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Context: Laser hair removal treatment for hairlines with an unsatisfactory appearance often leads to an unnatural appearance; however, few studies have reported treatment outcomes., Objective: To explore the satisfaction rate of laser hair removal involving the hairline., Design: Retrospective analysis., Setting: Data from 5 clinical institutions., Patients: Patients (915; 630 female and 285 male) who underwent laser hair removal., Interventions: Issues associated with hair removal were classified, and their proportions were calculated. Hair transplantation was performed to improve the appearance of different hairline issues., Main Outcome Measures: Relevant indicators of hair transplantation and postoperative effects., Results: Overall, 82 patients were unsatisfied with their hairline appearance; of these patients, 58 underwent hair transplantation to improve the hairline. Additionally, demographic statistics showed that 68% and 32% of patients were in the 20 to 30 and 30 to 40 years age groups, respectively; there were no patients in the 40 to 50 years age group. Among female patients who underwent hair transplantation, 25% had a poor hairline position, 64% had a stiff hairline appearance, and 11% experienced both issues. Among male patients, 50% had a stiff hairline appearance, 28% had temporal absence, and 22% experienced both issues. Surgical treatment included moving the hairline forward and rebuilding the frontal curves. All patients were satisfied with hair transplantation outcomes., Conclusions: Laser hair removal can result in diverse types of unnatural hairlines. Hair transplantation has been proven to effectively improve the aesthetic appearance of the hairline., (Copyright © 2024 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.)

Background: Recipient-area perifollicular erythema (RPE) may delay graft growth after hair transplantation. However, there is currently a lack of observational clinical studies of RPE., Objective: To study the clinical features and risk factors associated with RPE while analyzing its correlation with graft growth., Methods: We conducted a multicenter retrospective cohort study between June 2020 and January 2023., Results: A total of 1090 participants were included, 178 (16.33%) showed mild RPE, 56 (5.14%) showed moderate RPE, and 10 (0.92%) showed severe RPE. Patients with RPE had severe hair shaft shedding (P < 0.001) and a lower survival rate (P < 0.001) of grafts. Logistic regression analysis showed that folliculitis is a significant risk factor for mild RPE (OR 6.061, 95% CI 3.343-10.991, P < 0.001) and moderate RPE (OR 3.397, 95% CI 1.299-8.882, P = 0.013). Besides, untimely first postoperative hair washing was associated with the development of moderate RPE (OR 0.724, 95% CI 0.553-0.947, P = 0.018) and severe RPE (OR 1.553, 95% CI 1.156-2.086, P = 0.003)., Conclusion: RPE is a postoperative complication closely related to high hair shaft shedding proportion and low graft survival rate. Both postoperative folliculitis and untimely first postoperative hair washing may induce the occurrence of RPE., 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 ., (© 2024. Springer Science+Business Media, LLC, part of Springer Nature and International Society of Aesthetic Plastic Surgery.)

Dermal white adipose tissue (dWAT) is a dynamic component of the skin and closely interacts with the hair follicle. Interestingly, dWAT envelops the hair follicle during anagen and undergoes fluctuations in volume throughout the hair cycle. dWAT-derived extracellular vesicles can significantly regulate the hair cycle, and this provides a theoretical basis for utilizing adipose tissue as a feasible clinical strategy to treat hair loss. However, the amount and depth of the available literature are far from enough to fully elucidate the prominent role of dWAT in modulating the hair growth cycle. This review starts by investigating the hair cycle-coupled dWAT remodeling and the reciprocal signaling interplay underneath. Then, it summarizes the current literature and assesses the advantages and limitations of clinical research utilizing adipose-derived therapies for hair regeneration., Competing Interests: Conflicts of interest None disclosed., (Copyright © 2021 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2022 by the American Society for Dermatologic Surgery, Inc. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Background: Hair transplantation is the gold standard method for the treatment of alopecia. Recently, demand for the surgery has increased rapidly. However, high demands also require more professional training for the surgeons. With the maturing of hairline design skills, parietal whorl design has become the next challenge and no appropriate training models have yet been reported., Aims: To present an innovative, simple, and appropriate training model for designing the scalp parietal whorl., Methods: Outward divergent arc curves were drawn from the navel of an orange. Recipient sites were created with 23G needles or 1.0-mm knives or 1.0-mm blades according to the outward divergent arc curves, then hair shafts were transplanted using forceps., Results: Different densities of hair shafts were transplanted. Transplantation of 10-20 follicular units (FU)/cm 2 was too sparse, 30 FU/cm 2 achieved a good appearance, but 40-50 FU/cm 2 was better. Through practicing on the model, excellent results of parietal whorl transplantation on patients can be achieved., Conclusions: This new model can perfectly suit the lines and direction of the parietal whorl and also present different density transplantation practicing. We provide a training method for new surgeons as well as a rehearsal opportunity for previously trained doctors., (© 2019 Wiley Periodicals, Inc.)

