Introduction: There are few reports involving scalp microneedling in MPHL patients, and in most of them, physical stimulus is associated with other therapeutic agents. The aim of this study was to evaluate the efficacy and risks of isolated scalp microneedling in MPHL patients. Methods: Thirty patients were included in this randomized single-blinded study and submitted to 4 monthly scalp microneedling sessions. Two different microneedling devices were used: roller (n = 15) and tattoo cartridge (n = 15). Scalp coverage and hair density changes were measured 4 and 16 weeks after the last session. Adverse events were observed throughout the study, and scalp biopsies were performed before and after to investigate scarring changes. Results: Four of 12 participants in the roller group and 2 of 14 participants in the tattoo cartridge group showed an improvement in clinical pictures at the first follow-up visit. Only half of these patients sustained an improvement until the last follow-up visit. No benefit in hair density was observed in either group. No reports of adverse events were made. Neocollagenesis and elastolysis were noted in scalp biopsies. Discussion/Conclusion: Isolated scalp microneedling did not show improvement in scalp coverage or hair density of MPHL participants in this study.

Male pattern hair loss (MPHL) is the most frequent form of alopecia in men and is characterized by progressive frontotemporal and vertex hair loss due to hormone-induced miniaturization of genetically predisposed hair follicles [1]. It starts after puberty, and its frequency increases with age [2]. Hair loss has a significant impact on the quality of life of men and results in a continuous search for treatments that may halt the disease evolution [3].

Topical minoxidil and oral finasteride are the only treatments currently approved by the Food and Drug Administration (FDA) for the treatment of MPHL [4]. Both medications are clinically effective, but long-term adhesion to treatment is not always satisfactory mainly due to risk of side effects. The need for daily application, unsatisfactory cosmetic effect, hypertrichosis, and irritation by propylene glycol are some of the reasons that lead to discontinuation of minoxidil [5]. Regarding finasteride, the lack of adherence is related to the great concern about the sexual side effects [6]. Not all patients accept these risks, so new therapies for MPHL need to be studied.

Microneedling is a recently described technique that consists of multiple punctures deep enough to reach the superficial dermis and trigger an inflammatory stimulus with consequent neocollagenesis and release of growth factors. If no drug is applied before or after the trauma, systemic side effects are not expected. Efficacy in acne scar remodeling has been largely studied [7], but the effect on human hair growth still warrants investigation. In animal models, microneedling has been shown to stimulate hair regrowth through activation of bulge stem cells and overexpression of hair growth related genes [8, 9]. In the group of mice submitted to microneedling, hair regrowth happened earlier and faster compared to the untreated group [8].

In the English literature, there are nine reports involving scalp microneedling in MPHL patients [10‒18], but in most of them, the physical stimulus was associated with other therapeutic agents (minoxidil, finasteride, and platelet-rich plasma). The aim of this study was to evaluate the efficacy and the risks of isolated scalp microneedling in MPHL patients.

Subject Selection

Adult men aged 18 years or over with clinical diagnosis of MPHL, Norwood-Hamilton stage III vertex or greater, were included (Table 1). A wash-out period of 6 and 12 months was respected for topical and hormonal treatments, respectively. Previous microneedling, mesotherapy, or fractional laser therapy over the scalp area was considered as exclusion criteria. Subjects were not allowed to use any drug known to stimulate hair growth during the study.

Table 1.

Age and duration of androgenetic alopecia

 Age and duration of androgenetic alopecia
 Age and duration of androgenetic alopecia

Study Design

This was a randomized single-blinded study conducted at the Dermatology Clinic of Hospital do Servidor Público Municipal of São Paulo from July 2016 to August 2017. The study protocol and consent forms were approved by local institutional review boards (CAAE No. 52919216.1.0000.5442).

A total of 30 eligible men were enrolled in the study after signing an informed consent. Following simple randomization procedure (random number table), participants were randomly allocated into two different microneedling device groups: roller (n = 15) and tattoo cartridge (n = 15). All patients were submitted to scalp microneedling every 4 weeks for a total of 4 times. Follow-up visits occurred 4 and 16 weeks after the last session with a total study duration of 32 weeks.

Microneedling Devices

Two commercially available microneedling devices set at 1.5 mm depth were studied: Dr RollerR rollers with 192 needles (Moohan Enterprise Co., Gyeonggi-do, South Korea) and CheyenneR tattoo machine with magnum Art.-Nr. E-MC27-M30L cartridges containing 17 needles (Mt. Derm, Berlin, Germany).

Microneedling Procedure

Topical lidocaine and tetracaine cream were applied to the balding area for 30 min and thoroughly cleaned prior to scalp microneedling. The device was applied in vertical, horizontal, and oblique directions, until pinpoint bleeding. Both devices were applied with the same technique. Participants were instructed not to wash the area for 24 h.

Efficacy Assessment

The vertex region was chosen for efficacy evaluation. The primary efficacy endpoints were scalp coverage and hair density changes. Measurements were taken at baseline and after 4 and 16 weeks of the last scalp microneedling session.

