Poly‑D,L‑lactic acid (PDLLA) scalp microinjection protocol with optional light microneedling priming for non‑scarring alopecia: A prospective pilot case series.

Background: PDLLA demonstrates angiogenic and regenerative properties that may support hair regrowth by enhancing perifollicular perfusion. Objective: To evaluate clinical improvement after PDLLA scalp microinjection in 20 patients using standardized photography and Global Aesthetic Improvement Scale (GAIS) rated by two independent physicians. Methods: Twenty adults with non scarring alopecia received PDLLA scalp microinjections at baseline and week 4 (optional booster at week 8). Optional light microneedling priming (0.5-0.8 mm) was performed immediately before PDLLA injection in 14/20 patients to facilitate distribution. Primary endpoint was physician rated GAIS at week 12; secondary endpoints included patient GAIS and safety. Images were acquired with fixed camera to scalp distance and lighting. Results: Physician GAIS improved in 90% of patients at week 12 (mean ± SD 3.3 ± 0.6) and was maintained at week 24 (3.1 ± 0.7). Patient reported GAIS was 3.2 ± 0.7 at week 12. No serious adverse events occurred. Conclusions: In this pilot uncontrolled case series, PDLLA scalp microinjections were associated with physician‑rated GAIS improvement over 12-24 weeks with favorable short‑term tolerability. Given the subjective endpoint, the absence of a comparator arm, and optional microneedling priming in a subset of patients, the findings are preliminary and require confirmation in controlled studies with objective trichologic measurements and longer follow‑up.