Telocytes: current methods of research, challenges and future perspectives.

Telocytes (TCs) are CD34-positive interstitial cells that have long cytoplasmic projections, called telopodes; they have been identified in several organs and in various species. These cells establish a complex communication network between different stromal and epithelial cell types, and there is growing evidence that they play a key role in physiology and pathology. In many tissues, TC network impairment has been implicated in the onset and progression of pathological conditions, which makes the study of TCs of great interest for the development of novel therapies. In this review, we summarise the main methods involved in the characterisation of these cells as well as their inherent difficulties and then discuss the functional assays that are used to uncover the role of TCs in normal and pathological conditions, from the most traditional to the most recent. Furthermore, we provide future perspectives in the study of TCs, especially regarding the establishment of more precise markers, commercial lineages and means for drug delivery and genetic editing that directly target TCs.

Telocytes in the Luminal GI Tract.

Telocytes are unique mesenchymal cells characterized by multiple remarkably long cytoplasmic extensions that extend hundreds of micron away from the cell body. Through these extensions, telocytes establish a 3-dimensional network by connecting with other telocytes and various cell types within the tissue. In the intestine, telocytes have emerged as an essential component of the stem cell niche, providing Wnt proteins that are critical for the proliferation of stem and progenitor cells. However, the analysis of single-cell RNA sequencing has revealed other stromal populations and mechanisms for niche organization, raising questions about the role of telocytes as a component of the stem cell niche. This review explores the current state-of-the-art, existing controversies, and potential future directions related to telocytes in the luminal gastrointestinal tract.

Histological study of telocytes in mice intrauterine adhesion model and their positive effect on mesenchymal stem cells in vitro.

Intrauterine adhesions (IUA), the main cause of secondary infertility in women, result from irreversible fibrotic repair of the endometrium due to inflammation or human factors, accompanied by disruptions in the repair function of endometrial stem cells. This significantly impacts the physical and mental health of women in their childbearing years. Telocytes (TCs), a distinctive type of interstitial cells found in various tissues and organs, play diverse repair functions due to their unique spatial structure. In this study, we conduct the inaugural exploration of the changes in TCs in IUA disease and their potential impact on the function of stem cells. Our results show that in vivo, through double immunofluorescence staining (CD34+/Vimentin+; CD34+/CD31-), as endometrial fibrosis deepens, the number of TCs gradually decreases, telopodes shorten, and the three-dimensional structure becomes disrupted in the mouse IUA mode. In vitro, TCs can promote the proliferation and cycle of bone mesenchymal stem cells (BMSCs) by promoting the Wnt/ß-catenin signaling pathway, which were inhibited using XAV939. TCs can promote the migrated ability of BMSCs and contribute to the repair of stem cells during endometrial injury. In addition, TCs can inhibit the apoptosis of BMSCs through the Bcl-2/Bax pathway. In conclusion, our study demonstrates, for the first time, the resistance role of TCs in IUA disease, shedding light on their potential involvement in endometrial repair through the modulation of stem cell function.

A transmission electron microscopy investigation suggests that telocytes, skeletal muscles, myoblasts, and stem cells in common carp (Cyprinus carpio) respond to salinity challenges.

BACKGROUND: Telocytes are modified interstitial cells that communicate with other types of cells, including stem cells. Stemness properties render them more susceptible to environmental conditions. The current morphological investigation examined the reactions of telocytes to salt stress in relation to stem cells and myoblasts. The common carp are subjected to salinity levels of 0.2, 6, and 10 ppt. The gill samples were preserved and prepared for TEM. RESULTS: The present study observed that telocytes undergo morphological change and exhibit enhanced secretory activities in response to changes in salinity. TEM can identify typical telocytes. This research gives evidence for the communication of telocytes with stem cells, myoblasts, and skeletal muscles. Telocytes surround stem cells. Telopodes made planar contact with the cell membrane of the stem cell. Telocytes and their telopodes surrounded the skeletal myoblast. These findings show that telocytes may act as nurse cells for skeletal stem cells and myoblasts, which undergo fibrillogenesis. Not only telocytes undergo morphological alternations, but also skeletal muscles become hypertrophied, which receive telocyte secretory vesicles in intercellular compartments. CONCLUSION: In conclusion, the activation of telocytes is what causes stress adaptation. They might act as important players in intercellular communication between cells. It is also possible that reciprocal interaction occurs between telocytes and other cells to adapt to changing environmental conditions.

