The interaction between epidermal growth factor (EGF) and matrix metalloproteinase induces the development of sweat glands in human fetal skin

Objective:The development of sweat glands is a very complicated biological process involving many factors. In this study, we explore the inter-relationship between epidermal growth factor (EGF), matrix metalloproteinases (MMP-2,MMP-7) and development of sweat glands in human embryos. Furthermore, we hope to elucidate the mechanism(s) underlying the induction of epidermal stem cells into sweat gland cells.

In situ forming injectable MSC-loaded GelMA hydrogels combined with PD for vascularized sweat gland regeneration

Dear Editor,Three dimensional(3D)bioprinted extracellular matrix(ECM)can be used to provide both biochemical and biophysical cues to direct mesenchymal stem cells(MSCs)differentiation,and then differentiated cells were isolated for implantation in vivo using surgical procedures.However,the reduced cell activity after cell isolation from 3D constructs and low cell retention in injured sites limit its application[1].Methacrylated gelatin(GelMA)hydrogel has the advantage of fast crosslinking,which could resemble complex architectures of tissue construct in vivo[2].Here,we adopted a noninvasive bioprinting procedure to imitate the regenerative microenvironment that could simultaneously direct the sweat gland(SG)and vascular differentiation from MSCs and ultimately promote the replacement of glandular tissue in situ(Fig.1a).

Using bioprinting and spheroid culture to create a skin model with sweat glands and hair follicles

Background:Sweat glands(SGs)and hair follicles(HFs)are two important cutaneous appendages that play crucial roles in homeostatic maintenance and thermoregulation,and their interaction is involved in wound healing.SGs can be regenerated from mesenchymal stem cell-laden 3D bioprinted scaffolds,based on our previous studies,whereas regeneration of HFs could not be achieved in the same model.Due to the lack of an in vitro model,the underlying molecular mechanism of the interaction between SGs and HFs in regeneration could not be fully understood.The purpose of the present study was to establish an in vitro model of skin constructs with SGs and HFs and explore the interaction between these two appendages in regeneration.Methods:To investigate the interaction effects between SGs and HFs during their regeneration processes,a combined model was created by seeding HF spheroids on 3D printed SG scaffolds.The interaction between SG scaffolds and HF spheroids was detected using RNA expression and immunofluorescence staining.The effects of microenvironmental cues on SG and HF regeneration were analysed by altering seed cell types and plantar dermis homogenate in the scaffold.Results:According to this model,we overcame the difficulties in simultaneously inducing SG and HF regeneration and explored the interaction effects between SG scaffolds and HF spheroids.Surprisingly,HF spheroids promoted both SG and HF differentiation in SG scaffolds,while SG scaffolds promoted SG differentiation but had little effect on HF potency in HF spheroids.Specifically,microenvironmental factors(plantar dermis homogenate)in SG scaffolds effectively promoted SG and HF genesis in HF spheroids,no matter what the seed cell type in SG scaffolds was,and the promotion effects were persistent.Conclusions:Our approach elucidated a new model for SG and HF formation in vitro and provided an applicable platform to investigate the interaction between SGs and HFs in vitro.This platform might facilitate 3D skin constructs with multiple appendages and unveil the spatiotemporal molecular program of multiple appendage regeneration.

Differential Innervation of Secretory Coils and Ducts in Human Eccrine Sweat Glands

Background： Previous studies demonstrate that eccrine sweat glands are innervated by both cholinergic and adrenergic nerves. However, it is still unknown whether the secretory coils and ducts ofeccrine sweat glands are equally innervated by the sympathetic nerve fibers. To welt understand the mechanisms on sweat secretion and reabsorption, the differential innervation of secretory coils and ducts in human eccrine sweat glands was investigated in the study. Methods： From June 2016 to June 2017, six human skins were fixed, paraffin-embedded, and cut into 5 μm-thick sections, followed by costaining for nerve fiber markers protein gene product 9.5 （PGP 9.5）, tyrosine hydroxylase （TH） and vasoactive intestinal peptide （VIP）, and eccrine sweat gland markers K7, S100P, and K14 by combining standard immunofluorescence with tyramide signal amplification （IF-TSA）. Stained sections were observed under the microscope, photographed, and analyzed. Results： The fluorescent signals of PGP 9.5, TH, and VIP were easily visualized, by 1F-TSA, as circular patterns surrounding eccrine sweat glands, but only PGP 9.5 could be observed by standard IF. The IF-TSA method is more sensitivity than standard IF in detecting antigens expressed at low levels. PGP 9.5, TH, and VIP appeared primarily surrounding the secretory coils and sparsely surrounding the sweat ducts. Conclusion： Sweat secretion is mainly controlled by autonomic nerves whereas sweat reabsorption is less affected by nerve activity.

