"Prostate telocytes change their phenotype in response to castration or testosterone replacement"

Distribution and morphologic characterization of telocytes in rat ovary and uterus: insights from ultrastructural and immunohistochemical analysis

Telocytes (TCs) are characterized by a small oval-shaped cell body with long prolongations that are called telopods (Tps). PDGFR-β and c-kit markers may assist for the immunohistochemical identification of TCs; however, by these means they cannot be identified with absolute specificity. Transmission electron microscopy (TEM) is considered as a gold standard method for TCs observation. Studies on TCs in the female reproductive system are limited, and there is a lack of awareness regarding TCs in rat ovaries. We aimed to demonstrate the existence and morphology of TCs in rat ovaries, alongside previously studied TCs in rat uteri. Thus, ovaries and uteri from young adult Sprague-Dawley female rats (n = 8) with regular estrous cycles were collected. Then, left ovaries and uteri were proccessed for TEM analysis, while the right ones were used for immunohistochemistry. As a result, TCs were seen throughout the rat's ovarian stroma with their characteristic cell bodies, Tps, podomes (Pds) and podomers (Pdms). Tps were situated within the thecal layer of the follicles, surrounding the corpus luteum and blood vessels. Ovarian TCs were recognized to have relationship with other TCs/stromal cells. Subsequently, TCs were seen in stroma of endometrium with surrounding blood vessels and uterine glands, myometrium and perimetrium in rat uteri. There was also no statistical significance between the number of c-kit+ and PDGFR-β+ telocyte-like cells in both rat ovarian (p = 0.137) and endometrial stroma (p = 0.450). Further investigation of the roles and functions of TCs in the female reproductive system is needed.

Morphological identification and distribution comparison of telocytes in pituitary gland between normal and cryptorchid yaks

BACKGROUND

Telocytes (TCs) is a novel type of interstitial cells in many mammals organs, which participate in the organizational metabolism, mechanical support, immunomodulation and other aspects. The aim of this study was to explore the organizational chemical characteristics of TCs in pituitary gland and their changes in cryptorchid yaks.

METHODS

Transmission electron microscopy (TEM), toluidine blue staining, immunofluorescence, qRT-PCR, and Western blotting may enable us to understand TCs distribution characteristics and biological functions.

RESULT

TEM confirmed the presence of TCs in the pituitary gland with small bodies and moniliform telopodes (Tps). The Tps extending out from the cell body to the peri-sinusoidal vessels spaces, the number of Tps is closely related to the morphology of the nucleus. The most obvious changes of TCs in the pituitary gland of cryptorchid yaks is the Tps are relatively shorter and decreased secretory vesicles. H.E. and toluidine blue staining revealed that TCs not only distributed between the sinusoidal blood vessels and the glandular cell clusters, but also present on the surface of vascular endothelial cells. The co-expression of TCs biomarkers, such as Vimentin/CD34, CD117/CD34 and α-SMA/CD34, were evaluated by immunofluorescence to further determine the phenotypic characteristics of TCs. Besides, we analyzed the mRNA and protein expression of these biomarkers to determine the characteristics of TCs changes and possible biological roles. Both the mRNA and protein expression of CD117 were significantly higher in the pituitary gland of cryptorchid yaks than in the normal (p < 0.01), the protein expression of CD34 in the cryptorchid yaks was significantly higher than the normal (p < 0.01). There were no significant difference in mRNA expression of Vimentin and α-SMA (p>0.05), while the protein expression were significantly increased in the normal yaks (p < 0.05).

CONCLUSIONS

In summary, this study reports for the first time that the biological characteristics of TCs in yak pituitary gland. Although there is no significant change in the distribution characteristics, the changes in biological features of TCs in cryptorchid yaks are clear, suggesting that TCs participated in alteration in the local microenvironment of the pituitary gland. Therefore, our study provides clues for further investigating the role of TCs in the pituitary gland during the occurrence of cryptorchidism in yaks.

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.

