Advances in Hair Restoration

Design, proof-of-concept of single robotic hair transplant mechanisms for both harvest and implant of hair grafts

The design and development of a prototype for a singular robotic hair transplant system capable of harvesting and implanting hair grafts were executed in this study. To establish a proof-of-concept for hair transplant procedures involving harvesting and implantation, a test system using a spherical phantom of the scalp was selected. The developed prototype of the robotic hair transplant system demonstrates the potential to reduce the duration that grafts remain without a blood supply, thereby minimizing hair graft damage. Additionally, the overall operation time for follicular unit extraction is comparatively shorter than that of conventional systems. Results from the robot vision tests indicate an 89.6% accuracy for hair graft detection with a 4 mm hair length phantom and 97.4% for a 2 mm hair length phantom. In the robot position control test, the root mean square error was found to be 1.268°, with a standard error of the mean of 0.203°. These outcomes suggest that the proposed system performs effectively under the conditions of a spherical phantom with a 2 mm hair length and a 5 mm distance between harvests.

Surgical Management for Hair Restoration: A Review of Contemporary Techniques

BACKGROUND

Hair loss can cause psychological distress for patients, regardless of the etiology or extent of the defect. Many conservative and pharmacological approaches are successful in management, but refractory or severe cases often mandate surgical treatment. Surgical techniques have been refined over the course of a century, and we aim to review the most contemporary strategies.

METHODS

A review of the literature was performed using the databases PubMed, Web of Science, and Embase, in May 2020. Articles were included if they discussed techniques used within the past 10 years, in search of more contemporary strategies and the most widely used approaches.

RESULTS

The use of local flaps, scalp reduction surgery, and hair transplantation techniques are all used for various indications. Modern hair transplantation can be further divided into follicular unit excision and follicular unit transplantation, each with its own advantages. Local flaps are most often used for post-traumatic and reconstructive indication, while hair transplantation can be used for smaller cosmetic lesions or in combination with a variety of other reconstructive techniques.

CONCLUSION

Hair loss continues to be a challenging pathology for both patients and physicians, regardless of etiology. When conservative treatment is inadequate, there exist multiple surgical techniques that can feasibly restore hair, though the exact degree of success may vary between patients. The proper technique is dependent upon etiology, patient specific factors, as well as surgeon experience and comfort.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The pros and cons of follicular unit extraction (FUE) versus elliptical donor harvesting (FUT)

Hair transplantation has evolved as a practice since the 1960's with advances in technology and surgical technique. With various surgical techniques in existence, patients and practitioners have an abundance of options to curate the best results for the patient. However, with many options come various benefits and consequences that must be examined on a patient-by-patient basis. This review article sought to examine the various surgical modalities of hair transplantation, to outline the pros and cons of various techniques, and to help outline considerations when choosing a given surgical technique.

Optimal Hair Transplant Recipient Site Slit Design: Minimizing Vascular Damage

An often overlooked aspect of hair transplantation is the art of recipient site design and slit creation. There is also a lack of consensus on which technique provides the optimum coverage while minimizing vascular damage. This paper aims to provide logical arguments to determine the optimal instrument and method of slit creation, in order to ensure maximum density, optimal survival, minimal pop-out, and minimal damage to scalp vascularity.

The use of semiconical blades reduces the damage to the dermis and vascular plexus as compared with rectangular blades and needles, as the depth of penetration required is lower. The use of acute angle reduces the depth of penetration for the same length of slit and decreases damage to deep plexus. Coronal slits produce less vascular damage than that of sagittal slits with the same size blades.

We believe that these recommendations provide the optimum volume slits while causing minimal vascular damage.

Type 2 Diabetic Mellitus Inhibits Skin Renewal through Inhibiting WNT-Dependent Lgr5+ Hair Follicle Stem Cell Activation in C57BL/6 Mice

BACKGROUND

Hair follicles are important accessory organs of the skin, and it is important for skin renewal and performs variety of important functions. Diabetes can cause several dermatoses; however, its effect on hair follicles is unclear. The purpose of this study was to investigate the effect of type II diabetes (T2DM) on the hair follicles of mice.

