Platelet sonicates activate hair follicle stem cells and mediate enhanced hair follicle regeneration

A novel 22-bp InDel within FGF7 gene is significantly associated with growth traits in goat

Fibroblast growth factor 7 (FGF7) is involved in lipid metabolism, which is considered as a candidate gene with close relation with muscle development by eGWAs and RNA-Seq analyses. To date, limited research has been conducted on the relationship between FGF7 gene and growth traits. The main objective of this work was to further investigate the association between novel InDel within FGF7 gene and growth traits in goat. Herein, FGF7 mRNA expression levels were investigated in various Fuqing goat tissues. We found that FGF7 gene was expressed in six adult goat tissues with the highest mRNA levels in adipose tissue. This result suggested that FGF7 gene might play a critical role in fat deposition. We also detected potential polymorphisms in Fuqing, Nubian and Jianyang Daer breeds. A 22-bp InDel polymorphism in FGF7 gene was detected in 396 goats and the three genotypes were designated as II, ID, and DD. Correlation analysis revealed that InDel polymorphism was significantly associated with growth traits (P < 0.05). Goats with genotypes ID and/or II had superior growth traits compared to those with genotype DD. In summary, our findings suggested that the 22-bp InDel within FGF7 gene could act as a molecular marker to improve the growth traits of goats in breeding programs.

LncRNA018392 promotes the proliferation of Liaoning cashmere goat skin fibroblasts by upregulating CSF1R through binding to SPI1

BACKGROUND

Liaoning cashmere goat is recognized as a valuable genetic resource breed, with restrictions on genetic outflow in China. Hair follicle development in the cashmere goat is influenced by melatonin and long non-coding RNAs (lncRNAs). However, the role of lncRNAs in facilitating melatonin-promoted cashmere growth remains poorly understood. Previous studies have identified a new lncRNA, lncRNA018392, which is involved in the melatonin-promoted proliferation of cashmere skin fibroblasts.

METHOD

Flow cytometry and CCK-8 assays confirmed that silencing lncRNA018392 negates the effects of melatonin on cell proliferation, and that proliferation was reduced when the gene CSF1R, located near lncRNA018392, was inhibited. Further investigation using a dual-luciferase reporter assay showed that lncRNA018392 could positively regulate the promoter of CSF1R.

RESULTS

Results from RNA-binding protein immunoprecipitation (RIP) and chromatin immunoprecipitation sequencing (ChIP-Seq) revealed that lncRNA018392 interacts with the transcription factor SPI1, with CSF1R being a downstream target gene regulated by SPI1. This interaction was confirmed by ChIP-PCR, which demonstrated SPI1's binding to CSF1R.

CONCLUSIONS

This study found that the melatonin-responsive lncRNA018392 accelerates the cell cycle and promotes cell proliferation by recruiting SPI1 to upregulate the expression of the neighboring gene CSF1R. These findings provide a theoretical foundation for elucidating the molecular mechanisms of cashmere growth and for the molecular breeding of cashmere goats.

LncRNA RP11-818O24.3 promotes hair-follicle recovery via FGF2-PI3K/Akt signal pathway

A previous study indicated that patients with androgenic alopecia (AGA) have significantly reduced levels of LncRNA RP11-818O24.3. This study investigates whether LncRNA RP11-818O24.3 promotes hair-follicle recovery and its possible mechanism. Hair alteration and cutaneous histopathological changes induced by testosterone propionate were observed by H&E and bromodeoxyuridinc (BrdU) stain to evaluate the therapeutic effect of LncRNA RP11-818O24.3 in C57BL/6 J mice. The cellular viability was analyzed in LncRNA RP11-818O24.3-transfected human hair-follicle stem cells (HFSCs) in vitro. The signaling pathways and pro-proliferative factors were investigated by transcriptomic gene sequencing and qRT-PCR. LncRNA RP11-818O24.3 transfection successfully recovered hair growth and hair-follicle cells in AGA mice. In a series of HFSC studies in vitro, LncRNA RP11-818O24.3 transfection greatly promoted cellular proliferation and decreased cellular apoptosis. Transcriptome gene sequencing suggested that the phosphatidylinositol 3-kinase (PI3K)-Akt pathway was upregulated by LncRNA RP11-818O24.3. The qRT-PCR results showed that fibroblast growth factor (FGF)-2 was 14-times upregulated after LncRNA RP11-818O24.3 transfection. Hair-follicle recovery activity of LncRNA RP11-818O24.3 may involve the upregulation of FGF2 and PI3K-Akt to promote follicle stem cell survival. These data not only provide a theoretical basis for AGA development but also reveal a novel therapeutic method for AGA patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00624-3.