Sheet-like interstitial cells connect epithelial and smooth muscle cells in the mouse prostate

Epithelial-stromal relationship in the prostate gland is crucial for maintaining homeostasis, including functional differentiation, proliferation, and quiescence. Pathological stromal changes are believed to cause benign prostatic hyperplasia (BPH). The prostate stromal tissue is known to have several subtypes of interstitial cells that connect the epithelium and smooth muscle. However, the characteristics of their morphology and connection patterns are not fully understood. Therefore, we aimed to investigated the three-dimensional morphology and intercellular interactions of interstitial cells in the prostate ventral lobe of mature wild-type mice using immunohistochemistry and focused ion beam-scanning electron microscopy tomography (FIB-SEM tomography). The prostate interstitial cells exhibited immunohistochemical subtypes, including PDGFRα single-positive, CD34 single-positive, and CD34 and PDGFRα double-positive. PDGFRα single-positive cells were observed as elongated cells just below the epithelium, CD34 single-positive cells were observed as polygonal cells in the area away from the epithelium, and double-positive cells were observed as elongated cells situated slightly deeper than PDGFRα single-positive cells. Furthermore, connexin43-immunoreactive puncta were observed on interstitial cells just beneath the epithelium, suggestive of possible electrical connections among the PDGFRα single-positive interstitial cells. Three-dimensional structural analysis using FIB-SEM tomography revealed sheet-like multilayered interstitial cells that appear to separate the glandular terminal from the deeper interstitial tissue, which includes smooth muscle and capillaries. Further, epithelial cells might be indirectly connected to the smooth muscle and nerve fibers via these sheet-like multilayered interstitial cellular networks. These findings suggest that the cellular network that separates the glandular terminals from the deep interstitial tissue functionally bridges the epithelium and smooth muscle, possibly playing a pivotal role in prostate tissue homeostasis through the epithelial-smooth muscle or epithelial-stromal relationships.

Toward understanding the role of the interstitial tissue architects: Possible functions of telocytes in the male gonad

Telocytes represent a relatively recently discovered population of interstitial cells with a unique morphological structure that distinguishes them from other neighboring cells. Through their long protrusions extending from the cell body, telocytes create microenvironments via tissue compartmentalization and create homo- and hetero-cellular junctions. These establish a three-dimensional network enabling the maintenance of interstitial compartment homeostasis through regulation of extracellular matrix organization and activity, structural support, paracrine and juxtracrine communication, immunomodulation, immune surveillance, cell survival, and apoptosis. The presence of telocytes has also been confirmed in testicular interstitial tissue of many species of animals. The objective of this review is to summarize recent findings on telocytes in the male gonad, on which conclusions have been deduced that indicate the involvement of telocytes in maintaining the cytoarchitecture of the testicular interstitial tissue, in the processes of spermatogenesis and steroidogenesis, and photoperiod-mediated changes in the testes in seasonally reproductive animals.

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.

Evaluation of the Plasticity of Novel Regulatory Cells-Telocytes-in the Gonad of the Male Chinese Soft-Shelled Turtle (Pelodiscus sinensis) Associated with Seasonal Reproductive Activity

Telocyte (TC)—a new type of interstitial cell with long telopodes, can form cellular junctions with various tissues or cells to participate in the regulation of multitudes of physiological activities and diseases. This study aimed to characterize the morphology, molecular features, and potential functions of hormone regulation in Chinese soft-shelled turtle (Pelodiscus sinensis) testis TCs at different reproductive stages by histological evaluation, immunohistochemistry (IHC), immunofluorescence (IF), and transmission electron microscopy. During hibernation, TCs were widely distributed in the interstitial tissue. In contrast, during reproductive activity, TCs were noted to be in close proximity with peritubular myoid cells surrounding the seminiferous tubule. Moreover, formed cell–cell junctions were observed between TCs and PTMs. The results of IHC and IF showed that the immunophenotype of testicular TCs in hibernating Chinese soft-shelled turtles is CD34+Vimentin−, while the reproductive telopodes (Tps) show low expression of vimentin. The androgen receptor is expressed in Tps of TCs of testis during hibernation. Our results showed also that TCs in seasonal breeding animals regulate the activity of neighboring cells by releasing extracellular microvesicles (EXMVs), thus influencing the activity of spermatogenesis and steroidogenesis. Consideration of our novel and interesting results indicate that the whole area warrants further research.

