Microneedling Therapy For Alopecia Diseases

Microneedling therapy is a minimally invasive clinical technique that delivers physical and mechanical micro-injury stimulation to skin and soft tissues via fine needle devices to achieve therapeutic and aesthetic effects. Initially developed to stimulate collagen regeneration and repair skin tissues, it was widely applied in facial scar repair and skin rejuvenation. With continuous technological iteration and clinical exploration, microneedling therapy has been expanded to a broad range of clinical indications in modern dermatology and medical aesthetics. It is currently extensively used for the treatment of cosmetic skin disorders, transdermal drug delivery systems, and combined minimally invasive interventions with lasers, radiofrequency and other mainstream aesthetic technologies, gradually becoming a safe, efficient and multi-functional core treatment technique in clinical practice.

1 Overview of Microneedling Therapy

As a mature medical technology for clinical treatment and cosmetic improvement, microneedling therapy is usually combined with targeted drug delivery and functional active ingredient penetration to amplify therapeutic efficacy. Its common clinical indications for skin cosmetic treatment cover skin aging, sub-health skin conditions, various cosmetic skin diseases, inflammatory dermatoses, atrophic scars and abnormal skin textures. Compared with traditional clinical interventions and superficial skin care methods, microneedling therapy possesses prominent advantages including mild pain, minimal tissue damage, rapid postoperative recovery and significant improvement in transdermal absorption of active substances, which greatly improves the effectiveness and safety of dermatological treatment and skin maintenance.

1.1 Classification of Microneedles

In 2023, the Medical Device Standard Management Center of the National Medical Products Administration (NMPA) issued updated provisions on microneedle device classification, clarifying the management standards for single-use skin pricking needles. Such disposable sterile devices are composed of needle bodies and handles, manufactured with stainless steel and polycarbonate materials, and matched with electric operating instruments. The pricking depth can be precisely adjusted within a maximum range of (2.0±0.2) mm to create microchannels on the scalp and skin surface, thereby promoting the absorption of topical medicinal solutions. The devices are classified as Class III medical devices in China due to their invasive clinical application characteristics.

The U.S. Food and Drug Administration (FDA) divides microneedles into two categories based on needle length: cosmetic microneedles with a needle length of 0.1 to 0.3 mm and medical microneedles with a needle length of 0.5 to 3.0 mm. Cosmetic microneedles only act on the superficial epidermis without penetrating the epidermal layer, mainly used to assist transdermal absorption of active ingredients, and are applicable for home use and formal beauty institutions. In contrast, medical microneedles can penetrate the epidermis to the superficial dermis, triggering graded skin self-repair reactions, promoting proliferation and differentiation of epidermal and dermal cells, and accelerating the regeneration and reconstruction of extracellular matrix such as collagen. In addition, the 2021 Group Standard for Microneedling Operation Specifications formulated by the Chinese Association of Plastics and Aesthetics clarifies that nano-microneedles and stamp microneedles are the mainstream types for clinical alopecia treatment.

1.2 Mechanism of Microneedling Therapy

The mechanical micro-trauma caused by microneedling initiates a cascade of skin self-repair responses, stimulating the release of multiple growth factors and cytokines from the epidermis to dermis, and inducing extracellular matrix synthesis as well as tissue structure regeneration and remodeling. Different from traumatic skin damage, microneedle puncture only forms microchannels with a size of approximately four skin cells on the stratum corneum, temporarily breaking the physiological barrier of the skin surface without causing obvious destruction to skin cells. This unique micro-channel structure effectively enhances the transdermal absorption rate of macromolecular and hydrophilic active substances, providing a reliable and efficient carrier for combined topical drug treatment.

1.3 Mechanism of Microneedling Therapy for Alopecia

The auxiliary enhancement of topical drug absorption through microchannels is one of the core therapeutic mechanisms of microneedling for alopecia. Microneedling can activate the Wnt/β-catenin signaling pathway by building microchannels in the epidermis and superficial dermis, significantly improving the permeability and bioavailability of topical therapeutic drugs. Clinical studies have confirmed that microneedling intervention can effectively upregulate the mRNA and protein expression levels of frizzled-3 (FZD3), β-catenin and lymphoid enhancer-binding factor 1 (LEF-1) in alopecia lesions, thereby expanding follicle volume, increasing the number of viable hair follicles, and maintaining the stable growth phase of hair follicles.