Background: It is necessary to evaluate a successful cosmetic procedure from the patients' perspective. FACE-Q is a patient-reported outcome scale for patients undergoing cosmetic procedures. However, currently there are no FACE-Q scales used in the field of hair transplant surgery. This article aims to apply FACE-Q scales to evaluate the satisfaction of patients undergoing hair transplantation surgery., Methods: FACE-Q scales were modified to contain both preoperative and 6-month postoperative self-assessment, including baseline preoperative information of patients (such as age, family history of alopecia, Hamilton' alopecia grade),preoperative self-assessment (satisfaction with appearance, the preoperative visual age, expected visual age) and postoperative self-assessment (satisfaction with appearance, postoperative visual age, satisfaction with decision, psychological well-being and social function). Besides, early life impact and recovery early symptoms were also re-evaluated., Results: The mean difference between the 6-month satisfaction with appearance and baseline scores showed a significant increase of 29.62 (baseline, 46.97; 6-month, 76.59; P < 0.001) and patients perceived they appeared 5.81 years younger after surgery (P < 0.001). Postoperative satisfaction with appearance has no significant relevance with gender (P = 0.460), age (P = 0.529), marriage (P = 0.811) or family history of alopecia (P = 0.641). However, income (P = 0.003), educational level (P = 0.003), the purpose of hair transplantation (P = 0.018) and early life impact (P = 0.002) were shown to have a significant impact on satisfaction with appearance., Conclusions: The FACE-Q scales are a valid and reliable patient-reported outcome tool for patients undergoing hair transplantation and can be widely used to evaluate the satisfaction of patients undergoing such surgery., Level of Evidence Iv: 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 .

Hair transplantation involves the transplantation of hair, beard, eyebrows, eyelashes, and pubic hair. Based on our experience, the aesthetic result of hair transplantation mainly relies on 4 indicators, including selection of the donor site, direction and angle of grafted hairs, density, and survival rate of implanted hair follicles. We believe that good results can be achieved as long as attention is paid to the above 4 points.