Important immunohistochemical markers for identifying sweat glands

he major adnexal structures of the skin, the sweat glands, regulate the body temperature. There are twotypes of sweat glands in the human body, the eccrine type, which produces the NaCl-rich solution in response to heat, and the apocrine type, which releases a lipid-rich secretion. Human sweat glands have many immunohistochemical markers which have close relationship with sweat-related diseases. Recently, although numerous immunohistochemical markers appeared in sweat glands, these biomarkers scattered in the oceans of literature without a systemic review for the relationship between the immunohistochemical marker and their functions in the counterparts of the sweat glands. It is important for identifying sweat gland-derived neoplasms that originate from or differentiate into the ducts or secretory elements of the sweat glands by immunohistochemical markers. Therefore, it is necessary to make a review of the immunohistochemical markers systematically. Actually, we try to classify the immunohistochemical markers of the sweat glands into four groups according to their protein characters and the functions associated with their presumed physiological counterparts of the sweat apparatus.

Collagen triple helix repeat containing-1 promotes functional recovery of sweat glands by inducing adjacent microvascular network reconstruction in vivo

Background:Sweat glands(SGs)have low regenerative potential after severe burns or trauma and their regeneration or functional recovery still faces many obstacles.In practice,restoring SG function requires not only the structural integrity of the gland itself,but also its neighboring tissues,especially blood vessels.Collagen triple helix repeat containing-1(CTHRC1)was first identified in vascular repair,and increasing reports showed a close correlation between cutaneous appendage specification,patterning and regeneration.The purpose of the present study was to clarify the role of CTHRC1 in SGs and their adjacent microvessels and find therapeutic strategies to restore SG function.Methods:The SGs and their adjacent microvascular network of Cthrc^(1−/−)mice were first inves-tigated using sweat test,laser Doppler imaging,tissue clearing technique and transcriptome analysis.The effects of CTHRC1 on dermal microvascular endothelial cells(DMECs)were further explored with cell proliferation,DiI-labeled acetylated low-density lipoprotein uptake,tube for-mation and intercellular junction establishment assays.The effects of CTHRC1 on SG function restoration were finally confirmed by replenishing the protein into the paws of Cthrc(1−/−)mice.Results:CTHRC1 is a key regulator of SG function in mice.At the tissue level,Cthrc1 deletion resulted in the disorder and reduction of the microvascular network around SGs.At the molecular level,the knockout of Cthrc1 reduced the expression of vascular development genes and functional proteins in the dermal tissues.Furthermore,CTHRC1 administration considerably enhanced SG function by inducing adjacent vascular network reconstruction.Conclusions:CTHRC1 promotes the development,morphogenesis and function execution of SGs and their neighboring vasculature.Our study provides a novel target for the restoration or regeneration of SG function in vivo.

Morphological and distribution characteristics of sweat glands in hypertrophic scar and their possible effects on sweat gland regeneration

In hypertrophic scar tissue, no sweet gland and hair follicle exist usuallybecause of the dermal and epidermal damage in extensive thermal skin injury, thus imparingregulation of body temperature. This study was designed to reveal the morphological anddistributional characteristics of the sweat glands in normal skin and hypertrophic scar obtainedfrom children and adults, and to study the possible interfering effects of the scar on regenerationof the sweat gland after burn injury. Biopsies of hypertrophic scar were taken from four children(4 - 10 years) and four adults (35 -51 years). Normal, uninjured full-thickness skin adjacent to thescar of each patient was used as control. Keratin 19 (K19) was used as the marker for epidermalstem cells and secretory portion of the sweat glands, and keratin 14 (K14) for the tube portion,respectively. Immunohistochemical and histological evaluations were performed. Histological andimmunohistochemical staining of skin tissue sections from both the children and adults showed K19positive cells in the basement membrane of epidermis of normal skin. These cells were seen onlysingle layer and arranged regularly. The secretory or duct portion of the eccrine sweat glands wassituated in the dermis and epidermal layer. However, in the scar tissue, K19 positive cells werescant in the basal layer, and the anatomic location of the secretory portion of sweat glandschanged. They were located between the border of the scar and reticular layer of the dermis. Thesesecretory portions of sweat glands were expanded and were organized irregularly. But a few K14positive cells were scattered in the scar tissues in cyclic form. There are some residual sweatglands in scar tissues, in which the regeneration process of active sweat glands is present.Possibly the sweat glands could regenerate from adult epidermal stem cells or residual sweat glandsin the wound bed after burn injury.