METHODS

Seven-week-old male C57BL/6 littermate mice were divided into two groups. The treatment group was injected with streptozotocin (STZ) to induce T2DM, and the control group was parallelly injected with the same dose of buffer. Seven days after injection, the back is depilated to observe the hair follicle regeneration. Hair follicle regeneration was observed by naked eyes and HE staining. The proliferation of the skin cells was observed by PCNA and K14 staining. The altered genes were screened by RNA sequencing and verified by qRT-PCR. In addition, Lgr5 + GFP/mTmG transgenic mice were used to observe the effect of T2DM on Lgr5 hair follicle stem cells (HFSC). And the expression of WNT4 and WNT8A were measured by Western Blot.

RESULTS

T2DM inhibited hair follicle regeneration. Compared to control mice, T2DM mice had smaller hair follicles, reduced skin thickness, and less expression of PCNA and K14. RNA sequencing showed that the two groups had significant differences in cell cycle and proliferation-related pathways. Compared with the control mice, the mRNA expression of Lgr4, Lgr5, Wnt4, and Wnt8a was decreased in the T2DM group. Moreover, T2DM inhibited the activation of Lgr5 HFSC and the expression of WNT4 and WNT8A.

CONCLUSIONS

T2DM inhibited hair follicle regeneration and skin cells proliferation by inhibiting WNT-dependent Lgr5 HFSC activation. This may be an important reason for the reduction of skin renewal ability and the formation of chronic wounds caused by diabetes. It is important for the treatment of chronic diabetic wounds and the development of tissue engineering.

The Effectiveness and Tolerability of Preformed Growth Factors Vehiculated Through Iontophoresis on Patients with Androgenetic Alopecia and Telogen Effluvium: A Clinical Study

Background

Androgenetic alopecia is characterized by a progressive miniaturization of hair follicles in a pattern distribution in genetically predisposed individuals. The efficacy of conventional therapies is variable, therefore there is a need for adjuvant and newer treatment modalities to provide faster and better outcomes.

Objectives

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Materials and Methods

Treatment was performed between June 2018 and June 2019 on 60 patients with androgenetic alopecia and associated telogen effluvium. Each patient underwent 4 sessions in total, each session was performed every 3 weeks. Global photography and trichoscopy were collected at every session of therapy. All patients filed out a self-assessment questionnaire.

Results

Results were very promising, with improvement of hair density and thickening of the hair shaft diameter in most of patients seen with both global photography and trichoscopy. All patients were satisfied of the clinical result and reported a complete reduction in hair loss. No serious adverse side effects were reported.

Conclusions

The use of growth factors associated with iontophoresis technique is a useful treatment for treating and preventing androgenetic alopecia. In addition, in case of associated telogen effluvium, this technique allows for an early stop of hair shedding, especially when cosmetic procedures do not provide satisfactory results in patients.

Hair Follicle Transplantation for Wound Repair

Significance: Hair follicles are complex miniorgans that reside in the dermal layer of the skin. When the skin is wounded, epidermal stem cells in the hair follicle activate and start migrating into the wound site, differentiating into epidermal cells. and contributing to the reepithelialization of the wound. The hair follicles represent the deepest epidermal elements in the skin, which are extremely beneficial in partial-thickness burns and abrasions where the skin can regenerate from the hair follicles. Recent Advances: Advanced animal models have demonstrated that the contribution of epidermal stem cells in the hair follicle bulge and isthmus regions is important for wound healing. In addition, several clinical studies have shown successful harvesting and transplantation of hair follicles as a treatment modality to accelerate wound healing. Critical Issues: Deep and large wounds require hospitalization and, without exception, surgical treatment. Harvesting and direct transplantation of hair follicles could provide a great source of autologous epidermal stem cells for wound healing. The procedure can be done in an outpatient setting, quickly and without creating a large donor site wound. Future Directions: Transplantation of hair follicles in a combination with novel biomaterials could provide advantageous treatment possibilities for both chronic wounds and burns. There is a substantial amount of molecular signaling data available on the role of hair follicles during wound repair, but almost all the data are derived from rodent models, and thus, more information from large animals and most importantly from humans would be beneficial and help to advance this promising treatment further.

