Hair transplantation: current concepts and techniques

Nanotechnology-based techniques for hair follicle regeneration

The hair follicle (HF) is a multicellular complex structure of the skin that contains a reservoir of multipotent stem cells. Traditional hair repair methods such as drug therapies, hair transplantation, and stem cell therapy have limitations. Advances in nanotechnology offer new approaches for HF regeneration, including controlled drug release and HF-specific targeting. Until recently, embryogenesis was thought to be the only mechanism for forming hair follicles. However, in recent years, the phenomenon of wound-induced hair neogenesis (WIHN) or de novo HF regeneration has gained attention as it can occur under certain conditions in wound beds. This review covers HF-specific targeting strategies, with particular emphasis on currently used nanotechnology-based strategies for both hair loss-related diseases and HF regeneration. HF regeneration is discussed in several modalities: modulation of the hair cycle, stimulation of progenitor cells and signaling pathways, tissue engineering, WIHN, and gene therapy. The HF has been identified as an ideal target for nanotechnology-based strategies for hair regeneration. However, some regulatory challenges may delay the development of HF regeneration nanotechnology based-strategies, which will be lastly discussed.

Robotically Assisted Recipient Site Preparation in Hair Restoration Surgery: Surgical Safety and Clinical Outcomes in 31 Consecutive Patients

BACKGROUND

Recent advances in robotic surgery have extended to hair restoration surgery, using a robotic recipient site creation device.

OBJECTIVE

This study aimed to assess the surgical safety and postoperative clinical outcomes of using this robotic system.

MATERIALS AND METHODS

Thirty-one men diagnosed with androgenetic alopecia, who underwent hair transplantation with robotic recipient site creation, were retrospectively reviewed. Their mean age was 38.7 ± 9.5 (range, 22‒67) years.

RESULTS

The total number of robotically created recipient sites was 36,273. The average site creation speed was 1,593 ± 544 sites per hour. Postoperative crusting (54.8%) was the most frequent complication in the recipient area, followed by pruritus (12.9%), asymmetry (6.5%), and folliculitis (6.5%). The mean score of cosmetic outcomes and patient satisfaction, scored on a 5-point scale, was 4.10 ± 0.54 and 4.13 ± 0.85, respectively. No significant differences in cosmetic outcomes and patient satisfaction were found between 3 operators.

CONCLUSION

The current device can automatically make slit incisions in the recipient area with speed and consistency noninferior to manual site creation. It is both safe and reliable for clinical use, and it is also easily managed by different hair surgeons without a long learning curve.

Narrative review of facial gender surgery: approaches and techniques for the frontal sinus and upper third of the face

Facial gender confirmation surgery (FGCS) is a series of procedures which seek to harmonize a patient's face with his/her self-image and gender identity. Originally described in San Francisco in the 1980s, FGCS has evolved to encompass all elements of the craniofacial skeleton and facial soft tissue. This field in plastic and reconstructive surgery has quickly gained more attention in the past decade due to the pioneering work of groups around the world along with increased social acceptance and medical care of the transgender community. This narrative review focuses on the upper third of the face. Key differences in the forehead and the hairline of cis men and women are discussed which inform pharmacologic and surgical interventions. Hairline modifying therapies including pharmacotherapy and hair transplantation are explained. Virtual surgical planning (VSP), a tool broadly used in surgical fields, has a special role in FGCS and we offer advice in using VSP when addressing the frontal sinus. Use of VSP allows the surgeon to provide reproducible and accurate results. We then discuss the history of the frontal sinus setback and offer our algorithmic approach to recontouring the forehead with detailed description of the operative steps and decision making. Finally, postoperative care and complications considered.

Follicular Unit Extraction (FUE) Hair Transplant: Curves Ahead

The hair transplant has become widely popular aesthetic procedure. Follicular unit transplantation (FUT) and follicular unit extraction (FUE) are two commonly used and accepted techniques. FUT requires excision of strip of tissue from occipital donor area leading to linear scar. To overcome scarring and other complications of FUT, FUE technique has been attempted which involves harvesting of small individual follicular units. Hair transplantation has been successfully used in correction of alopecia, cleft lip scars, post-burn or surgical scars, vitiligo and as an adjuvant to other maxillofacial procedures. FUE demands greater skills and orientation but can yield excellent results in experienced hands. Several maxillofacial surgeons have incorporated hair transplantation procedure in their aesthetic practice successfully. Sound knowledge of surgical technique, armamentarium and proper surgical planning are essential for desired results. The aim of this article is to explain FUE technique, risk and complications, holding solutions and other associated factors in detail. A simple protocol has been put forth for reference and for better understanding of the technique.