Two distinctive types of telocytes in gills of fish: A light, immunohistochemical and ultra-structure study

Telocytes (TCs) are a vital constituent of interstitial tissue. They contribute to regulating cell function in heterotypic connections via direct contact or paracrine singling. Few studies mentioned intraepithelial TCs; however, they have been identified with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In this study, we investigated the intraepithelial and interstitial TCs using immunohistochemistry (IHC) and TEM. TCs can be identified by their distinctive telopodes (TPs), which consist of podoms and podomere, using TEM and immunohistochemical staining with CD34, CD117, and VEGF antibodies. Intraepithelial TCs established heterocontact with the lamellar capillary and interstitial TCs connected with the blood vessel in lamina propria. Intraepithelial TCs established direct contact with epithelial cells, which formed the lymph space while interstitial TCs connected with the secondary vascular vessels. The study provides evidence for TCs' heterocontact with lamellar blood capillaries, the blood vessels, chloride cells, and immune cells, such as rodlet cells and lymphocytes. In conclusion, TCs have a role in regulating respiratory activities, maintaining osmotic pressure, modulating the immune response, and conducting immunosurveillance. RESEARCH HIGHLIGHTS: We investigated the intraepithelial and interstitial TCs using immunohistochemistry (IHC) and TEM. TCs can be identified by their distinctive telopodes (TPs), which consist of podoms and podomere, using TEM and immunohistochemical staining with CD34, CD117, and VEGF antibodies. Intraepithelial TCs established heterocontact with the lamellar capillary and interstitial TCs connected with the blood vessel in lamina propria.

The complex role of telocytes in female prostate tumorigenesis in a rodent model

The prostate is not an organ exclusive to the male. It is also found in females of several species, including humans, in which part of the Skene gland is homologous to the male prostate. Evidence is accumulating that changes in the stroma are central to tumorigenesis. Equally, telocytes, a recently discovered type of interstitial cell, are essential for the maintenance of stromal organization. However, it is still uncertain whether there are telocytes in the female prostate and if they play a role in tumorigenesis. The present study used ultrastructural and immunofluorescence techniques to investigate the presence of telocytes in the prostate of Mongolian gerbil females, a rodent model that often has a functional prostate in females, as well as to assess the impact of a combination of N-ethyl-N-nitrosourea, testosterone, and estradiol on telocytes. The results point to the presence of telocytes in the female prostate in the perialveolar and interalveolar regions, and reveal that these cells are absent in regions of benign and premalignant lesions in the gland, in which the perialveolar smooth muscle is altered. Additionally, telocytes are also closely associated with infiltrated immune cells in the stroma. Our data suggest that telocytes are important for both the maintenance of smooth muscle and prostatic epithelium integrity, which indicates a protective role against the advancement of tumorigenesis. But telocytes are also associated with immune cells and a proinflammatory/proangiogenic role for these cells cannot be ruled out, implying that telocytes have a complex role in prostatic tumorigenesis in females.

Telocytes in the Female Reproductive System: Up-to-Date Knowledge, Challenges and Possible Clinical Applications

From their initial description in 2005 to this day, telocytes (TCs) have been described in the ovary, uterine tubes, uterus, vagina, mammary gland, and placenta. Their morphological features, immunophenotype, physiological functions, and roles in disease have been thoroughly documented in both animal models and human subjects. TCs, with their extremely long cytoplasmic processes called telopodes, play a pivotal role in the morphological and functional interconnection of all the components of the interstitial compartment, but also with constituents of the parenchyma. Although there is no specific immunohistochemical marker for their identification, the most cited are CD 117, CD 34, platelet-derived growth factor receptor (PDGFR), vimentin, and specific markers typical for the female reproductive system (FRS)-estrogen and progesterone receptors (ER and PR). This immunophenotype provides important clues to their physiological roles. Their main functions include the regulation of hormone-dependent processes, intercellular signaling, immune surveillance, microenvironmental maintenance, and the nursing of stem cells. In a situation where TCs are functionally or morphologically decimated, many disease entities may develop, including premature ovarian failure, endometriosis, ectopic pregnancy, infertility, preeclampsia, or even breast cancer. The common denominator of many of these conditions is that their etiopathogenesis is either partially known or completely obscure. Even though the exact role of TCs in these conditions is yet to be revealed, multiple lines of research indicate that their future clinical application may enrich diagnostic-therapeutic strategies of countless conditions. TCs are also heavily debated in terms of their possible use in regenerative medicine and tissue engineering. Some of the concepts related to TC research are strongly substantiated by experimental data, while others are highly speculative. Only future research endeavors will clearly distinguish dead-end lines of research from genuine contributions to the field.

