https://en.wikipedia.org/wiki/Microneedles

For a long time, there has been a core problem in the treatment of skin diseases: topical medications are difficult to penetrate the stratum corneum and reach the lesion site, while systemic medication often comes with systemic side effects. The emergence of microneedle technology has provided dermatologists with an ideal solution between the two - it can achieve local high-concentration drug delivery while avoiding the risks of invasive surgery. This "precision intervention" treatment effect is changing the diagnosis and treatment paradigm of various stubborn skin diseases such as psoriasis, vitiligo, and acne.

In the treatment of psoriasis, microneedles have demonstrated significant therapeutic advantages. The characteristic of psoriasis plaques is thickened stratum corneum and excessive epidermal hyperplasia. Traditional topical corticosteroids or vitamin D3 derivatives have difficulty penetrating the thick scale layer. Clinical studies have shown that by using a hollow microneedle array to create microchannels on the plaques in advance, and then applying calcipotriol ointment, the improvement rate of the psoriasis area and severity index after 4 weeks reached 62%, while the control group that only applied the ointment showed only 38%. More importantly, microneedle-assisted drug delivery can reduce the dosage of hormones and lower the risk of long-term side effects such as skin atrophy.

The treatment of vitiligo is another area where microneedling shines brightly. Although autologous epidermal transplantation is effective, it is invasive. 308nm excimer phototherapy takes a long time. The microneedling combined with tacrolimus or rusostatin cream regimen activates melanocyte stem cells through mechanical stimulation and delivers immunomodulators to the basal layer simultaneously. This dual approach promotes pigment regeneration. A randomized controlled trial involving 120 patients with stable vitiligo showed that the microneedling combined treatment group achieved a color reversion rate of 71% after 6 months, significantly higher than the 45% of the group receiving only phototherapy. The results were the best in thin and delicate areas such as the face and neck.

In the fields of acne and rosacea, microneedling also performs exceptionally well. For cystic acne, traditional methods require incision for drainage or injection of triamcinolone acetonide, which can easily result in depressed scars. However, microneedling combined with local introduction of isotretinoin or clindamycin can precisely target the hair follicle sebaceous gland units, inhibit the Propionibacterium acnes, and reduce sebum secretion. After treatment, the average count of inflammatory skin lesions in patients decreased by 80%, and there were almost no traces left. Patients with rosacea benefited from the microneedling combined with ivermectin treatment, and the improvement of erythema and papulopustular lesions lasted for more than 6 months.

The application of microneedles in dermatology is not limited to drug delivery; their own physical stimulation also has therapeutic value. The controllable micro-injuries caused by microneedles can induce collagen remodeling and angiogenesis, which is an effective treatment method for atrophic scars and photo-aged skin. When microneedles are combined with photodynamic therapy, radiofrequency, and other technologies, the therapeutic effect shows a synergistic effect of 1+1>2. It can be predicted that with the continuous optimization of microneedle array design, this "micron-level key" in the hands of dermatologists will open the door to the treatment of more difficult diseases.