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Key points: •Longissimus activity in the lumbar region was measured using indwelling electromyography to characterize the territory of its motor units.•The distribution of motor units in the longissimus pars lumborum muscle was mainly grouped into two distinct regions.•Regional activation of the longissimus pars lumborum was also observed during functional tasks involving trunk movements.•The regional activation of the longissimus pars lumborum muscle may play a role in segmental stabilization of the lumbar spine. The longissimus pars lumborum contributes to lumbar postural control and movement. While animal studies suggest a segmental control of this muscle, the territory of motor units constituting the human longissimus pars lumborum remains unknown. The aims of this study were to identify the localization of motor unit territories in the longissimus and assess the activation of this muscle during functional tasks. Eight healthy participants were recruited. During isometric back extension contractions, single motor‐unit (at L1, L2, L3 and L4) and multi‐unit indwelling recordings (at L1, L1‐L2, L2, L2‐L3, L3, L3‐L4 and L4) were used to estimate motor unit territories in the longissimus pars lumborum based on the motor‐unit spike‐triggered averages from fine‐wire electrodes. A series of functional tasks involving trunk and arm movements were also performed. A total of 73 distinct motor units were identified along the length of the longissimus: only two motor units spanned all recording sites. The majority of the recorded motor units had muscle fibres located in two main rostro‐caudal territories (32 motor units spanned L1 to L3 and 30 spanned ∼L3 to L4) and 11 had muscle fibres outside these two main territories. We also observed distinct muscle activation between the rostral and caudal regions of the longissimus pars lumborum during a trunk rotation task. Our results show clear rostral and caudal motor unit territories in the longissimus pars lumborum muscle and suggest that the central nervous system can selectively activate regions of the superficial lumbar muscles to provide local stabilization of the spine. Key points: •Longissimus activity in the lumbar region was measured using indwelling electromyography to characterize the territory of its motor units.•The distribution of motor units in the longissimus pars lumborum muscle was mainly grouped into two distinct regions.•Regional activation of the longissimus pars lumborum was also observed during functional tasks involving trunk movements.•The regional activation of the longissimus pars lumborum muscle may play a role in segmental stabilization of the lumbar spine. [ABSTRACT FROM AUTHOR]

Wnt signalling is involved in multiple aspects of embryonic development and adult tissue homeostasis, notably via controlling cellular proliferation and differentiation. Wnt signalling is subject to stringent positive and negative regulation to promote proper development and homeostasis yet avoid aberrant growth. Such multi-layer regulation includes post-translational modification and processing of Wnt proteins themselves, R-spondin (Rspo) amplification of Wnt signalling, diverse receptor families, and intracellular and extracellular antagonists and destruction and transcription complexes. In the gastrointestinal tract, Wnt signalling is crucial for development and renewal of the intestinal epithelium. Intestinal stem cells (ISCs) undergo symmetric division and neutral drift dynamics to renew the intestinal epithelium. Sources of Wnts and Wnt amplifers such as R-spondins are beginning to be elucidated as well as their functional contribution to intestinal homeostasis. In this review we focus on regulation of ISCs and intestinal homeostasis by the Wnt/Rspo pathway, the potential cellular sources of Wnt signalling regulators and highlight potential future areas of study. [ABSTRACT FROM AUTHOR]

The test for the cancer stem cell (CSC) hypothesis is to find a target expressed on all, and only CSCs in a patient tumor, then eliminate all cells with that target that eliminates the cancer. That test has not yet been achieved, but CSC diagnostics and targets found on CSCs and some other cells have resulted in a few clinically relevant therapies. However, it has become apparent that eliminating the subset of tumor cells characterized by self‐renewal properties is essential for long‐term tumor control. CSCs are able to regenerate and initiate tumor growth, recapitulating the heterogeneity present in the tumor before treatment. As great progress has been made in identifying and elucidating the biology of CSCs as well as their interactions with the tumor microenvironment, the time seems ripe for novel therapeutic strategies that target CSCs to find clinical applicability. On May 19–21, 2021, researchers in cancer stem cells met virtually for the Keystone eSymposium "Cancer Stem Cells: Advances in Biology and Clinical Translation" to discuss recent advances in the understanding of CSCs as well as clinical efforts to target these populations. [ABSTRACT FROM AUTHOR]