Are telocytes related to maintenance of vascular homeostasis in normal and pathological aorta?

The telocyte (TC) is a new interstitial cell type described in a wide variety of organs and loose connective tissues around small vessels, but its presence in large arteries remains unexplored. TCs have small cell bodies and remarkably thin, long, moniliform processes called telopods (Tps). Using transmission electron microscopy and immunofluorescence, we identified TCs in normal human thoracic aortas and in those with aneurysm or acute dissection (TAAD). In normal aortas the TCs were distributed throughout the connective tissue of the adventitial layer, in its innermost portion and at the zone of transition with the medial layer, with their long axes oriented parallel to the external elastic lamellae, forming a three-dimensional network, without prevalence in the media layer. In contrast, TAAD TCs were present in the medial layer and in regions of neovascularization. The most important feature of the adventitia of diseased aortas was the presence of numerous contacts between TCs and stem cells, including vascular progenitor cells. Although the biologically functional correlations need to be elucidated, the morphological observations presented here provide strong evidence of the involvement of TCs in maintaining vascular homeostasis in pathological situations of tissue injury.

The Potential of Berberine to Target Telocytes in Rabbit Heart.

A brand-new class of interstitial cells, called telocytes, has been detected in the heart. Telocytes can connect and transmit signals to almost all cardiomyocytes; this is highly interrelated with the occurrence and development of heart diseases. Modern studies have shown that berberine has a therapeutic effect on cardiovascular health. However, berberine's mechanism of action on the cardiovascular system through cardiac telocytes is unclear. Interestingly, 5 µm of berberine remarkably decreased the concentration of intracellular calcium and membrane depolarization in cultured telocytes, upregulated the expression of CX43 and ß-catenin, and downregulated the expressions of TRPV4 and TRPV1. Here, telocytes were identified in the vascular adventitia and intima, endocardium, myocardium, adventitia, and heart valves. Moreover, telocytes were broadly dispersed around cardiac vessels and interacted directly through gap junctions and indirectly through extracellular vesicles. Together, cardiac telocytes interact with berberine and then deliver drug information to the heart. Telocytes may be an essential cellular target for drug therapy of the cardiovascular system.

Telocyte-Derived Exosomes Provide an Important Source of Wnts That Inhibits Fibrosis and Supports Regeneration and Repair of Endometrium.

Intrauterine adhesions (IUAs) often occurred after common obstetrical and gynecological procedures or infections in women of reproductive age. It was characterized by the formation of endometrial fibrosis and prevention of endometrial regeneration, usually with devastating fertility consequences and poor treatment outcomes so far. Telocytes (TCs), as a novel interstitial cell type, present in female uterus with in vitro therapeutic potential in decidualization-defective gynecologic diseases. This study aims to further investigate the role of TC-derived Wnt ligands carried by exosomes (Exo) in reversal of fibrosis and enhancement of regeneration repair in endometrium. IUA cellular and animal models were established from endometrial stromal cells (ESCs) and mice, followed with treatment of TC-conditioned medium (TCM) or TC-derived Exo. In cellular model, fibrosis markers (collagen type 1 alpha 1 [COL1A1], fibronectin [FN], and α-smooth muscle actin [α-SMA]), angiogenesis (vascular endothelial growth factor [VEGF]), and pathway protein (ß-catenin) were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blotting (WB), and immunofluorescence. Results showed that, TCs (either TCM or TC-derived Exo) provide a source of Wnts that inhibit cellular fibrosis, as evidenced by significantly elevated VEGF and ß-catenin with decreased fibrotic markers, whereas TCs lost salvage on fibrosis after being blocked with Wnt/ß-catenin inhibitors (XAV939 or ETC-159). Further in mouse model, regeneration repair (endometrial thickness, number of glands, and fibrosis area ratio), fibrosis markers (fibronectin [FN]), mesenchymal-epithelial transition (MET) (E-cadherin, N-cadherin), and angiogenesis (VEGF, microvessel density [MVD]) were studied by hematoxylin-eosin (HE), Masson staining, and immunohistochemistry. Results demonstrated that TC-Exo treatment effectively promotes regeneration repair of endometrium by relieving fibrosis, enhancing MET, and angiogenesis. These results confirmed new evidence for therapeutic perspective of TC-derived Exo in IUAs.

