Background Adipose extracellular matrix/stromal vascular fraction gel（SVF-gel）, which contains adipose-derived stem cells, endothelial cells, smooth muscle cells, pericytes, and other cell components.

Objective To determine the efficacy and safety of SVF-gel for treating acne scars and to compare the results with CO2 fractional laser.

Methods Seventeen patients with moderate to severe acne scars were treated with SVF-gel filling and CO2 fractional laser through a 24-week, randomized split-face study. One randomly assigned half side of each patient's received one SVF-gel filling treatment and the other side by two CO2 fractional laser treatment once one months. Clinical improvement was assessed by two blinded investigators with Echelle d'Evaluation Clinique des Cicatrices d'acne (ECCA) scale, VISIA and Antaro-3D detection.

This study was designed as a 24-week, prospective, randomized split-face protocol that compared clinical courses between two facial sides either receiving SVF-gel injection or CO2 fractional laser for acne scars. At the initial presentation, the evaluation of the severity of acne scar by Echelle d'Evaluation Clinique des Cicatrices d'acne (ECCA) scale (Table1), VISIA and Antera 3D analysis for all enrolled patients. Then, each facial side of every patient was randomly assigned into either SVF-gel injection or CO2 fractional laser treatment side. A random allocation sequence was created using computer-based random number generators to assign the treatment modality of each side. Randomization codes were secured in a safe until all data analyses were finished. Each patient was received SVF-gel injection for just one time on one half face, CO2 fractional laser treatment for two consecutive sessions at 8-week intervals on the other half face, with a follow-up visit at 16 weeks after the final CO2 fractional laser treatment. Evaluations of each treatment sessions were performed after 1 week, 2 months of every treatment. Two dermatologists evaluating the severities of acne scars were blinded to the assignment. At patients' each evaluation visit, photographic assessments by dermatologists, VISIA and Antera 3D analysis and patients' subjective assessments were conducted.

Inclusion Criteria:

• Acne scar patients with severity of moderate to severe by ECCA scale evaluation.
• All the subjects were not allowed to use any systemic, topical, or light-based acne scar treatment during the course of this study.

Exclusion Criteria:

• pregnancy, mental illness.
• Intake of oral isotretinoin within 3 months
• Application of the other chemical peeling and light-based treatments within 8 weeks

No plan to describe

Two dermatologists evaluating the severity of acne scars were blinded to the assignment. At patients' each evaluation visit, photographic assessments by dermatologists, VISIA and Antera 3D analysis and patients' subjective assessments were conducted.