Isolation and Characterization of Equine Uterine Extracellular Vesicles: A Comparative Methodological Study.

Extracellular vesicles (EVs) have been identified in the uterine fluid in different species and have been pointed as key players in the embryo-maternal dialogue, maternal recognition of pregnancy and establishment of pregnancy. However, little is known about the uterine EVs in the mare. Therefore, the present study aimed at characterizing EVs from uterine lavage of cyclic mares by comparing five EVs isolation methods and the combination of them: (1) ultracentrifugation (UC); (2) concentration of lavage volume by Centricon ultrafiltration (CE); (3) the use of CE with different washing steps (phosphate-buffered saline with or without trehalose); (4) size-exclusion chromatography with iZON-qEV columns, and (5) a combination of the methods with best results based on EVs yield, purity, and protein cargo profiles. Transmission electron microscopy and Western blotting confirmed the isolation of EVs by all methods but with quantitative and qualitative differences. Mass spectrometry provided differences in protein profiles between methods, number of identified proteins, and protein classes. Our results indicate that the combination of CE/trehalose/iZON/UC is an optimal method to isolate equine uterine EVs with good yield and purity that can be applied in future studies to determine the role of equine uterine EVs in embryo-maternal interactions.

Site-specific opening of the blood-brain barrier by extracellular histones.

BACKGROUND: Increased extracellular histones in the bloodstream are known as a biomarker for vascular dysfunction associated with severe trauma or sepsis. There is limited information regarding the pathogenic role of circulating histones in neuroinflammation and cerebrovascular endothelial injury. Particularly, it remains unclear whether histones affect the blood-brain barrier (BBB) permeability function. METHODS: The direct effects of unfractionated histones on endothelial barrier properties were first assessed in brain microvascular endothelial cell monolayers by measuring transendothelial electrical resistance and solute flux. This was followed by in vivo mouse experiments, where BBB function was assessed by quantifying brain tissue accumulation of intravenously injected tracers of different molecular sizes, and comparison was made in mice receiving a sublethal dose of histones versus sterile saline. In parallel, the endothelial barrier ultrastructure was examined in histone- and saline-injected animals under transmission electron microscopy, corresponding to the expression of tight junction and adherens junction proteins. RESULTS: Histones increased paracellular permeability to sodium fluorescein and reduced barrier resistance at 100 µg/mL; these responses were accompanied by discontinuous staining of the tight junction proteins claudin-5 and zona ocludens-1. Interestingly, the effects of histones did not seem to result from cytotoxicity, as evidenced by negative propidium iodide staining. In vivo, histones increased the paracellular permeability of the BBB to small tracers of < 1-kDa, whereas tracers larger than 3-kDa remained impermeable across brain microvessels. Further analysis of different brain regions showed that histone-induced tracer leakage and loss of tight junction protein expression mainly occurred in the hippocampus, but not in the cerebral cortex. Consistently, opening of tight junctions was found in hippocampal capillaries from histone-injected animals. Protein expression levels of GFAP and iBA1 remained unchanged in histone-injected mice indicating that histones did not affect reactive gliosis. Moreover, cell membrane surface charge alterations are involved in histone-induced barrier dysfunction and tight junction disruption. CONCLUSIONS: Extracellular histones cause a reversible, region-specific increase in BBB permeability to small molecules by disrupting tight junctions in the hippocampus. We suggest that circulating histones may contribute to cerebrovascular injury or brain dysfunction by altering BBB structure and function.

Stay hydrated: basolateral fluids shaping tissues.

During development, embryos perform a mesmerizing choreography, which is crucial for the correct shaping, positioning and function of all organs. The cellular properties powering animal morphogenesis have been the focus of much attention. In contrast, much less consideration has been given to the invisible engine constituted by the intercellular fluid. Cells are immersed in fluid, of which the composition and physical properties have a considerable impact on development. In this review, we revisit recent studies from the perspective of the fluid, focusing on basolateral fluid compartments and taking the early mouse and zebrafish embryos as models. These examples illustrate how the hydration levels of tissues are spatio-temporally controlled and influence embryonic development.

