Self-assembling Peptide Based Nanoscaffolds to Manipulate the Inflammatory Responses

• Author / Creator

  Lu, Lei

• Inflammation is generally considered to be a protective response, however the effects of inflammation can also be harmful and even fatal. The study of regulating the inflammatory response in damaged tissue by using engineered biomaterials is not only essential for enhancing the biocompatibility of implantable biomaterials and devices, but also important for treatments that need for anti-inflammation. In addition, mast cells play a distinct role in the innate immunity and allergic inflammatory responses. Although the number of related study is somewhat limited, the potential of using nanomaterials directly interact with mast cells has showing a great potential in regulation inflammatory responses. Engineered nanoscaffolds, especially in situ forming nanoscaffolds are ideal platforms for modulating inflammatory responses, due to their localized in situ formation, good biocompatibility, porous 3D structure and programmability, etc. The self-assembling peptide (RADA)4 based nanoscaffolds have a wide range of applications in the field of tissue repair and tissue regeneration. This thesis focuses on the utilization of (RADA)4 nanoscaffolds to manipulate the inflammatory responses, which could generate new therapeutic strategies for various diseases. The research include two aspects: i. the controlled release of anti-inflammatory drug by nanoscaffolds; ii. the modulation of mast cell inflammatory responses by nanoscaffolds. Two strategies involving encapsulation of anti-inflammatory drug dexamethasone (Dex) within (RADA)4 matrix via negatively charged cyclodextrins were developed. One strategy is using chitosan/carboxymethyl-β-cyclodextrin nanoparticle system to load Dex, then form hybrid nanoscaffolds with the (RADA)4 nanofibers. The in vitro release of Dex from the hybrid system was observed to be pH sensitive. At pH 7.4, release was observed for more than 8 days, with three distinct kinetic domains in the first 6 days. Another strategy is using anionic sulfobutyl ether β-cyclodextrin (SBE-β-CD) as a carrier to load Dex in the peptide self-assembly nanofiber system. The ionic interaction between SBE-β-CD and the (RADA)4 peptide dramatically affects nanofiber formation, and the stability of the nanoscaffold matrix is highly dependent on the SBE-β-CD/(RADA)4 ratio. The different concentrations of SBE-β-CD and (RADA)4 peptides significantly affects the release kinetics. Prior to manipulation mast cells by engineered nanoscaffolds, the fundamental study on the effect of (RADA)4 nanoscaffolds on marrow-derived murine mast cell (BMMC) activity has been carried out. The results show BMMCs spontaneously adhere to the matrix without activation. IgE/antigen induced degranulation of adherent BMMCs is inhibited by the matrix. Through the literature review, we realized that most of peptide stimuli share a structural similarity, and activate human mast cell through MRGPRX2 receptor. To manipulate human mast cell activation, one peptide stimulus, PAMP-12 motif was conjugated with self-assembling peptide (RADA)4 via a -GG- bridge. The extended peptide, (RADA)4-GG-(PAMP-12) can freely mix with (RADA)4 to form nanofiber matrix in solution. The activation of human mast cell can be controlled by the ratio of (RADA)4-GG-(PAMP-12) in the co-cultured nanoscaffold matrix, which provide a new platform to modulate mast cells for various therapies, such as wound healing, angiogenesis, host defense against pathogens and toxins, etc.

• Subjects / Keywords

  • Nanoscaffold
  • Inflammatory responses
  • Mast cell
  • Drug delivery
  • Self-assembling peptide

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3KW57Z1X

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.