Despite extensive literature on vascular endothelial growth factor (VEGF) expression and regulation by steroid hormones, the lack of clear understanding of the mechanisms of angiogenesis in the endometrium is a major limitation for use of antiangiogenic therapy targeting endometrial vessels. In the current work, we used the rhesus macaque as a primate model and the decidualized mouse uterus as a murine model to examine angiogenesis during endometrial breakdown and regeneration. We found that blockade of VEGF action with VEGF Trap, a potent VEGF blocker, completely inhibited neovascularization during endometrial regeneration in both models but had no marked effect on preexisting or newly formed vessels, suggesting that VEGF is essential for neoangiogenesis but not survival of mature vessels in this vascular bed. Blockade of VEGF also blocked reepithelialization in both the postmenstrual endometrium and the mouse uterus after decidual breakdown, evidence that VEGF has pleiotropic effects in the endometrium. In vitro studies with a scratch wound assay showed that the migration of luminal epithelial cells during repair involved signaling through VEGF receptor 2-neuropilin 1 (VEGFR2-NP1) receptors on endometrial stromal cells. The leading front of tissue growth during endometrial repair was strongly hypoxic, and this hypoxia was the local stimulus for VEGF expression and angiogenesis in this tissue. In summary, we provide novel experimental data indicating that VEGF is essential for endometrial neoangiogenesis during postmenstrual/ postpartum repair. [ABSTRACT FROM AUTHOR]

Human intestinal organoids from primary human tissues have the potential to revolutionize personalized medicine and preclinical gastrointestinal disease models. A tunable, fully defined, designer matrix, termed hyaluronan elastin‐like protein (HELP) is reported, which enables the formation, differentiation, and passaging of adult primary tissue‐derived, epithelial‐only intestinal organoids. HELP enables the encapsulation of dissociated patient‐derived cells, which then undergo proliferation and formation of enteroids, spherical structures with polarized internal lumens. After 12 rounds of passaging, enteroid growth in HELP materials is found to be statistically similar to that in animal‐derived matrices. HELP materials also support the differentiation of human enteroids into mature intestinal cell subtypes. HELP matrices allow stiffness, stress relaxation rate, and integrin‐ligand concentration to be independently and quantitatively specified, enabling fundamental studies of organoid–matrix interactions and potential patient‐specific optimization. Organoid formation in HELP materials is most robust in gels with stiffer moduli (G' ≈ 1 kPa), slower stress relaxation rate (t1/2 ≈ 18 h), and higher integrin ligand concentration (0.5 × 10−3–1 × 10−3m RGD peptide). This material provides a promising in vitro model for further understanding intestinal development and disease in humans and a reproducible, biodegradable, minimal matrix with no animal‐derived products or synthetic polyethylene glycol for potential clinical translation. [ABSTRACT FROM AUTHOR]

Human intestinal organoids from primary human tissues have the potential to revolutionize personalized medicine and preclinical gastrointestinal disease models. A tunable, fully defined, designer matrix, termed hyaluronan elastin‐like protein (HELP) is reported, which enables the formation, differentiation, and passaging of adult primary tissue‐derived, epithelial‐only intestinal organoids. HELP enables the encapsulation of dissociated patient‐derived cells, which then undergo proliferation and formation of enteroids, spherical structures with polarized internal lumens. After 12 rounds of passaging, enteroid growth in HELP materials is found to be statistically similar to that in animal‐derived matrices. HELP materials also support the differentiation of human enteroids into mature intestinal cell subtypes. HELP matrices allow stiffness, stress relaxation rate, and integrin‐ligand concentration to be independently and quantitatively specified, enabling fundamental studies of organoid–matrix interactions and potential patient‐specific optimization. Organoid formation in HELP materials is most robust in gels with stiffer moduli (G' ≈ 1 kPa), slower stress relaxation rate (t1/2 ≈ 18 h), and higher integrin ligand concentration (0.5 × 10−3–1 × 10−3m RGD peptide). This material provides a promising in vitro model for further understanding intestinal development and disease in humans and a reproducible, biodegradable, minimal matrix with no animal‐derived products or synthetic polyethylene glycol for potential clinical translation. [ABSTRACT FROM AUTHOR]

Blood vessels are part of the stem cell niche in the developing cerebral cortex, but their in vivo role in controlling the expansion and differentiation of neural stem cells ( NSCs) in development has not been studied. Here, we report that relief of hypoxia in the developing cerebral cortex by ingrowth of blood vessels temporo-spatially coincided with NSC differentiation. Selective perturbation of brain angiogenesis in vessel-specific Gpr124 null embryos, which prevented the relief from hypoxia, increased NSC expansion at the expense of differentiation. Conversely, exposure to increased oxygen levels rescued NSC differentiation in Gpr124 null embryos and increased it further in WT embryos, suggesting that niche blood vessels regulate NSC differentiation at least in part by providing oxygen. Consistent herewith, hypoxia-inducible factor ( HIF)-1α levels controlled the switch of NSC expansion to differentiation. Finally, we provide evidence that high glycolytic activity of NSCs is required to prevent their precocious differentiation in vivo. Thus, blood vessel function is required for efficient NSC differentiation in the developing cerebral cortex by providing oxygen and possibly regulating NSC metabolism. [ABSTRACT FROM AUTHOR]

