Hair-bearing human skin generated entirely from pluripotent stem cells.

The skin is a multilayered organ, equipped with appendages (that is, follicles and glands), that is critical for regulating body temperature and the retention of bodily fluids, guarding against external stresses and mediating the sensation of touch and pain1,2. Reconstructing appendage-bearing skin in cultures and in bioengineered grafts is a biomedical challenge that has yet to be met3-9. Here we report an organoid culture system that generates complex skin from human pluripotent stem cells. We use stepwise modulation of the transforming growth factor ß (TGFß) and fibroblast growth factor (FGF) signalling pathways to co-induce cranial epithelial cells and neural crest cells within a spherical cell aggregate. During an incubation period of 4-5 months, we observe the emergence of a cyst-like skin organoid composed of stratified epidermis, fat-rich dermis and pigmented hair follicles that are equipped with sebaceous glands. A network of sensory neurons and Schwann cells form nerve-like bundles that target Merkel cells in organoid hair follicles, mimicking the neural circuitry associated with human touch. Single-cell RNA sequencing and direct comparison to fetal specimens suggest that the skin organoids are equivalent to the facial skin of human fetuses in the second trimester of development. Moreover, we show that skin organoids form planar hair-bearing skin when grafted onto nude mice. Together, our results demonstrate that nearly complete skin can self-assemble in vitro and be used to reconstitute skin in vivo. We anticipate that our skin organoids will provide a foundation for future studies of human skin development, disease modelling and reconstructive surgery.

GFP-labeled Schwann cell-like cells derived from hair follicle epidermal neural crest stem cells promote the acellular nerve allografts to repair facial nerve defects in rats.

BACKGROUND: Acellular nerve allografts (ANAs) have been successfully applied to bridge facial nerve defects, and transplantation of stem cells may enhance the regenerative results. Up to now, application of hair follicle epidermal neural crest stem cell-derived Schwann cell-like cells (EPI-NCSC-SCLCs) combined with ANAs for bridging facial nerve defects has not been reported. METHODS: The effect of ANAs laden with green fluorescent protein (GFP)-labeled EPI-NCSC-SCLCs (ANA + cells) on bridging rat facial nerve trunk defects (5-mm-long) was detected by functional and morphological examination, as compared with autografts and ANAs, respectively. RESULTS: (1) EPI-NCSC-SCLCs had good compatibility with ANAs in vitro. (2) In the ANA + cells group, the GFP signals were observed by in vivo imaging system for small animals within 8 weeks, and GFP-labeled EPI-NCSC-SCLCs were detected in the tissue slices at 16 weeks postoperatively. (3) The facial symmetry at rest after surgery in the ANA + cells group was better than that in the ANA group (p < 0.05), and similar to that in the autograft group (p > 0.05). The initial recovery time of vibrissal and eyelid movement in the ANA group was 2 weeks later than that in the other two groups. (4) The myelinated fibers, myelin sheath thickness and diameter of the axons of the buccal branches in the ANA group were significantly worse than those in the other two groups (P < 0.05), and the results in the ANA + cells group were similar to those in the autograft group (p > 0.05). CONCLUSIONS: EPI-NCSC-SCLCs could promote functional and morphological recovery of rat facial nerve defects, and GFP labeling could track the transplanted EPI-NCSC-SCLCs in vivo for a certain period of time. These may provide a novel choice for clinical treatment of peripheral nerve defects.

Instrumentation and Devices Specific to Follicular Unit Excision.

The volume of hair transplantation procedures done via the follicular unit excision (FUE) harvesting technique has increased tremendously over the last few years. With this growth, new advances in technology have come along. The wide variety of instrumentation and devices can be overwhelming, especially for a novice surgeon. This chapter aims to discuss the relevant aspects of FUE and its relationship to the devices that are used to harvest grafts. The development and overview of all the major types of instrumentation will be reviewed.

Follicular Unit Excision-Linear Ellipse Donor Harvesting Technique: Combining Standard Follicular Unit Excision with Follicular Unit Excision inside a Linear Strip (Modified Linear Strip Excision) to Optimize Graft Yield.

