The History of Telocyte Discovery and Understanding

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.

Identification of telocytes in the oviduct of the mare

Telocytes (TCs), a recently discovered special type of stromal cells, have been identified in many organs of many species, including the female and male reproductive system, with proposed multiple potential bio-functions such as homeostasis, immunomodulation, tissue remodeling and regeneration, embryogenesis, angiogenesis and even tumorigenesis. The aim of this study was to investigate the existence, and characteristics of telocytes in normal equine oviduct. To identify them, we used routine light microscopy, non-conventional light microscopy (NCLM), transmission electron microscopy (TEM), and immunohistochemistry. We found that telocytes of the equine oviduct can be recognized in fixed specimens by light microscopy (methylene blue staining), with more details on Epon semi-thin sections (toluidine blue staining) by NCLM, and that they showed positive immunostaining for CD34. The telocytes, with their typical long and moniliform prolongations, formed networks in the stromal space of the submucosa, muscular and serosa layers, particularly in the lamina propia where they were observed in greater quantity. By TEM we have also confirmed the presence of cells ultrastructurally identifiable as telocytes (cells with telopodes alternating podomers and podoms) in the aforementioned locations. Direct intercellular contacts between epithelial cells and neighboring telocytes were evidenced. EIn conclusion, we demonstrated that telocytes are present in the equine oviduct as previously reported in other species. The potential implication of telocytes in multiple potential functions of physiological and pathological processes deserves further investigation.

Ultrastructural and immunohistochemical characteristics of telocytes in human scalp tissue

This study was designed to characterize the location, morphology and ultrastructure of telocytes (TCs) in human scalp tissue. After obtaining approval for this study and informed consent from the patient, a scalp specimen was obtained. The distribution and morphology of TCs in human scalp tissue was assessed by immunohistochemical staining of CD34 and CD117/c-KIT, and the ultrastructure of TCs was investigated using transmission electron microscopy (TEM). Immunohistochemical staining of CD34 revealed that TCs were located in the connective tissue of human scalp, and were concentrated around hair follicles (HFs), blood vessels, sweat glands, sebaceous glands and adipose lobules. Immunohistochemical staining of CD117 revealed that TCs were mainly located in the dermis of human scalp, surrounding the HFs and sweat glands. Under TEM, TCs were seen and confirmed by their special morphological features. These cells were spindle-shaped, had small cell bodies and long thin processes, and surrounded stem cell clusters in the bulge region of HFs. These results demonstrate that TCs in human scalp were positive for CD34 and CD117, and their strategic positioning surrounding stem cells suggests their possible involvement in local regeneration, remodeling and homeostasis of the skin.

Ischemia Reperfusion Injury: Mechanisms of Damage/Protection and Novel Strategies for Cardiac Recovery/Regeneration

Ischemic diseases in an aging population pose a heavy social encumbrance. Moreover, current therapeutic approaches, which aimed to prevent or minimize ischemia-induced damage, are associated with relevant costs for healthcare systems. Early reperfusion by primary percutaneous coronary intervention (PPCI) has undoubtedly improved patient's outcomes; however, the prevention of long-term complications is still an unmet need. To face these hurdles and improve patient's outcomes, novel pharmacological and interventional approaches, alone or in combination, reducing myocardium oxygen consumption or supplying blood flow via collateral vessels have been proposed. A number of clinical trials are ongoing to validate their efficacy on patient's outcomes. Alternative options, including stem cell-based therapies, have been evaluated to improve cardiac regeneration and prevent scar formation. However, due to the lack of long-term engraftment, more recently, great attention has been devoted to their paracrine mediators, including exosomes (Exo) and microvesicles (MV). Indeed, Exo and MV are both currently considered to be one of the most promising therapeutic strategies in regenerative medicine. As a matter of fact, MV and Exo that are released from stem cells of different origin have been evaluated for their healing properties in ischemia reperfusion (I/R) settings. Therefore, this review will first summarize mechanisms of cardiac damage and protection after I/R damage to track the paths through which more appropriate interventional and/or molecular-based targeted therapies should be addressed. Moreover, it will provide insights on novel non-invasive/invasive interventional strategies and on Exo-based therapies as a challenge for improving patient's long-term complications. Finally, approaches for improving Exo healing properties, and topics still unsolved to move towards Exo clinical application will be discussed.

Onset of Appearance and Potential Significance of Telocytes in the Developing Fetal Lung

CD34, vimentin, and vascular endothelial growth factor immunohistochemical analysis and electron microscopic tools were employed to record the initial appearance of telocytes (TCs) and stage-by-stage variations in TC localizations in the developing rabbit lung. TCs could not be identified in the primitive embryonic lung until day 18 of gestation. In the pseudoglandular lung, CD34+ TCs had been recorded under the cartilage of the main bronchus, in the wall of large-sized pulmonary vessels and large epithelial tubes. In the canalicular phase, TCs could be demonstrated in the smooth muscle layer of the bronchioles including the terminal ones. The strength of CD34 immunoreactive signals had been amplified by age until the day of parturition. Ultrastructurally, TCs consisted of a tiny body and exceptionally long telopodes (Tps). The Tp consisted of alternating thin segments (podomers) and dilated ones (podoms). The Tp sometimes branched with a dichotomous pattern. TCs interconnected in a network either by homocellular junctions with neighboring TCs or by heterocellular junctions with smooth muscle cells and alveolar cells. Collectively, early detection of TCs in pulmonary vessels suggests a potential role for TCs in their angiogenesis. For the lung tissue, TCs seem to be involved in the regulation of lung histogenesis.

