters. In the third phase of the research, two-layer scaffolds are made using optimized alternatives of each layer and evaluations such as mechanical properties, viscoelastic properties, the rate of drug release, MTT cell viability in the presence of fibroblast cells, and cell adhesion, have been done. In the final step, double-layer scaffolds without/with the placenta extract drug are tested in-vivo to determine its function in regenerating second-degree burn wounds. The results showed that the chitosan /gelatin composite scaffold in the presence of 0.6% v/v of the EDC/NHS cross linker had the closest properties compared to the dermal mimic alternatives. In addition, a 2: 1 carboxyl-methylcellulose to sodium alginate composite scaffold in the presence of 10% ECH cross linker has the most suitable properties such as water absorption capacity, swelling rate, crosslinking percentage and degradation in PBS. Finally, the double-layer scaffold created properties such as yield strength of 0.0637 MPa, Young's modulus of 0.0154 MPa, final strain of 138.5%, 75% drug release in 18 days, halo diameter of about 37 mm and L929 viability is about 56.6%. The results of in-vivo evaluations also showed that the use of bilayer scaffolding in this study reduced the rate of infection, better collagen formation, more angiogenesis and more fibroblast cell migration, on the seventh day, compared to the negative control groups (without treatment) and Positive control (burn cream)
  9. Keywords:
  10. Tissue Engineering ; Hydrogel ; Natural Polymer ; Skin Tissue Engineering ; Hydrogel Scaffold ; Bilayer Scaffold ; Human Placenta Extract ; Porous Scaffolds

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