Background: It has been reported that collagenases (matrix metalloproteinase 2 [MMP-2] and matrix metalloproteinase 9 [MMP-9]) are associated with hair cycle, whereas the mechanism of the association is largely unknown., Methods: The mice were randomly allocated into four groups: saline, and 5, 10, and 15 nM SB-3CT. Immunohistochemical analysis was employed to examine MMP-2 and MMP-9 protein. Real-time polymerase chain reaction and enzyme-linked immunosorbent assay were performed to determine mRNA and protein levels of VEGF, IGF-1, TGF-β, and GAPDH. Growing hair follicles from anagen phase III-IV were scored based on hematoxylin and eosin staining. Hair regrowth was also evaluated., Results: Results showed that mRNA expressions of enzymes changed with a peak at late anagen and a trough at telogen after depilation. Immunostaining showed that the highest expression of MMP-2 was more than that of MMP-9, and the highest expression of enzymes changed during anagen. The localizations of MMP-2 changed from dermal papilla, keratinocyte strand, out of root sheath, and basal plate at early anagen, to hair bulb, inner root sheath, and outer root sheath at late anagen. The localization of MMP-9 changed from partial keratinocyte to dermal papilla at early anagen and to outer root sheath at late anagen. VEGF, IGF-1, and TGF-β have been shown to regulate hair growth. We found mRNA and protein expressions of VEGF and IGF-1 fluctuated with a peak at anagen and a decrease at catagen to telogen. In contrast, mRNA and protein expressions of TGF-β changed with highest and lowest levels at anagen and telogen, respectively. With selective inhibitor of collagenase IV, SB-3CT, mice showed significant suppressed hair growth and decreased expression of VEGF, IGF-1, and TGF-β. The MMPs agonist also significantly increased expression of VEGF, IGF-1, and TGF-β. Meanwhile, SB-3CT treatment significantly suppressed hair growth., Conclusion: All these data suggest that the type IV collagenases, MMP-2 and MMP-9, play important roles in hair cycle, and this could be mediated by induced expression of VEGF, IGF-1, and TGF-β.

Objective: To investigate the effect of 6-gingerol, the main active component of ginger, on hair shaft elongation in vitro and hair growth in vivo., Methods: Firstly, Hair follicles were co-cultured with 3 different concentration of 6-gingerol for 5 days and hair elongation in three groups was measured. Secondly, The proliferative effect of 6-gingerol on DPCs was measured using MTT assay. Thirdly, the expression of Bcl-2 and Bax in DPCs were measured using Western blotting. In vivo study, the influence of 6-gingerol on hair growth in C57BL/6 rats was measured through topical application of 6-gingerol on the dorsal skin of each animal., Results: The length of hair shaft in 20 microg/ml 6-Gingerol group (0.50 +/- 0.08 mm) is less than 0 microg/ml (0.66 +/- 0.19) mm and 10 microg/ml (0.64 +/- 0.03) mm 6-Gingerol group (P < 0.05). In cell culture, compared to 0 microg/ml and 5 microg/ml 6-Gingerol, 10 microg/ml 6-Gingerol can significantly inhibited the proliferation of DPCs (P < 0.05). Along with the growth inhibition of DPCs by 6-gingerol, the Bax/Bcl-2 ratio increased obviously. In vivo study, the hair length and density decreased a lot after using 1 mg/ml 6-gingerol., Conclusions: 6-Gingerol can suppress human hair shaft elongation because it has pro-apoptotic effects on DPCs via increasing Bax/Bcl-2 ratio. It might inhibit hair growth by prolonging the telogen stage in vivo.

Objective: To investigate the effect of embryonic dermal signal on the hair-inductive capacity of neonatal mice dermal cells which have been amplified in vitro., Methods: Embryonic mice dermal cells of embryonic day 14 were added to a chamber on the back of nude mice with neonatal mice dermal cells which had been amplified in vitro for 3 days and freshly isolated neonatal mice epidermal cells. The hair regeneration was compared between the groups with or without embryonic mice dermal cells. Meanwhile, chambers with following cells respectively were constructed as controls: embryonic mice dermal cells + neonatal mice epidermal cells; freshly isolated neonatal mice dermal cells + neonatal mice epidermal cells; amplified neonatal mice dermal cells only; embryonic mice dermal cells only; freshly isolated neonatal mice dermal cells only; neonatal mice epidermal cells only., Results: The number of regenerated hairs with the aid of embryonic mice dermal cells (207 +/- 15. 948) was significantly higher than that (67 +/- 8.963) in the group without embryonic mice dermal cells (n = 3, t = 7.653, P = 0.002)., Conclusion: Embryonic dermal signal can enhance the hair-inductive capacity of neonatal mice dermal cells which have been amplified in vitro.

