SMOOTH protocol: A pilot randomised prospective intra-patient single-blinded observational study for examining the mechanistic basis of ablative fractional carbon dioxide laser therapy in treating hypertrophic scarring

PLoS One. 2023 Sep 8;18(9):e0285230. doi: 10.1371/journal.pone.0285230. eCollection 2023.

Abstract

Background: Burn injuries are the fourth most common type of trauma and are associated with substantial morbidity and mortality. The impact of burn injury is clinically significant as burn injuries often give rise to exuberant scarring. Hypertrophic scarring (HTS) is a particular concern as up to 70% of burns patients develop HTS. Laser therapy is used for treating HTS and has shown positive clinical outcomes, although the mechanisms remain unclear limiting approaches to improve its effectiveness. Emerging evidence has shown that fibroblasts and senescent cells are important modifiers of scarring. This study aims to investigate the cellular kinetics in HTS after laser therapy, with a focus on the association of scar reduction with the presence of senescent cells.

Methods: We will conduct a multicentre, intra-patient, single-blinded, randomised controlled longitudinal pilot study with parallel assignments to achieve this objective. 60 participants will be recruited to receive 3 interventional ablative fractional CO2 laser treatments over a 12-month period. Each participant will have two scars randomly allocated to receive either laser treatment or standard care. Biopsies will be obtained from laser-treated, scarred-no treatment and non-scarred tissues for immune-histological staining to investigate the longitudinal kinetics of p16INK4A+-senescent cells and fibroblast subpopulations (CD90+/Thy1+ and αSMA+). Combined subjective scar assessments including Modified Vancouver Scar Scale, Patient and Observer Scar Assessment Scale and Brisbane Burn Scar Impact Profile; and objective assessment tools including 3D-Vectra-H1 photography, DermaScan® Cortex, Cutometer® and ColoriMeter®DSMIII will be used to evaluate clinical outcomes. These will then be used to investigate the association between senescent cells and scar reduction after laser therapy. This study will also collect blood samples to explore the systemic biomarkers associated with the response to laser therapy.

Discussion: This study will provide an improved understanding of mechanisms potentially mediating scar reduction with laser treatment, which will enable better designs of laser treatment regimens for those living with HTS.

Trial registration: ClinicalTrials.gov: NCT04736251.

Publication types

  • Clinical Trial Protocol
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon Dioxide
  • Cicatrix, Hypertrophic* / radiotherapy
  • Humans
  • Lasers, Gas* / therapeutic use
  • Low-Level Light Therapy*
  • Multicenter Studies as Topic
  • Observational Studies as Topic
  • Pilot Projects
  • Prospective Studies
  • Randomized Controlled Trials as Topic

Substances

  • Carbon Dioxide

Associated data

  • ClinicalTrials.gov/NCT04736251

Grants and funding

This project is funded by the Scar Free Foundation (https://scarfree.org.uk/). The award was received by NM. The funders did not and will not have a role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.