**3. Microneedling in the treatment of alopecia**

#### **3.1. Introduction**

Microneedling is a medical procedure done by a drum‐shaped roller device with hundreds of micron‐sized microneedles (0.5–1.5 mm in length) projecting on it. Before the treatment, local anesthetics should be applied to the area.

### **3.2. Method**

Roller device is applied in vertical, horizontal, and diagonal directions. By rolling the device across the skin, these microneedles pierce the stratum corneum and create numerous transient microchannels over the applied surface without damaging the epidermis [36, 37]. Microneedling provides direct entry to viable epidermis where it acts on, and does not contact with the dermal nerves and capillaries [37].

Generally, microneedling is applied at 4–6 week intervals in order to wait for new collagen synthesis. For acne scars, 3–4 treatment sessions may be required [36]. However, there is no standard protocol for the application of microneedling in alopecia treatment.

#### **3.3. Mechanism of action**

Microtrauma caused by puncturing of the skin induces the collagen synthesis and neo‐angiogenesis through the wound healing response [36, 37]. Microneedling leads the stimulation of stem cells and activation of growth factors [38–40]. It increases the blood flow to the hair follicles [40]. Also, it was reported that the expression of hair growth related genes are induced after microneedling [41]. Additionally, transient micropores formed through the procedure allow the delivery of molecules into the epidermis. Therefore, after microneedling many cosmeceutical agents have been suggested to be delivered deep to the skin [37, 42, 43]. Accordingly, in mesotherapy, substances can be given with mesoroller device, as mentioned above [11].

#### **3.4. Side effects**

Erythema is rapidly recovered in 24–48 hours of treatment. No serious side effects have been associated with microneedling [37, 43]. Patients can complaint from mild pain [42]. As the microchannels close immediately after the application, infection is not expected after the procedure [36]. In order to avoid potential side effects, appropriate sterilization of the device and the use of only fully licensed and tested agents together with microneedling are important [37].

#### **3.5. Evidence for efficacy**

The effect of microneedling has been investigated on 100 men with AGA. Authors randomized the patients into two groups. First group (50 men) treated with weekly microneedling and 5% minoxidil twice daily (except the day of microneedling) and second group only treated with 5% minoxidil twice daily. After 12 weeks of treatment, the results regarding mean change in hair count were statistically better in the microneedling plus minoxidil group [38]. Additionally, the authors evaluated the supplementary effect of microneedling on four men with AGA who were on oral finasteride and topical 5% minoxidil therapy. New hair growth was seen after 8–10 sessions. Patients treated weekly for the first four weeks, then 11 sessions were applied at 2‐week intervals. After 6 months of treatment grade +2 to +3 response was seen in all patients on photographic assessment. Regarding the patient's subjective assessment scale three patients showed more than 75% satisfaction and one patient showed more than 50% satisfaction. After 18 months of follow up, the results of microneedling were reported to be sustained [44].

**3. Microneedling in the treatment of alopecia**

anesthetics should be applied to the area.

with the dermal nerves and capillaries [37].

**3.3. Mechanism of action**

**3.4. Side effects**

**3.5. Evidence for efficacy**

Microneedling is a medical procedure done by a drum‐shaped roller device with hundreds of micron‐sized microneedles (0.5–1.5 mm in length) projecting on it. Before the treatment, local

Roller device is applied in vertical, horizontal, and diagonal directions. By rolling the device across the skin, these microneedles pierce the stratum corneum and create numerous transient microchannels over the applied surface without damaging the epidermis [36, 37]. Microneedling provides direct entry to viable epidermis where it acts on, and does not contact

Generally, microneedling is applied at 4–6 week intervals in order to wait for new collagen synthesis. For acne scars, 3–4 treatment sessions may be required [36]. However, there is no

Microtrauma caused by puncturing of the skin induces the collagen synthesis and neo‐angiogenesis through the wound healing response [36, 37]. Microneedling leads the stimulation of stem cells and activation of growth factors [38–40]. It increases the blood flow to the hair follicles [40]. Also, it was reported that the expression of hair growth related genes are induced after microneedling [41]. Additionally, transient micropores formed through the procedure allow the delivery of molecules into the epidermis. Therefore, after microneedling many cosmeceutical agents have been suggested to be delivered deep to the skin [37, 42, 43]. Accordingly, in mesotherapy, substances can be given with mesoroller device, as mentioned above [11].

Erythema is rapidly recovered in 24–48 hours of treatment. No serious side effects have been associated with microneedling [37, 43]. Patients can complaint from mild pain [42]. As the microchannels close immediately after the application, infection is not expected after the procedure [36]. In order to avoid potential side effects, appropriate sterilization of the device and the use of only fully licensed and tested agents together with microneedling are important [37].

The effect of microneedling has been investigated on 100 men with AGA. Authors randomized the patients into two groups. First group (50 men) treated with weekly microneedling and 5% minoxidil twice daily (except the day of microneedling) and second group only treated with 5% minoxidil twice daily. After 12 weeks of treatment, the results regarding

standard protocol for the application of microneedling in alopecia treatment.

**3.1. Introduction**

322 Hair and Scalp Disorders

**3.2. Method**

Lee et al. applied microneedling in conjunction with topical growth factors on eleven FPHL patients. In their scalp‐split, single‐blinded, and placebo‐controlled trial, they treated patients weekly for five sessions. One half of the scalp was treated with a solution containing growth factors (basic fibroblast growth factor, insulin‐like growth factor‐1, vascular endothelial growth factor, stem cell factor, keratinocyte growth factor‐2, superoxide dismutase‐1, and Noggin) plus microneedling, whereas the other half was treated with saline plus microneedling. The increase in hair shaft density and hair count was significant in growth factor plus microneedling group. Also patients' satisfaction was reported to be higher in the same group compared to saline group [42].

Other than AGA, the effect of microneedling was also assessed in resistant AA. Deepak et al. reported three cases of AA (one patchy AA, two alopecia universalis) that were previously unsuccessfully treated with contact sensitizers, topical tacrolimus, minoxidil, and corticosteroids and oral mini pulse betamethasone. Authors applied microneedling with a solution containing triamcinolone acetonide, mesotherapy cocktail (growth factors, copper tripeptide‐1, multivitamins, amino acids, and minerals), and minoxidil 2–5%. Marked clinical response was seen in all the three of cases after 4–6 sessions. The authors suggested that scalp roller therapy might be an effective and safe complementary intervention for the treatment of resistant AA [43].

In another study, two cases of patchy AA were successfully treated with microneedling plus topical triamcinolone. After three sessions which were applied at 3‐week intervals, both patients showed marked response and no recurrence was seen after 3 months follow up [40].

The role of photodynamic therapy (PDT) with methyl 5‐aminolevulinic acid (MAL) has been studied for the treatment of AA with variable results. The lack of response has been attributed to the inadequate transepidermal penetration of the drug. With regard to facilitator effect of microneedling in drug delivery, the efficacy of roller therapy in the penetration of MAL in PDT of AA has been evaluated in two studies. Patients are treated with PDT with MAL with only half scalp application of microneedling. In both study, as none of the patients showed hair growth, authors concluded that PDT with MAL may not be an effective strategy for AA, regardless of adjunctive microneedling to enhance the drug passage deep into the skin [45, 46].

Recently, an animal study has demonstrated that micro injury caused by microneedling induced hair regrowth in two pomeranian dogs with alopecia X (hair cycle arrest) [47]. In another animal study assessing the hair growth effect of mycophenolic acid (MP), microneedling was found to accelerate the stimulatory growth of topical MP on anagen follicles [48].