Objective: To construct a convenient, reliable and visual model of hair follicle development to test the hair-inductive potential of follicular cells and investigate the molecular mechanism regulating hair follicle morphogenesis and cycling., Methods: An open chamber was transplanted into the nude mice dorsal skin, dermal and epidermal cells isolated from newborn C57BL/6 mice skin were mixed at a specific ratio and then injected into the chamber together, 1 week after transplantation, the chamber was removed, and then, hair formation and regeneration after hair plucking was observed., Results: 1 week after cells implantation, the wound was moist without apparent contraction and among that pink and translucent tissue was formed. 2 weeks after implantation, the wound healed completely. 3 weeks after implantation, black hair grew from the skin was observed. 4 weeks after implantation, thick and black hair grew from the skin vertically. Completely developed structure of hair follicle was observed with paraffin section and HE staining. 1 week after plucking, new hair had regrown. The ratio of cell component was varied, whereas the other component was fixed at 1 x 10(7) cells. When the number of epidermal cells was reduced to 1 x 10(6) cells, the efficiency of hair follicle reconstitution was mostly unchanged. On the other hand, the density of newly formed hair was diminished considerably by reducing the number of dermal cells to 5 x 10(6) cells or lower. Neither epidermal cells nor dermal cells transplanted alone formed hair follicle., Conclusions: Newborn mice skin cells transplanted by chamber method can construct a complete model of hair follicle development, which can be used to test the hair-inductive potential of follicular cells and investigate the molecular mechanism regulating hair follicle morphogenesis and cycling.

Objective: To observe the hair development after subcutaneous implantation of embryonic skin cells in nude mice, and construct a model of hair development., Methods: Dermal and epidermal cells isolated from embryonic mouse skin were mixed at a given ratio and injected subcutaneously in nude mice, and hair formation after the implantation was observed under a microscope., Results: Formation of the hair follicles and fibers under the skin of the recipient nude mice and emergence of the hair shaft were observed microscopically., Conclusion: Embryonic skin cells be used to construct a complete model of hair development after implantation in vivo.

Objective: To study the shaft elongation and morphological changes of follicle-unit (FUs) grafts subjected to controlled injury in different parts., Methods: Human FUs were isolated by microdissection under a dissecting microscope. The single hair of anagen FUs were randomly divided into A, B and C groups, and A and B groups were subjected to controlled injury with microsurgery imposed to the dermal papilla and the bulge of FUs, respectively, with C as the control group without any treatment. HE staining was used to detect the histological changes of the cells, and organ culture for 10 days was conducted to observe the morphological changes and elongation of FUs., Results: There were no histological or morphological changes in A, B and C groups. The average elongation of hair shaft was 1.293-/+0.245, 2.116-/+0.423 and 2.235-/+0.379 mm, respectively. There were significant differences between groups A and B (P<0.05) and between groups A and C (P<0.05). No significant difference was found between groups B and C (P>0.05)., Conclusion: Damage of the dermal papilla should be avoided in hair transplantation surgery.

In order to promote the development of hair transplantation, particularly the establishment of standards, the Hair Transplantation Expert Group of Plastic and Aesthetic National Medical Quality Control Center invited experts in the field of hair transplantation across China and formed a draft of the Expert Consensus on Standard Terminology for Hair Transplantation based on the collation of relevant literature and monographs. By combining Delphi methodology and consensus meetings, the expert group conducted several rounds of consultations on issues such as follicular unit anatomy, harvesting, dissection, and implantation, ultimately presenting 54 terminologies. This consensus considers the original Chinese and English meanings as well as the professional characteristics of terms used in hair transplantation, highlights the unique features and advantages of hair transplantation, and preserves its essence while promoting innovation, with the hope of providing valuable reference for clinical researchers engaged in hair transplantation both domestically and internationally, and better facilitating the standardization and advancement of the field.