Follicular unit excision (FUE) graft dissection has become the dominant method of donor harvesting globally, however, only a percentage of donor hair can be excised inside the safe donor area before visible donor thinning occurs. Compared to linear strip excision (LSE) where all follicular units inside the harvested ellipse of hair are used, FUE poses substantial limitations for lifetime graft yield and, therefore, cosmetic coverage in patients with advanced pattern hair loss. This paper reviews how combining the donor harvesting methods of FUE and LSE has been shown to optimize graft yield while minimizing the risk of donor depletion from overharvesting. It then describes a surgical technique called FUE-Linear Ellipse (FUE-LE) where FUE dissection of grafts inside a demarcated linear ellipse eliminates the need for a large dissection team which has posed a barrier for many new practices that offer both the donor harvesting methods. For practices that currently offer only FUE, the addition of the LSE method by the modified FUE-LE technique is possible without specialized staff training or associated equipment costs. In this paper, surgery practices that have adopted this technique will report on their experiences. Hair restoration surgeons are encouraged to provide both methods of donor harvesting (FUE and LSE using FUE-LE) in order to optimize graft yield for patients and avoid long-term donor depletion. Based on limited experience, it appears the technique of FUE-LE will help achieve this goal.

Advancements in Graft Placement Techniques.

For decades, the placement of follicular units (FUs) into incisions in the recipient area was exclusively carried out using forceps. In 1992, Dr. Choi introduced an instrument known as the "implanter," which had the advantage of simultaneously creating incisions and placing FUs without damaging sensitive parts. Its initial popularity was greater in the East, primarily due to the characteristics of Asian hair. Asian hair is typically straight and thick, with FUs mostly consisting of just one or two hair.With the description of the follicular unit excision (FUE) technique in 2002 and its widespread adoption nearly a decade later, the advantages of using the implanter also gained popularity in the West. The uniformity in the size of FUs provided by the FUE technique and the possibility of delegating the placement were key attractions in the use of this placement tool. In addition to the traditional Korean implanter with a sharp needle, other implanters and inserters have been described.The choice of implantation technique depends on individual adaptation and the advantages and disadvantages offered by each instrument. Although forceps allow for safe placement in the hands of well-trained teams, the increased fragility of FUs obtained with the FUE technique has led to the growing acceptance of techniques that employ implanters and inserters.

Paradigm Shift from Linear Strip to Follicular Unit Excision in Hair Restoration Surgery.

Follicular unit excision (FUE) is a very effective and valuable modality for obtaining donor hair follicles using manual, motorized, or robotic devices to harvest individual donor follicular units in situ without a linear donor scar or visible scarring making it ideal for patients who wish to wear their hair short and hide signs of surgery. Over the past two decades, FUE has become increasingly popular, and the rising demand for FUE has driven the worldwide market size of hair restoration surgery (HRS) to an unprecedented height.FUE has revolutionized the HRS industry and offers excellent cosmesis and high patient satisfaction. Unfortunately, a large part of the favorable appeal of FUE is due to false claims that it is "minimally invasive," "scarless," or "not even surgery." Most patients opt-in for FUE due to these misconceptions, which are advertised by "black-market" clinics offering low-cost FUE surgery performed by amateur, nonprofessional technicians on unsuspected patients. The technique appears deceptively simple, and many neophyte surgeons falsely believe that the learning curve of FUE is short because the barrier of entry is low and no previous surgical skill is required. Nevertheless, injuries on grafts are extremely easy to occur since FUE is a blind technique and can be minimized only with excellent technique, which takes years to master.FUE actually presents unique challenges for the surgeon and carries potential long-term permanent side effects if not performed properly. The surgeon must have a thorough understanding of the nuances of the FUE surgical technique to ensure consistent graft quality and favorable cosmesis of both donor and recipient areas. Efficient FUE requires dexterity, training, dedication, devotion, enthusiasm, cognitive clarity, scientific knowledge, experience, and an extended learning curve.FUE is an invaluable addition to the armamentarium of a hair restoration surgeon but has to be judiciously performed.

Follicular Unit Excision (FUE) Basics.

Follicular unit excision (FUE) has risen to the forefront as the world's most popular hair transplant procedure. However, most writing on this subject has catered to the advanced practitioner. The goal of this article will be to focus on safe planning and decision making along with key technical steps that will guide the beginner surgeon to harvest a graft safely and to harvest the donor area in a uniform way to avoid overharvesting. Topics covered in this article also include instrumentation and decision making between FUE versus linear strip excision.

Concepts, Terminology, and Innovations in Follicular Unit Excision Hair Restoration Surgery.