Multiplane Forehead Shortening: Sparing the Frontalis Muscle and Supraorbital Nerve

BACKGROUND

An appropriate forehead-to-face ratio is an important factor contributing to a balanced and attractive face. Conventional methods have been used to correct long forehead, but these methods have drawbacks. The primary objective of this study was to introduce a modified technique with better results.

METHODS

Between March of 2015 and March of 2017, 525 patients with long forehead underwent multiplane forehead shortening with sparing of the frontalis muscle and supraorbital nerve. The operation began with a design indicating the area of skin excision. The sensory nerves were preserved during the skin excision, and the frontalis muscle was not cut. Subgaleal dissection was performed through a small window on the galea. The postoperative assessments included the change in forehead length, sensory changes on the scalp, the presence of a scar, alopecia, and synchronous movement of the flap.

RESULTS

A mean forehead shortening of 2.0 cm (range, 1.1 to 2.8 cm) was observed. Sensory deficits were observed only in the anteromedian scalp, which the supratrochlear nerve innervates. However, sensation recovered to the normal level within 6 months. Scars were barely visible or not visible at all in 85.5 percent of the patients. Postoperative alopecia occurred in only two cases. The synchronous movement of the forehead and scalp was natural in all cases.

CONCLUSION

This modified technique of multiplane forehead shortening with sparing the frontalis muscle and supraorbital nerve provided both cosmetic and functional benefits.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

A Guide to Studying Human Hair Follicle Cycling In Vivo

Hair follicles (HFs) undergo lifelong cyclical transformations, progressing through stages of rapid growth (anagen), regression (catagen), and relative "quiescence" (telogen). Given that HF cycling abnormalities underlie many human hair growth disorders, the accurate classification of individual cycle stages within skin biopsies is clinically important and essential for hair research. For preclinical human hair research purposes, human scalp skin can be xenografted onto immunocompromised mice to study human HF cycling and manipulate long-lasting anagen in vivo. Although available for mice, a comprehensive guide on how to recognize different human hair cycle stages in vivo is lacking. In this article, we present such a guide, which uses objective, well-defined, and reproducible criteria, and integrates simple morphological indicators with advanced, (immuno)-histochemical markers. This guide also characterizes human HF cycling in xenografts and highlights the utility of this model for in vivo hair research. Detailed schematic drawings and representative micrographs provide examples of how best to identify human HF stages, even in suboptimally sectioned tissue, and practical recommendations are given for designing human-on-mouse hair cycle experiments. Thus, this guide seeks to offer a benchmark for human hair cycle stage classification, for both hair research experts and newcomers to the field.

Primary cicatricial alopecia: recent advances in understanding and management

Primary cicatricial alopecias (PCA) are a rare group of disorders, in which the hair follicle is the main target of destructive inflammation resulting in irreversible hair loss with scarring of affected lesions. The most typical clinical manifestation of PCA is the loss of visible follicular ostia. The histopathological hallmark of a fully developed lesion is the replacement of the hair follicle structure by fibrous tissue. PCA could share similar clinical manifestations and eventually lead to "burn-out" alopecia. Some subsets are hardly distinguishable histopathologically and the mechanisms that elicit such a destructive reaction have not been fully elucidated. Thus, the management of PCA represents one of the most challenging clinical problems for dermatologists. The aim of this review is to provide a concise and comprehensive summary of recent advances in PCA management, especially focusing on novel methodologies to aid diagnosis, and updates on our understanding of the etiopathogenesis. Dermoscopy, a new pathological preparation technique and direct immunofluorescence analysis enable more accurate clinicopathological diagnosis of PCA. Microarray analysis may be beneficial to distinguish PCA subtypes. Currently suggested mechanisms underlying PCA include loss of immune protection of stem cells, impaired stem cell self-maintenance, enhanced autoimmunity by pro-inflammatory cytokines and environmental/genetic predispositions. Interestingly, recent data indicates the association between lipid metabolism dysregulation and PCA development, implying an important role of the sebaceous gland dysfunction in the etiopathogenesis. Based on that hypothesis and observations, novel therapeutic approaches have been proposed, including the use of peroxisome proliferator-activated receptor-γ agonist for lichen planopilaris.