Concentrated growth factor therapy as cosmetic treatment in discoid lupus erythematosus

Discoid lupus erythematosus (DLE) is a disfigurement disease. The atrophic scar and hair loss of this disease are followed by cosmetic defects and profoundly impact psychological health. Concentrated growth factor (CGF) has been widely adopted in medical cosmetology. Here we report a 36-year-old female systemic lupus erythematosus patient with a 5-year history of alopecia in DLE, who was recommended for CGF therapy and experienced hair regrowth. We suggest that CGF may be an effective cosmetic treatment for DLE.

Effectiveness of Platelet-Rich Plasma in the Treatment of Androgenic Alopecia: A Meta-Analysis

BACKGROUND

Androgenetic alopecia (AGA) is a common yet difficult-to-treat condition, which is an important psychosocial problem. Platelet-rich plasma (PRP) therapy has been considered as a promising treatment for AGA. However, the current evidence on the efficacy of PRP for treating AGA is still controversial. This study evaluated the efficacy of PRP monotherapy in the treatment of AGA.

METHODS

We searched PubMed, Embase, Cochrane Library and Web of Science to collect randomized controlled trials on use of PRP in AGA for a meta-analysis.

RESULTS

Ten trials with a total 555 treatment units were identified. The hair density in PRP group was significantly higher than control group [MD = 25.09, 95%CI: 9.03-41.15, p = 0.002], but there was no significant difference in hair diameter between two groups [SMD = 0.57, 95%CI: - 0.23 to 1.38, p = 0.16]. Subgroup analyses indicated that hair density was significantly higher among the male-only trials than in the mixed-sex samples (p = 0.02). In addition, neither the split-head design nor the year of publication affected hair density (p = 0.05, p = 0.06). However, hair density was significantly higher in trials with a sample size less than 30 (p = 0.0004).

CONCLUSIONS

PRP treatment increased hair density in participants with AGA, but not hair diameter. In terms of hair density, PRP elicits stronger effects in male patients. There was a trend toward differed treatment effect by gender with PRP injection, which warrants further investigation. Especially in the case of female.

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 https://www.springer.com/00266 .

Isolation, characterization and differentiation of dermal papilla cells from Small-tail Han sheep

Dermal papilla cells (DPCs) are the key dermal component of the hair follicle that directly regulates hair follicle development, growth and regeneration. Successfully isolated and cultured DPCs from Small-tail Han sheep could provide a good model for the study of hair follicle development mechanism in vitro. DPCs were isolated using enzyme digestion and dissecting microscope from Small-tail Han sheep. Adherent cells were identified by cell characteristics, particular gene expression, differentiation capability to adipocyte and osteoblast using specific differentiation mediums. Additionally, flow cytometry was used to detect the cell cycle of DPCs. Cells originating from the dermal papilla showed the morphological appearance of mesenchymal cells (fibroblast-like cells). Purified DPCs were positive for α-SMA (α smooth muscle actin) and vimentin; in addition to their strong proliferation abilities in vitro, these DPCs can be differentiated into adipocyte and osteoblasts lineage under appropriate culture condition. DPCs were successfully isolated and subcultured from Small-tail Han sheep, which exhibited progenitor cell features and multiple differentiation potency. It provides a material for studying the molecular mechanism of hair follicle development and hair cycle, which will promote wool production in the future.

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.

