Rationale: Reconstruction of hair follicles (HFs) and eccrine sweat glands (ESGs) is essential for functional skin regeneration. In skin reconstruction research, we found that foreskin-derived epidermal cells reconstructed HF organoids unidirectionally, but not ESG organoids. Methods: To investigate key genes and pathways influencing the fate of ESG and HF, a transcriptome profiling of ESG placode-containing skin and HF placode-containing skin was employed, and key DEGs were identified and validated by RT-qPCR and immunofluorescence staining in mice and rats. Subsequently, adult human epidermal cell-derived organoids were reconstructed to probe functional roles and mechanisms of FGF7 and FGF10 by series of approaches integrating RT-qPCR, immunofluorescence-staining, WB, apoptosis assay, and pathway interference assay. Results: All members of FGF7 subfamily were among the key DEGs screened, the differential expression of FGF7 and FGF10 and their receptors FGFR1/FGFR2 was verified between ESG placode-containing skin and HF placode-containing skin. In vivo and in vitro Matrigel plug models showed that both FGF7 and FGF10 promoted fate transition of human epidermal cell-derived organoids to ESG phenotype organoids, FGF7 and FGF10 had a synergistic effect, and mainly function through the FGFR1/2-MEK1/2-ERK1/2 pathway. Conclusions: Adult epidermal cells can be manipulated to reconstruct personalized HF and ESG to meet different needs.

The development of an effective transdermal drug delivery protocol to eccrine sweat glands is important for the advancement of research on the human sweating response. We investigated whether microneedle treatment prior to the application of pilocarpine, a hydrophilic and sudorific agent that does not induce sweating due to a limited percutaneous passive diffusion by skin application alone, augments sweat production. We applied three microneedle arrays to forearm skin sites simultaneously (n = 20). Upon removal of the microneedles, 1 % pilocarpine was applied to each site for 5-, 15-, and 30-min for the assessment of sweat gland function. In parallel, pilocarpine was administered by transdermal iontophoresis (5-min) at a separate site. Sweat rate was assessed continuously via the ventilated capsule technique. Pilocarpine augmented sweat rate at the 15- and 30-min periods as compared to the application at 5-min. The sweating responses induced by the 15- and 30-min application of pilocarpine were equivalent to ∼ 80 % of that measured at the iontophoretically treated sites. Notably, we observed a correlation in sweat rate between these two transdermal drug delivery methods. Altogether, our findings show that pre-treatment of microneedle arrays can enhance transdermal delivery efficiency of pilocarpine to human eccrine sweat glands.

BACKGROUND: Sweat chloride concentration is used both for CF diagnosis and for tracking CFTR modulator efficacy over time, but the relationship between sweat chloride and lung health is heterogeneous and informed by CFTR genotype. Here, we endeavored to characterize ion transport in eccrine sweat glands (ESGs).
METHODS: First, ESGs were microdissected from a non-CF skin donor to analyze individual glands. We established primary cultures of ESG cells via conditional reprogramming for functional testing of ion transport by short circuit current measurement and examined cell composition by single-cell RNA-sequencing (scRNA-seq) comparing with whole dissociated ESGs. Secondly, we cultured nasal epithelial (NE) cells and ESGs from two people with CF (pwCF) to assess modulator efficacy. Finally, NEs and ESGs were grown from one person with the CFTR genotype F312del/F508del to explore genotype-phenotype heterogeneity.
RESULTS: ESG primary cells from individuals without CF demonstrated robust ENaC and CFTR function. scRNA-seq demonstrated both secretory and ductal ESG markers in cultured ESG cells. In both NEs and ESGs from pwCF homozygous for F508del, minimal baseline CFTR function was observed, and treatment with CFTR modulators significantly enhanced function. Notably, NEs from an individual bearing F312del/F508del exhibited significant baseline CFTR function, whereas ESGs from the same person displayed minimal CFTR function, consistent with observed phenotype.
CONCLUSIONS: This study has established a novel primary culture technique for ESGs that allows for functional ion transport measurement to assess modulator efficacy and evaluate genotype-phenoytpe heterogeneity. To our knowledge, this is the first reported application of conditional reprogramming and scRNA-seq of microdissected ESGs.