Follicular unit excision (FUE) has emerged as the preferred method for hair transplants. Standardized terms and definitions established by members of the International Society of Hair Restoration Surgery and prominent hair restoration surgeons have become the standard, enabling effective knowledge sharing. This chapter provides an overview of the terminology relating to the field.The historical evolution of FUE and its pivotal role in modern hair transplantation is summarized. Anatomical terminology and graft-related definitions follow, providing insights into the scalp's complex structures and graft characteristics. The subsequent sections detail the terminology associated with graft excision and extraction, shedding light on the precise techniques and procedures employed. An exploration of various FUE techniques and the evolving landscape of FUE devices underscores the continual refinement of hair restoration practices. The chapter proceeds to discuss the "safe'" scalp donor zones, donor assessment terminology, and elements in identifying the optimal donor area for a successful FUE procedure. Additionally, punch dynamics and technique characteristics are examined, emphasizing their pivotal role in achieving superior FUE outcomes. The chapter concludes by discussing the classification of punches and graft evaluation terms, offering insights into the tools, and criteria used to assess graft quality and viability.

Utility of Follicular Unit Excision Using Nonscalp Donor Hair.

Nonscalp donor hair harvesting or body hair transplantation offers patients an additional source of donor hair in cases when the scalp does not have an adequate supply for the intended recipient area. The most common applications for nonscalp donor hair are for patients with advanced hair loss or to camouflage scarring from prior hair restoration procedures. For patients with available body hair, the beard is probably the best source followed by the chest and abdomen. Combined, these sources may be able to provide thousands of additional grafts for transplantation. Nonscalp hair donor harvesting is technically challenging and should be performed by those with extensive experience in follicular unit excision surgical techniques.

Patient Selection for Follicular Unit Extraction versus Linear Strip Donor Harvesting.

Follicular unit grafts can be harvested using two methods: strip follicular unit transplantation and follicular unit excision. Each method can generate outstanding results, but both are uniquely different with respect to the advantages and disadvantages they offer. Devising a sound surgical plan is instrumental to assure that a patient's short-term and long-term goals can be met, but creating the best plan possible for the graft harvest process is not straightforward. This paper will review the various advantages and disadvantages of each graft harvest method, along with their short-term and long-term ramifications, so as to provide insight into the process by which a sound surgical plan can be developed for any patient seeking surgical hair restoration.

Follicular Unit Excision in Patients of African Descent: A Skin-Responsive Technique.

BACKGROUND: Follicular unit excision is a favored minimally invasive hair transplantation method. However, it is suboptimal for many patients of African descent because of wide variations in hair and skin characteristics. OBJECTIVE: To evaluate the performance of a skin-responsive follicular unit excision device, which accommodates hair curliness, skin thickness, and firmness in patients of African descent. MATERIALS AND METHODS: The authors retrospectively evaluated patients who underwent scalp follicular unit (FU) excision using a skin-responsive technique at 7 multinational clinics. The preoperative donor grading for the anticipated difficulty used a scale with Class V indicating the highest degree of hair curliness, skin thickness, and firmness. RESULTS: Of 64 eligible patients (45 males and 19 females), 28 had Class V FU excision donor grades. The mean transection rate for all patients was 3%-6%, which was highest in class V patients. Skin thickness and firmness had a greater effect on the maximum transection rate than hair curliness. Only 19 or 18 G punches were used. CONCLUSION: The authors report consistence success of a new skin-responsive FU excision device for all patients of African descent with a mean graft transection rate of less than 10%. The findings support skin thickness and firmness as major influencers of graft attrition rate.

The application of electrolysis of depigmented hair using a trichiasis electrolyzer combined with single hair follicle transplantation for the treatment of vitiligo-associated leukotrichia.

Leukotrichia is one of the difficulties of vitiligo treatment. Hair follicle transplantation is an efficient method to treat vitiligo-associated leukotrichia. A trichiasis electrolyzer, commonly used for treating trichiasis, can be used to damage and remove the depigmented hair follicles. To evaluate the efficacy of the electrolysis of depigmented hair using a trichiasis electrolyzer combined with single hair follicle transplantation for the treatment of vitiligo-associated leukotrichia. A total of 15 patients with stable vitiligo-associated eyebrow and eyelash leukotrichia were enrolled from Department of Dermatology, Hangzhou Third People's Hospital between January 2020 and January 2021. All patients were treated using a trichiasis electrolyzer combined with single hair follicle transplantation. The patients were followed up at the first week, the first month, the third month, and the sixth month after surgery. The texture and growth state of the transplanted hair were observed, and the number of surviving transplanted follicles and regenerating depigmented follicles were recorded. The transplanted hair grew as expected with natural shape. No local infection or obvious scar was observed. Most of the depigmented hair in the lesion area re-pigmented and only a few depigmented hairs regenerated. The average survival rate of the transplanted hair follicles was 71.6%, and the average regeneration rate of the depigmented hair was 11.6%. The electrolysis of depigmented hair using a trichiasis electrolyzer combined with single hair follicle transplantation was an effective and safe method to treat vitiligo-associated leukotrichia.