Liquid biopsy biomarkers of renal interstitial fibrosis based on urinary exosome.

Renal interstitial fibrosis (RIF) is difficult to diagnose. This paper explored liquid biopsy markers in urinary exosomes derived from RIF patients. Urine samples from 32 patients with various degrees of RIF and 20 non-RIF patients were collected. The size and morphology of urinary exosomes isolated by polyethylene glycol were observed with electron microscopy. Protein biomakers of exosomes were analyzed by Western blot. qRT-PCR was used to detect the levels of biomarkers (miR-29c, miR-21, E-cadherin, and vimentin) of epithelial mesenchymal transition in urinary exosomes. The diagnostic value was detected with ROC curves. Results displayed successfully isolated urinary exosomes. The examined miRNAs and mRNAs were checked from all urinary exosomes samples, except for two cases of RIF which lacked E-cadherin mRNA. RNA levels were different in patients with diverse degrees of RIF. Urinary miR-29c was decreased with the progress of fibrosis. Levels of E-cadherin mRNA were first decreased and then increased. The contents of miR-21 and vimentin mRNA were also depended on the degrees of RIF. ROC curve analysis showed that the area under the curve (AUC) of miR-29c was 0.8621, statistically significant compared with the non-RIF group (P < 0.05). The miR-29c level within the urinary exosomes is a promising marker for the diagnosis of RIF.

Epithelial Sodium Channel Regulates Adult Neural Stem Cell Proliferation in a Flow-Dependent Manner.

One hallmark of adult neurogenesis is its adaptability to environmental influences. Here, we uncovered the epithelial sodium channel (ENaC) as a key regulator of adult neurogenesis as its deletion in neural stem cells (NSCs) and their progeny in the murine subependymal zone (SEZ) strongly impairs their proliferation and neurogenic output in the olfactory bulb. Importantly, alteration of fluid flow promotes proliferation of SEZ cells in an ENaC-dependent manner, eliciting sodium and calcium signals that regulate proliferation via calcium-release-activated channels and phosphorylation of ERK. Flow-induced calcium signals are restricted to NSCs in contact with the ventricular fluid, thereby providing a highly specific mechanism to regulate NSC behavior at this special interface with the cerebrospinal fluid. Thus, ENaC plays a central role in regulating adult neurogenesis, and among multiple modes of ENaC function, flow-induced changes in sodium signals are critical for NSC biology.

Mechanisms of sampling interstitial fluid from skin using a microneedle patch.

Although interstitial fluid (ISF) contains biomarkers of physiological significance and medical interest, sampling of ISF for clinical applications has made limited impact due to a lack of simple, clinically useful techniques that collect more than nanoliter volumes of ISF. This study describes experimental and theoretical analysis of ISF transport from skin using microneedle (MN) patches and demonstrates collection of >1 µL of ISF within 20 min in pig cadaver skin and living human subjects using an optimized system. MN patches containing arrays of submillimeter solid, porous, or hollow needles were used to penetrate superficial skin layers and access ISF through micropores (µpores) formed upon insertion. Experimental studies in pig skin found that ISF collection depended on transport mechanism according to the rank order diffusion < capillary action < osmosis < pressure-driven convection, under the conditions studied. These findings were in agreement with independent theoretical modeling that considered transport within skin, across the interface between skin and µpores, and within µpores to the skin surface. This analysis indicated that the rate-limiting step for ISF sampling is transport through the dermis. Based on these studies and other considerations like safety and convenience for future clinical use, we designed an MN patch prototype to sample ISF using suction as the driving force. Using this approach, we collected ISF from human volunteers and identified the presence of biomarkers in the collected ISF. In this way, sampling ISF from skin using an MN patch could enable collection of ISF for use in research and medicine.

Characterization of the Micro-Environment of the Testis that Shapes the Phenotype and Function of Testicular Macrophages.