Unveiling Cellular Diversity in the Buffalo Corneal Stroma: Insights into Telocytes and Keratocytes Using Light Microscope, Transmission Electron Microscope, and Immunofluorescence Analysis.

Telocytes and keratocytes are important cells that maintain the structure and function of the cornea. The buffalo cornea, known for its resilience in harsh conditions, has not been extensively studied regarding the presence and role of telocytes and keratocytes. We used light microscopy, transmission electron microscopy (TEM), and immunofluorescence assays with platelet-derived growth factor receptor alpha (PDGFRα), CD34, and Vimentin markers to investigate their expression and localization in the cornea. TEM analysis confirmed the presence of spindle-shaped keratocytes with intercellular connections, while telocytes exhibited small spindle-shaped bodies with long, thin branches connecting to corneal keratocytes. Immunofluorescence findings showed that CD34 was more abundant near the endothelium, Vimentin was prominently expressed near the epithelium, and PDGFRα was uniformly distributed throughout the corneal stroma. Co-expression of CD34 and Vimentin, PDGFRα and Vimentin, as well as CD34 and PDGFRα, was observed in keratocytes and telocytes within the stroma, indicating the potential presence of mesenchymal cells. These results suggest the involvement of telocytes and keratocytes in corneal wound healing, transparency maintenance, and homeostasis. The co-expression of these markers highlights the critical role of telocytes and keratocytes in regulating corneal physiological functions, further enhancing our understanding of corneal biology in the buffalo model.

Involvement of small leucine-rich proteoglycans and telocytes in thin and thick human endometrium: immunohistochemical and ultrastructural examination.

Thin endometrium, defined as an endometrial thickness of less than 7 mm during the late follicular phase, is a common cause of frequent cancelation of embryo transfers or recurrent implantation failure during assisted reproductive treatment. Small proteoglycans regulate intracellular signaling cascades by bridging other matrix molecules and tissue elements, affecting cell proliferation, adhesion, migration, and cytokine concentration. The aim of the study is to investigate the role of small leucine-rich proteoglycans in the pathogenesis of thin and thick human endometrium and their differences from normal endometrium in terms of fine structure properties. Normal, thin, and thick endometrial samples were collected, and small leucine-rich proteoglycans (SLRPs), decorin, lumican, biglycan, and fibromodulin immunoreactivities were comparatively analyzed immunohistochemically. The data were compared statistically. Moreover, ultrastructural differences among the groups were evaluated by transmission electron microscopy. The immunoreactivities of decorin, lumican, and biglycan were higher in the thin endometrial glandular epithelium and stroma compared to the normal and thick endometrium (p < .001). Fibromodulin immunoreactivity was also higher in the thin endometrial glandular epithelium than in the normal and thick endometrium (p < .001). However, there was no statistical difference in the stroma among the groups. Ultrastructural features were not profoundly different among cases. Telocytes, however, were not seen in the thin endometrium in contrast to normal and thin endometrial tissues. These findings suggest a possible role of changes in proteoglycan levels in the pathogenesis of thin endometrium.

Expression and functional study of cholecystokinin-A receptors on the interstitial Cajal-like cells of the guinea pig common bile duct.

BACKGROUND: Many studies have shown that interstitial Cajal-like cell (ICLC) abnormalities are closely related to a variety of dynamic gastrointestinal disorders. ICLCs are pacemaker cells for gastrointestinal movement and are involved in the transmission of nerve impulses. AIM: To elucidate the expression profile and significance of cholecystokinin-A (CCK-A) receptors in ICLCs in the common bile duct (CBD), as well as the role of CCK in regulating CBD motility through CCK-A receptors on CBD ICLCs. METHODS: The levels of tyrosine kinase receptor (c-kit) and CCK-A receptors in CBD tissues and isolated CBD cells were quantified using the double immunofluorescence labeling technique. The CCK-mediated enhancement of the movement of CBD muscle strips through CBD ICLCs was observed by a muscle strip contraction test. RESULTS: Immunofluorescence showed co-expression of c-kit and CCK-A receptors in the CBD muscularis layer. Observations of isolated CBD cells showed that c-kit was expressed on the surface of ICLCs, the cell body and synapse were colored and polygonal, and some cells presented protrusions and formed networks adjacent to the CBD while others formed filaments at the synaptic terminals of local cells. CCK-A receptors were also expressed on CBD ICLCs. At concentrations ranging from 10-6 mol/L to 10-10 mol/L, CCK promoted CBD smooth muscle contractility in a dose-dependent manner. In contrast, after ICLC removal, the contractility mediated by CCK in CBD smooth muscle decreased. CONCLUSION: CCK-A receptors are highly expressed on CBD ICLCs, and CCK may regulate CBD motility through the CCK-A receptors on ICLCs.

