Sustained drug delivery to reduce the extent of burn progression

• Main Author: Moogaambikai D/O Thangaveloo
• Other Authors: David Lawrence Becker
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Medicine, Health and Life Sciences
• Online Access: https://hdl.handle.net/10356/173605
• Institution: Nanyang Technological University

Burns are highly dynamic injuries characterized by an initial zone of necrosis that progresses to compromise surrounding tissue. Acute inflammation and cell death are the two main factors contributing to burn progression. These processes are modulated by Connexin43 (Cx43) hemichannels and gap junctions in traumatic injuries such as burns and chronic wounds. Particularly, Cx43 hemichannel mediated ATP release interacts with P2X7 to activate the NLRP3 inflammasome pathway. This study used a rat burn model to evaluate the effect of a gap junction modulator, Cx43 antisense oligodeoxynucleotides, or Cx43 hemichannel blocker, Tonabersat, for the inhibition of inflammasome activation and use as a potential treatment for burn injury. In Chapter 3, I described our rat burn model, which was created with a hand-held soldering iron, and wounds were subjected to a scoring matrix that best mimicked features of human burn wounds. In the following chapter, burn wounds were treated with topical Cx43 antisense oligodeoxynucleotide or Tonabersat using the characterized rat burn model. I evaluated the immunofluorescence expression levels of Cx43, hemichannels, inflammasome markers (NLRP3, Cas-1, and IL-1β), inflammatory markers MPO and CD68, and skin fibrosis markers αSMA and HSP47 at various timepoints. To evaluate the overall effects on burn wound healing, quantitative analysis with H&E and Masson’s trichrome was performed. Our data showed that sustained release of Cx43 antisense oligodeoxynucleotide reduced protein expression of Cx43 hemichannels and gap junctions, and Tonabersat at high concentrations reduced Cx43 gap junctions protein expression. This concomitantly reduced inflammation and NLRP3 inflammasome complex assembly in rat burn injuries, leading to improved wound healing and reduced scarring. In the final two chapters, a preliminary study was conducted on a porcine scald burn model. Tonabersat and Cx43 antisense oligodeoxynucleotide were applied topically or in a form of scaffold dressing to treat porcine scald burn wounds. I evaluated the immunofluorescence expression levels of Cx43, hemichannels, inflammasome markers NLRP3 and Cas-1, inflammatory markers MPO and CD68, and skin fibrosis makers αSMA and HSP47 at various timepoints. Finding from this study shows that Cx43 hemichannels and gap junctions play a central role in the amplification and perpetuation of inflammation in burn injury. The Cx43-targeted therapeutics mitigating burn progression might reduce the healthcare cost of burn care and allow for better functional recovery in burn patients.