Transplantation of human bone marrow-derived mesenchymal stem cells transfected with ectodysplasin for regeneration of sweat glands

Background Patients with severe full-thickness burn injury suffer from their inability to maintain body temperature through perspiration because the complete destructed sweat glands can not be regenerated. Bone marrow-derived mesenchymal stem cells （BM-MSCs） represent an ideal stem-cell source for cell therapy because of their easy purification and multipotency. In this study, we attempted to induce human BM-MSCs to differentiate into sweat gland cells for sweat gland regeneration through ectodysplasin （EDA） gene transfection. Methods The dynamic expression of EDA and EDA receptor （EDAR） were firstly observed in the sweat gland formation during embryological development. After transfection with EDA expression vector, human BM-MSCs were transplanted into the injured areas of burn animal models. The regeneration of sweat glands was identified by perspiration test and immunohistochemical analysis. Results Endogenous expression of EDA and EDAR correlated with sweat gland development in human fetal skin. After EDA transfection, BM-MSC acquired a sweat-gland-cell phenotype, evidenced by their expression of sweat gland markers by flow cytometry analysis. Immunohistochemical staining revealed a markedly contribution of EDA-transfected BM-MSCs to the regeneration of sweat glands in the scalded paws. Positive rate for perspiration test for the paws treated with EDA-transfected BM-MSCs was significantly higher than those treated with BM-MSCs or EDA expression vector （P 〈0.05）. Conclusions Our results confirmed the important role of EDA in the development of sweat gland. BM-MSCs transfected with EDA significantly improved the sweat-gland regeneration. This study suggests the potential application of EDA-modified MSCs for the repair and regeneration of injured skin and its appendages.

Porocarcinoma in a palm reconstructed with a full thickness skin graft: A case report

BACKGROUND Porocarcinoma is a rare type of skin cancer that originates from sweat gland tumors.It is an aggressive malignant skin cancer that is difficult to diagnose clinically owing to its rarity and similarity to squamous cell carcinoma(SCC).CASE SUMMARY This case involved a 92-year-old woman,a farmer by profession,presented with an exophytic and verrucous mass on her left palm that had formed 2 years prior and caused chronic pain and frequent bleeding.Initially,the patient was diagnosed with SCC using a punch biopsy;however,a repeat biopsy with addi-tional immunohistochemical tests was performed for porocarcinoma.Ultimately,the patient was diagnosed with porocarcinoma and reconstruction was planned using a full-thickness skin graft.After treatment,the range of motion of the palm was preserved,and the aesthetic outcome was favorable.At 6 mo of follow-up,the patient was satisfied with the outcome.CONCLUSION Porocarcinoma is commonly misdiagnosed as SCC;therefore,clinicians should consider porocarcinomas when evaluating mass-like lesions on the hands.

Eccrine porocarcinoma in the tempus of an elderly woman:A case report

BACKGROUND Eccrine porocarcinoma(EPC)is a rare skin tumor that mainly affects the elderly population.Tumors often present with slow growth and a good prognosis.EPCs are usually distinguished from other skin tumors using histopathology and immunohistochemistry.However,surgical management alone may be inadequate if the tumor has metastasized.However,currently,surgical resection is the most commonly used treatment modality.CASE SUMMARY A seventy-four-year-old woman presented with a slow-growing nodule in her left temporal area,with no obvious itching or pain,for more than four months.Histopathological examination showed small columnar and short spindle-shaped cells;thus,basal cell carcinoma was suspected.However,immunohistochemical analysis revealed the expression of cytokeratin 5/6,p63 protein,p16 protein,and Ki-67 antigen(40%),and EPC was taken into consideration.The skin biopsy was repeated,and hematoxylin and eosin staining revealed ductal differentiation in some cells.Finally,the patient was diagnosed with EPC,and Mohs micrographic surgery was performed.We adapted follow-up visits in a year and not found any recurrence of nodules.CONCLUSION This case report emphasizes the diagnosis and differentiation of EPC.