Compared to imaging in the visible and nearinfrared regions below 900 nm, imaging in the second nearinfrared window (NIR-II, 1000-1700 nm) is a promising method for deep-tissue high-resolution optical imaging in vivo mainly owing to the reduced scattering of photons traversing through biological tissues. Herein, semiconducting single-walled carbon nanotubes with large diameters were used for in vivo fluorescence imaging in the long-wavelength NIR region (1500-1700 nm, NIR-IIb). With this imaging agent, 3-4 μm wide capillary blood vessels at a depth of about 3 mm could be resolved. Meanwhile, the blood-flow speeds in multiple individual vessels could be mapped simultaneously. Furthermore, NIR-IIb tumor imaging of a live mouse was explored. NIR-IIb imaging can be generalized to a wide range of fluorophores emitting at up to 1700 nm for high-performance in vivo optical imaging. [ABSTRACT FROM AUTHOR]

Compared to imaging in the visible and nearinfrared regions below 900 nm, imaging in the second nearinfrared window (NIR-II, 1000-1700 nm) is a promising method for deep-tissue high-resolution optical imaging in vivo mainly owing to the reduced scattering of photons traversing through biological tissues. Herein, semiconducting single-walled carbon nanotubes with large diameters were used for in vivo fluorescence imaging in the long-wavelength NIR region (1500-1700 nm, NIR-IIb). With this imaging agent, 3-4 mm wide capillary blood vessels at a depth of about 3 mm could be resolved. Meanwhile, the blood-flow speeds in multiple individual vessels could be mapped simultaneously. Furthermore, NIR-IIb tumor imaging of a live mouse was explored. NIR-IIb imaging can be generalized to a wide range of fluorophores emitting at up to 1700 nm for high-performance in vivo optical imaging. [ABSTRACT FROM AUTHOR]

R5339 --> 731.8 --> Background: Small intestinal bicarbonate transport, is critical for epithelial protection, digestion, and absorption. Membrane trafficking and/or recycling of transporters is a critical means to modulate their function, however, the cellular mechanisms that drive these processes in the duodenum remain unclear. The inositol 1,4,5‐trisphosphate (IP3) receptor binding protein released with IP3 (IRBIT) is an intracellular protein that has been shown to regulate localization of bicarbonate transporters outside of the intestine, yet its role in regulating duodenal bicarbonate secretion is unknown. Aim: To examine duodenal expression and function of IRBIT in regulating bicarbonate transport. Methods: Duodenal endoscopic biopsies from subjects without gross or histological evidence of disease were used directly or cultured using traditional apical‐in or flipped apical‐out enteroids. mRNA expression was evaluated using qPCR and re‐analysis of a duodenal sc‐RNAseq dataset. Protein expression and localization was determined by Western blot and confocal immunofluorescence, respectively. In vivo bicarbonate secretion was measured in anesthetized mice by duodenal perfusion and back‐titration. Results: IRBIT is highly expressed in human duodenal biopsies, with protein densitometric analysis showing ≥3.5‐fold higher expression than Calu‐3 airway submucosal gland cells or HEK293 kidney‐derived cells (n=1 each). Analysis of duodenal sc‐RNAseq data (1,625 cells) showed ACHYL1 in crypts and villi. Immunofluorescence staining of human duodenal biopsies (n=3) showed IRBIT staining along the crypt‐villus axis, primarily localizing in E‐cadherin positive epithelial cells, but also present in the lamina propria. In patient‐derived duodenal enteroids, IRBIT was expressed in both crypt‐like (undifferentiated) and villus‐like (differentiated) enteroids (n=3 each), with greater IRBIT mRNA and protein expression in the latter, a pattern similar to SLC26A3 and SLC26A6 chloride/bicarbonate exchangers (n=3 each). In sc‐RNAseq analysis, AHCYL1 and SLC26A3 were co‐expressed in 38% of all villus cells, compared to only 5% co‐expressing AHCYL1 and SLC26A6. CFTR‐independent duodenal bicarbonate secretion stimulated by linaclotide (10‐7 M) was significantly inhibited by phospholipase C inhibition (U7312, 10‐6 M; 91±11%, n=3), which we showed disrupts IRBIT membrane localization, or SLC26A3 inhibition (DRAinh‐A250, 10‐5 M; 68±8%, n=10). Linaclotide stimulation of apical‐out enteroids increased both IRBIT (n=3) and SLC26A3 (n=12) membrane trafficking. Summary and Conclusions: IRBIT is highly expressed in the duodenum and appears to functionally interact with SLC26A3. IRBIT may be an attractive target to modulate small intestinal pH in diseases like cystic fibrosis, where impaired bicarbonate secretion contributes to intestinal disease and malnutrition. [ABSTRACT FROM AUTHOR]

