Facial Skin Rejuvenation Using Poly- dl -Lactic Acid Injected With a Laser-Generated Needle-Free Microjet Injector.

BACKGROUND: A laser-induced needle-free microjet injector was developed for rapid, high-speed drug delivery of microliters into the skin. OBJECTIVE: This study evaluated the clinical rejuvenation effect of repeated dermal injections of the collagen simulator poly- dl -lactic acid (PDLA) using a laser-induced needle-free microjet injector. METHODS: Five PDLA injection sessions using a laser-induced needle-free microjet injector were conducted in patients concerned about aging skin. Facial uplifting, darkness, redness, roughness, pore size, subjective satisfaction, and side effects were evaluated before each session and 4 weeks after treatment completion. Histological evaluation was also performed with immunohistochemical staining of collagen and elastic fibers. RESULTS: The clinical results of 27 female patients were evaluated. The treatment resulted in a noticeable skin surface uplifting (0.711 ± 0.42 mm) and significant improvements in darkness ( p = .013), redness ( p = .009), and roughness ( p = .036), with no significant difference in the pore size ( p = .770). Patients were reported being satisfied with the overall therapeutic effects, despite mild and tolerable adverse effects. Histological findings revealed growth and thickening of collagen and elastic fibers, with marked increase in collagen I and III levels. CONCLUSION: Repeated dermal injections of PDLA using a laser-induced microjet injector offer excellent drug delivery, achieving high efficacy in skin rejuvenation, patient satisfaction, and safety.