Microneedling
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.
References:
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
Microneedling
Microneedling is a minimally dermatologic invasive procedure in which the skin is punctured with the use of a rolling device containing miniature fine needles. It is traditionally used as collagen induction therapy for scars caused by acne, post-traumatic injuries, and burns, as well as for skin rejuvenation, hyperhidrosis, alopecia, and stretch marks; more recently, however, it also functions as a transdermal delivery system for therapeutic drugs and vaccines. A standard microneedling dermaroller has a drum-shaped cylinder with 8 rows and 24 arrays of 192 pointed protrusions and a 12 cm handle extending from the microneedling portion. The individual, single-use needles are 0.5-3 millimeter in length and 0.1-0.25 millimeter in diameter, and are made out of silicon or medical-grade stainless steel, and are pre-sterilized by gamma irradiation.
Light pressure is applied in a rolling motion onto the skin, producing controlled skin injury without damaging the epidermis. Superficial bleeding ensues, leading to a wound healing cascade that releases different types of 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). Further, the needles break down hardened scar strands, allowing the skin to revascularize. The process of neovascularization and neocollagenesis takes place as a result of fibroblasts migrating and proliferating to the epidermis. After 5 days of microneedling injury, a fibronectin matrix forms and collagen deposits, and the individual should expect skin tightening that lasts 5-7 years due to collagen III. To determine therapeutic efficacy of microneedling, a histological examination reveals up to 400% increase in collagen and elastin deposition at 6 months from 4 microneedling sessions performed 1 month apart. At 1 year post-operation, the stratum spinosum thickened with normal rete ridges. Further, the collagen fiber bundles have a normal lattice pattern instead of parallel bundles seen in scar tissue. Thus, microneedling is beneficial in promoting collagen and elastin production in those with scarred skin.
Another mechanism by which microneedling functions is upon the needles’ close proximity to the cell membrane, the cell’s resting electrical membrane potential of -70 mV goes to -100mV, triggering increased cell activity. The change in membrane potential initiates the release of proteins, potassium, and growth factors into the exterior, which lead to fibroblast migration to the site of injury and induces collagen production. Thus, the body is tricked into believing that there is injury which results in the aforementioned cellular processes. In terms of drug delivery, microneedling allows drugs to deposit directly to the vascularized dermis, surpassing the skin barrier and bypassing the stratum corneum. Evidence also shows that the follicular infundibulum widens by 47%, which increases drug penetration across the skin barrier. Drugs that can be transdermally delivered via microneedling include macromolecular biopharmaceuticals: insulin, heparin, albumin; immunobiologicals: hepatitis B, tetanus toxoid, and influenza vaccines; as well as aspirin, minoxidil, tretinoin, and L-ascorbic acid. For improved drug penetration, microneedling can also be combined with micropumps, sonophoresis, iontophoresis, and electroporation. In regards to microneedling for the treatment of alopecia, minoxidil and platelet-rich plasma are used.
Microneedling procedures usually last 10 to 20 minutes depending on the affected area of the skin and are performed in a dermatology office. Patient counseling on the procedure regarding expected outcomes, delayed response, etc. must be conducted. Before the procedure takes place, the patient’s skin must be prepped at least one month prior with vitamin A and C formulations twice a day in order to maximize collagen formation. It is found that vitamin A affects 400 to 1000 genes that control the proliferation and differentiation of epidermal and dermal cells, and hence aid in collagen production. Likewise, Vitamin C is a cofactor for prolyl hydroxylase and lysyl hydroxylase, which are enzymes that catalyze the hydroxylation of proline and lysine residues of procollagen thereby promoting the proper folding of collagen in its triple-helix conformation. To ensure a pain-free procedure, topical anesthesia containing a eutectic mixture of lignocaine and prilocaine/tetracaine is applied and let stand for 45 minutes to 1 hour. Antiseptic and saline is also applied thereafter. The skin is held taut as one hand rolls the instrument perpendicularly against the skin. Rolling is completed 5 times in horizontal, vertical, and oblique motions. Uniform pin-point bleeding is an expected endpoint of the procedure. After the procedure, the skin is dampened with saline. The patient is advised to apply ice packs to minimize stinging sensations and swelling, and to wear sunscreen daily. Each session is performed at 3-8 week intervals, with each session enhancing dermatologic outcomes. It is expected that the skin’s elasticity and scarring is improved 3-6 months after treatment discontinuation.
Microneedling is effective in collagen induction for individuals suffering from scars, hyperhidrosis, alopecia, and stretch marks, and is a transdermal drug delivery system for macromolecular biopharmaceuticals and immunobiologicals. It can improve aesthetic appearance and ultimately bring confidence in those who feel vulnerable with their skin conditions.
References
Singh, Aashim, and Savita Yadav. “Microneedling: Advances and Widening Horizons.” Indian Dermatology Online Journal, Aug. 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC4976400/#:~:text=Microneedling%20has%20been%20found%20to,the%20dermis%20at%201%20year.