Microneedling is a relatively new minimally invasive procedure involving superficial and controlled puncturing of the skin by rolling with miniature fine needles. Microneedling was initially introduced for skin rejuvenation, but now it’s used for a wide range of indications, including acne scars, acne, post-traumatic/burn scar, alopecia, skin rejuvenation, drug delivery, hyperhidrosis, stretch marks, and many more. It is very safe for dark skin types, where risk of postinflammatory pigmentation is very high with other techniques that damage the epidermis. Traditionally, it’s used as a collagen induction therapy for facial scars and skin rejuvenation, but it is now widely used as a transdermal delivery system for therapeutic drugs and vaccines.
The standard medical dermaroller has a 12 cm long handle with a 2 x 2 cm wide drum-shaped cylinder at one end studded with 8 rows and 24 circular arrays of 192 fine microneedles, usually 0.5–3mm in length and 0.1–0.25 mm in diameter. The microneedles are synthesized by reactive ion etching techniques on silicon or medical-grade stainless steel and pre-sterilized by gamma irradiation. Rolling with the standard dermaroller over an area of skin for 15 times results in about 250 holes per square cm up to the papillary dermis depending on the pressure applied. Each pass produces 16 micro punctures in the stratum corneum per square cm without damaging the epidermis significantly.
Micro punctures are created using microneedles to produce a controlled skin injury without actually damaging the epidermis. The micro injuries lead to minimal superficial bleeding and set up a wound healing cascade with release of various growth factors such as platelet derived growth factor (PGF), transforming growth factor alpha and beta (TGF-𝛂 and TGF-𝜷 ), connective tissue activating protein, connective tissue growth factor, and fibroblast growth factor (FGF). The needles also break down the old hardened scar strands and allow it to revascularize. Neovascularization and neocollagenesis is initiated by the migration and proliferation of fibroblasts and laying down of intercellular matrix. Another proposed hypothesis explains that resting electrical membrane potential of cells is approximately -70 mV, and when needles come near the membrane, it increases quickly to -100mV, triggering increased cell activity and the release of various proteins, potassium, and growth factors from the cells into the exterior leading to the migration of fibroblasts to the site of injury, which causes collagen induction. The needles do not create a wound in a real sense, just fooling the cells in believing that the injury has occured.
Consumers can buy at-home microneedling rollers over the counter. But for best results, microneedling should be administered by a dermatologist using more advanced equipment. The dermatologist can adjust the device depth according to the area of the skin and deposit medication, such as topical tretinoin or vitamin C, deeper into the skin. At-home microneedling devices only superficially affect the skin, penetrating just the outer layer, the stratum corneum or epidermis and reaching 0.25 mm deep. Professional devices can go deeper (2 mm to 3 mm deep), reaching the dermis. Professional devices are also electrically powered and evenly pushes the microneedles into the skin. Home versions rely on manually rolling the barrel over the skin to create small punctures.
Singh, A., & Yadav, S. (2016). Microneedling: Advances and Widening Horizons. Indian dermatology online journal. Retrieved March 21, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4976400/
Yale Medicine. (2021, June 23). Microneedling. Yale Medicine. Retrieved March 21, 2022, from https://www.yalemedicine.org/conditions/microneedling