Chronologic improvement in hair yield with follicular unit excision with changes in punch devices: A 10-year experience of a single center.

Follicular unit excision (FUE), which is a newer hair transplant procedure was thought to be only usable in limited areas at the beginning. However, it is the most preferred technique these days. It is known transection rates have decreased with punch technology (and experience) over the years. We analyzed the data from so-so many male patients who underwent hair transplantation by FUE method at our clinic retrospectively to elucidate how the development of punch technology affected the number of total grafts and FU containing multiple hairs. Between the years 2011 and 2020, male hair transplant patients operated with the FUE method at the author's dermatology clinic, was investigated retrospectively. Overall 1415 cases were included in the study. Total graft numbers and 1-4 hair FUs were calculated. There was a statistically significant difference in terms of number of total grafts, one hair follicular unit (I FU) three hair follicular unit (III FU) distributions according to operation year and punch type (p < 0.05). The serrated punch resulted in a significant increase in the numbers of total grafts and the trumpet punch resulted in a significant increase in the number of 3FU grafts. Our study has shown that hair yield has been increased with new punch technologies. With an increasing hair yield by the aid of evolving punch technology, hair transplantation with the FUE method has become the first choice for hair transplantation preferred by both doctors and patients.

The role of autologous micrografts injection from the scalp tissue in the treatment of COVID-19 associated telogen effluvium: Clinical and trichoscopic evaluation.

The clinical presentation of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2 COVID-19) varies from asymptomatic infection to a life-threatening, multiorgan disease. One of these manifestations is telogen effluvium (TE) which is characterized by diffuse hair loss occurring in patients previously infected with SARS-CoV-2 and lasts ~3 months, after which excessive hair loss follows. Hair follicles are known to contain a well-characterized niche for adult stem cells which is the bulge containing epithelial and melanocytic stem cells. Stem cells in the hair bulge, a demarcated structure within the lower permanent portion of hair follicles, can generate the interfollicular epidermis, hair follicle structures, and sebaceous glands. This study aims to evaluate autologous micrografts from scalp tissues as a therapeutic modality in the management of TE caused by COVID-19. Twenty patients of previous COVID-19 infection suffered from TE were included in this study for human follicle stem cells micrograft scalp treatment and they were evaluated after 3 months of treatment and after 6 months. There was significant improvement of the hair thickness and density compared with the start of the treatment and 6 months of follow-up. Autologous micrograft of the scalp showed marked improvement in the treatment of COVID-19 TE.

Frontal-Temporal Triangle Area Hair for Eyebrow Restoration in Asians: A Comparative Study With Periauricular and Occipital Hair.

BACKGROUND: The frontal-temporal triangle area (FTTA) hair has a slow growth rate and thin caliber, which are similar to those of eyebrow hair. However, a comparison of cosmetic outcomes between FTTA and other scalp hair grafts in eyebrow transplantation has not been performed. OBJECTIVE: To compare the cosmetic outcomes of FTTA hair and periauricular and occipital area (POA) hair in eyebrow restoration. METHODS: A retrospective analysis of 155 patients with FTTA or POA hair transplants was performed. Comparative variables included patient characteristics, hair density, diameter, percentage of one-hair follicular units (FUs), number of transplanted FUs, harvesting time, transection rate, hair survival rate, frequency of eyebrow trimming, and patient satisfaction. RESULTS: There was a significant difference in hair density, diameter, percentage of one-hair FUs, and harvesting time between the FTTA and POA hair transplants. The FTTA hair grew significantly slower than the POA hair did. The patients in the FTTA group trimmed their postoperative eyebrows at a significantly longer interval than those in the POA group. The percentage of patients who were very satisfied with the surgery results was higher in the FTTA group. CONCLUSION: The FTTA hair grafts can provide aesthetically pleasing cosmetic results in eyebrow restoration.

Comparative Graft Survival Study of Follicular Unit Excision Grafts With or Without Minor Injury.