Telocytes in Fibrosis Diseases: From Current Findings to Future Clinical Perspectives

Telocytes (TCs), a distinct type of interstitial (stromal) cells, have been discovered in many organs of human and mammal animals. TCs, which have unique morphological characteristics and abundant paracrine substance, construct a three-dimensional (3D) interstitial network within the stromal compartment by homocellular and heterocellular communications which are important for tissue homeostasis and normal development. Fibrosis-related diseases remain a common but challenging problem in the field of medicine with unclear pathogenesis and limited therapeutic options. Recently, increasing evidences suggest that where TCs are morphologically or numerically destructed, many diseases continuously develop, finally lead to irreversible interstitial fibrosis. It is not difficult to find that TCs are associated with chronic inflammation and fibrosis. This review mainly discusses relationship between TCs and the occurrence of fibrosis in various diseases. We analyzed in detail the potential roles and speculated mechanisms of TCs in onset and progression of systemic fibrosis diseases, as well as providing the most up-to-date research on the current therapeutic roles of TCs and involved related pathways. Only through continuous research and exploration in the future can we uncover its magic veil and provide strategies for treatment of fibrosis-related disease.

Stromal cell interplay in prostate development, physiology, and pathological conditions

Advances in prostatic stroma studies over the past few decades have demonstrated that the stroma not only supports and nourishes the gland's secretory epithelium but also participates in key aspects of morphogenesis, in the prostate's hormonal metabolism, and in the functionality of the secretory epithelium. Furthermore, the stroma is implicated in the onset and progression of prostate cancer through the formation of the so-called reactive stroma, which corresponds to a tumorigenesis-permissive microenvironment. Prostatic stromal cells are interconnected and exchange paracrine signals among themselves in a gland that is highly sensitive to endocrine hormones. There is a growing body of evidence that telocytes, recently detected interstitial cells that are also present in the prostate, are involved in stromal organization, so that their processes form a network of interconnections with both the epithelium and the other stromal cells. The present review provides an update on the different types of prostate stromal cells, their interrelationships and implications for prostate development, physiology and pathological conditions.

Telocytes of the male urogenital system: Interrelationships, possible functions, and pathological implications

The male urogenital system is composed of the reproductive system and the urinary tract; they have an interconnected embryonic development and share one of their anatomical components, the urethra. This system has a highly complex physiology deeply interconnected with the circulatory and nervous systems, as well as being capable of adapting to environmental variations; it also undergoes changes with aging and, in the case of the reproductive system, with seasonality. The stroma is an essential component in this physiological plasticity and its complexity has increased with the description in the last decade of a new cell type, the telocyte. Several studies have demonstrated the presence of telocytes in the organs of the male urogenital system and other systems; however, their exact function is not yet known. The present review addresses current knowledge about telocytes in the urogenital system in terms of their locations, interrelationships, possible functions and pathological implications. It has been found that telocytes in the urogenital system possibly have a leading role in stromal tissue organization/maintenance, in addition to participation in stem cell niches and an association with the immune system, as well as specific functions in the urogenital system, lipid synthesis in the testes, erythropoiesis in the kidneys and the micturition reflex in the bladder. There is also evidence that telocytes are involved in pathologies in the kidneys, urethra, bladder, prostate, and testes.

Telocytes contribute to aging-related modifications in the prostate

Telocytes are interstitial cells present in the stroma of several organs, including the prostate. There is evidence that these cells are present during prostate alveologenesis, in which these cells play a relevant role, but there is no information about the presence of and possible changes in telocytes during prostate aging. Throughout aging, the prostate undergoes several spontaneous changes in the stroma that are pro-pathogenic. Our study used histochemistry, 3D reconstructions, ultrastructure and immunofluorescence to compare the adult prostate with the senile prostate of the Mongolian gerbil, in order to investigate possible changes in telocytes with senescence and a possible role for these cells in the age-associated alterations. It was found that the layers of perialveolar smooth muscle become thinner as the prostatic alveoli become more dilated during aging, and that telocytes form a network that involves smooth muscle cells, which could possibly indicate a role for telocytes in maintaining the integrity of perialveolar smooth muscles. On the other hand, with senescence, VEGF+ telocytes are seen in stroma possibly contributing to angiogenesis, together with TNFR1+ telocytes, which are associated with a pro-inflammatory microenvironment in the prostate. Together, these data indicate that telocytes are important both in understanding the aging-related changes that are seen in the prostate and also in the search for new therapeutic targets for pathologies whose frequency increases with age.