Fabrication of carboxymethyl cellulose/hyaluronic acid/polyvinylpyrrolidone composite pastes incorporation of minoxidil-loaded ferulic acid-derived lignin nanoparticles and valproic acid for treatment of androgenetic alopecia

Androgenetic alopecia (AGA) is a transracial and cross-gender disease worldwide with a higher prevalence among young individuals. Traditional oral or subcutaneous injections are often used to treat AGA, however, they may cause severe side-effects and therefore effective treatments for AGA are currently lacking. In this work, to treat AGA, we developed a composite paste system based on minoxidil (MXD)-loaded nanoparticles and valproic acid (VPA) with the assistance of roller-microneedles (roller-MNs). The matrix of composite paste systems is carboxymethyl cellulose (CMC), hyaluronic acid (HA) and polyvinylpyrrolidone (PVP). The roller-MNs can create microchannels in the skin to enhance drug transdermal efficiency. With the combined effects of the stimulation hair follicle (HF) regrowth by upregulating Wnt/beta-catenin of VPA and the mechanical microchannels induced by roller-MNs, the as-prepared composite paste systems successfully boost perifollicular vascularization, and activate hair follicle stem cells, thereby inducing notably faster hair regeneration at a lower administration frequency on AGA mouse model compared with minoxidil. This approach offers several benefits, including the avoidance of efficacy loss due to the liver's first-pass effect associated with oral drug, reduction in the risk of infection from subcutaneous injection, and significant decrease in the side effects of lower-dose MXD.

Platelet lysate promotes hair growth: In vitro and in vivo mechanism and randomized, controlled trial

BACKGROUND

Platelet lysate (PL), a novel platelet derivative, has been widely used in regenerative medicine and is a potential therapy for improving hair growth. It is necessary to fully clarify the potential mechanism and evaluate preliminary clinical effect of PL on hair growth.

METHODS

We used the C57BL/6 model, organ-cultured hair follicles, and RNA-seq analysis to explore the mechanisms of PL regulating hair growth. Then, we performed a randomized, controlled, double-blind study of 107 AGA patients to verify the therapeutic efficacy of PL.

RESULTS

The results confirmed that PL improved hair growth and accelerated hair cycling in mice. Organ-cultured hair follicle evaluation confirmed that PL prolonged anagen remarkably and down-regulated IL-6, C-FOS, and p-STAT5a. Clinically, diameter, hair counts, absolute anagen counts and changes from baseline in the PL group showed a significant improvement at 6 months.

CONCLUSIONS

We elucidated the specific molecular mechanism of PL action on hair growth and proved equal changes in hair follicle performance after PL vs PRP in AGA patients. This study provided novel knowledge of PL, making it ideal for AGA.

Innovative Approaches and Advances for Hair Follicle Regeneration

Pathological hair loss (also known as alopecia) and shortage of hair follicle (HF) donors have posed an urgent requirement for HF regeneration. With the revelation of mechanisms in tissue engineering, the proliferation of HFs in vitro has achieved more promising trust for the treatments of alopecia and other skin impairments. Theoretically, HF organoids have great potential to develop into native HFs and attachments such as sweat glands after transplantation. However, since the rich extracellular matrix (ECM) deficiency, the induction characteristics of skin-derived cells gradually fade away along with their trichogenic capacity after continuous cell passaging in vitro. Therefore, ECM-mimicking support is an essential prelude before HF transplantation is implemented. This review summarizes the status of providing various epidermal and dermal cells with a three-dimensional (3D) scaffold to support the cell homeostasis and better mimic in vivo environments for the sake of HF regeneration. HF-relevant cells including dermal papilla cells (DPCs), hair follicle stem cells (HFSCs), and mesenchymal stem cells (MSCs) are able to be induced to form HF organoids in the vitro culture system. The niche microenvironment simulated by different forms of biomaterial scaffold can offer the cells a network of ordered growth environment to alleviate inductivity loss and promote the expression of functional proteins. The scaffolds often play the role of ECM substrates and bring about epithelial-mesenchymal interaction (EMI) through coculture to ensure the functional preservation of HF cells during in vitro passage. Functional HF organoids can be formed either before or after transplantation into the dermis layer. Here, we review and emphasize the importance of 3D culture in HF regeneration in vitro. Finally, the latest progress in treatment trials and critical analysis of the properties and benefits of different emerging biomaterials for HF regeneration along with the main challenges and prospects of HF regenerative approaches are discussed.

