opinion leaders in dermatology and plastic surgery from around the world.
History
Microneedling, or percutaneous collagen induction therapy, was introduced in the 1990s for the treatment of scars, striae, and laxity [1]. The use of needles for nonablative skin treatment was first described by Orentreich and Orentreich in 1995 as subcision surgery, which is the release of depressed scars and wrinkles with a needle from their attachment to the underlying skin. This controlled trauma leads to the formation of connective tissue to fill the created gap.
Figure 1.1 Original microneedling roller created by Dr. Desmond Fernandes in 2001. Fixed needle length of 3.0 mm multiuse roller; designed for reuse on a single patient for approximately six treatment sessions. The original rollers were not able to be autoclaved at that time. They were sterilized by soaking in instrument cleaning fluid.
Source: Dr. Desmond Fernandes.
In 1996, skin needling using a roller device was introduced by Fernandes at the International Society of Aesthetic Plastic Surgery (ISAPS) congress in Taipei [2]. In 1997, Camirand and Doucet introduced dry tattooing without pigment as needle dermabrasion and proposed it as a technique to improve the appearance of scars [3].
Fernandes, in 2001, developed the original percutaneous collage induction dermaroller with needles. His pilot roller device was a drum‐shaped tool, with a cylinder and 3 mm needles that reach the fibroblasts deep in the reticular layer (see Figure 1.1).
Zeitter et al. confirmed Fernandes’s findings and made a modified roller. They concluded that 1 mm needles show similar results to 3 mm needles, with the advantage of less downtime, swelling, and pain [3, 4].
Mechanism of action
The mechanism of action is thought to be a disruption of the epidermis and dermis. Micropunctures are created using microneedles, which produce a controlled skin injury without damaging the epidermis. The mechanical microinjury results in the classic wound‐healing cascade and stimulates cellular proliferation and migration through the stimulation of growth factors (see Figure 1.2).
These microinjuries lead to minimal superficial bleeding and set up a wound‐healing cascade with release of various growth factors, such as platelet‐derived growth factor (PDGF), transforming growth factor alpha and beta (TGFα and TGFβ), connective tissue activating protein, connective tissue growth factor, and fibroblast growth factor (FGF) [5]. The needles also break down the scar strands and allow them to revascularize. Neovascularization and neocollagenesis are initiated by migration and proliferation of fibroblasts and laying down of an intercellular matrix [6, 7]. A fibronectin matrix forms five days after injury and determines the deposition of collagen, resulting in skin tightening persisting for five to seven years in the form of collagen III. The depth of neocollagenesis has been found to be 5–600 μm with a 1.5 mm length needle. Histological examination of the skin treated with four microneedling sessions one month apart shows up to 400% increase in collagen and elastin deposition at six months postoperatively, with a thickened stratum spinosum and normal rete ridges at one year postoperatively [8]. Collagen fiber bundles appear to have a normal lattice pattern rather than parallel bundles as in scar tissue [9].
Figure 1.2 The electric pen‐shaped device has adjustable settings to control the speed and depth of needle penetration.
Source: skvalval/Shutterstock.
The devices used create transient epidermal and dermal openings ranging in size from 25 to 3000 um in depth as a microinjury, with the goal of stimulating the inherent skin repair mechanisms. These microwounds or microinjuries initiate the release of growth factors, which trigger and stimulate collagen and elastin formation in the dermis. That leads to healthier skin with improved texture. The microwounds are microchannels and heal following the classic wound‐healing cascade: inflammation, proliferation, and remodeling. This cascade is brought on by the needles’ disruption of the stratum corneum; the endothelial lining and the subendothelial matrix recruits platelets and neutrophils to the site of injury. Needling exposes thrombin and collagen fragments, which attract and activate platelets. The platelets form a plug and initiate the clotting cascade, which involves local platelet aggregation, inflammation, and blood coagulation through increased levels of thrombin and fibrin.
The needles carry an electric potential that stimulates fibroblast proliferation [10]. The mechanical injury triggers the release of potassium and proteins that alter intercellular resting potential, drawing in fibroblasts and stimulating neocollagenesis and revascularization [6].
Research has shown up‐regulation of TGFβ3, a cytokine that prevents aberrant scarring; increased gene expression for collagen type I; and elevated levels of vascular endothelial growth factor, fibroblast growth factor, and epidermal growth factor [11–13]. Histological studies have shown huge variation in epidermal thickness. Randomized murine studies have reported statistically significant epidermal thickening from 140% up to 685% after microneedling plus topical vitamins A and C when compared to control [13, 14]. This is thought to be one of the reasons microneedling is effective for scar therapy and notable skin rejuvenation.
A human study of 480 patients treated with microneedling plus topical vitamins A and C reported thickening of the stratum spinosum lasting up to one year [8, 15].
Increased collagen types I, III, and VII and tropoelastin in human biopsies were found after six sessions of microneedling, ten with elevated levels of collagen type I and elastin persisting at six months. The number of melanocytes was unchanged postprocedurally.
These results support the safe use of this modality in patients with darker skin types [8, 15]. Having a safe and effective treatment modality for all skin types is advantageous in an aesthetic practice.
The devices
Modern microneedling devices consist of rollers, stamps, and pens. Needling devices have evolved over the past decade through a variety of advancements. Currently, there are multiple devices based on needle length, drum size, and automation. To date, there are five FDA‐approved pen devices. Physicians and providers need to consider important factors like needle length, needle material, and clinical indications in selecting which device to utilize [9].
Pens
Most pens utilize sterile single‐use cartridges and variable needle length to be able to customize the treatment depending on the unique characteristics of the patient’s skin and the area being treated. They are automated and the physician has the ability to adjust the needle length for customized treatment options and the pressure and depth during treatment can be more uniform (see Figure 1.3) [16].
The pen itself is reusable, and most pens have a protective disposable sleeve. The needle tips are the disposable/consumable in these devices. Because of their