Integrin beta1 mediates the effect of telocytes on mesenchymal stem cell proliferation and migration in the treatment of acute lung injury.

Co-transplantation of mesenchymal stem cells (MSCs) with telocytes (TCs) was found to have therapeutic effects, although the mechanism of intercellular communication is still unknown. Our current studies aim at exploring the potential molecular mechanisms of TCs interaction and communication with MSCs with a focus on integrin beta1 (ITGB1) in TCs. We found that the co-culture of MSCs with ITGB1-deleted TCs (TCITGB1-ko ) changed the proliferation, differentiation and growth dynamics ability of MSC in responses to LPS or PI3K inhibitor. Changes of MSC proliferation and apoptosis were accompanied with the dysregulation of cytokine mRNA expression in MSCs co-cultured with TCITGB1-ko during the exposure of PI3Kα/δ/ß inhibitor, of which IL-1ß, IL-6 and TNF-α increased, while IFN-γ, IL-4 and IL-10 decreased. The responses of PI3K p85, PI3K p110 and pAKT of MSCs co-cultured with TCITGB1-ko to LPS or PI3K inhibitor were opposite to those with ITGB1-presented TCs. The intraperitoneal injection of TCITGB1-ko , TCvector or MSCs alone, as well as the combination of MSCs with TCITGB1-ko or TCvector exhibited therapeutic effects on LPS-induced acute lung injury. Thus, our data indicate that telocyte ITGB1 contributes to the interaction and intercellular communication between MSCs and TCs, responsible for influencing other cell phenomes and functions.

Inhibitory effect of telocyte-induced M1 macrophages on endometriosis: Targeting angiogenesis and invasion.

PURPOSE: Telocytes (TCs), a novel type of stromal cells found in tissues, induce macrophage differentiation into classically activated macrophages (M1) types and enhance their phagocytic function. The purpose of this study was to investigate the inhibitory effects of TC-induced M1 macrophages on endometriosis (EMs). METHODS: mouse uterine primary TCs and endometrial stromal cells (ESCs) were isolated and identified using double immunofluorescence staining. For the in vitro study, ESCs were treated with TC-induced M1 macrophages, and the vascular endothelial growth factor (VEGF), matrix metalloproteinase 9 (MMP9), and nuclear factor kappa B (NF-κb) genes were identified by quantitative real-time PCR (qRT-PCR) or western blotting (WB). For the in vivo study, an EMs mouse model received TC-conditioned medium (TCM) via abdominal administration, and characterized the inhibitory effects on growth (lesion weight, volume, and pathology), tissue-resident macrophages differentiation by immunostaining, angiogenic capacity (CD31 and VEGF), invasive capacity (MMP9), and NF-κb expression within EMs lesions. RESULTS: immunofluorescent staining showed that uterine TCs expressed CD34+ and vimentin+, whereas ESCs expressed vimentin+ and cytokeratin-. At the cellular level, TC-induced M1 macrophages can significantly inhibit the expression of VEGF and MMP9 in ESCs through WB or qRT-PCR, possibly by suppressing the NF-κb pathway. The in vivo study showed that macrophages switch from the alternatively activated macrophages (M2) in untreated EMs lesions to the M1 subtype after TCM exposure. Thereby, TC-induced M1 macrophages contributed to the inhibition of EMs lesions. More importantly, this effect may be achieved by suppressing the expression of NF-κb to inhibit angiogenesis (CD31 and VEGF) and invasion (MMP9) in the tissue. CONCLUSION: TC-induced M1 macrophages play a prevailing role in suppressing EMs by inhibiting angiogenic and invasive capacity through the NF-κb pathway, which provides a promising therapeutic approach for EMs.

