TARGETING FIBROBLAST-MATRIX INTERACTIONS TO TREAT VOCAL FOLD SCARRING

Voice disorders have a lifetime prevalence of nearly 30%, resulting in $13 billion in annual economic burden. The greatest refractory cause of dysphonia, defined as poor voice, after laryngeal injury is vocal fold (VF) scarring, which typically follows upper airway trauma or iatrogenic injury. After initial VF damage, immune cells infiltrate the wound bed and secrete various cytokines, including transforming growth factor-β (TGF-β), to promote tissue repair. In response to these biochemical cues, VF fibroblasts undergo a fibroblast-to-myofibroblast transition. While myofibroblasts are required for wound closure and VF repair, persistent myofibroblast activation results in the over-accumulation of a collagen-rich extracellular matrix (ECM), leading to tissue stiffening and scar formation. Patients experience vocal hoarseness, vocal fatigue, and poor voice control. The current standard of care is intracordal steroid injections; however, this approach only alleviates symptoms of dysphonia and does not target any specific profibrotic mechanisms underlying VF scarring. As a result, steroid injections exhibit low therapeutic efficacy. The goal of this work is to describe the profibrotic signaling pathways driving VF myofibroblast activation and to engineer controlled drug delivery systems targeting the cellular drivers of VF scarring. Our governing hypothesis is that matrix remodeling during fibrotic wound healing regulates VF scarring via fibroblast interactions and myofibroblast activation, which can be targeted through local delivery of antifibrotics to prevent scar formation. In this study, we compare the transcriptome of human VF myofibroblasts to fibroblasts to identify the myocardin related transcription factor A (MRTF-A)/serum response factor (SRF) signaling axis as required for VF myofibroblast activation. We demonstrate the therapeutic potential of MRTF-A/SRF inhibition across in vitro and in vivo models of VF scarring. In parallel, we show that decorin (DCN), a key proteoglycan in the healthy VF ECM, is downregulated in VF myofibroblasts and in scarred VFs. We investigate the anti-fibrotic potential of DCN using RNA sequencing, 2D and 3D in vitro models, and a rat model of VF scarring. We also design injectable hyaluronic acid microgels for controlled DCN protein delivery and show that DCN-loaded microgels prevent the hallmarks of VF scarring in vivo. Together, this work describes new fibroblast-ECM interactions and profibrotic signaling mechanisms driving VF myofibroblast activation, and it highlights the therapeutic potential of controlled drug delivery platforms for mechanistically-selective antifibrotics for the treatment of VF scarring.

Author dc:creator

• Friedman, Ryan, Michael

Advisor dc:contributor.advisor

• Gottardi, Riccardo

• Engineering
• Pharmacology, Toxicology and Environmental Health

Language dc:language.iso

en

Repository record dc:identifier.uri

https://repository.upenn.edu/handle/20.500.14332/62289

OAI identifier oai:identifier

oai:repository.upenn.edu:20.500.14332/62289