R-spondin proteins are adult stem cell growth factors capable of stimulating gut development by activating LGR4, 5, and 6 receptors to promote Wnt signaling. Although multiple Wnt ligands and cognate Frizzled receptors are expressed in the ovary, their physiological roles are unclear. Based on bioinformatic and in situ hybridization analyses, we demonstrated the exclusive expression of R-spondin2 in oocytes of ovarian follicles. In cultured somatic cells from preantral follicles, R-spondin2 treatment (ED50:3 ng/ml) synergized with Wnt3a to stimulate Wnt signaling. In cultured ovarian explants from prepubertal mice containing preantral follicles, treatment with R-spondin2, similar to follicle stimulating hormone, promoted the development of primary follicles to the secondary stage. In vivo administration of an R-spondin agonist stimulated the development of primary follicles to the antral stage in both immature mice and gonadotropin releasing hormone antagonist-treated adult mice. Subsequent treatment with gonadotropins allowed the generation of mature oocytes capable of undergoing early embryonic development and successful pregnancy. Furthermore, R-spondin agonist treatment of immune-deficient mice grafted with human cortical fragments stimulated the development of primary follicles to the secondary stage. Thus, oocyte-derived R-spondin2 is a paracrine factor essential for primary follicle development, and R-spondin agonists could provide a new treatment regimen for infertile women with low responses to the traditional gonadotropin therapy. [ABSTRACT FROM AUTHOR]

Angiogenesis is a highly organized process controlled by a series of molecular events. While much effort has been devoted to identifying angiogenic factors and their reciprocal receptors, far less information is available on the molecular mechanisms underlying directed endothelial cell migration. To search for novel proteins that participate in this process, we used the serial analysis of gene expression (SAGE) transcript profiling approach to identify genes that are selectively expressed in endothelial cells (ECs). Two EC SAGE libraries were constructed from human umbilical vein and artery ECs to enable data-mining against other non-ECs. A novel endothelial protein, Thrombospondin Type I Domain Containing 7A (THSD7A), with preferential expression in placenta vasculature and in human umbilical vein endothelial cells (HUVECs) was identified and targeted for further characterization. Overexpression of a THSD7A carboxyl-terminal fragment in HUVECs inhibited cell migration and disrupted tube formation, while suppression of THSD7A expression enhanced HUVEC migration and tube formation. Immunohistological analysis revealed that THSD7A was expressed at the leading edge of migrating HUVECs, and it co-localized with αVβ3 integrin and paxillin. This distribution was dispersed from focal adhesions after disruption of the actin cytoskeleton, suggesting the involvement of THSD7A in cytoskeletal organization. Our results show that THSD7A is a novel placenta endothelial protein that mediates EC migration and tube formation, and they highlight its potential as a new target for anti-angiogenic therapy. J. Cell. Physiol. 222: 685–694, 2010. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Declining learning and memory function is associated with the attenuation of adult hippocampal neurogenesis. As in humans, chronic stress or depression in animals is accompanied by hippocampal dysfunction, and neurogenesis is correspondingly down regulated, in part, by the activity of the hypothalamic–pituitary–adrenal axis as well as glutamatergic and serotonergic networks. Antidepressants can reverse this effect over time but one of the most clinically effective moderators of stress or depression and robust stimulators of neurogenesis is simple voluntary physical exercise such as running. Curiously, running also elevates circulating stress hormone levels yet neurogenesis is doubled in running animals. In evaluating the signalling that running provides to the central nervous system in mice, we have found that peripheral vascular endothelial growth factor (VEGF) is necessary for the effects of running on adult hippocampal neurogenesis. Peripheral blockade of VEGF abolished running-induced neurogenesis but had no detectable effect on baseline neurogenesis in non-running animals. These data suggest that VEGF is an important element of a ‘somatic regulator’ of adult neurogenesis and that these somatic signalling networks can function independently of the central regulatory networks that are typically considered in the context of hippocampal neurogenesis. [ABSTRACT FROM AUTHOR]