Macrophages are important in the activation of innate immune responses and in a tissue-specific manner in the maintenance of organ homeostasis. Testicular macrophages (TM), which reside in the testicular interstitial space, comprise the largest leukocyte population in the testes and are assumed to play a relevant function in maintaining testicular immune privilege. Numerous studies have indicated that the interstitial fluid (IF) surrounding the TM has immunosuppressive properties, which may influence the phenotype of TM. However, the identity of the immunosuppressive molecules present in the IF is poorly characterized. We show that the rat testicular IF shifted GM-CSF-induced M1 toward the M2 macrophage phenotype. IF-polarized M2 macrophages mimic the properties of TM, such as increased expression of CD163, high secretion of IL-10, and low secretion of TNF-α. In addition, IF-polarized macrophages display immunoregulatory functions by inducing expansion of immunosuppressive regulatory T cells. We further found that corticosterone was the principal immunosuppressive molecule present in the IF and that the glucocorticoid receptor is needed for induction of the testis-specific phenotype of TM. In addition, TM locally produce small amounts of corticosterone, which suppresses the basal expression of inflammatory genes as a means to render TM refractory to inflammatory stimuli. Taken together, these results suggest that the corticosterone present in the testicular environment shapes the immunosuppressive function and phenotype of TM and that this steroid may play an important role in the establishment and sustenance of the immune privilege of the testis.

Cortical Spreading Depression Closes Paravascular Space and Impairs Glymphatic Flow: Implications for Migraine Headache.

Functioning of the glymphatic system, a network of paravascular tunnels through which cortical interstitial solutes are cleared from the brain, has recently been linked to sleep and traumatic brain injury, both of which can affect the progression of migraine. This led us to investigate the connection between migraine and the glymphatic system. Taking advantage of a novel in vivo method we developed using two-photon microscopy to visualize the paravascular space (PVS) in naive uninjected mice, we show that a single wave of cortical spreading depression (CSD), an animal model of migraine aura, induces a rapid and nearly complete closure of the PVS around surface as well as penetrating cortical arteries and veins lasting several minutes, and gradually recovering over 30 min. A temporal mismatch between the constriction or dilation of the blood vessel lumen and the closure of the PVS suggests that this closure is not likely to result from changes in vessel diameter. We also show that CSD impairs glymphatic flow, as indicated by the reduced rate at which intraparenchymally injected dye was cleared from the cortex to the PVS. This is the first observation of a PVS closure in connection with an abnormal cortical event that underlies a neurological disorder. More specifically, the findings demonstrate a link between the glymphatic system and migraine, and suggest a novel mechanism for regulation of glymphatic flow.SIGNIFICANCE STATEMENT Impairment of brain solute clearance through the recently described glymphatic system has been linked with traumatic brain injury, prolonged wakefulness, and aging. This paper shows that cortical spreading depression, the neural correlate of migraine aura, closes the paravascular space and impairs glymphatic flow. This closure holds the potential to define a novel mechanism for regulation of glymphatic flow. It also implicates the glymphatic system in the altered cortical and endothelial functioning of the migraine brain.

Focal Solute Trapping and Global Glymphatic Pathway Impairment in a Murine Model of Multiple Microinfarcts.

Microinfarcts occur commonly in the aging brain as a consequence of diffuse embolic events and are associated with the development of vascular dementia and Alzheimer's disease. However, the manner in which disperse microscopic lesions reduce global cognitive function and increase the risk for Alzheimer's disease is unclear. The glymphatic system, which is a brain-wide perivascular network that supports the recirculation of CSF through the brain parenchyma, facilitates the clearance of interstitial solutes including amyloid ß and tau. We investigated whether glymphatic pathway function is impaired in a murine model of multiple microinfarcts induced by intraarterial injection of cholesterol crystals. The analysis showed that multiple microinfarcts markedly impaired global influx of CSF along the glymphatic pathway. Although suppression of global glymphatic function was transient, resolving within 2 weeks of injury, CSF tracers also accumulated within tissue associated with microinfarcts. The effect of diffuse microinfarcts on global glymphatic pathway function was exacerbated in the mice aged 12 months compared with the 2- to 3-month-old mice. These findings indicate that glymphatic function is focally disrupted around microinfarcts and that the aging brain is more vulnerable to this disruption than the young brain. These observations suggest that microlesions may trap proteins and other interstitial solutes within the brain parenchyma, increasing the risk of amyloid plaque formation.SIGNIFICANCE STATEMENT Microinfarcts, small (<1 mm) ischemic lesions, are strongly associated with age-related dementia. However, how these microscopic lesions affect global cognitive function and predispose to Alzheimer's disease is unclear. The glymphatic system is a brain-wide network of channels surrounding brain blood vessels that allows CSF to exchange with interstitial fluid, clearing away cellular wastes such as amyloid ß. We observed that, in mice, microinfarcts impaired global glymphatic function and solutes from the CSF became trapped in tissue associated with microinfarcts. These data suggest that small, disperse ischemic lesions can impair glymphatic function across the brain and trapping of solutes in these lesions may promote protein aggregation and neuroinflammation and eventually lead to neurodegeneration, especially in the aging brain.