Telocytes are associated with tissue remodeling and angiogenesis during the postlactational involution of the mammary gland in gerbils

The postlactational involution of the mammary gland is a complex process. It involves the collapse of the alveoli and the remodeling of the extracellular matrix, which in turn implies a complex set of interrelations between the epithelial, stromal, and extracellular matrix elements. The telocytes, a new type of CD34-positive stromal cell that differs from fibroblasts in morphological terms and gene expression, were detected in the stroma of several tissues, including the mammary gland; however, their function remains elusive. The present study employed three-dimensional reconstructions and immunohistochemical, ultrastructural, and immunofluorescence techniques in histological sections of the mammary gland of the Mongolian gerbil during lactation and postlactational involution to evaluate the presence of telocytes and to investigate a possible function for these cells. By means of immunofluorescence assays for CD34 and c-kit, major markers of telocytes, and also through morphological and ultrastructural evidences, telocytes were observed to surround the mammary ducts and collapsing alveoli. It was also found that these cells are associated with matrix metalloproteinase 9, which indicates that telocytes can play a role in extracellular matrix digestion, as well as vascular endothelial growth factor, a factor that promotes angiogenesis. Together, these data indicate that telocytes are a distinct cell type in the mammary gland and, for the first time, show that these cells possibly play a role in tissue remodeling and angiogenesis during the postlactional involution of the mammary gland.

Telocytes in Different Organs of Vertebrates: Potential Essence Cells of the Meridian in Chinese Traditional Medicine

Telocytes (TCs) are very long, non-neuronal, somatic cells whose function is widely believed to be involved in providing connections between different cells within the body. The cellular characteristics of TCs in various organs have been studied by immunohistochemistry, double immunofluorescence and electron microscopy in different vertebrate species, and here we investigate the proposed properties of these cells in the context of the "meridian" in Chinese Traditional Medicine (CTM). The results show that TCs and their long extensions, telopodes (Tps) develop a complicated network by homo- and heterocellular junctions in the connective tissue throughout the body, which can connect the skin with distant organs. In concept, this is the analogue of ancient meridian maps connecting skin acupoints with the viscera. Various active cells and extracellular vesicles including exosomes move along Tps, which, along with developed mitochondria within the podoms of Tps, may account for the structural evidence for "Qi" (vital energy and signal communication) in CTM. Morphological associations of TCs with the nerve, vascular, endocrine, and immune systems are also compatible with previously proposed meridian theories in CTM. Close relationships exist between TCs and collagen fiber bundles and some structures in skin fascia provide the microanatomical support for acupuncture treatment based on the meridian principle. The dynamicity in the distribution and structure of TCs reflects the plasticity of the meridian at the cellular level. As the same attribute, both the meridian and the TC have been associated with various diseases. Here, we summarize structural analogues between the TC and the meridian, suggesting that TCs have the cytological characteristics of the CTM meridian. We, therefore, hypothesize that TCs are the "essence cells" of the CTM meridian, which can connect and integrate different cells and structures in the connective tissue.

An Immunohistochemical Study of Gastric Mucosa and Critical Review Indicate that the Subepithelial Telocytes are Prelymphatic Endothelial Cells

Background and Objectives: There are only a few studies regarding gut subepithelial telocytes (TCs). The telopodes, namely peculiar TCs’ prolongations described on two-dimensional cuts, are not enough to differentiate this specific cell type. Subepithelial TCs were associated with the intestinal stem niche but a proper differential diagnosis with lymphatic endothelial cells (LECs) was not performed. In this study, we will also critically review studies suggesting that distinctive TCs could be positioned within the lamina propria. Materials and Methods: We performed an immunohistochemical study of human gastric mucosa to test the expression of D2-40, the lymphatic marker, as well as that of CD31, CD34, CD44, CD117/c-kit, α-smooth muscle actin (α-SMA) and vimentin in the gastric subepithelial niche. Results: The results support the poorly investigated anatomy of intramural gastric lymphatics, with circumferential collectors located on both sides of the muscularis mucosae (mucosal and then submucosal) and myenteric collectors in the muscularis propria. We also found superficial epithelial prelymphatic channels bordered by D2-40+ but CD31–TC-like cells. Deep epithelial lymphatic collectors drain in collectors within the lamina propria. Blood endothelial cells expressed CD31, CD34, CD44, and vimentin. Conclusions: Therefore, the positive diagnosis of TC for subepithelial CD34+ cells should be regarded with caution, as they could also be artefacts, resulting from the two-dimensional examination of three dimensional structures, or as LECs. Lymphatic markers should be routinely used to discriminate TCs from LECs.