Eccrine angiomatous hamartoma is rare, slow-growing, and benign neoplasm that is diagnosed based on clinical characteristics and histological findings. It usually presents as a solitary nodule on the extremities and may arise at birth or in childhood. Although it is usually asymptomatic, in some cases it can cause pain and hyperhidrosis. From a histological perspective, it is characterized by an increase in the number of eccrine glands and a proliferation of vascular channels. We present the case of a 26-year-old woman who developed an eccrine angiomatous hamartoma in her right leg. The rapid growth of the lesion during pregnancy coupled with the challenges posed by a superficial biopsy, complicated the differential diagnosis.

BACKGROUND: Each eccrine sweat gland (ESG) is a single-tubular structure with a central lumen, and the formation of hollow lumen in the initial solid cell mass is a key developmental process. To date, there are no reports on the mechanism of native ESG lumen formation.
METHODS: To investigate the lumen morphogenesis and the lumen formation mechanisms of Sprague-Dawley (SD) rat ESGs, SD rat hind-footpads at E20.5, P1-P5, P7, P9, P12, P21, P28 and P56 were obtained. The lumen morphogenesis of ESGs was examined by HE staining and immunofluorescence staining for polarity markers. The possible mechanisms of lumen formation were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay and autophagy marker LC3B immunofluorescence staining, and further explored by ouabain intervention experiment.
RESULTS: In SD rat ESGs, the microlumen was formed at P1, and the small intact lumen with apical-basal polarity appeared at P3. The expression of apical marker F-actin, basal marker Laminin, basolateral marker E-cadherin was consistent with the timing of lumen formation of SD rat ESGs. During rat ESG development, apoptosis and autophagy were not detected. However, inhibition of Na+-K+-ATPase (NKA) with ouabain resulted in decreased lumen size, although neither the timing of lumen formation nor the expression of polarity proteins was altered.
CONCLUSIONS: Epithelial polarity-driven membrane separation but not cavitation regulates lumen formation of SD rat ESGs. NKA-regulated fluid accumulation drives lumen expansion.

Emotional stress-induced sweating in glabrous skin of the palm and sole, which can be excessive in some individuals (hyperhidrosis), can negatively impact quality of life. Understanding the mechanisms underlying this response can lead to potential treatments. Transdermal iontophoresis is a method to administer ionized sudorific agents to sweat glands within the dermis. However, due to the reduced permeability of pharmacological agents in thicker skin such as the palms, this technique has been shown to be less effective when applied in thicker skin. Thus, we assessed the effectiveness of pre-treating palmar skin with microneedles to create micropores on the stratum corneum of the palm to enhance the iontophoretic delivery of pilocarpine to modulate sweat production. On three separate sessions, we applied microneedles (0.78 cm2, 190 needles with a length of 875 μm) to palm and forearm skin sites. Upon removal of the microneedles, we assessed the number of perforations colored by gentian violet in the forearm only (Protocol 1, n = 20), skin barrier function indexed by transepidermal water loss (TEWL) (Protocol 2, n = 21), and sweating induced by the iontophoretic application of 1% pilocarpine (Protocol 3, n = 43). Briefly, we measured 1) ∼172 dyed spots on forearm skin, 2) an increase of ∼300% and ∼ 900% in TEWL on palm and forearm skin, respectively; and 3) a 2-fold increase in sweating on the palm only following the application of the microneedles. Notably, the microneedle array failed to enhance pilocarpine delivery at either the palm or forearm skin sites. We showed the application of a microneedle array enhanced skin permeability and sweat production on the palm without a concomitant increase in pilocarpine delivery. Therefore, this methodology could be employed to advance our understanding of the causes and treatments of medical conditions such as hyperhidrosis.