Organoids have attracted extensive attention in the field of hair follicle (HF) tissue engineering and regeneration. However, HF organoid implantation faces a number of difficulties, such as low viability ratios, invasive trauma, and complicated procedures. To overcome these issues, a convenient and minimally invasive delivery approach with high efficiency and cell viability is required. Here, HF organoid‐loaded methacrylated gelatin‐cryomicroneedles (GelMA‐cryoMNs) that are capable of efficient transdermal delivery and can maintain the viability of the embedded organoids are developed. The GelMA‐cryoMNs are fabricated by a stepwise cryogenic molding process using a balanced ratio of cryopreservation agents and GelMA hydrogel. They can be inserted easily into porcine skin and melted without leaving residue after delivering the organoids. In vitro and in vivo, organoids delivered by the cryoMNs retain cell viability, self‐assembly, and differentiation ability. In mice, HF organoid‐loaded GelMA‐cryoMNs are delivered to the superficial dermis, resulting in subsequent HF development and the formation of an array of biomimetic hair tufts that broke through the skin surface. A promising strategy is provided here for biomimetic hair neogeneration that benefits from minimal invasion, low cost, and simple fabrication. The GelMA‐cryoMNs developed here could also have broader applications in tissue engineering and organ regeneration. [ABSTRACT FROM AUTHOR]

As one of the earliest and most visible phenomenon of aging, gray hair makes it a unique model system for investigating the mechanism of aging. Ionizing radiation successfully induces gray hair in mice, and also provides a venue to establish an organ-cultured human gray hair model. To establish a suitable organ-cultured human gray HF model by IR, which imitates gray hair in the elderly, and to explore the mechanisms behind the model. By detecting growth parameters, melanotic and senescence markers of the model, we found that the model of 5 Gy accords best with features of elderly gray hair. Then, we investigated the formation mechanisms of the model by RNA-sequencing. We demonstrated that the model of organ-cultured gray HFs after 5 Gy irradiation is closest to the older gray HFs. Moreover, the 5 Gy inhibited the expression of TRP-1, Tyr, Pmel17, and MITF in hair bulbs/ORS of HFs. The 5 Gy also significantly induced ectopically pigmented melanocytes and increased the expression of DNA damage and senescence in HFs. Finally, RNA-seq analysis of the model suggested that IR resulted in cell DNA damage, and the accumulation of oxidative stress in the keratinocytes. Oxidative stress and DNA damage caused cell dysfunction and decreased melanin synthesis in the gray HFs. We found that HFs irradiated at 5 Gy successfully constructed an appropriate aging HF model. This may provide a useful model for cost-effective and predictable treatment strategies to human hair graying and the process of aging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Layer-by-layer (LbL) self-assembly to construct nanoscale biomimetic ECM. • Ca2+ as a cross-linking agent to make size controllable dermal papilla (DP) spheroids. • Tissue engineering controllable human microtissue rich in ECM and vessels. • Vascularization prevents hypoxia-induced necrosis and functions in connection with host vessels. • Biomimetic ECM and vascularization triple hair induction efficiency. Regenerative medicine is a promising approach for hair loss; however, its primary challenge is the inductivity of human dermal papilla cells (DPCs), which rapidly lose hair growth-inducing properties in 2D culture. Despite extensive research efforts to construct DPCs, current 3D microenvironments fabricated to restore hair inductivity remain insufficient. Here, we aimed to fabricate ECM-enriched controllable vascularized dermal papilla (DP) spheroids that highly mimic in vivo DPCs microenvironments to restore their hair inductivity. We employed layer-by-layer (LbL) self-assembly using gelatin and alginate to construct nanoscale biomimetic ECM for DPCs, with Ca2+ as a cross-linking agent to create controllable DP spheroids. DPCs were also co-cultured with human umbilical vein endothelial cells to construct vascularized DP spheroids. Immunofluorescence staining and angiography was used to detect angiogenesis in vitro and in vivo. RNA sequencing and in vivo implantation were employed to investigate DPCs signature. LbL technology enabled DPCs to aggregate into controllable DP spheroids of size and cell numbers similar to those of primary DP. Vascularization prevented hypoxia-induced necrosis and functioned in association with host vessels post-transplantation. Compared with traditional 3D culture, nanoscale ECM and vascularization were found to restore the transcriptional signature of DPCs and triple hair induction efficiency following engraftment. Our novel biomimetic developmental tissue engineering strategy is a crucial step toward the recovery of human DPC hair inductivity, which would enable the rapid clinical application of large-scale hair regeneration platforms. [ABSTRACT FROM AUTHOR]