The levels of serine proteases in colon tissue interstitial fluid and serum serve as an indicator of colorectal cancer progression.

The proteins in tissue interstitial fluids (TIFs) can spread into the blood and have been proposed as an ideal material to find blood biomarkers. The colon TIFs were collected from 8-, 13-, 18-, and 22-week ApcMin/+, a typical mouse model of colorectal cancer (CRC), and wild-type mice. iTRAQ-based quantification proteomics was conducted to survey the TIF proteins whose abundance appeared to depend on tumor progression. A total of 46 proteins that exhibited consecutive changes in abundance were identified, including six serine proteases, chymotrypsin-like elastase 1 (CELA1), chymotrypsin-like elastase 2A (CEL2A), chymopasin, chymotrypsinogen B (CTRB1), trypsin 2 (TRY2), and trypsin 4 (TRY4). The observed increases in the abundance of serine proteases were supported in another quantitative evaluation of the individual colon TIFs using a multiple reaction monitor (MRM) assay. Importantly, the increases in the abundance of serine proteases were also verified in the corresponding sera. The quantitative verification of the serine proteases was further extended to the clinical sera, revealing significantly higher levels of CELA1, CEL2A, CTRL/chymopasin, and TRY2 in CRC patients. The receiver operating characteristic analysis illustrated that the combination of CELA1 and CTRL reached the best diagnostic performance, with 90.0% sensitivity and 80.0% specificity. Thus, the quantitative target analysis demonstrated that some serine proteases are indicative of CRC progression.

Preimplantation genetic testing: polar bodies, blastomeres, trophectoderm cells, or blastocoelic fluid?

OBJECTIVE: To investigate the blastocoelic fluid (BF) for the presence of DNA that could be amplified and analyzed; the extent to which its chromosomal status corresponds to that found in trophectoderm (TE) cells, polar bodies (PBs), or blastomeres; and the identification of segmental abnormalities. DESIGN: Longitudinal cohort study. SETTING: In vitro fertilization unit. PATIENT(S): Fifty-one couples undergoing preimplantation genetic screening or preimplantation genetic diagnosis for translocations by array-comparative genomic hybridization on PBs (n = 21) or blastomeres (n = 30). INTERVENTION(S): BFs and TE cells were retrieved from 116 blastocysts, whose chromosome status had already been established by PB or blastomere assessment. Separate chromosome analysis was performed in 70 BFs. MAIN OUTCOME MEASURE(S): Presence of DNA in BFs, evaluation of the chromosome condition, and comparison with the diagnosis made in TE cells and at earlier stage biopsies. RESULT(S): DNA detection was 82%, with a net improvement after refinement of the procedure. In 97.1% of BFs, the ploidy condition corresponded to that found in TE cells, with one false positive and one false negative. The rate of concordance per single chromosome was 98.4%. Ploidy and chromosome concordance with PBs were 94% and 97.9%, respectively; with blastomeres, the concordances were 95% and 97.7%, respectively. Segmental abnormalities, which were detected in PBs or blastomeres of 16 blastocysts, were also identified in the corresponding BFs. CONCLUSION(S): BF represents to a good extent the blastocyst ploidy condition and chromosome status when compared with TE cells. If the proportion of clinically useful BFs is improved, blastocentesis could become the preferred source of DNA for chromosomal testing.