Oct4 and klf4 reprogram dermal papilla cells into induced pluripotent stem cells

Direct reprogramming of somatic cells into induced pluripotent stem (iPS) cells by only four transcription factors (Oct4, Sox2, Klf4, and c-Myc) has great potential for tissue-specific regenerative therapies, eliminating the ethical issues surrounding the use of embryonic stem cells and the rejection problems of using non-autologous cells. The reprogramming efficiency generally is very low, however, and the problems surrounding the introduction of viral genetic material are only partially investigated. Recent efforts to reduce the number of virally expressed transcription factors succeeded at reprogramming neural stem cells into iPS cells by overexpressing Oct4 alone. However, the relative inaccessibility and difficulty of obtaining neural cells in humans remains to be resolved. Here we report that dermal papilla (DP) cells, which are specialized skin fibroblasts thought to instruct hair follicle stem cells, endogenously express high levels of Sox2 and c-Myc, and that these cells can be reprogrammed into iPS cells with only Oct4 and Klf4. Moreover, we show that DP cells are reprogrammed more efficiently than skin and embryonic fibroblasts. iPS cells derived from DP cells expressed pluripotency genes and differentiated into cells from all germ layers in vitro and widely contributed to chimeric mice in vivo, including the germline. Our work establishes DP cells as an easily accessible source to generate iPS cells with efficiency and with less genetic material. This opens up the possibility of streamlined generation of skin-derived, patient-specific pluripotent stem cells and of ultimately replacing the remaining two factors with small molecules for safe generation of transplantable cells.

The Ludwig pattern of androgenetic alopecia is due to a hierarchy of androgen sensitivity within follicular units that leads to selective miniaturization and a reduction in the number of terminal hairs per follicular unit

BACKGROUND

Hair follicles exist within follicular units (FUs). In utero the central primary hair follicles are surrounded by smaller secondary follicles. Each FU is nourished by a single arborizing arrector pili muscle that attaches circumferentially around the primary follicle with variable attachment to other follicles. Androgenetic alopecia (AA) miniaturizes susceptible scalp hair follicles in a distinctive and reproducible fashion manifesting in different patterns between men and women.

OBJECTIVES

We hypothesized that there is an additional layer to the patterning in AA, with a hierarchy of susceptibility within FUs to AA, and that the diffuse hair loss seen in women with AA is due to a reduction in the number of terminal hairs per FU rather than uniform miniaturization of entire FUs.

METHODS

We compared the mean numbers of FUs and terminal hairs per FU in 4-mm scalp punch biopsies in 24 women with AA with those in 21 controls.

RESULTS

There was no significant difference in the number of FUs; however, women with AA had 2.40 terminal hairs per FU compared with 3.38 in the control group (P=0.0001) associated with a mean increase of 0.6 vellus hairs per FU. Complete miniaturization of all hairs within the FU was not seen.

CONCLUSIONS

Diffuse hair loss in women with AA is due to a reduction in the number of terminal hairs per FU and an increase in the number of vellus hairs. This supports the hypothesis of a hierarchy of susceptibility within FUs to AA. Further investigation is required to ascertain whether secondary and tertiary hair follicles are more susceptible than primary follicles.

Management of primary cicatricial alopecias: options for treatment

Primary cicatricial alopecias (PCAs) are a poorly understood group of disorders that result in permanent hair loss. Clinically, they are characterized not only by permanent loss of hair shafts but also of visible follicular ostia along with other visible changes in skin surface morphology, while their histopathological hallmark usually (although not always) is the replacement of follicular structures with scar-like fibrous tissue. As hair follicle neogenesis in adult human scalp skin is not yet a readily available treatment option for patients with cicatricial alopecias, the aim of treatment, currently, remains to reduce symptoms and to slow or stop PCA progression, namely the scarring process. Early treatment is the key to minimizing the extent of permanent alopecia. However, inconsistent terminology, poorly defined clinical end-points and a lack of good quality clinical trials have long made management of these conditions very challenging. As one important step towards improving the management of this under-investigated and under-serviced group of dermatoses, the current review presents evidence-based guidance for treatment, with identification of the strength of evidence, and a brief overview of clinical features of each condition. Wherever only insufficient evidence-based advice on PCA management can be given at present, this is indicated so as to highlight important gaps in our clinical knowledge that call for concerted efforts to close these in the near future.

Androgenetic alopecia

Androgenetic alopecia (AGA), or male pattern hair loss, affects approximately 50% of the male population. AGA is an androgen-related condition in genetically predisposed individuals. There is no treatment to completely reverse AGA in advanced stages, but with medical treatment (eg, finasteride, minoxidil, or a combination of both), the progression can be arrested and partly reversed in the majority of patients who have mild to moderate AGA. Combination with hair restoration surgery leads to best results in suitable candidates. Physicians who specialize in male health issues should be familiar with this common condition and all the available approved treatment options.