Platelets Facilitate Wound Healing by Mitochondrial Transfer and Reducing Oxidative Stress in Endothelial Cells

As a critical member in wound healing, vascular endothelial cells (ECs) impaired under high levels of reactive oxygen species (ROS) would hamper neovascularization. Mitochondria transfer can reduce intracellular ROS damage under pathological condition. Meanwhile, platelets can release mitochondria and alleviate oxidative stress. However, the mechanism by which platelets promote cell survival and reduce oxidative stress damage has not been clarified. Here, first, we selected ultrasound as the best method for subsequent experiments by detecting the growth factors and mitochondria released from manipulation platelet concentrates (PCs), as well as the effect of manipulation PCs on the proliferation and migration of HUVECs. Then, we found that sonicate platelet concentrates (SPC) decreased the level of ROS in HUVECs treated with hydrogen peroxide in advance, increased mitochondrial membrane potential, and reduced apoptosis. By transmission electron microscope, we saw that two kinds of mitochondria, free or wrapped in vesicles, were released by activated platelets. In addition, we explored that platelet-derived mitochondria were transferred to HUVECs partly by means of dynamin-dependent clathrin-mediated endocytosis. Consistently, we determined that platelet-derived mitochondria reduced apoptosis of HUVECs caused by oxidative stress. What is more, we screened survivin as the target of platelet-derived mitochondria via high-throughput sequencing. Finally, we demonstrated that platelet-derived mitochondria promoted wound healing in vivo. Overall, these findings revealed that platelets are important donors of mitochondria, and platelet-derived mitochondria can promote wound healing by reducing apoptosis caused by oxidative stress in vascular endothelial cells. And survivin is a potential target. These results further expand the knowledge of the platelet function and provide new insights into the role of platelet-derived mitochondria in wound healing.

Direct Reprograming of Mouse Fibroblasts into Dermal Papilla Cells via Small Molecules

The reprogramming of somatic fibroblasts into alternative cell linages could provide a promising source of cells for regenerative medicine and cell therapy. However, the direct conversion of fibroblasts into other functional cell types is still challenging. In this study, we show that dermal-papilla-cell-like cells (DPC-LCs) can be generated by treating fibroblasts, including L929 mouse fibroblast cell lines and somatic mouse fibroblasts, with small molecules. Based on alkaline phosphatase activity and other molecular markers, different compounds or their combinations are needed for converting the two different fibroblasts into DPC-LCs. Notably, we found that TTNPB alone can efficiently convert primary adult mouse fibroblasts into DPC-LCs. DPC-LCs generated from mouse fibroblasts showed a stronger hair-inducing capacity. Transcriptome analysis reveals that expression of genes associated with a hair-inducing capacity are increased in DPC-LCs. This pharmacological approach to generating functional dermal papilla cells may have many important implications for hair follicle regeneration and hair loss therapy.

Integrative analysis of circRNAs from Yangtze River Delta white goat neck skin tissue by high-throughput sequencing (circRNA-seq)

The Yangtze River Delta white goat is a unique goat species that can produce superior-quality brush hair. The formation of this brush hair is controlled by a series of critical genes and related signaling pathways. Circular RNAs (circRNAs), are ubiquitous endogenous non-coding RNAs that regulate many biological and physiological processes in mammals. However, little is known about the potential regulatory role of circRNAs on superior-quality brush hair formation in Yangtze River Delta white goat. In this study, high-throughput sequencing technology was used to only detect circRNAs in the neck skin tissue of normal-quality goats (NHQs) and superior-quality goats (HQs). A total of 61 803 circRNAs were identified and 32 of them were differentially expressed in the NHQ group vs. the HQ group. Functional enrichment analysis showed that the source gene of differentially expressed circRNAs (DE-circRNAs) was enriched mostly in platelet activation and the focal adhesion signal pathway. Action mechanism analysis revealed that DE-circRNAs could sponge to many identified miRNAs, including miR-31, miR-125b, miR-let-7a and miR-149-5p, which have important roles in goat hair follicle stem cell growth, hair follicle development and morphogenesis. Altogether, our findings provide a valuable basis for studying circRNAs involved in superior-quality brush hair traits and meanwhile advance our understanding of circRNA complex regulation mechanisms in Yangtze River Delta white goat skin hair follicle development.