Mast cells kill Candida albicans in the extracellular environment but spare ingested fungi from death.

Mast cells (MCs) reside in tissues that are common targets of Candida spp. infections, and can exert bactericidal activity, but little is known about their fungicidal activity. MCs purified from rat peritoneum (RPMC) and a clinical isolate of C. albicans, were employed. Ingestion was evaluated by flow cytometry (FACS) and optical microscopy. The killing activity was assayed by FACS analysis and by colony forming unit method. RPMC degranulation was evaluated by ß-hexosaminidase assay and phosphatidylserine externalization by FACS. Phagocytosing RPMC were also analyzed by transmission electron microscopy. Herein, we show that the killing of C. albicans by RPMC takes place in the extracellular environment, very likely through secreted granular components. Ultrastructural analysis of the ingestion process revealed an unusual RPMC-C. albicans interaction that could allow fungal survival. Our findings indicate that MCs have a positive role in the defense mechanism against Candida infections and should be included among the cell types involved in host-defense against this pathogen.

Leukocyte migration in the interstitial space of non-lymphoid organs.

Leukocyte migration through interstitial tissues is essential for mounting a successful immune response. Interstitial motility is governed by a vast array of cell-intrinsic and cell-extrinsic factors that together ensure the proper positioning of immune cells in the context of specific microenvironments. Recent advances in imaging modalities, in particular intravital confocal and multi-photon microscopy, have helped to expand our understanding of the cellular and molecular mechanisms that underlie leukocyte navigation in the extravascular space. In this Review, we discuss the key factors that regulate leukocyte motility within three-dimensional environments, with a focus on neutrophils and T cells in non-lymphoid organs.

Measurement of Tissue interstitial volume in healthy patients and those with amyloidosis with equilibrium contrast-enhanced MR imaging.

PURPOSE: To investigate equilibrium contrast material-enhanced magnetic resonance (MR) imaging measurement of extracellular volume (ECV) fraction within healthy abdominal tissues and to test the hypotheses that tissue ECV in systemic amyloid light-chain (AL) amyloidosis is greater than in healthy patients and show that this increase correlates with organ amyloid burden. MATERIALS AND METHODS: A local ethics committee approved the study and all patients gave written informed consent. Forty healthy volunteers (18 men, 22 women; median age, 43 years; age range, 24-88 years) and 67 patients with AL amyloidosis (43 men, 24 women; median age, 65 years; age range, 38-81 years) underwent equilibrium MR imaging of the upper abdomen. ECV was measured in the liver, spleen, and paravertebral muscle. Patients with amyloidosis also underwent serum amyloid P (SAP) component scintigraphy so that specific organ involvement by amyloid could be scored. Variation in ECV between tissues was assessed by using a Friedman Test. Tissue ECV in healthy and amyloidosis groups were compared by using a Mann-Whitney U test. Spearman correlation was used to test for an association between the organ SAP score and ECV. RESULTS: ECV measured at equilibrium MR imaging varied significantly between organs in healthy volunteers (χ(2) = 31.0; P < .001). ECV was highest in the spleen (0.34), followed by liver (0.29) and muscle (0.09). ECVs measured within the spleen (0.39; P< .001), liver (0.31; P = .005), and muscle (0.16; P< .001) were significantly higher in patients with amyloidosis than in healthy control subjects. ECV measured in the liver and spleen showed increasing organ amyloid burden assessed at SAP scintigraphy (liver, rs = 0.54; spleen, rs = 0.57). CONCLUSION: Equilibrium MR imaging can be used to define ECV within healthy tissues. ECV is increased in amyloidosis compared with healthy tissues, and this increase correlates with rising tissue amyloid burden.

Differential cell reaction upon Toll-like receptor 4 and 9 activation in human alveolar and lung interstitial macrophages.