Scalp coverage changes observed in clinical pictures taken before and after treatment were graded by three blinded evaluators using a standardized 7-point rating scale (−3 = greatly decreased, −2 = moderately decreased, −1 = slightly decreased, 0 = no change, +1 = slightly increased, +2 = moderately increased, +3 = greatly increased).

Hair density was analyzed through dermoscopy pictures taken from a 0.79-square inch clipped area. Central tattooing was performed to ensure reproducibility of the same area at different times. The image was analyzed by an automated validated hair counting method (TrichoscanR). The variation of the mean total hair count observed after the protocol was analyzed for each device and for the whole group of participants. The potential influence of the disease severity on treatment response was investigated by stratification of results according to Hamilton-Norwood’s (HN) classification.

Safety Assessment

Patients were evaluated throughout the study for adverse events such as local infection, erythema, edema, seborrheic dermatitis, and itching. Pain severity was assessed on every session using the Visual Analog Scale, constructed as a horizontal line numbered from 0 (no pain) to 10 (worst pain imaginable). The medians of pain severity for each group during the 4 sessions were analyzed.

The presence of new collagen bundles and destruction of elastic fibers were used as a histologic hallmark of dermal scarring process [19]. Neocollagenesis and elastolysis secondary to scalp microneedling were analyzed in 4-mm punch biopsies of the scalp.

The tissue samples were taken under local anesthesia at baseline and after 16 weeks of the last scalp microneedling session. Specimens were fixed in 10% formalin fixation, processed with hematoxylin eosin and Masson trichrome staining, and analyzed under a light microscope by two blinded pathologists with experience in skin disease.

Statistical Methods

Continuous data were analyzed by using mean values, standard deviation, minimum and maximum values; comparison between groups were made by Students t tests for dependent (over time) and independent samples (different groups), as appropriate. Categorical data were analyzed as absolute numbers and percentages, and comparisons were made by the Fisher exact test. To compare hair density change by HN classification, the ANOVA table was used. It was considered a threshold of significance of 5% for two-tailed test. The analyses were done considering the intent of treatment (ITT).

A total of 30 patients were included in the study, 15 in the roller group and 15 in the tattoo cartridge group. Three participants in the roller group and one participant in the tattoo cartridge group did not present for the first follow-up visit. For the second follow-up visit (16 weeks after the last microneedling session), there were another 4 patients in the roller group and another 3 patients in the tattoo cartridge group who were lost of follow-up. Dropout was not related to adverse effects (Fig. 1). There was no difference in the percentage of dropout between the two groups (p = 0.439).

Fig. 1.

Distribution of participants in roller and cartridge groups.

Fig. 1.

Distribution of participants in roller and cartridge groups.

Close modal

Demographic Characteristics

The mean age of the population was 45.6 ± 11.2 years (range 23–67 years). Duration of baldness varied from 2 to 30 years, with a mean of 12.8 ± 7.8 years. The mean age at onset of the disease was 31.6 ± 11.3 years. The stage of MPHL did not differ among groups (Table 2).

Table 2.

Characteristics of the participants at baseline

 Characteristics of the participants at baseline
 Characteristics of the participants at baseline

Efficacy Assessment

Scalp Coverage

At the first follow-up visit, 4/12 participants in the roller group and 2/14 participants in the tattoo cartridge group showed an improvement in clinical pictures. Among the responders, only 2 patients in the roller group and one in the cartridge group sustained an improvement on the last follow-up visit. Clinical pictures of the last follow-up visit of 3 patients (1 in the roller group and 2 in the cartridge group) were not available (Fig. 2).

Fig. 2.

Number of patients and degree of coverage changes 4 and 16 weeks after the last microneedling session, using both devices (roller and tattoo cartridge).

Fig. 2.

Number of patients and degree of coverage changes 4 and 16 weeks after the last microneedling session, using both devices (roller and tattoo cartridge).

Close modal

Hair Density

Neither group presented an improvement in total hair count after 4 monthly sessions of scalp microneedling. When analyzed as a whole, all patients presented a decrease in hair density after 4 and 16 weeks of last treatment session, but the difference did not reach statistical significance. Decrease in hair density was more pronounced in the roller group compared to the cartridge tattoo group after 16 weeks of the last microneedling session (p = 0.03) (Fig. 3). Response to treatment did not depend on HN stage (Table 3).

Table 3.

Hair density changes (hairs/cm2) 4 and 16 weeks after the last microneedling session according to HN classification

 Hair density changes (hairs/cm2) 4 and 16 weeks after the last microneedling session according to HN classification
 Hair density changes (hairs/cm2) 4 and 16 weeks after the last microneedling session according to HN classification
Fig. 3.

Hair density (in hairs/cm2) changes 4 and 16 weeks after the last microneedling session.

Fig. 3.

Hair density (in hairs/cm2) changes 4 and 16 weeks after the last microneedling session.

