Single‐cell transcriptome analysis of fractional CO₂ laser efficiency in treating a mouse model of alopecia

Abstract

Objectives Hair loss, including alopecia, is a common dermatological issue worldwide. At present, the application of fractional carbon dioxide (CO2) laser in the treatment of alopecia has been documented; however, the results vary between reports. These varying results may be due to the limited knowledge of cellular action in laser‐irradiated skin. The objective of this study was to investigate the molecular and cellular mechanisms of laser treatment under effective conditions for hair cycle initiation. Methods A fractional CO2 laser was applied and optimized to initiate the hair cycle in a mouse model of alopecia. Several cellular markers were analyzed in the irradiated skin using immunofluorescence staining. Cellular populations and their comprehensive gene expression were analyzed using single‐cell RNA sequencing and bioinformatics. Results The effective irradiation condition for initiating the hair cycle was found to be 15 mJ energy/spot, which generates approximately 500 μm depth columns, but does not penetrate the dermis, only reaching approximately 1 spot/mm2. The proportion of macrophage clusters significantly increased upon irradiation, whereas the proportion of fibroblast clusters decreased. The macrophages strongly expressed C–C chemokine receptor type 2 (Ccr2), which is known to be a key signal for injury‐induced hair growth. Conclusions We found that fractional CO2 laser irradiation recruited Ccr2 positive macrophages, and induced hair regrowth in a mouse alopecia model. These findings may contribute to the development of stable and effective fractional laser irradiation conditions for human alopecia treatment.

Ablative fractional laser treatment reduces hedgehog pathway gene expression in murine basal cell carcinomas

“…It is plausible that AFL monotherapy reduces hedgehog gene expression by ablating the microscopic tumors present in the skin, but since the density of the AFL treatment was 5%, ablation most likely does not fully account for the reduction of hedgehog gene expression reported in this study. Other studies have shown that AFL treatment impacts tissue homeostasis by modifying keratinocyte proliferation, immune cell recruitment, and fibroblast activation [ 9 , 14 , 27 ]. These changes also impact mRNA expression.…”

Identification of a novel immune landscape signature as effective diagnostic markers related to immune cell infiltration in diabetic nephropathy

“…CCR2, namely C–C motif chemokine receptor 2, located on chromosome 3, is a member of the G protein-coupled receptor (GPCR) superfamily and a receptor of monocyte chemoattractant proteins (MCP) 1–4, which are chemical inducers of proinflammatory response ( 38 ). CCR2 exists on the surface of a variety of immune cells and can guide immune cells to reach inflammatory and tumor sites.…”

Ablative fractional CO2 laser treatment promotes wound healing phenotype in skin macrophages

“…15,18,20,21 While previous studies have indicated that AFL induces infiltration of myeloid immune cells, e.g., macrophages and neutrophil granulocytes in skin, 12,22,23 no studies have investigated AFL's influence on macrophages' phenotype. 12,22,23 In this study, we hypothesize that AFL treatment polarizes skin macrophages toward a wound healing phenotype characterized by an increased level of anti-inflammatory markers (Arg1 and CD206) and decreased major histocompatibility complex class II molecules (MHC II). 15 Thus, this study aims to investigate AFL's impact on the inflammatory phenotype of macrophages in skin characterized by expression of these inflammatory markers.…”

“…19 Moreover, Arg1 is considered a primary marker of wound healing macrophages that has been shown to inhibit an inflammatory response during wound healing and promote collagen deposition. 15,18,20,21 While previous studies have indicated that AFL induces infiltration of myeloid immune cells, e.g., macrophages and neutrophil granulocytes in skin, 12,22,23 no studies have investigated AFL's influence on macrophages' phenotype. 12,22,23 In this study, we hypothesize that AFL treatment polarizes skin macrophages toward a wound healing phenotype characterized by an increased level of anti-inflammatory markers (Arg1 and CD206) and decreased major histocompatibility complex class II molecules (MHC II).…”