BACKGROUND: Investigations on pulmonary macrophages (MΦ) mostly focus on alveolar MΦ (AM) as a well-defined cell population. Characteristics of MΦ in the interstitium, referred to as lung interstitial MΦ (IM), are rather ill-defined. In this study we therefore aimed to elucidate differences between AM and IM obtained from human lung tissue. METHODS: Human AM and IM were isolated from human non-tumor lung tissue from patients undergoing lung resection. Cell morphology was visualized using either light, electron or confocal microscopy. Phagocytic activity was analyzed by flow cytometry as well as confocal microscopy. Surface marker expression was measured by flow cytometry. Toll-like receptor (TLR) expression patterns as well as cytokine expression upon TLR4 or TLR9 stimulation were assessed by real time RT-PCR and cytokine protein production was measured using a fluorescent bead-based immunoassay. RESULTS: IM were found to be smaller and morphologically more heterogeneous than AM, whereas phagocytic activity was similar in both cell types. HLA-DR expression was markedly higher in IM compared to AM. Although analysis of TLR expression profiles revealed no differences between the two cell populations, AM and IM clearly varied in cell reaction upon activation. Both MΦ populations were markedly activated by LPS as well as DNA isolated from attenuated mycobacterial strains (M. bovis H37Ra and BCG). Whereas AM expressed higher amounts of inflammatory cytokines upon activation, IM were more efficient in producing immunoregulatory cytokines, such as IL10, IL1ra, and IL6. CONCLUSION: AM appear to be more effective as a non-specific first line of defence against inhaled pathogens, whereas IM show a more pronounced regulatory function. These dissimilarities should be taken into consideration in future studies on the role of human lung MΦ in the inflammatory response.

Plasticity and physiological role of stem cells derived from skeletal muscle interstitium: contribution to muscle fiber hyperplasia and therapeutic use.

Stem cells other than satellite cells that can give rise to primary myoblasts, which are able to form additional new fibers postnatally, are present in the interstitial spaces of skeletal muscle. These cells are sorted into CD34(+)/45(-) (Sk-34) and CD34(-)/45(-) (Sk-DN) cell fractions, and they are wholly (>99%) negative for Pax7 at initial isolation. Colony-forming units of these cells typically include non-adherent type myogenic cells, while satellite cells are known to be adherent in cell culture. In addition, both Pax7(-) and Pax7(+) cells are produced, depending on asymmetric cell division. A large number of myotubes are also formed in each colony, thus suggesting that putative Pax7(+) satellite cells also present in each colony. Interestingly, interstitial myogenic cells show basal lamina formation at early stages of myogenesis in response to various types of stimulation in compensatory enlarged muscle, a property that satellite cells do not possess in the parent fiber basal lamina cylinder. Basal lamina formation and production of satellite cells are essential before muscle fiber establishment in vivo. It is therefore likely that myogenic cells in skeletal muscle can be divided into two populations: 1) basal lamina-producing myogenic cells; and 2) basal lamina-non-producing myogenic cells. The latter population may be Pax7(+) satellite cells showing adherent capacity in cell culture, while the lamina-producing myogenic population derived from interstitial multipotent stem cells, which is predominant among Sk-34 and Sk-DN cells, plays a role in primary myoblast generation and shows non-adherent behavior in culture. Therefore, the physiological role of interstitial myogenic cells is as a source for new postnatal muscle fiber formation, and multinucleated muscle fibers (cells) are potentially formed clonally.

Capacity for stochastic self-renewal and differentiation in mammalian spermatogonial stem cells.

Mammalian spermatogenesis is initiated and sustained by spermatogonial stem cells (SSCs) through self-renewal and differentiation. The basic question of whether SSCs have the potential to specify self-renewal and differentiation in a cell-autonomous manner has yet to be addressed. Here, we show that rat SSCs in ex vivo culture conditions consistently give rise to two distinct types of progeny: new SSCs and differentiating germ cells, even when they have been exposed to virtually identical microenvironments. Quantitative experimental measurements and mathematical modeling indicates that fate decision is stochastic, with constant probability. These results reveal an unexpected ability in a mammalian SSC to specify both self-renewal and differentiation through a self-directed mechanism, and further suggest that this mechanism operates according to stochastic principles. These findings provide an experimental basis for autonomous and stochastic fate choice as an alternative strategy for SSC fate bifurcation, which may also be relevant to other stem cell types.