Telocytes in Human Embryonic Development: A Preliminary Microscopic Anatomy Study / Telocitos en el Desarrollo Embrionario Humano: Un Estudio Preliminar de Anatomía Microscópica

SUMMARY: Telocytes are a cell population described in 2011 with a multitude of functions such as tissue support, regulation of stem cell niches or intercellular signal transmission. However, there are no studies about their embryonic origin, their function in development, or their moment of appearance. The objective of this work is to try to answer these questions through histological and immunofluorescence studies with samples from the embryological collection of the Department of Anatomy of the University of Granada. In the results obtained, as demonstrated by immunofluorescence for CD34, the presence of these cells can be seen in the fourth week of embryonic development in the perinotochordal region. Its presence is evident from the sixth week of development in a multitude of organs such as the heart, skeletal muscle tissue and supporting tissue of various organs such as the kidney, brain or pericardium. Its function seems to be when the embryonic histological images are analyzed in an evolutionary way, to act as a scaffold or scaffold for the subsequent population by mature tissue elements. In conclusion, telocytes appear at a very early stage of embryonic development and would have a fundamental role in it as scaffolding and directors of organ and tissue growth.

Los telocitos son una población celular descrita en 2011 con multitud de funciones como el sostén tisular, la regulación de los nichos de células madre o la transmisión de señales intercelulares. Sin embargo, no existen estudios acerca del origen embrionario de los mismos, su función en el desarrollo ni su momento de aparición. El objetivo de este trabajo es tratar de responder a estos interrogantes mediante estudios histológicos y por inmunofluorescencia con muestras de la colección embriológica del Departamento de Anatomía de la Universidad de Granada. En los resultados se puede observar como se demuestra mediante inmunofluorescencia para CD34, la presencia de estas células en la cuarta semana del desarrollo embrionario en la región perinotocordal. Su presencia se evidencia a partir de la sexta semana del desarrollo en multitud de órganos como corazón, tejidos músculo esqueléticos y tejidos de sostén de diversos órganos como riñón, encéfalo o pericardio. Su función parece ser al ser analizadas las imágenes histológicas embrionarias de forma evolutiva, la de actuar como un andamiaje o scafold para el posterior poblamiento por elementos tisulares maduros. Como conclusión, los telocitos aparecen en un momento muy precoz del desarrollo embrionario y presentarían una función fundamental en el mismo como andamiajes y directores del crecimiento de los órganos y tejidos.

Telocytes protect against lung tissue fibrosis through hexokinase 2-dependent pathway by secreting hepatocyte growth factor.

Pulmonary fibrosis (PF) is one of the common manifestations of end-stage lung disease. Chronic lung failure after lung transplantation is mainly caused by bronchiolitis obliterans syndrome (BOS) and is mainly characterized by lung tissue fibrosis. Pulmonary epithelial-mesenchymal transformation (EMT) is crucial for pulmonary fibrosis. Telocytes (TCs), a new type of mesenchymal cells, play a protective role in various acute injuries. For exploring the anti-pulmonary fibrosis effect of TCs in the BOS model in vitro and the related mechanism, rat tracheal epithelial (RTE) cells were treated with transforming growth factor-ß (TGF-ß) to simulate lung tissue fibrosis in vitro. The RTE cells were then co-cultured with TCs primarily extracted from rat lung tissue. Western blot, Seahorse XF Analysers and enzyme-linked immunosorbent assay were used to detect the level of EMT and aerobic respiration of RTE cells. Furthermore, anti-hepatocyte growth factor (anti-HGF) antibody was exogenously added to the cultured cells to explore further mechanisms. Moreover, hexokinase 2 (HK2) in RTE cells was knocked down to assess whether it influences the blocking effect of the anti-HGF antibody. TGF-ß could induce lung tissue fibrosis in RTE cells in vitro. Nevertheless, TCs co-culture decreased the level of EMT, glucose metabolic indicators (lactate and ATP) and oxygen levels. Furthermore, TCs released hepatocyte growth factor (HGF). Therefore, the exogenous addition of anti-HGF antibody in the co-culture system blocked the anti-lung tissue fibrosis effect. However, HK2 knockdown attenuated the blocking effect of the anti-HGF antibody. In conclusion, TCs can protect against lung tissue fibrosis by releasing HGF, a process dependent on HK2.

Stromal cell-derived factor 1 (SDF-1) increases the number of telocytes in ex vivo and in vitro assays.