A systematic summary of survival and death signalling during the life of hair follicle stem cells

Hair follicle stem cells (HFSCs) are among the most widely available resources and most frequently approved model systems used for studying adult stem cells. HFSCs are particularly useful because of their self-renewal and differentiation properties. Additionally, the cyclic growth of hair follicles is driven by HFSCs. There are high expectations for the use of HFSCs as favourable systems for studying the molecular mechanisms that contribute to HFSC identification and can be applied to hair loss therapy, such as the activation or regeneration of hair follicles, and to the generation of hair using a tissue-engineering strategy. A variety of molecules are involved in the networks that critically regulate the fate of HFSCs, such as factors in hair follicle growth and development (in the Wnt pathway, Sonic hedgehog pathway, Notch pathway, and BMP pathway), and that suppress apoptotic cues (the apoptosis pathway). Here, we review the life cycle, biomarkers and functions of HFSCs, concluding with a summary of the signalling pathways involved in HFSC fate for promoting better understanding of the pathophysiological changes in the HFSC niche. Importantly, we highlight the potential mechanisms underlying the therapeutic targets involved in pathways associated with the treatment of hair loss and other disorders of skin and hair, including alopecia, skin cancer, skin inflammation, and skin wound healing.

The role of CTHRC1 in hair follicle regenerative capacity restored by plantar dermis homogenate

Restoration of hair follicle (HF) regenerative capacity is the cornerstone in tissue engineering for the loss of regenerative capacity during in vitro expansion of skin-derived precursors (SKPs). Microenvironmental cues facilitated tissue or organ regeneration offers a potential strategy to overcome this difficulty. In our previous work, plantar dermis matrix homogenate (PD) has been proved to induce sweat glands regeneration both in vivo and in vitro. Here, we found PD also restore regenerative capacity of culture impaired HF spheroids (IHFS). Further, followed by our previous iTRAQ results, the CTHRC1 was identified as a potential regulator in PD facilitated restorative effects in HF regeneration. Knockout of Cthrc1 impaired HF regenerative capacity in spheroids, decreased the diameter of HF in 28 postnatal days mice and shortened invagination of HF bud in 18 days of gestation mice. In IHFS and Cthrc1-/- spheroids, PD partially restored HF regenerative capacity while Cthrc1-/- PD (PDKO) has less or no effect. Taken together, PD is an effective microenvironmental cues for HF regenerative capacity restoration and CTHRC1 played an important role in HF regeneration.

Platelet lysate: a promising candidate in regenerative medicine

Human platelet lysate has attracted much interest from many researchers as it is growth-factor rich for cell expansion, which is employed as a new therapeutic strategy. Not only are human platelet lysates used for cell therapy, but they are also used for the completion of basal media in mesenchymal stem cell cultures. Due to the presence of a large number of growth factors, platelet lysates have potential roles in wound healing, treatment of ocular graft-versus-host disease, osteoarthritis, Parkinson's disease, tendon regeneration, infertility, androgenetic alopecia, nerve repair and regenerative tissue, such as bone regeneration. In this review, we summarize that platelet lysates could be valuable candidates for the treatment of a variety of diseases in regenerative medicine.

Effects and mechanism of platelet-rich plasma on military drill injury: a review

Military drill injury is a significant part of military medical research. The increase of training intensity and changes in training methods lead to differences in injury types. The ideal therapeutic modality should allow rapid healing at a reasonable cost and minimize impact on patients' life. Platelet -rich plasma (PRP), a platelet concentrate, is rich in a variety of growth factors and widely used clinically as a minimally invasive treatment. It plays an important role in injury repair and rehabilitation. In this article, we review the therapeutic role of PRP in military drill injury and its possible underlying mechanisms, with a focus on plantar fasciitis, stress fractures and other common injuries, in order to provide basic support for military reserve.

