Scaffold Fabrication for Corneal Regeneration

Mahdavi Salimi, Sharareh | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53658 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Abdekhodaie, Mohammad Jafar; Mashayekhan, Shohreh; Baradaran Rafiei, Alireza
  7. Abstract:
  8. 3D bioprinting technology is a promising approach for corneal stromal tissue regeneration. At first, two different concentrations of GelMA macromer (7.5% and 12.5%) were tested for corneal stroma bioprinting. Due to high macromer concentrations, 12.5% GelMA was stiffer than 7.5% GelMA, which made it easier to handle. In terms of water content and optical transmittance of the bioprinted scaffolds, we observed that scaffold with 12.5% GelMA concentration was closer to the native corneal stroma tissue. Subsequently, cell proliferation, gene and protein expression of human corneal stromal cells encapsulated in the bioprinted scaffolds were investigated. Cytocompatibility in 12.5% GelMA scaffolds was observed to be 81.86% and 156.11% at day 1 and 7, respectively, which were significantly higher than those in 7.5% GelMA scaffolds. Elongated corneal stromal cells were observed in 12.5% GelMA samples after 7 days, indicating the cell attachment, growth, and integration within the scaffold. The gene expression of collagen type I, lumican and keratan sulfate increased over time for the cells cultured in 12.5% GelMA scaffolds as compared to those cultured on the plastic tissue culture plate. However, the low mechanical properties of GelMA make it hard to suture and handle. Different ratios of 12.5% GelMA and 10% PEGDA were tested for corneal stromal cells delivery. Moreover, collagen nanofibers were incorporated into 75G25P hydrogel to improve the mechanical and biomimetic properties of the construct (75G25P-E). The mixture containing 75% GelMA and 25% PEGDA (75G25P) was found to have reasonable cell viability and suturing strength. ). The hybrid structure was obtained by injecting the optimized bioink on the electrospun collagen mats and crosslinking the structure using visible light. Subsequently, gene and protein expression of corneal stromal cell were assessed in 75G25P hydrogel with and without collagen nanofibers. Spatial elongated corneal stromal cells were observed in 75G25P-E samples after 14 days. The gene expression of corneal stromal cells markers (lumican and keratan sulfate) and collagen type I up-regulated within 75G25P-E hydrogel over time as compared to cells encapsulated in 75G25P samples. Finally, expressions of collagen type I and lumican after 4 weeks implied that the proposed structure can be a promising equivalent for corneal stroma tissue
  9. Keywords:
  10. Crosslinking ; Biomaterials ; Three Dimentional Printing ; Biopolymer ; Bio-Printing ; Corneal Tissue Engineering ; Corneal Stromal Cells

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