Close modal

Safety Profile

There were no reports of local infection, erythema, edema, seborrheic dermatitis, and itching during the study protocol. The average pain score on the Visual Analog Scale during the procedure was 6.75 ± 0.30. The degree of pain did not differ between the groups (p = 0.61).

The presence of neocollagenesis and elastolysis was noted in scalp biopsies of 6 and 4 patients, respectively. These histopathological findings were not significantly different between the groups (Table 4).

Table 4.

Histopathological changes after 16 weeks of the last microneedling session

 Histopathological changes after 16 weeks of the last microneedling session
 Histopathological changes after 16 weeks of the last microneedling session

Our study evaluated the effectiveness of two commercially available devices in Brazil and showed no benefit in hair density or scalp coverage for MPHL patients after 4 monthly sessions of scalp microneedling. Our results differ from previous studies that showed improvement in hair growth parameters in MPHL patients after scalp microneedling [10‒18].

The largest scalp microneedling study was a double-blind randomized trial that included 100 patients with moderate MPHL (HN III and IV). Hair density and scalp coverage changes were evaluated after 12 weeks of scalp microneedling associated to topical minoxidil and showed statistically superior results than the use of topical minoxidil alone. Response was maintained 8 weeks after the last microneedling session [10]. The superiority of the association of topical minoxidil and scalp microneedling compared to topical minoxidil alone is corroborated by three other studies. Compared to our cohort, all of them involved younger participants with shorter disease duration and a greater number of scalp microneedling sessions [12, 17, 18] (Table 5). All of these factors influence the effectiveness of MPHL treatments and could partly explain our different findings, in addition to the presence of topical minoxidil.

Table 5.

Overview of studies analyzing microneedling for the treatment of MPHL

 Overview of studies analyzing microneedling for the treatment of MPHL
 Overview of studies analyzing microneedling for the treatment of MPHL

Improvement was also noted when scalp microneedling was associated with platelet-rich plasma and topical minoxidil in MPHL patients [13, 14] (Table 5). The association of all three therapies proved to be superior to isolated minoxidil [1, 2] or minoxidil associated with only platelet-rich plasma [2] in a self-questionnaire. In these studies, patients were younger and with lower disease severity than in our group.

Hair growth improvement observed in studies that associate microneedling to topical minoxidil [10, 12, 17, 18], and platelet-rich plasma injections [13‒15], may not be related to efficacy of scalp microneedling itself. Microneedling creates holes in the stratum corneum, leading to increased penetration of topical treatments, a mechanism called transdermal drug delivery [14]. In these cases, changes might be explained by the greater effect of the associated therapy and not directly to the effect of scalp punctures.

The additional hair growth benefit of scalp microneedling in patients using anti-androgenic systemic treatment has also been reported [11, 16]. In this case, an increased penetration is not implicated, but scalp trauma could act as a trigger for a telogen effluvium and favor the action of these drugs in the early anagen phases of the hair cycle.

It was not until recently that two published articles evaluated scalp microneedling alone for MPHL treatment [17, 18] and showed an improvement in hair count comparable to that of topical minoxidil [18]. Differently from our results, only three of 56 participants (5.4%) showed no improvement in MPHL at the end of 24 weeks in one of these studies [18]. In the other study, follow-up data on isolated microneedling are not provided [17]. In our study, patients had longer disease duration, in addition to having fewer microneedling sessions, which could explain our different results.

Our results are in accordance with a scalp-split study in women with female pattern hair loss which compared isolated microneedling with its association to a blend of growth factors [20]. After 5 weeks of weekly treatment, there was an improvement in hair density on the side treated with the association, while the side treated with isolated microneedling showed worsening of hair density [20].

Diverse results in the literature could derive from the lack of a standardized scalp microneedling procedure. There are no previous studies comparing different microneedling devices, and the application technique varies in frequency, number of sessions, and endpoint among published studies. As known from a murine model, needle length and number of passes influence hair growth microneedling stimulus [9].

Limitations of our work include small sample size, dropout of 11 patients, older age of patients, higher disease severity, and a longer disease duration. Although not effective, the procedure was considered safe as no significant adverse effect was observed. Moderate pain was referred during the procedure, in spite of the device type.

Isolated scalp microneedling did not show improvement in scalp coverage or hair density of MPHL participants in this study.

Subjects have given their written informed consent. The study protocol and consent forms were approved by the HSPM Ethics Committee (CAAE No. 52919216.1.0000.5442).

The author(s) of this manuscript do(es) not have any conflict of interest to declare.

This manuscript did not receive any funding.

Priscila Kakizaki: development of study and paper writing. Leticia Arsie Contin: paper writing and reviewer of protocol results. Marina Barletta: enrollment at protocol development and paper writing. Carla Jorge Machado: statistics. Nilceo Schwery Michalany and Neusa Yurico Sakai Valente: pathology analysis and paper writing on pathology findings. Aline Donati: protocol writing, reviewer of results, and paper writing.

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.

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