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- Type of Document: Ph.D. Dissertation
- Language: Farsi
- Document No: 55901 (06)
- University: Sharif University of Technology
- Department: Computer Engineering
- Advisor(s): Abdekhodaie, Mohammad Jafar; Saadatmand, Maryam; Nekoofar, Mohammad Hossein
- Abstract:
- Pulp necrosis in immature teeth disrupts root development and predisposes roots to fracture as a consequence of their thin walls and open apices. Regenerative endodontics is a developing treatment modality whereby necrotic pulps are replaced with newly formed healthy pulp-like tissue. Many clinical studies have demonstrated the potential of this strategy to stimulate root maturation and apical root-end closure. However, clinical outcomes are patient-dependent and unpredictable. The development of predictable clinical protocols is achieved through the interplay of the three classical elements of tissue engineering, namely, stem cells, signaling molecules, and scaffolds. Scaffolds provide structural support for cells to adhere and proliferate and also regulate cell differentiation and metabolism. Hence, designing and fabricating an appropriate scaffold is a crucial step in tissue engineering. The present study aimed to develop a bicomponent bioactive hydrogel as a potential scaffold for pulp-dentine complex tissue engineering. In this regard, a bicomponent hydrogel based on photo-activated naturally derived polymers, methacrylated chitosan and methacrylated collagen, was fabricated. In the first part of the study, to increase the bioactivity of the developed hydrogel, an extract of platelet rich fibrin (PRFe) was added to the structure as an endogenous source of growth factors. The optimized formulation of PRFe-loaded bicomponent hydrogel can be rapidly photocrosslinked using available dental light curing units. Compared to bicomponent hydrogels without PRFe, the PRFe-loaded hydrogel exhibited greater viscoelasticity and higher cytocompatibility to stem cells from the apical papilla (SCAP). Moreover, it promoted cell proliferation and migration in vitro. It also supported the odontogenic differentiation of SCAP as evidenced by promoting biomineralization and upregulating the gene expression for ALP, COL I, DSPP, and DMP1 as well as facilitated angiogenesis by enhancing VEGFA gene expression. In the second part of the study, PRFe was replaced with antimicrobial peptides to develop a potential scaffold with antimicrobial and regenerative features. Two different antimicrobial peptides, i.e. LLKKK18 and Tet213 were used. The optimized concentration of LLKKK18 and Tet213 had appropriate antimicrobial activity against Gram-positive Enterococcus fæcalis and did not exhibit any cytotoxicity to SCAP encapsulated within the hydrogels compared to the control group without AMPs. The presence of AMPs also significantly promoted migration and differentiation of SCAP. In the AMP-loaded groups, greater levels of calcified nodules deposition, ALP, COL I, DSPP, DMP1, and VEGF mRNA gene expression, and COL I and DSPP protein expression were observed. Overall, the results indicated the potential of engineered bioactive hydrogels for application in tissue engineering-based strategies to regenerate the pulp-dentine complex
- Keywords:
- Hydrogel Scaffold ; In-Situ Forming Hydrogel ; Antibacterial Peptides ; Dental Rehabitation ; Regenerative Endodontics ; Platelet Rich Fibrin Extract ; Pulp/Dentine Complex Tissue Engineering ; Antimicrobial Peptides
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