Small molecules facilitate single factor-mediated sweat gland cell reprogramming

Background: Large skin defects severely disrupt the overall skin structure and can irreversibly damage sweat glands(SGs), thus impairing the skin’s physiological function. This study aims to develop a stepwise reprogramming strategy to convert fibroblasts into SG lineages, which may provide a promising method to obtain desirable cell types for the functional repair and regeneration of damaged skin.Methods: The expression of the SG markers cytokeratin 5(CK5), cytokeratin 10(CK10), cytokeratin 18(CK18), carcinoembryonic antigen(CEA), aquaporin 5(AQP5) and α-smooth muscle actin(α-SMA) was assessed with quantitative PCR(qPCR), immunofluorescence and flow cytometry. Calcium activity analysis was conducted to test the function of induced SG-like cells(iSGCs). Mouse xenograft models were also used to evaluate the in vivo regeneration of iSGCs.BALB/c nude mice were randomly divided into normal group, SGM treatment group and iSGC transplantation group.Immunocytochemical analyses and starch-iodine sweat tests were used to confirm the in vivo regeneration of iSGCs.Results: Ectodermal dysplasia antigen(EDA) overexpression drove human dermal fibroblast(HDF) conversion into i SGCs in SG culture medium(SGM). qPCR indicated significantly increased mRNA levels of the SG markers CK5, CK18and CEA in iSGCs, and flow cytometry data demonstrated(4.18±0.04)% of iSGCs were CK5 positive and(4.36±0.25)%of iSGCs were CK18 positive. The addition of chemical cocktails greatly accelerated the SG fate program. qPCR results revealed significantly increased mRNA expression of CK5, CK18 and CEA in iSGCs, as well as activation of the duct marker CK10 and luminal functional marker AQP5. Flow cytometry indicated, after the treatment of chemical cocktails,(23.05±2.49)% of iSGCs expressed CK5^(+) and(55.79±3.18)% of iSGCs expressed CK18^(+), respectively. Calcium activity analysis indicated that the reactivity of iSGCs to acetylcholine was close to that of primary SG cells [(60.79±7.71)% vs.(70.59±0.34)%, ns]. In vivo transplantation experiments showed approximately(5.2±1.1)% of the mice were sweat test positive, and the histological analysis results indicated that regenerated SG structures were present in iSGCs-treated mice.Conclusions: We developed a SG reprogramming strategy to generate functional iSGCs from HDFs by using the single factor EDA in combination with SGM and small molecules. The generation of iSGCs has important implications for future in situ skin regeneration with SG restoration.

Reciprocal interaction between vascular niche and sweat gland promotes sweat gland regeneration

The incorporation of vasculature is known to be effective in tissue or organ functional regeneration.However,a vague understanding of the interaction between epidermal appendages and their vascular niches is a foremost obstacle to obtaining sweat gland(SG)-specific vasculature units.Here,we map their precise anatomical con-nections and report that the interplay between SG cells(SGCs)and the surrounding vascular niche is key for glandular development and homeostasis maintenance.To replicate this interplay in vitro,we used three-dimensional(3D)bioprinting to generate reproducible SGC spheroids from differentiated adipose-derived mesenchymal stem cells(ADSCs).With dermal microvascular endothelial cells(DMECs),sacrificial templates made from poly(ε-caprolactone)(PCL)were fabricated to pattern the vascular niche.This interplay model promoted physiologically relevant vascularized glandular morphogenesis in vitro and in vivo.We identified a reciprocal regulatory mechanism for promoting SGs regeneration via contact-independent cell communication and direct cell-cell interactions between SGs and the vasculature.We envision the successful use of our approach for vascularized organ regeneration in the near future.

3D-bioprinted microenvironments for sweat gland regeneration

The development of 3D bioprinting in recent years has provided new insights into the creation of in vitro microenvironments for promoting stem cell-based regeneration.Sweat glands(SGs)are mainly responsible for thermoregulation and are a highly differentiated organ with limited regenerative ability.Recent studies have focused on stem cell-based therapies as strategies for repairing SGs after deep dermal injury.In this review,we highlight the recent trend in 3D bioprinted native-like microenvironments and emphasize recent advances in functional SG regeneration using this technology.Furthermore,we discuss five possible regulatory mechanisms in terms of biochemical factors and structural and mechanical cues from 3D bioprinted microenvironments,as well as the most promising regulation from neighbor cells and the vascular microenvironment.

