About 160 million people worldwide suffer from alopecia areata. It is an autoimmune disease that causes the patient’s immune system to attack the hair follicles — the tubular microscopic organs in the skin that regulate hair growth. This leads to hair loss from the scalp in patches, eventually causing partial or complete baldness in many patients. 

Alopecia areata isn’t the only type of alopecia (the medical term for hair loss). However, this one condition affects over 6.5 million individuals in the US, making it one of the most common causes of hair loss. Unfortunately, as of now, there is no cure for this condition. 

Although some treatment options can restore hair growth, they have several limitations and don’t work for every patient. However, a new study from researchers at Harvard Medical School’s Brigham and Women’s Hospital reveals a novel microneedle patch-based therapy that may effectively reverse hair loss caused by alopecia areata.

“Our microneedle patch offers a novel and innovative approach to treating alopecia areata, addressing many of the limitations of current treatments,” Natalie Artzi, one of the study authors and an associate professor of medicine at Harvard Medical School, told ZME Science. 

Problems with current alopecia areata treatment methods

Existing treatments for alopecia areata primarily include drugs such as corticosteroids and Janus kinase (JAK) inhibitors. The former are anti-inflammatory medicines that mimic the effect of certain natural hormones, and the latter work by suppressing the activity of an enzyme (JAK) involved in immune response regulation. 

According to the study authors, both drugs have several limitations and may pose risks to human health. Corticosteroids can weaken immune responses, leading to an increased risk of infections, osteoporosis, hypertension, and other systemic effects.  

On the other hand, JAK inhibitors are effective for some patients, but they can also elevate the risk of infections and potentially lead to other serious conditions, such as malignancies (cancerous tumors and other abnormal growths). 

“Additionally, many current treatment methods require regular and frequent administration, which can be inconvenient and burdensome for patients, often leading to poor adherence to treatment regimens. Moreover, not all patients respond to existing treatments, and some may experience only partial regrowth or no improvement at all, making the variability in effectiveness frustrating and discouraging,” Artzi said.

Microneedle patch offers painless targeted treatment 

The primary reason why current alopecia treatments are problematic is that they typically target the entire body and not just the affected areas. This leads to widespread side effects and limits their long-term use.

The microneedle patch, on the other hand, works by using microscopic, painless needles to deliver specific proteins directly to the affected area of the scalp. This localized and targeted delivery ensures that the drug is concentrated where it is needed most. Naturally, this aims to maximize effectiveness in stimulating hair regrowth while minimizing side effects. 

However, before delving deep into the working mechanism of the microneedle patch, one first needs to understand what exactly causes alopecia areata. The condition occurs when the balance between effector T cells and regulatory T cells (T_reg) is impaired. T lymphocytes are white blood cells, part of the immune system. Effector T cells help to defend the body directly while T_reg cells prevent autoimmune disorders by ensuring that the immune response doesn’t become overactive. 

In alopecia areata, the number of T_reg cells reduces so much that a person’s effector T cells become overactive and launch an attack on the hair follicles. 

The microneedle patch delivers two proteins to the affected sites, CCL22 and IL-2 (Interleukin-2). These proteins recruit and expand the number of regulatory T cells, restoring immune system balance and generating tolerance against the hair follicle antigen. This eventually results in hair growth.

“Since the microneedle patch is designed to be less invasive, it causes minimal discomfort compared to traditional injections or systemic treatments, which can improve patient compliance and make the treatment process more manageable,” Artzi told ZME Science.

Testing the patch in mice

To check their treatment method’s effectiveness, the researchers administered the CCL22 and IL-2 loaded microneedle patch on mice (with alopecia) 10 times over three weeks. 

“The patch did show the ability to reverse hair loss effectively in mice. The hair regrowth was observed to be sustained over a significant period of time (even after therapy cessation), indicating a potentially long-lasting effect,” Artzi said. 

Next, they performed a similar experiment but this time instead of CCL22 and IL-2, they injected baricitinib in mice models using the microneedle patch. Baricitinib is an approved JAK inhibitor that works by suppressing the entire immune system.

The study authors discovered that the microneedle patch containing CCL22 and IL-2 was far more effective than the baricitinib patch at increasing the number of regulatory T-cells at the alopecia-affected sites in mice. 

“Our approach specifically enriches regulatory T cells at the site of antigen encounter (where the hair follicles are), and therefore work to restore immune balance, rather than suppress the entire immune system such as in the case of baricitinib,” Artzi said.

Can we use the patch to reverse hair loss in humans?

Initial tests suggest that the patch can be stored for at least one year without losing its effectiveness, making it a convenient option for patients and healthcare providers.

Moreover, the patch also has the potential to be adapted for other medical conditions that could benefit from localized immune modulation or delivery of therapeutic agents, such as psoriasis, vitiligo, or atopic dermatitis, according to the study authors.

However, while the patch has shown promising results in animal models, it is not yet ready for use in humans. It is currently in the preclinical phase and will require some more years of rigorous testing, manufacturing, and regulatory approval before it can be widely available for human use.

“We have seen encouraging data when using human skin transplant in mice inducing effective immune regulation, indicating that the translation is possible. However, human biology can be quite different, and further testing is necessary to confirm the efficacy and safety in humans.”  

The researchers are also planning to start a company dedicated to bringing this microneedle patch to market once it is ready for use in humans.

The study is published in the journal Advanced Materials.