Cellular heterogeneity in hypertrophic burn scars in response to carbon dioxide laser therapy
Fractional carbon dioxide (AFCO2) laser therapy is used for treating pathological scarring, but the clinical outcomes are variable and the mechanisms of scar reduction poorly understood. We investigated the mechanisms underpinning efficacy of AFCO2 laser therapy, performing single-cell RNA sequencing in skin biopsies from patients with hypertrophic scars after AFCO2 laser therapy. Patients with younger scars (Good Responder, GR, <6 years from healing) had better scar reduction than patients with older scars (Poor Responder, PR, >6 years from healing) by various measures of scarring. scRNAseq analysis revealed that genes enriched in GR were associated with extracellular matrix and structure organisation (COL14A1, POSTN, SPARC); whereas genes enriched in PR were related to enhanced immune responses (IL-12, MSTN, HLA-DQA). The groups had distinct intercellular communication networks and differentiation trajectories after AFCO2, with regenerative Mesenchymal fibroblasts associated with a good response and inflammatory Secretory Papillary and Inflammatory Fibroblasts with a poor response.