INTRODUCTION
Microneedling (MN), or percutaneous collagen induction therapy, was introduced in the 1990’s for the treatment of scars, striae, and laxity.1 By rolling or gliding a needling device across the skin, thousands of vertical channels of injury are created, triggering a scarless healing cascade and neocollagenesis.2 With lack of heat or chromophore target, MN offers an excellent safety profile in all skin types.
Mechanism of Action
Needles carry an electric potential that stimulates fibroblast proliferation.3 MN-induced mechanical injury triggers the release of potassium and proteins that alter intercellular resting potential, drawing in fibroblasts and stimulating neocollagenesis and revascularization.4 MN studies have shown up-regulation of TGFβ3, a cytokine that prevents aberrant scarring, increased gene expression for collagen type I, and elevated levels of vascular endothelial growth factor, fibroblast growth factor, and epidermal growth factor.5,6,7 Histological studies have shown huge variation in epidermal thickness. Randomized murine studies have reported statistically significant epidermal thickening from 140% up to 685% after MN plus topical vitamins A and C when compared to control.7,8 A human study of 480 patients treated with MN plus topical vitamins A and C reported 40% thickening of the stratum spinosum lasting up to 1-year later.9 Increased collagen types I, III, VII, and tropoelastin in human biopsies were found after 6 sessions of MN10 with elevated levels of collagen type I and elastin persisting at 6-months.11 Number of melanocytes was unchanged post-procedurally.9 Acne Scars MN Monotherapy Many studies have demonstrated statistically significant efficacy with MN monotherapy for acne scars in all skin types.12-17 A randomized, evaluator blinded, clinical trial of 46 patients with atrophic acne scars, compared MN versus nonablative fractional Erbium 1,340-nm laser.18 After 3 monthly sessions, there was no statistical difference between groups on the Quantitative Global Grading System for Post-Acne Scarring scale at 2 and 6 months post-treatment (P=0.264). Of note, 13.6% of laser patients experienced post-inflammatory hyperpigmentation (PIH), while the needling group had none. Another randomized, spit-face study of 30 patients with atrophic acne scars treated subjects with either fractional Erbium doped Yttrium Aluminum Garnet (Er:YAG) laser or MN over 5 monthly sessions.19 Objective and subjective assessments at baseline and 3-months after post-treatment showed clinical and histological bene t in both treatment groups. However, the fractional Er:YAG group demonstrated 70% improvement, versus 30% in the MN group (P<0.001), and significantly lower pain scores with fractional Er:YAG. The MN group experienced shorter downtime. Another randomized, evaluator-blinded study of 30 patients with acne scars compared 4 monthly sessions of MN or 100% trichloracetic acid (TCA) chemical reconstruction of skin