BACKGROUND: Various types of follicular trauma occur during follicular unit excision (FUE). However, the effects of different types of follicular injury on graft survival have not been reported. OBJECTIVE: This study was performed to evaluate the differences in hair follicle survival by the type of follicular injury, including paring, fracture, and bulb injury. METHODS: Seven healthy patients who underwent hair transplant surgery by FUE were enrolled in the study. For each patient, 10 single-hair follicular unit grafts per injury group (paring, fracture, bulb injury, or intact) were differentiated. Using sharp implanters, 10 grafts of each of the 4 injury types were transplanted into mice, and the mice were sacrificed 5 months after transplantation. The skin was excised at each of the 4 locations, and newly formed follicular units were counted and photographed under a microscope. RESULTS: Of 70 hair follicles in each group, the number of successfully engrafted follicles was 50 (71.43%) in the intact group, 36 (51.43%) in the paring injury group, 9 (12.86%) in the fracture injury group, and 31 (44.29%) in the bulb injury group. CONCLUSION: Grafts with minor injury had a lower survival rate than intact grafts. Fractured follicles showed the lowest survival rate.

Extensive Scarring Alopecia Treated Through a Single Dense-Packing Follicular Unit Extraction Megasession.

BACKGROUND: Follicular unit extraction (FUE) is becoming more popular in hair restoration. However, its potential for treating extensive scarring alopecia is unknown. METHODS: Patients with scarring alopecia larger than 100 cm2 were enrolled from 2015 to 2018. After assessing scar quality regarding vascularity, pliability, and thickness, dense-packing megasession (DPM)-FUE was performed on high-quality recipient sites. Patients were followed up at 1 week and 12 months postoperatively to evaluate complications, survival rates of grafts, and patient satisfactions. Cases of nonscarring alopecia were reviewed as controls. RESULTS: Fifty-two scarring alopecia and 55 nonscarring alopecia patients were enrolled. The mean scar area was 120 cm2, and the procedure required an average of 8 operative hours, with no difference between groups (p > .05). Graft amount and postoperative complications were similar as well (p > .05). The survival rate in scarring alopecia was lower than that in the control but was still 85% (p < .05). Follow-up photographs showed effective scar camouflage after DPM-FUE. Most patients were very satisfied with the final results (p > .05). CONCLUSION: DPM-FUE is a safe and effective treatment for extensive scarring alopecia.

Effect of De-epithelialization on Graft Survival Rate After Follicular Unit Extraction.

BACKGROUND: To achieve a natural postoperative appearance, hair grafts are often de-epithelialized from the epidermis during follicular unit extraction (FUE). However, the effect of de-epithelialization on the survival rate of transplanted hair follicles (HFs) has not been investigated. OBJECTIVE: To investigate the effect of de-epithelialization on the survival rate of transplanted HFs. METHODS: A total of 64 male patients with androgenetic alopecia were included in this study. They were randomly divided into de-epithelialization and control groups. Organ culture was performed to assess the elongation of hair shaft and the percentage of anagen HFs in both groups. Patients were followed up postoperatively to evaluate complications, postoperative shedding, survival rates, and satisfaction. RESULTS: No significant difference in hair shaft elongation and percentage of anagen HFs was observed between both groups. The immediate postoperative satisfaction in the control group was much lower than that in the de-epithelialization group (71.25% and 100%, respectively). No significant differences in shedding rate, graft survival rate, and complications were noticed between both groups. CONCLUSION: Follicular de-epithelialization does not affect the survival rate of graft in FUE. Based on these data, de-epithelialization may improve immediate postoperative appearance and lead to a more pleasing cosmetic outcome.

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.

Progenitor-cell-enriched micrografts as a novel option for the management of androgenetic alopecia.

Regenerative medicine is a multidisciplinary field that combines engineering and life science principles to promote regeneration, potentially restoring the physiological condition in diseased tissues. Specifically, the developments of complex grafts enhance the intrinsic regenerative capacity of the host by altering its environment. Autologous micrografts obtained through Rigenera® micrografting technology are able to promote derma and bone regeneration. Androgenetic alopecia (AGA) leads to a progressive thinning of scalp hair affecting 60-70% of the adult population worldwide. Pharmacological treatment offers moderate results and hair transplantation represents the only permanent treatment option. The aim of this study was to demonstrate the role of dermis micrografting in the treatment of AGA by clinical and histological evaluations after 4, 6, and 12 months. Hair growth and density were improved at all indicated times. Those outcomes were also confirmed by the TrichoScan® analysis, reporting an increase of total hair count and density with an increase and reduction of anagen and telogen phases, respectively. Scalp dermoscopic analysis showed an improvement of hair density and histological analysis indicated a clear amelioration of the scalp, development of hair follicles, and a beginning of cuticle formation. Collectively, those results suggest a possible use of the micrografts as a novel therapeutic option in the management of AGA.