TNF-α suppresses sweat gland differentiation of MSCs by reducing FTO-mediated m^6 A-demethylation of Nanog mRNA

An effect of inhibition of tumor necrosis factor-α(TNF-α)on differentiation of mesenchymal stromal cells(MSCs)has been demonstrated,but the exact mechanisms that govern MSCs differentiation remain to be further elucidated.Here,we show that TNF-αinhibits the differentiation of MSCs to sweat glands in a specific sweat gland-inducing environment,accompanied with reduced expression of Nanog,a core pluripotency factor.We elucidated that fat mass and obesity-associated protein(FTO)-mediated m^6 A demethylation is involved in the regulation of MSCs differentiation potential.Exposure of MSCs to TNF-αreduced expression of FTO,which demethylated Nanog m RNA.Reduced expression of FTO increased Nanog m RNA methylation,decreased Nanog m RNA and protein expression,and significantly inhibited MSCs capacity for differentiation to sweat gland cells.Our finding is the first to elucidate the functional importance of m^6 A modification in MSCs,providing new insights that the microenvironment can regulate the multipotency of MSCs at the post-transcriptional level.Moreover,to maintain differentiation capacity of MSCs by regulating m^6 A modification suggested a novel potential therapeutic target for stem cellmediated regenerative medicine.

Future application of hair follicle stem cells： capable in differentiation into sweat gland cells

Background Sweat glands （SGs） can not regenerate after complete destruction in the severe skin injury, so it is important to find a ideal stem cell source in order to regenerate functional SGs. Hair follicle stem cells （HFSCs） possess the obvious properties of the adult stem cells, which are multipotent and easily accessible. In this research, we attempted to direct the HFSCs suffered from the sweat gland cells （SGCs） special differentiation by a cooperative co- culture system in vitro. Methods The designed co-culture microenvironment in the transwell was consist of two critial factors： heat shocked SGCs and dermis-like mesenchymal tissue, which appeared independently in the two control groups; after induction, the purified induced SGC-like cells were transplanted into the full-thickness scalded wounds of the nude mice, after 4 weeks, the reconstructed SG-like structures were identified by immunohistochemical and immunofluorescence analysis. Results A part of HFSCs in experimental group finally expressed SGCs phenotypes, by contrast, the control group 1 which just containing dermis-like mesenchymal tissue failed and the control group 2 consisted of heat shocked SGCs was in a poor efficiency; by immunofluorescence staining and flow cytometry analysis, the expression of HFSCs special biomarkers was down regulated, instead of the positive efficiency of SGCs special antigens increased; besides, the induced SGCs displayed a high expression of ectodysplasin A （EDA） and ectodysplasin A receptor （EDAR） genes and proteins; after cell transplantation, the youngest SG-like structures formed and be positive in SGCs special antigens, which never happened in untreated wounds （P 〈0.05）. Conclusion The HFSCs are multipotential and capable in differentiating into SGCs which promise a potential stem cells reservoir for future use; our special co-culture microenvironment is promising for HFSCs differentiating; the induced SGCs are functional and could work well in the regeneration of SGs.

Redirecting differentiation of mammary progenitor cells by 3D bioprinted sweat gland microenvironment

Background:Mammary progenitor cells(MPCs)maintain their reproductive potency through life,and their specific microenvironments exert a deterministic control over these cells.MPCs provides one kind of ideal tools for studying engineered microenvironmental influence because of its accessibility and continually undergoes postnatal developmental changes.The aim of our study is to explore the critical role of the engineered sweat gland(SG)microenvironment in reprogramming MPCs into functional SG cells.Methods:We have utilized a three-dimensional(3D)SG microenvironment composed of gelatin-alginate hydrogels and components from mouse SG extracellular matrix(SG-ECM)proteins to reroute the differentiation of MPCs to study the functions of this microenvironment.MPCs were encapsulated into the artificial SG microenvironment and were printed into a 3D cell-laden construct.The expression of specific markers at the protein and gene levels was detected after cultured 14 days.Results:Compared with the control group,immunofluorescence and gene expression assay demonstrated that MPCs encapsulated in the bioprinted 3D-SG microenvironment could significantly express the functional marker of mouse SG,sodium/potassium channel protein ATP1a1,and tend to express the specific marker of luminal epithelial cells,keratin-8.When the Shh pathway is inhibited,the expression of SG-associated proteins in MPCs under the same induction environment is significantly reduced.Conclusions:Our evidence proved the ability of differentiated mouse MPCs to regenerate SG cells by engineered SG microenvironment in vitro and Shh pathway was found to be correlated with the changes in the differentiation.These results provide insights into regeneration of damaged SG by MPCs and the role of the engineered microenvironment in reprogramming cell fate.