Telocytes are interstitial cells that are present in various tissues, have long cytoplasmic projections known as telopodes, and are classified as CD34+ cells. Telopodes form extensive networks that permeate the stroma, and there is evidence that these networks connect several stromal cell types, giving them an important role in intercellular communication and the maintenance of tissue organisation. Data have also shown that these networks can be impaired and the number of telocytes reduced in association with many pathological conditions such as cancer and fibrosis. Thus, techniques that promote telocyte proliferation have become an important therapeutic target. In this study, ex vivo and in vitro assays were conducted to evaluate the impact on prostatic telocytes of SDF-1, a factor involved in the proliferation and migration of CD34+ cells. SDF-1 caused an increase in the number of telocytes in explants, as well as morphological changes that were possibly related to the proliferation of these cells. These changes involved the fusion of telopode segments, linked to an increase in cell body volume. In vitro assays also showed that SDF-1 enriched prostate stromal cells with telocytes. Altogether, the data indicate that SDF-1 may offer promising uses in therapies that aim to increase the number of telocytes. However, further studies are needed to confirm the efficiency of this factor in different tissues/pathological conditions.

Telocytes and ezrin expression in normal-appearing tissues adjacent to urothelial bladder carcinoma as predictors of invasiveness and recurrence.

Recurrence and progression rates vary widely among different histological subtypes of bladder cancer (BC). Normal-appearing mucosa in non-muscle invasive bladder cancer and muscle-invasive bladder cancer in cystoscopy and histopathology is a factor in staging and treatment. Telocytes (TCs) are spindle-shaped cells that connect with other cell types allowing communication though cytoskeletal signaling. They are involved in tissue regeneration and pathogenesis of diseases and cancer. In this study, 12 normal-appearing tissues from urinary bladder with BC, both invasive and non-invasive were evaluated in patients who had either trans-urethral resection of bladder tumor or cystectomy. In each case, cystoscopy, intraoperative inspection, and histopathology all confirmed the absence of cancerous elements. Five patients with neurogenic bladder were used as a control group. Immunohistochemistry revealed that c-Kit + cells were intensively distributed in bladder layers from BC samples, while they were seldom detected in the control group. Ultrastructural examination of reprocessed tissue showed an intense distribution of TCs and telopodes in the submucosa and between smooth muscle cells in BC. Telopodes were numerous, arborizing, and intercommunicating. Whereas TCs and telopodes were scarce in the neurogenic bladder. Also, cancerous tissue had the highest expression level of ezrin protein, and this level gradually decreased as we moved away from the tumor. Our finding of TCs number in normal-appearing tissues in conjunction with ezrin expression may compete invasiveness and possibly a trail to reduce recurrence rates.

Isolation of Murine Intestinal Mesenchyme Resulting in a High Yield of Telocytes.

The murine small intestine, or colon mesenchyme, is highly heterogenous, containing distinct cell types including blood and lymphatic endothelium, nerves, fibroblasts, myofibroblasts, smooth muscle cells, immune cells, and the recently identified cell type, telocytes. Telocytes are unique mesenchymal cells with long cytoplasmic processes, reaching a distance of tens to hundreds of microns from the cell body. Telocytes have recently emerged as an important intestinal stem cell niche component, providing Wnt proteins that are essential for stem and progenitor cell proliferation. Although protocols on how to isolate mesenchyme from the mouse intestine are available, it is not clear whether these procedures allow the efficient isolation of telocytes. Isolating telocytes efficiently requires special protocol adjustments that would allow dissociation of the strong cell-cell contact between telocytes and neighboring cells without affecting their viability. Here, available intestinal mesenchyme isolation protocols were adjusted to support the successful isolation and culture of mesenchyme containing a relatively high yield of viable single-cell telocytes. The obtained single-cell suspension can be analyzed by several techniques, such as immunostaining, cell sorting, imaging, and mRNA experiments. This protocol yields mesenchyme with sufficiently conserved antigenic and functional properties of telocytes, and can be used for several applications. For example, they can be used for co-culture with mouse- or human-derived organoids to support organoid growth with no growth factor supplementation, to better reflect the situation in the original tissue.

Identification and protective role of CD34+ stromal cells/telocytes in experimental autoimmune encephalomyelitis (EAE) mouse spleen.

