Effectiveness of a rhGM-CSF-containing Gel on Promoting Recovery After 1927-nm Fractional Thulium Fiber Laser Treatment of Atrophic Acne Scars: a Prospective, Randomized, Split-face, and Evaluator-blinded Clinical Trial

Acne vulgaris is a prevalent chronic inflammatory skin disorder affecting approximately 9% of the global population, with 3-7% of patients developing scarring. Among these, atrophic acne scars (AAS) are the most common subtype, exerting profound aesthetic and psychological burdens that substantially impair patients' quality of life.

The 1927-nm fractional thulium fiber laser (TFL) has emerged as a leading treatment for AAS due to its ability to induce controlled microthermal injury in the superficial dermis, stimulating collagen remodeling and dermal regeneration. Its favorable safety profile-characterized by minimal tissue trauma, rapid recovery, and a low risk of post-inflammatory hyperpigmentation (PIH)-supports its clinical utility. Nonetheless, during the treatment of AAS, the ablative energy generated by the laser inevitably leads to disruption of the epidermal barrier and thermal injury, often resulting in erythema, exudation, crusting, or pigmentation changes during recovery.

Cutaneous wound healing is a multifactorial biological process involving coordinated inflammation, proliferation, and tissue remodeling. Cytokines are essential mediators in this cascade, orchestrating angiogenesis, fibroblast activation, and epithelial regeneration to restore barrier integrity. In the context of post-laser skin wound healing, cytokine-based interventions such as epidermal growth factor (EGF) and fibroblast growth factor (FGF) have demonstrated efficacy in enhancing re-epithelialization and reducing adverse sequelae.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multifunctional cytokine secreted by keratinocytes, macrophages, and T lymphocytes that promotes fibroblast proliferation, keratinocyte migration, angiogenesis, and granulation tissue formation. Emerging research suggests its efficacy in wound healing. Distinct from EGF and FGF, GM-CSF also modulates local inflammation, improves microcirculation, and reduces infection risk, thereby optimizing the immune and metabolic milieu for cutaneous repair. Topical GM-CSF formulations have shown promising outcomes in chronic ulcers, radiation dermatitis and burns, accelerating wound closure and minimizing scar formation. However, evidence regarding its efficacy in laser-induced skin injury remains scarce.

This study represents the first investigation of recombinant human GM-CSF (rhGM-CSF) gel as an adjunctive therapy following 1927-nm TFL treatment for atrophic acne scars. We aimed to evaluate its efficacy in promoting postoperative wound healing and restoring skin barrier function, as well as its clinical value in reducing inflammation, enhancing patient comfort, shortening recovery time, and preventing hyperpigmentation. These findings may provide a theoretical basis for developing optimized, cytokine-assisted post-laser repair strategies in aesthetic dermatology.