Capacity of human umbilical cord-derived mesenchymal stem cells to differentiate into sweat gland-like cells:a preclinical study

Human umbilical cord-derived mesenchymal stem cells(hUC-MSCs)possess various advantageous properties,including self-renewal,extended proliferation potential,multi-lineage differentiation potential and capacity for differentiating into sweat gland-like cells in certain conditions.However,little is known about the effect of clinical-grade culture conditions on these properties and on the differentiative potential of hUC-MSCs.In this study,we sought to investigate the properties of hUC-MSCs expanded with animal serum free culture media(ASFCM)in order to determine their potential for differentiation into sweat gland-like cells.We found that primary cultures of hUC-MSCs could be established with ASFCM.Moreover,cells cultured in ASFCM showed vigorous proliferation comparable to those of cells grown in classical culture conditions containing fetal bovine serum(FBS).Morphology of hUC-MSCs cultured in ASFCM was comparable to those of cells grown under classical culture conditions,and hUC-MSCs grown in both of the two culture conditions tested showed the typical antigen profile of MSCs—positive for CD29,CD44,CD90,and CD105,and negative for CD34 and CD45,as expected.Chromosomal aberration assay revealed that the cells were stable after long-term culture under both culture conditions.Like normal cultured MSCs,hUC-MSCs induced under ASFCM conditions exhibited expression of the same markers(CEA,CK14 and CK19)and developmental genes(EDA and EDAR)that are characteristic of normal sweat gland cells.Taken together,our findings indicate that the classical culture medium used to differentiate hUC-MSCs into sweat gland-like cells can be replaced safely by ASFCM for clinical purposes.

Autophagy,not apoptosis,plays a role in lumen formation of eccrine gland organoids

Background:Sweat secreted by eccrine sweat glands is transported to the skin surface through the lumen.The eccrine sweat gland develops from the initial solid bud to the final gland structure with a lumen,but how the lumen is formed and the mechanism of lumen formation have not yet been fully elucidated.This study aimed to investigate the mechanism of lumen formation of eccrine gland organoids(EGOs).Methods:Human eccrine sweat glands were isolated from the skin for tissue culture,and the primary cultured cells were collected and cultured in Matrigel for 14 daysin vitro.EGOs at different development days were collected for hematoxylin and eosin(H&E)staining to observe morphological changes and for immunofluorescence staining of proliferation marker Ki67,cellular motility marker filamentous actin(F-actin),and autophagy marker LC3B.Western blotting was used to detect the expression of Ki67,F-actin,and LC3B.Moreover,apoptosis was detected using a terminal deoxynucleotidyl transferase dUTP nick end labeling(TUNEL)apoptosis assay kit,and the expression of poly(ADP-ribose)polymerase and Caspase-3 was detected by Western blot.In addition,3-methyladenine(3MA)was used as an autophagy inhibitor to detect whether the formation of sweat glands can be effectively inhibited.Results:The results showed that a single gland cell proliferated rapidly and formed EGOs on day 4.The earliest lumen formation was observed on day 6.From day 8 to day 14,the rate of lumen formation in EGOs increased significantly.The immunofluorescence and Western blot analyses showed that the expression of Ki67 gradually decreased with the increase in days,while the F-actin expression level did not change.Notably,the expression of autophagy marker LC3B was detected in the interior cells of EGOs as the apoptosis signal of EGOs was negative.Compared with the control group,the autophagy inhibitor 3MA can effectively limit the formation rate of the lumen and reduce the inner diameter of EGOs.Conclusion:Using our model of eccrine gland 3D-reconstruction in Matrigel,we determined that autophagy rather than apoptosis plays a role in the lumen formation of EGOs.