Experimental autoimmune encephalomyelitis (EAE) is a classical animal model of human multiple sclerosis (MS) that is most commonly used to study the neuropathology and therapeutic effects of the disease. Telocytes (TCs) are a specialized type of interstitial or mesenchymal cell first identified by Popescu in various tissues and organs. However, the existence, distribution and role of CD34+ stromal cells (SCs)/TCs in the EAE-induced mouse spleen remain to be elucidated. We conducted immunohistochemistry, immunofluorescence (double staining for CD34 and c-kit, vimentin, F4/80, CD163, Nanog, Sca-1, CD31 or tryptase) and transmission electron microscopy experiments to investigate the existence, distribution and role of CD34+ SCs/TCs in the EAE-induced mouse spleen. Interestingly, immunohistochemistry, double-immunofluorescence, and transmission electron microscopy results revealed that CD34+ SCs/TCs were significantly upregulated in the EAE mouse spleen. Immunohistochemical or double-immunofluorescence staining of CD34+ SCs/TCs showed positive expression for CD34, c-kit, vimentin, CD34/vimentin, c-kit/vimentin and CD34/c-kit, and negative expression for CD31 and tryptase. Transmission electron microscopy (TEM) results demonstrated that CD34+ SCs/TCs established close connections with lymphocytes, reticular cells, macrophages, endothelial cells and erythrocytes. Furthermore, we also found that M1 (F4/80) or M2 (CD163) macrophages, and haematopoietic, pluripotent stem cells were markedly increased in EAE mice. Our results suggest that CD34+ SCs/TCs are abundant and may play a contributing role in modulating the immune response, recruiting macrophages and proliferation of haematopoietic and pluripotent stem cells following injury to promote tissue repair and regeneration in EAE mouse spleens. This suggests that their transplantation combined with stem cells might represent a promising therapeutic target for the treatment and prevention of multiple autoimmune and chronic inflammatory disorders.

Morphological and histochemical identification of telocytes in adult yak epididymis.

Telocytes (TCs) are a newly discovered type of mesenchymal cell that are closely related to the tissue's internal environment. The study aimed to investigate the morphological identification of TCs in the epididymis of adult yak and their role in the local microenvironment. In this study, transmission electron microscopy (TEM), scanning electron microscopy, immunofluorescence, qRT-PCR, and western blotting were used to analyze the cell morphology of TCs. The results showed that there are two types of TCs in the epididymal stroma of yak by TEM; one type is distributed around the capillaries with full cell bodies, longer TPs, and a large number of secretory vesicles; the other is distributed outside the basement membrane with irregularly long, striped, large nuclei and short telopodes (TPs). In addition, these TCs formed complex TC cell networks through TPs with epididymal interstitial capillaries and basal fibroblasts. TCs often appear near the capillaries and basement membrane by special staining. The surface markers of TCs (CD34, vimentin, and CD117) were positively expressed in the epididymal stroma and epithelium by immunohistochemistry, and immunofluorescence co-expression of vimentin + CD34 and CD117 + CD34 was observed on the surface of TCs. The trends in the mRNA and protein expression of TCs surface markers revealed expression was highest in the caput epididymis. In summary, this is first report of TCs in the epididymis of yak, and two phenotypes of TCs were observed. The existence and distribution characteristics of TCs in the epididymis of plateau yaks provide important clues for further study of the adaptation to reproductive function in the plateau.

Estradiol enhances T-type calcium channel activation in human myometrium telocytes.

Uterine peristalsis is essential for gamete transport and embryo implantation. It shares the characteristics of spontaneity, rhythmicity, and directivity with gastrointestinal peristalsis. Telocytes, the "interstitial Cajal-like cells" outside the digestive canal, are also located in the uterus and may act as pacemakers. To investigate the possible origin and regulatory mechanism of periodic uterine peristalsis in the human menstrual cycle, telocytes in the myometrium were studied to determine the effect of estradiol on T-type calcium channel regulation. In this study, biopsies of the human myometrium were obtained for cell culture, and double-labeling immunofluorescence screening was used to identify telocytes and T-type calcium channel expression. Intracellular calcium signal measurements and patch-clamp recordings were used to investigate the role of T-type calcium channels in regulating calcium currents with or without estradiol. Our study demonstrates that telocytes exist in the human uterus and express T-type calcium channels. The intracellular Ca2+ fluorescence intensity marked by Fluo-4AM was dramatically decreased by NNC 55-0396, a highly selective T-type calcium channel blocker, but enhanced by estradiol. T-type calcium current amplitude increased in telocytes incubated with estradiol in a dose-dependent manner compared to the control group. In conclusion, our study demonstrated that telocytes exist in the human myometrium, expressing T-type calcium channels and estradiol-enhanced T-type calcium currents, which may be a reasonable explanation for the origin of uterine peristalsis. The role of telocytes in the human uterus as pacemakers and message transfer stations in uterine peristalsis may be worth further investigation.