Influence of gene modification in biological behaviors and responses of mouse lung telocytes to inflammation

BACKGROUND

Telocytes play key roles in maintenance of organ/tissue function and prevention of organ injury. However, there are great challenges to investigate telocytes functions using primary telocytes, due to the difficulties of isolation, identification, and stability. The present study aims at constructing continuous cell strain of mouse lung telocyte cell line with stable characters by gene modification and investigating biological behaviors and responses of gene-modified telocytes to inflammation.

METHODS

Mouse primary lung telocytes were isolated and identified using immune-labeling markers and immunoelectron microscopy. Primary telocytes were transformed with Simian vacuolating virus 40 small and large T antigen (SV40). Biological characters, behaviors morphology, and proliferation of those gene-modified telocytes were defined and monitored dynamically for 50 generations, as compared with primary lung telocytes. Cell cycle of mouse primary lung telocytes or gene-modified telocytes was detected by flow cytometry.

RESULTS

Gene modified telocytes of generations 5, 10, 30 and 50 were observed with telopodes and also showed CD34 and ckit positive. Multiple cellular morphology were also observed on telocyte cell-line under monitor of celliq and enhanced cell proliferation were showed. SV40 transduction was also reduced apoptosis and increased the ratio of S and G2 phases in telocyte cell-line.

CONCLUSION

We successfully constructed mouse lung telocyte cell-line which maintained the biological properties and behaviors as primary telocytes and could responses to inflammation induced by LPS. Thus, gene-modified lung telocytes, Telocyte Line, would provide a cell tool for researchers exploring the roles and applications of telocytes involved in physiological and pathological states in future.

Telocytes constitute a widespread interstitial meshwork in the lamina propria and underlying striated muscle of human tongue

Telocytes have recently emerged as unique interstitial cells defined by their extremely long, thin and moniliform prolongations termed telopodes. Despite growing evidence that these cells consistently reside in the stromal compartment of various organs from human beings, studies dealing with telocytes in structures of the oral cavity are scarce. Hence, the present morphologic study was undertaken to explore for the first time the presence and specific localization of telocytes within tissues of the normal human tongue, a complex muscular organ whose main functions include taste, speech, and food manipulation in the oral cavity. Telocytes were initially identified by CD34 immunostaining and confirmed by CD34/PDGFRα double immunofluorescence and transmission electron microscopy. CD34+/PDGFRα+ telocytes were organized in interstitial meshworks either in the tongue lamina propria or in the underlying striated muscle. Lingual telocytes were immunonegative for CD31, c-kit and α-SMA. Telopodes were finely distributed throughout the stromal space and concentrated beneath the lingual epithelium and around CD31+ vessels, skeletal muscle bundles/fibers, and intramuscular nerves and ganglia. They also enveloped salivary gland units outside the α-SMA+ myoepithelial cells and delimited lymphoid aggregates. These findings establish telocytes as a previously overlooked interstitial cell population worth investigating further in the setting of human tongue pathophysiology.

Telocytes in normal and keratoconic human cornea: an immunohistochemical and transmission electron microscopy study

Telocytes (TC) are typically defined as cells with telopodes by their ultrastructural features. Their presence was reported in the interstitium of various organs in vertebrates, including humans. However, no study has yet described the presence of TC in the human eye and in particular, within the stromal compartment of the cornea. To address this issue, samples of normal and pathologic (keratoconic) human corneas were tested by immunohistochemistry for CD34, platelet‐derived growth factor receptor α (PDGFRα) and c‐kit/CD117 or examined by transmission electron microscopy. We found that TC coexpressing CD34 and PDGFRα were distributed throughout the whole normal corneal stroma with different TC subtypes being distinguishable on the basis of the expression of the stemness marker c‐kit (i.e. c‐kit‐positive and c‐kit‐negative TC subpopulations). Transmission electron microscopy examination confirmed the existence of spindle‐shaped and bipolar TC typically displaying two long and thin moniliform telopodes establishing intercellular contacts formed by gap junctions. Keratoconic corneas were characterized by ultrastructural damages and patchy loss of TC with an almost complete depletion of the c‐kit‐positive TC subpopulation. We propose that TC may contribute to the maintenance of corneal stromal homoeostasis and that, in particular, the c‐kit‐positive TC subtype might have stemness capacity participating in corneal regeneration and repair processes. Further studies are needed to clarify the differential roles of corneal TC subtypes as well as the possible therapeutic applications of TC in degenerative corneal disorders such as keratoconus.

Mitochondrial DNA in Telocytes

Telocyte (TC) is a new identified interstitial cell type with a small nuclear and one or several long and thin prolongations with enlargements on them. They were found in many mammals including humans, mouse, rats, dogs, and monkeys and play vital roles in many physiological and pathological conditions. The ultrastructure of mitochondria was observed in TCs, and the alterations were found in TCs from inflammatory ureter tissue. MtDNA is associated with mitochondria normal functions and involved in physiological and pathological processes. However, mitochondria and mtDNA in TCs were not investigated deeply. This review will introduce the origin, distribution, morphology, and functions of TCs and the distribution and functions of TC mitochondria in order to improve a better understanding of the potential functions of mtDNA in TCs.