Presence of foam cells in kidney interstitium is associated with progression of renal injury in patients with glomerular diseases.

BACKGROUND: Renal interstitial foam cells (FCs) are occasionally observed in various renal diseases. The goal of the present study was to determine the relationship between the formation of renal interstitial FCs and the degree of proteinuria and hyperlipidemia, as well as the progression of these diseases. METHODS: 125 patients with Alport syndrome (AS), 192 patients with idiopathic membranous nephropathy (IMN), 388 patients with IgA nephropathy (IgAN), and 137 patients with focal segmental glomerulosclerosis (FSGS) were investigated retrospectively. RESULTS: FCs were observed in various glomerular diseases. The frequency of interstitial FCs was 64.8% in AS, 21.4% in MN, 12.4% in IgAN, and 36.5% in FSGS. Regardless of the pathologic diagnosis of the glomerular disease, segmental glomerular sclerosis occurred more frequently in patients with FCs than in patients without FCs. In the AS or IgAN group, interstitial fibrosis was more severe, and levels of proteinuria and serum lipids were significantly higher in FC-positive patients than in patients without FCs. CONCLUSION: FC formation in renal interstitium is associated with the degree of proteinuria and hyperlipidemia in patients with AS and IgAN. The presence of FCs in renal interstitium may contribute to the progression of glomerular diseases.

Cardiac renewing: interstitial Cajal-like cells nurse cardiomyocyte progenitors in epicardial stem cell niches.

Recent studies suggested that various cell lineages exist within the subepicardium and we supposed that this area could host cardiac stem cell niches (CSCNs). Using transmission electron microscopy, we have found at least 10 types of cells coexisting in the subepicardium of normal adult mice: adipocytes, fibroblasts, Schwann cells and nerve fibres, isolated smooth muscle cells, mast cells, macrophages, lymphocytes, interstitial Cajal-like cells (ICLCs) and cardiomyocytes progenitors (CMPs). The latter cells, sited in the area of origin of coronary arteries and aorta, showed typical features of either very immature or developing cardiomyocytes. Some of these cells were connected to each other to form columns surrounded by a basal lamina and embedded in a cellular network made by ICLCs. Complex intercellular communication occurs between the ICLCs and CMPs through electron-dense nanostructures or through shed vesicles. We provide here for the first time the ultrastructural description of CSCN in the adult mice myocardium, mainly containing ICLCs and CMPs. The existence of resident CMPs in different developmental stages proves that cardiac renewing is a continuous process. We suggest that ICLCs might act as supporting nurse cells of the cardiac niches and may be responsible for activation, commitment and migration of the stem cells out of the niches. Briefly, not only resident cardiac stem cells but also ICLCs regulate myocyte turnover and contribute to both cardiac cellular homeostasis and endogenous repair/remodelling after injuries.

Cerebrospinal fluid and interstitial fluid volume measurements in the human brain at 3T with EPI.

Cerebrospinal fluid (CSF) diffusion into periventricular white matter is one of the pathophysiological features of hydrocephalus of any kind. In standard clinical routine periventricular hyperintensities, size of the ventricular system, and invasive CSF pressure measurement are the key diagnostic methods. Recently a method called quantitative blood oxygenation level-dependent (qBOLD) was proposed by He and Yablonskiy (Magn Reson Med 2007;57:115-126), which uses the signal evolution of a GESSE sequence to extract quantitative information about hemodynamic parameters. In this study a similar method was used to extract volume fraction information of CSF and interstitial fluid (ISF) in the human brain. A standard gradient recalled echo / echo planar imaging (GRE-EPI) sequence with variable echo time was used for the acquisition of the MRI signal. A first test on healthy subjects yielded consistent results for ISF/CSF volume fraction, which were in good agreement with results found in the literature.