Hematohidrosis is an extremely rare condition characterized by the oozing or secretion of blood through intact skin and mucosa, particularly through eccrine glands. Although there is not much literature available on the condition, examples of Hematohidrosis include the crying and sweating of blood. The fluid may have a bloody tinge or may be frank blood. The anomaly has no identifiable etiology, and patients generally present in a good state of health. In this report, we present a 19-year-old female who had weekly occurrences of bloody diaphoresis that had been present consistently for one year. During her presentation at the hematology clinic, she was investigated thoroughly for alternative causes, but none were found. The patient was diagnosed with hematohidrosis and was offered treatment with propranolol, which she declined. She continues to follow up routinely in the hematology clinic with persistent symptoms.

Solid cystic hidradenoma, or clear cell hidradenoma, is a distinct and histologically rare tumor formed at the sweat glands, found mainly in adults and majorly among women. In this case, a 26-year-old female presented with asymptomatic swelling in her left inguinal area. Similar cases have been discussed in the literature considering the same kind of tumor. The present case is reported owing to the rarity of the type of tumor in terms of size and region of occurrence with the associated condition of pregnancy.

Eccrine sweat gland (SG) restrictedly exists in mouse foot pads indicating that mouse plantar dermis (PD) contains the SG lineage-restricted niches. However, it is still unclear how these niches can affect stem cell fate towards SG. In this study, we tried to find the key cues by which stem cells sense and interact with the SG lineage-specific niches both in vivo and in vitro. Firstly, we used transcriptomics RNA sequencing analysis to screen differentially expressed genes between SG cells and epidermal stem cells (ES), and used proteomic analysis to screen differentially expressed proteins between PD and dorsal dermis (DD). Notch1 was found differentially expressed in both gene and protein levels, and was closely related to SG morphogenesis based on Gene Ontology (GO) enrichment analysis. Secondly, the spatial-temporal changes of Notch1 during embryonic and post-natal development of SG were detected. Thirdly, mouse mesenchymal stem cells (MSCs) were introduced into SG-like cells in vitro in order to further verify the possible roles of Notch1. Results revealed that Notch1 was continuously down-regulated along with the process of SG morphogenesis in vivo, and also along with the process that MSCs differentiated into SG-like cells in vitro. Hence, we suggest that Notch1 possibly acts as with roles of \"gatekeeper\" during SG development and regulates the interactions between stem cells and the SG lineage-specific niches. This study might help for understanding mechanisms of embryonic SG organogenesis.

BACKGROUND: Eccrine sweat glands (ESGs) and hair follicles (HFs) are the prominent skin appendages regulating human body temperature. C57BL/6 mice and Sprague-Dawley (SD) rats are the most commonly used model animals for studying ESGs and HFs. Previous studies have shown the distribution of ESGs and HFs in volar hindfeet of C57BL/6 mice, but there are few or no reports on the distribution of ESGs and HFs in volar forefeet of C57BL/6 mice and volar feet of SD rats. Here, we investigated the differential distribution and genetic determination of ESGs and HFs in the volar skin of C57BL/6 mice and SD rats through gross observation, iodine-starch sweat test, double staining with Nile Blue A and Oil Red O, hematoxylin and eosin (HE) staining, double immunofluorescence staining of LIM Homeobox 2 (LHX2)/Na+-K+-ATPase α1(NKA) or LHX2/Na+-K+-2Cl－ cotransporter 1 (NKCC1), and qRT-PCR detection of ESG-related gene Engrailed 1 (En1) and HF-related gene LHX2.
RESULTS: The results showed ESGs but no HFs in the footpads of C57BL/6 mice and SD rats, both ESGs and HFs in the inter-footpads (IFPs) of C57BL/6 mice, and neither ESGs nor HFs in the IFPs of SD rats. The relative quantitative change in En1 was consistent with the differential distribution of ESGs, and the relative quantitative change of LHX2 was consistent with the differential distribution of HFs.
CONCLUSIONS: C57BL/6 mice and SD rats had their own characteristics in the distribution of ESGs and HFs in the volar skin, and researchers should choose mice or rats, and even forefeet or hindfeet as their research object according to different purposes. The study provides a basis for selection of optimal animal models to study development, wound healing and regeneration of skin appendages.