Intracutaneous transplantation of trichogenic cells is a currently endorsed strategy to realize hair regeneration in vivo. However, skin is not the most advantageous transplant site due to the robust mechanical property and deficient physiological perfusion. Herein, a subcutaneous space made of prevascularized collagen fibers (PVCF) generated by controlling the duration of in situ foreign body reaction is reported. In contrast to skin, an optimally preprogrammed PVCF presents a larger tissue volume (171 mm3), low Young's modulus (1/2‐fold), high flexibility high mechanical energy dissipation rate (1.3‐fold), highly permeable surface structure, and plentiful vascular network. Remarkably, cells transplanted into PVCF suffer less apoptosis and necrosis, and generate more mature hairs (≈289 per site) than that in intracutaneous transplantation (≈177 per site). The RNA‐sequencing profiling indicates similar trends under molecular level. This work provides a promising strategy to improve graft site microenvironment physiologically and mechanically, with a low‐cost and simple fabrication process. [ABSTRACT FROM AUTHOR]

Introduction: Beard hair serves as an important additional donor supply to support hair transplantation in hirsute patients with extensive alopecia and lacking sufficient occipital hair. However, the efficacy and safety of large-scale beard hair extraction have not been studied extensively in the East Asian population. Methods: Data obtained from hirsute patients with extensive alopecia who underwent hair transplantation between March 2017 and December 2018 at Nanfang Hospital were analyzed. Occipital and beard hair were evaluated separately during the pre-, intra-, and post-operative periods. Individual beard hair follicular units (FUs) were harvested under tumescence using a hollow punch with an outer diameter of 0.8–0.9 mm. Follow-up examinations were scheduled at 3–5 days, 1 month, and 9 months postoperatively to check for complications, determine the survival rate of mixed, transplanted FU grafts, and assess patient satisfaction. Data were collected and analyzed statistically. Results: A total of 36 hirsute, male patients with advanced androgenetic alopecia (AGA) (Norwood-Hamilton V–VI) were included in this study. The density of the occipital and beard areas was 78.6 ± 4.6 and 48.4 ± 9.3 FU, respectively. It took 3.1 ± 0.9 h to harvest 3135 ± 863 FUs from the occipital area and 2.1 ± 0.6 h to harvest 2352 ± 599 FUs from the beard area. The transection rate for occipital FUs and beard FUs was 3.7 ± 0.4 and 3.9 ± 0.2%, respectively. Completion of the operation took approximately 10.0 ± 0.9 h, and no serious complications were reported 5 days after the procedure. An FU survival rate of 95.7 ± 1.6% was observed at 9 months after transplantation, with no visible hypopigmented scars observed in the bare areas. All patients were satisfied with the resulting cosmetic appearance. Conclusion: Large-scale beard extraction, when combined with occipital hair extraction, is a safe and effective treatment to enhance the cosmetic appearance of East Asian men with advanced AGA. [ABSTRACT FROM AUTHOR]

