The purpose of this study was to determine the effect of combined treatment using nonablative laser and human stem cell media (HSCM) on the regeneration of hypertrophic scars that occurred after burns.

The purpose of this study was to determine the effect of combined treatment using nonablative laser and human stem cell media (HSCM) on the regeneration of hypertrophic scars that occurred after burns. Nonablative laser treatment was performed on 30 patients with hypertrophic scars on both sides of the same part of the body. Immediately after the laser treatment, the hypertrophic scars of right side to which HSCM was applied and the left side with the same body position were defined as a control scar, and normal saline was applied. Over the next 6 days, HSCM and moisturizer were applied on the scars of right side, and only moisturizer was applied on the control scar of left side. Laser treatment was performed three times on the hypertrophic scar at 4 weeks intervals. The skin test on hypertrophic scar was evaluated before laser treatment and re-evaluated on the 7the day after the 3rd laser treatment. The thickness was measured with a ultrasonic wave equipment (128 BW1 Medison, Korea). Mexameter® (MX18, Courage-Khazaka Electronics GmbH, Germany) was used to measure melanin levels and the severity of erythema. The higher values indicating a darker and redder skin. Transepidermal water loss (TEWL) was measured with a Tewameter® (Courage-Khazaka Electronic GmbH, Germany), which is used for evaluating water evaporation. Sebum in the scars was measured with the Sebumeter® (Courage-Khazaka Electronic GmbH, Germany). The measurement is based on the principle of grease-spot photometry using a cassette with its special tape. A microprocessor calculates the result, which is shown on the display in μg/cm2. Elasticity was measured using Cutometer SEM 580® (Courage-Khazaka Electronic GmbH, Cologne, Germany), which applies negative pressure (450 mbar) on the skin. The numeric values (mm) of the skin's distortion is presented as the elasticity (Table 1). Two seconds of negative pressure of 450 mbar is followed by 2 s of recess, and this consists of a complete cycle. Three measurement cycles were conducted, and the average values were obtained. To evaluate the effect of HSCM, investigators compared the skin test results (thickness, melanin, erythema, TEWL, sebum, and skin elasticity levels) between the right side and control side, from baseline measures immediately before the laser treatment and measures on the 7the day after the 3rd laser treatment. Outcome measurements and data analyses were performed by a trained and blinded outcome assessor who was not involved in the intervention. Possible complications (pain, ecchymosis, skin abrasion, and swelling) were observed.

Inclusion Criteria:

• partial or full-thickness burns that healed spontaneously or required skin grafting
• with hypertrophic scars on the right and left sides of the same body part

Exclusion Criteria:

• Patients with open wounds or infection on the burn scars
• those taking steroids for the scars
• with allergies to topical anesthetic cream
• those who were pregnant
• undergoing any other medical treatment or condition affecting wound healing (e.g., diabetes)

After laser treatment on hypertrophic scars, human stem cell media was applied to one side and physiological saline was applied to the other side.