Microneedling in the Management of Atrophic Acne Scars: Mechanisms, Clinical Applications, and Future Perspectives

Abstract

Background: Microneedling, also known as percutaneous collagen induction therapy, is a minimally invasive dermatologic procedure widely used for the management of post-acne atrophic scars. The technique creates controlled micro-injuries within the epidermis and dermis, thereby initiating a coordinated wound-healing cascade involving inflammation, cellular proliferation, angiogenesis, extracellular matrix deposition, and subsequent collagen remodeling. These biological responses promote fibroblast activation and increase the synthesis of collagen types I and III, elastin, and glycosaminoglycans, leading to dermal thickening and improvement in scar texture and depth. Microneedling also produces transient microchannels that bypass the stratum corneum and enhance the transdermal delivery of topical and biologic agents, making it a valuable platform for combination therapies such as platelet-rich plasma. Clinical evidence demonstrates that microneedling can significantly improve rolling and boxcar acne scars, whereas icepick scars generally show a limited response and often require additional procedures. Automated pen devices provide more consistent and controllable needle penetration than manual rollers, while fractional radiofrequency microneedling adds thermal stimulation to further enhance collagen formation. The procedure has a favorable safety profile across different skin phototypes, including darker skin, with mostly mild and transient adverse effects such as erythema, edema, and pinpoint bleeding. However, treatment outcomes remain influenced by scar type, needle depth, device configuration, number of sessions, and the use of adjunctive therapies.