Organ regeneration is becoming a promising choice for many patients; however, many details about the mechanisms underlying organ regeneration remain unknown. As regenerative organs, hair follicles offer a good model to study the mechanisms associated with regenerative medicine. The relevant studies have mainly focused on donor cells, and there are no systematic studies involving the effect of host factors on hair follicle reconstruction. Thus, we intend to explore the effect of host cells on hair follicle reconstruction. Epidermal and dermal cells from red fluorescent protein (RFP) transgenic newborn mice were injected into green fluorescent protein (GFP) transgenic mice. In addition, we wrapped the mixed dermal and epidermal cells from GFP transgenic and RFP transgenic mice by the Cell-in-a-Box kit to form "capsules," so that the cells within would be isolated from host cells. These capsules were cultured in vitro and transplanted in vivo. Fully developed reconstructed hair follicles were observed after the injection of mixed cells. These reconstructed follicles mainly consisted of donor cells, as well as a small number of host cells. The encapsulated cells gradually aggregated into cell spheres in vitro without apparent differentiation towards hair follicles. With respect to the transplanted capsules, concentric circle structures were observed, but no hair follicles or hair shafts formed. When the concentric circle structures were transplanted in vivo, mature hair follicles were observed 30 days later. Host cells were found in the reconstructed hair follicles. Thus, we conclude that host cells participate in the process of hair follicle reconstruction, and they play a vital role in the process, especially for the maturation of reconstructed hair follicles. Furthermore, we established a special hair follicle reconstruction system with the help of capsules: transplant cells were isolated from host, but other factors from host could exchange with cells inside. [ABSTRACT FROM AUTHOR]

[Display omitted] • A temperature-sensitive Platelet-rich Plasma (PRP) induced fibrin gel interpenetrated with the GelMA on a detachable transdermal microneedle (MN) for hair regrowth. • Duo-role PRP: temperature-induced fibrin gel as microneedle's enhanced network and GFs reservoir for microneedles to promote hair regrowth. • PRP-released GFs can be anchored into a GelMA/PRP matrix with an increased lifespan for a truly controlled release. • The application of PRP-MNs has promising effects and more cost-effective for hair regrowth due to the synergistic effect of multiple GFs. • PRP-MNs can benefit many other applications, such as oral and maxillofacial surgery, refractory wound, skin disease and rejuvenation, and reproductive medicine. Alopecia concerns more than half our adult population. Platelet-rich plasma (PRP) has been applied in skin rejuvenation and hair loss treatment. However, the pain and bleeding during injection and the troublesome for fresh preparation of each action limit PRP's in-depth applying dedication to clinics. We report a temperature-sensitive PRP induced fibrin gel included in a detachable transdermal microneedle (MN) for hair growth. PRP gel interpenetrated with the photocrosslinkable gelatin methacryloyl (GelMA) to realize sustained release of growth factors (GFs) and led to 14% growth in mechanical strength of a single microneedle whose strength reached 1.21 N which is sufficient to penetrate the stratum corneum. PRP-MNs' release of VEGF, PDGF, and TGF-β were characterized and quantitatively around the hair follicles (HFs) for 4–6 days consecutively. PRP-MNs promoted hair regrowth in mice models. From transcriptome sequencing, PRP-MNs induced hair regrowth through angiogenesis and proliferation. The mechanical and TGF-β sensitive gene Ankrd1 was significantly upregulated by PRP-MNs treatment. PRP-MNs show convenient, minimally invasive, painless, inexpensive manufacture, storable and sustained effects in boosting hair regeneration. [ABSTRACT FROM AUTHOR]

Lysozyme is a well-known antimicrobial peptide that exists widely in mammalian skin and it is also expressed by pilosebaceous units. However, the exact location of lysozyme in hair follicles and whether it exerts any direct effects on hair follicle growth are unclear. To determine whether lysozyme affected hair growth in vitro , micro-dissected mouse vibrissae follicles (VFs) were treated in serum-free organ culture for 3 days with lysozyme (1–10 μg/ml). After that, the effects of lysozyme on dermal papilla (DP) cells were also investigated. Lysozyme was mainly identified in DP and dermal sheath regions of VF by immunochemistry. In addition, 5–10 μg/ml lysozyme had a promoting effect on shaft production. It was also associated with significant proliferation of matrix keratinocytes by immunofluorescence observation. Furthermore, lysozyme promoted hair growth by increasing the levels of alkaline phosphatase and lymphoid enhancer factor 1 in DP, as determined by Western blotting. These results indicate that lysozyme is a promoter of VF growth via enhancing the hair-inductive capacity of DP cells during organ culture. [ABSTRACT FROM AUTHOR]