Moreover, microneedle mechanical stimulation can activate dermal papilla cells and hair follicle stem cells, improve local blood perfusion of hair follicles, and facilitate hair regeneration. It can upregulate the expression of 5-bromodeoxyuridine (BrdU) and fibroblast growth factor (FGF) in growing hair follicles, and increase the mRNA levels of vascular endothelial growth factor receptors (VEGFR-2, FGF-2) and epidermal growth factor (EGF), ultimately promoting the formation and stable development of growing hair follicles. At present, mainstream transdermal drug delivery systems include microneedle-assisted delivery, drug-encapsulated microneedles, biodegradable drug-loaded microneedles and hollow microneedles. Clinical consensus shows that the optimal needle depth for alopecia treatment ranges from 0.5 mm to 1.0 mm, while 0.2 to 0.3 mm microneedles are preferred for simple drug penetration; excessive depth may damage hair follicle bulge tissues and inhibit follicle activation.

2 Overview of Alopecia

2.1 Common Types of Alopecia

2.1.1 Androgenetic Alopecia (AGA)

Androgenetic alopecia, also known as hereditary alopecia, is the most prevalent type of pathological hair loss. Epidemiological data shows that the prevalence rate is approximately 21.3% in Chinese males and 6.0% in females. Its pathogenesis is jointly determined by genetic susceptibility, androgen levels and hair follicle sensitivity. Specifically, testosterone in hair follicles is converted into highly active dihydrotestosterone (DHT) by 5α-reductase. The combination of DHT and androgen receptors activates specific gene expressions, induces follicle sensitization, shortens the hair growth cycle, causes progressive follicle atrophy, and ultimately leads to persistent hair thinning and shedding.

2.1.2 Alopecia Areata (AA)

Alopecia areata is a common autoimmune skin disease with complex pathogenic factors involving immune abnormalities, genetics, environment and hormonal disorders. The core pathogenesis is autoimmune dysfunction, where the immune system mistakenly identifies hair follicle cells as foreign antigens and triggers targeted immune responses. A large number of T lymphocytes accumulate around lesion hair follicles and secrete inflammatory mediators such as IFN-γ and TNF-α, which destroy the normal structure and physiological function of hair follicles and hinder normal hair growth and development.

2.1.3 Other Pathological Alopecia

Other secondary alopecia includes drug-induced alopecia, infectious alopecia, thyroid-related alopecia, iron deficiency anemia-related alopecia, lupus-related alopecia and traction alopecia. Chemotherapy drugs, anticoagulants and antiepileptic drugs may cause temporary or permanent hair loss. Fungal and bacterial scalp infections can directly damage follicle structures. Thyroid disorders and iron deficiency anemia disrupt hair cycle balance and follicle metabolism, while long-term mechanical traction can loosen hair roots and induce localized alopecia.

2.2 Conventional Clinical Treatments for Alopecia

Current mainstream alopecia interventions include drug therapy, low-level laser therapy, hair transplantation and stem cell therapy. Systemic oral drugs such as finasteride and spironolactone, together with topical minoxidil, can inhibit androgen-induced follicle damage and promote hair regrowth. Low-level laser therapy improves follicle blood circulation and metabolic activity. Hair transplantation achieves aesthetic repair by transplanting healthy follicles to bald areas, limited by the number of donor follicles. In addition, nutritional supplementation of B vitamins, vitamin D, iron and zinc, together with balanced diet, adequate sleep and stress relief, can effectively assist in maintaining healthy hair growth.

References

[1] Zhao Liangsen, Zhang Zerong, Liao Yong. Research Progress of Microneedling Therapy in the Treatment of Alopecia[J]. Journal of Practical Dermatology, 2024,17(04):221-225+240.

[2] Lv Juan, Zhou Jing. Research Progress of Microneedling in the Treatment of Alopecia Diseases[J]. Journal of Diagnosis and Therapy on Dermato-venereology, 2024,31(08):567-571.