Platelet-rich plasma accelerates skin wound healing by promoting re-epithelialization

BACKGROUND

Autologous platelet-rich plasma (PRP) has been suggested to be effective for wound healing. However, evidence for its use in patients with acute and chronic wounds remains insufficient. The aims of this study were to comprehensively examine the effectiveness, synergy and possible mechanism of PRP-mediated improvement of acute skin wound repair.

METHODS

Full-thickness wounds were made on the back of C57/BL6 mice. PRP or saline solution as a control was administered to the wound area. Wound healing rate, local inflammation, angiogenesis, re-epithelialization and collagen deposition were measured at days 3, 5, 7 and 14 after skin injury. The biological character of epidermal stem cells (ESCs), which reflect the potential for re-epithelialization, was further evaluated in vitro and in vivo.

RESULTS

PRP strongly improved skin wound healing, which was associated with regulation of local inflammation, enhancement of angiogenesis and re-epithelialization. PRP treatment significantly reduced the production of inflammatory cytokines interleukin-17A and interleukin-1β. An increase in the local vessel intensity and enhancement of re-epithelialization were also observed in animals with PRP administration and were associated with enhanced secretion of growth factors such as vascular endothelial growth factor and insulin-like growth factor-1. Moreover, PRP treatment ameliorated the survival and activated the migration and proliferation of primary cultured ESCs, and these effects were accompanied by the differentiation of ESCs into adult cells following the changes of CD49f and keratin 10 and keratin 14.

CONCLUSION

PRP improved skin wound healing by modulating inflammation and increasing angiogenesis and re-epithelialization. However, the underlying regulatory mechanism needs to be investigated in the future. Our data provide a preliminary theoretical foundation for the clinical administration of PRP in wound healing and skin regeneration.

Crosstalk between noncoding RNAs and ferroptosis: new dawn for overcoming cancer progression

Cancer progression including proliferation, metastasis, and chemoresistance has become a serious hindrance to cancer therapy. This phenomenon mainly derives from the innate insensitive or acquired resistance of cancer cells to apoptosis. Ferroptosis is a newly discovered mechanism of programmed cell death characterized by peroxidation of the lipid membrane induced by reactive oxygen species. Ferroptosis has been confirmed to eliminate cancer cells in an apoptosis-independent manner, however, the specific regulatory mechanism of ferroptosis is still unknown. The use of ferroptosis for overcoming cancer progression is limited. Noncoding RNAs have been found to play an important roles in cancer. They regulate gene expression to affect biological processes of cancer cells such as proliferation, cell cycle, and cell death. Thus far, the functions of ncRNAs in ferroptosis of cancer cells have been examined, and the specific mechanisms by which noncoding RNAs regulate ferroptosis have been partially discovered. However, there is no summary of ferroptosis associated noncoding RNAs and their functions in different cancer types. In this review, we discuss the roles of ferroptosis-associated noncoding RNAs in detail. Moreover, future work regarding the interaction between noncoding RNAs and ferroptosis is proposed, the possible obstacles are predicted and associated solutions are put forward. This review will deepen our understanding of the relationship between noncoding RNAs and ferroptosis, and provide new insights in targeting noncoding RNAs in ferroptosis associated therapeutic strategies.

PI3K/Akt signaling pathway is essential for de novo hair follicle regeneration

Background

Cultured epidermal stem cells (Epi-SCs) and skin-derived precursors (SKPs) were capable of reconstituting functional hair follicles after implantation, while the signaling pathways that regulate neogenic hair follicle formation are poorly investigated. In this study, we aimed to understand the interactions between Epi-SCs and SKPs during skin organoid formation and to uncover key signal pathways crucial for de novo hair follicle regeneration.

Methods

To track their fate after transplantation, Epi-SCs derived from neonatal C57BL/6 mice were labeled with tdTomato, and SKPs were isolated from neonatal C57BL/6/GFP mice. A mixture of Epi-SCs-tdTomato and SKPs-EGFP in Matrigel was observed under two-photon microscope in culture and after implantation into excisional wounds in nude mice, to observe dynamic migrations of the cells during hair follicle morphogenesis. Signaling communications between the two cell populations were examined by RNA-Seq analysis. Potential signaling pathways revealed by the analysis were validated by targeting the pathways using specific inhibitors to observe a functional loss in de novo hair follicle formation.