Plasma Zinc Levels in Males with Androgenetic Alopecia as Possible Predictors of the Subsequent Conservative Therapy's Effectiveness

Androgenic alopecia (AGA) is the most common type of progressive hair loss in man. The search for reliable predictors of the conservative treatment’s effectiveness is an urgent problem today. Forty-eight patients with AGA, stages I–IV by the Norwood–Hamilton scale, were treated for 4 months with 5% topical minoxidil joints with corrections for trace element and vitamin imbalances. In most cases, the positive therapy’s effect was shown in the parietal but not in the occipital area, whereas that effect was observed in others. The attempts to associate the therapy’s effectiveness with initially defined genetic, hormonal, and metabolic parameters showed the absence of differences between groups with positive and negative outcomes. Among the studied nutrient parameters (Zn, Cu, Mg, Ca, Fe, and Se, as well as vitamins B12, E, D, and folic acid), differences between these groups was shown in zinc content only. The starting point from a zinc plasma level above 10 µmol/L likely provides the success of the subsequent conservative therapy and correlates with an increase in the hair density and diameter in the parietal area. The integral predictive value of the Zn plasma level was assessed as 72.3% (positive predictive value: −88%; and negative predictive value: −55%).

Contemporary Management of Alopecia: A Systematic Review and Meta-analysis for Surgeons

BACKGROUND

The decision of surgical approach for hair restoration often involves evaluation of the type of alopecia; however, the impact of surgical hair restoration from existing techniques in specific population subsets has not been comprehensively investigated.

OBJECTIVES

The authors sought to systematically review the literature on micrografts, minigrafts, mini-micrografts, tissue grafts, tissue flaps and expanders, as well as evaluate graft survival and satisfaction within specific populations in a meta-analysis.

METHODS

PubMed and Scopus literature searches between 1980 and 2018 yielded 57 articles for systematic review and 34 articles for meta-analysis. Study design, mean patient age and gender, patient alopecia type, surgical hair restoration technique, number of treatment areas, mean follow-up, graft survival rate and satisfaction rate were extracted from each study, and a meta-analysis was performed.

RESULTS

The pooled rates of graft survival were 84.98% (95% CI 78.90-91.06) using micrografts and 93.11% (95% CI 91.93-94.29) using micrografts and minigrafts in nonscarring alopecia patients, as well as 88.66% (95% CI 80.12-97.20) using micrografts and 86.25% (95% CI 74.00-98.50) using micrografts and minigrafts in scarring alopecia patients. The pooled rates of satisfaction were 89.70% (95% CI 82.64-96.76) using micrografts and 97.00% (95% CI 92.48-100.0) using micrografts and minigrafts in nonscarring alopecia patients, as well as 97.80% (95% CI 94.59-100.0) using micrografts and 88.70% (95% CI 66.49-100.0) using micrografts and minigrafts in scarring alopecia patients. Dot plots depict rates of graft survival rate from micrografts and satisfaction from micrografts and minigrafts.

CONCLUSION

Surgical hair restoration for nonscarring and scarring alopecia yields high graft survival and satisfaction rates.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Laser-assisted Hair Regrowth: Fractional Laser Modalities for the Treatment of Androgenic Alopecia

Background:

A large proportion of the population is at sometime affected by androgenic alopecia. Current therapies consisting of minoxidil or finasteride are often the first choices for treatment. These regimens are limited by their efficacy, side-effect profiles, and often lengthy treatment courses. Low level laser/light has shown to be relatively effective and safe for the treatment of hair loss, and a number of products are currently available to consumers. Recently, fractional lasers have been examined as treatment options for androgenic alopecia. The mechanism of action of these minimally invasive resurfacing procedures is thought to be 2-fold. First, the microscopic injuries created by these treatments may induce a favorable wound healing environment that triggers hair growth. Alternatively, disruption of the stratum corneum allows for improved transdermal passage of well-established therapeutic drugs to the hair roots.

Methods:

A literature review was performed to evaluate the efficacy of these emerging treatments on hair regrowth.

Results:

Nine original studies examining the effect of fractional lasers on hair growth in androgenic alopecia have been reviewed.

Conclusions:

Preliminary evidence suggests that fractional laser therapies have a positive effect on hair regrowth; however, most of the literature is limited to case reports, and small prospective and retrospective series. Further studies, in the form of well-designed randomized controlled trials, are necessary to evaluate the efficacy, safety, and optimal treatment courses.