Atrophic acne scars (AAS) is one of the most common skin sequelae following acne vulgaris. Fractional laser has shown great therapeutic potential in recent years, while there is no standard of wound care after laser resurfacing. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multifunctional cytokine, and has shown its value in many other acute wounds healing. In the present study, we investigated the efficacy and safety of topical recombinant human GM-CSF combined with 1927-nm fractional thulium fiber laser (TFL) in AAS treatment.

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.

Inclusion Criteria:

• Patients diagnosed with atrophic acne scars with essentially symmetric bilateral facial lesion areas, and a Global Scarring Severity (GSS) scale score of Grade 2 or 3 (qualitative assessment);
• Patients with normal cognitive function and mental status;
• Patients with adequate communication ability;
• Patients who voluntarily participate in the split-face controlled study and provide written informed consent.

Exclusion Criteria:

• Having received systemic medications, dermabrasion, or laser therapy within the past 3 months;
• Females who are pregnant, lactating, or planning to become pregnant;
• Presence of severe systemic diseases;
• Psychiatric disorders or impaired capacity for self-care;
• Photosensitivity or having taken photosensitizing medications within the past month;
• Atopic diathesis or history of severe allergic reactions;
• History of skin exposure to intense sunlight within the past month;
• History of keloid formation;
• Presence of active skin tumors or infections;
• Subjects allergic to rhGM-CSF gel or similar products;
• Other subjects deemed ineligible for the study.