Results

Two-photon microscopy analysis indicated that when Epi-SCs and SKPs were mixed in Matrigel and cultured, they underwent dynamic migrations resulting in the formation of a bilayer skin-like structure (skin organoid), where Epi-SCs positioned themselves in the outer layer; when the mixture of Epi-SCs and SKPs was grafted into excisional wounds in nude mice, a bilayer structure resembling the epidermis and the dermis formed at the 5th day, and de novo hair follicles generated subsequently. RNA-Seq analysis of the two cell types after incubation in mixture revealed dramatic alterations in gene transcriptome, where PI3K-Akt signaling pathway in Epi-SCs was significantly upregulated; meanwhile, elevated expressions of several growth factors and cytokine potentially activating PI3K were found in SKPs, suggesting active reciprocal communications between them. In addition, inhibition of PI3K or Akt by specific inhibitors markedly suppressed the hair follicle regeneration mediated by Epi-SCs and SKPs.

Conclusions

Our data indicate that the PI3K-Akt signaling pathway plays a crucial role in de novo hair follicle regeneration, and the finding may suggest potential therapeutic applications in enhancing hair regeneration.

Thymosin β4 Identified by Transcriptomic Analysis from HF Anagen to Telogen Promotes Proliferation of SHF-DPCs in Albas Cashmere Goat

Increasing cashmere yield is one of the important goals of cashmere goat breeding. To achieve this goal, we screened the key genes that can improve cashmere performance. In this study, we used the RNA raw datasets of the skin and dermal papilla cells of secondary hair follicle (SHF-DPCs) samples of hair follicle (HF) anagen and telogen of Albas cashmere goats and identified a set of significant differentially expressed genes (DEGs). To explore potential associations between gene sets and SHF growth features and to identify candidate genes, we detected functional enrichment and constructed protein-protein interaction (PPI) networks. Through comprehensive analysis, we selected Thymosin β4 (Tβ4), Rho GTPase activating protein 6 (ARHGAP6), ADAM metallopeptidase with thrombospondin type 1 motif 15, (ADAMTS15), Chordin (CHRD), and SPARC (Osteonectin), cwcv and kazal-like domains proteoglycan 1 (SPOCK1) as candidate genes. Gene set enrichment analysis (GSEA) for these genes revealed Tβ4 and ARHGAP6 have a close association with the growth and development of SHF-DPCs. However, the expression of Tβ4 in the anagen was higher than that in the telogen, so we finally chose Tβ4 as the ultimate research object. Overexpressing Tβ4 promoted and silencing Tβ4 inhibited the proliferation of SHF-DPCs. These findings suggest that Tβ4 can promote the growth and development of SHF-DPCs and indicate that this molecule may be a valuable target for increasing cashmere production.

Platelet sonicates activate hair follicle stem cells and mediate enhanced hair follicle regeneration

An increasing number of studies show that platelet-rich plasma (PRP) is effective for androgenic alopecia (AGA). However, the underlying cellular and molecular mechanisms along with its effect on hair follicle stem cells are poorly understood. In this study, we designed to induce platelets in PRP to release factors by calcium chloride (PC) or by sonication where platelet lysates (PS) or the supernatants of platelet lysate (PSS) were used to evaluate their effect on the hair follicle activation and regeneration. We found that PSS and PS exhibited a superior effect in activating telogen hair follicles than PC. In addition, PSS injection into the skin activated quiescent hair follicles and induced K15⁺ hair follicle stem cell proliferation in K14-H2B-GFP mice. Moreover, PSS promoted skin-derived precursor (SKP) survival in vitro and enhanced hair follicle formation in vivo. In consistence, protein array analysis of different PRP preparations revealed that PSS contained higher levels of 16 growth factors (out of 41 factors analysed) than PC, many of them have been known to promote hair follicle regeneration. Thus, our data indicate that sonicated PRP promotes hair follicle stem cell activation and de novo hair follicle regeneration.