ACS Nano: good news for hair loss patients: self activated electric stimulation of wearable omnidirectional pulse generator for hair regeneration

Alopecia, a skin disease, is usually caused by a lack of growth factors or hair cycle disorders In the United States, about 35 million men and 21 million women suffered from hair loss in 2015 At present, the main treatment methods of hair loss include local treatment, oral medicine and hair transplantation to restore healthy hair growth cycle Because of non-invasive and high absorption, local treatment is the most common choice for patients Minoxidil and finasteride are two FDA approved drugs, which are widely used to prevent and treat hair loss However, since minoxidil and finasteride can only reduce hair loss, but not significantly increase the number of hair follicles, patients need to continue to use drugs to produce lasting effects In addition, these two drugs may cause serious side effects, such as sexual dysfunction, excessive hypertrophy and fetal defects As an alternative to taking medicine, hair transplantation can help patients grow new hair, but it requires several rounds of surgery, a lot of cost and time, and will bring discomfort Therefore, it is urgent to develop a non-invasive, non pharmacological, cost-effective and convenient method to treat hair loss At present, researchers have developed several promising non drug therapies, such as heat, laser and electrical stimulation, and are gradually entering the clinical research stage Among them, electrical stimulation can induce non-invasive biological effect, which is called electrical proliferation (ETG) Although the optimal ETG parameters have not been clinically confirmed, alternating electric fields in the range of 0.1-10 VCM and frequency < 15 Hz are usually used, and the damage to tissues is negligible ETG can enhance the influx of calcium into dermal papilla cells through voltage-gated transmembrane ion channels, promote the synthesis of ATP in mitochondria, activate protein kinase, and stimulate protein synthesis and cell division ETG can regulate the secretion of various hair growth factors, promote the proliferation of hair follicles, prolong the growth period, and ultimately promote hair regeneration Although the state-of-the-art in vitro processing equipment has minimized its size to fit wearable devices, due to the limitation of battery capacity and output current, the whole system is still large and inconvenient for daily use Fig 1 Structure of wearable electrical stimulation device (source: ACS Nano) Professor Wang Xudong and Professor Cai Weibo of University of Wisconsin Madison worked together to design a general-purpose motor activated and wearable electrical stimulation device (m-esd), which can effectively promote hair regeneration through random body movement The results of hair regeneration in Sprague Dawley (SD) rats and nude mice were significantly improved When m-esd was used, higher hair follicle density and longer hair stem length were observed in SD rats The results show that m-esd can promote hair follicle proliferation and improve the secretion of vascular endothelial growth factor (VEGF) and keratinocyte growth factor (KGF), so as to reduce hair keratinosis, increase the number of hair follicles and promote hair regeneration of genetically defective nude mice Although rat and nude mouse models were used in this study, this study has become a valuable step in evaluating the effect of human hair follicles under such electrical stimulation Relevant achievements were published on ACS Nano (DOI: 10.1021 / acsno 9b03912), an international authoritative journal of chemistry, under the title of "self activated electrical simulation for effective hairregeneration via a wearable omnidirectional pulse generator" The m-esd consists of two modules: the omnidirectional friction generator (OTG) which is used as the electric pulse generator and a pair of interdigital trimming electrodes which provide the spatial distribution electric field OTG is connected by a soft ecoflex band, which can stretch, bend and twist arbitrarily within about 900% of the strain limit A pair of concentric gold electrode arrays on the nanostructured polytetrafluoroethylene film were designed as charge transfer electrode (CTE) to collect the static charge generated in the process of movement, and CTE and finger electrode were installed on the base of polyethylene terephthalate A concentric copper ring electrode array was also fabricated on square poly (terephthalic acid) (PET) The square pet was used as the bottom friction layer to generate friction charge (CGE) The whole OTG was coated with polyimide film Fig 2 the growth of hair stimulated by wearable electrical stimulation device (source: ACS Nano) The author applied m-esd to the hair regeneration of rats M-esd was attached to the back of rats, CGE layer was fixed to the head of rats, CTE layer was fixed to the neck and back Based on this design, all random motions of the head and neck can generate electrical pulses with similar amplitude These electrical impulses are transmitted to a fixed dressing pad and provide alternating electric fields to the exposed skin to stimulate hair regeneration The voltage V PP generated by mouse action is 320 MV, similar to the voltage generated by computer-controlled shaking table induction The long-term stability of m-esd has been tested by commercial oscillator After 28 days of continuous operation, all equipment showed good structural integrity without any observable defects The almost constant voltage amplitude confirms the excellent stability and durability of m-esd This highly flexible and stretchable device has minimal effect on normal daily behavior in rats In addition, compared with electrical stimulation and minoxidil method for clinical hair regeneration, m-esd showed faster, more effective hair hyperplasia and shorter treatment time The results showed that the spontaneous electric pulse produced by m-esd could significantly promote hair regeneration and hair follicle proliferation in SD rats After confirming the positive effect on hair regeneration of SD rats, the author further studied how the electric pulse generated by m-esd affects hair regeneration of genetically deficient nude mice with 21 day hair cycle Compared with minoxidil, vitamin D 3 and normal saline, the authors studied the hair regeneration behavior stimulated by m-esd during the growth period of 21 days In nude mice, hair loss is due to the growth of hair entering the catalyst stage and telomere stage After the catalyst, the hair follicle is dormant in the catalyst phase, and the hair follicle stem cells are activated in the catalyst growth phase transition, thus starting a new round of hair growth This phenomenon shows that electrical stimulation only promotes hair growth, but has little effect on natural hair growth cycle Compared with other control groups, m-esd produced significantly longer hair, higher density and longer occurrence time Summary: the team of Professor Xudong Wang and Professor Cai Weibo from the University of Wisconsin Madison have developed a general-purpose motor activated and wearable electrical stimulation device (m-esd), which can effectively promote hair regeneration through random body movements In shaved SD rats, m-esd can accelerate hair growth and promote hair follicle proliferation Compared with other traditional drug therapies (minoxidil and vitamin D 3), the hair growth rate of m-esd area is 0.73mm per day, minoxidil is 0.41mm per day, vitamin D 3 is 0.33mm per day, and the hair follicle density stimulated by m-esd is 141% of that of minoxidil and vitamin D 3 treatment area M-esd stimulation can overcome the genetic keratin disorder and achieve effective hair regeneration in nude mice by affecting the paracrine mechanism of hair growth factors (VEGF and KGF) In the context of non drug self powered wearable electronic devices, the author's development provides an effective hair regeneration strategy It is expected that it can rapidly develop into a practical and simple solution to the problem of hair loss suffered by billions of people around the world.