Multiparametric MRI based assessment of kidney injury in a mouse model of ischemia reperfusion injury.

Kidney diseases pose a global healthcare burden, with millions requiring renal replacement therapy. Ischemia/reperfusion injury (IRI) is a common pathology of acute kidney injury, causing hypoxia and subsequent inflammation-induced kidney damage. Accurate detection of acute kidney injury due to IRI is crucial for timely intervention.

Mesothelial Cells Exhibit Characteristics of Perivascular Cells in an In Vitro Angiogenesis Assay.

Mesothelial cells have been shown to have remarkable plasticity towards mesenchymal cell types during development and in disease situations. Here, we have characterized the potential of mesothelial cells to undergo changes toward perivascular cells using an in vitro angiogenesis assay. We demonstrate that GFP-labeled mesothelial cells (GFP-MCs) aligned closely and specifically with endothelial networks formed when human dermal microvascular endothelial cells (HDMECs) were cultured in the presence of VEGF-A on normal human dermal fibroblasts (NHDFs) for a 7-day period.

Near infrared conjugated polymer nanoparticles (CPN™) for tracking cells using fluorescence and optoacoustic imaging.

Tracking the biodistribution of cell therapies is crucial for understanding their safety and efficacy. Optical imaging techniques are particularly useful for tracking cells due to their clinical translatability and potential for intra-operative use to validate cell delivery. However, there is a lack of appropriate optical probes for cell tracking.

Umbilical cord mesenchymal stromal cell-derived extracellular vesicles lack the potency to immunomodulate human monocyte-derived macrophages in vitro.

Mesenchymal stromal cells (MSCs) have been reported to display efficacy in a variety of preclinical models, but without long-term engraftment, suggesting a role for secreted factors, such as MSC-derived extracellular vesicles (EVs). MSCs are known to elicit immunomodulatory effects, an important aspect of which is their ability to affect macrophage phenotype. However, it is not clear if these effects are mediated by MSC-derived EVs, or other factors secreted by the MSCs.

Intravenous Administration of Human Umbilical Cord Mesenchymal Stromal Cells Leads to an Inflammatory Response in the Lung.

Mesenchymal stromal cells (MSCs) administered intravenously (IV) have shown efficacy in preclinical models of various diseases. This is despite the cells not reaching the site of injury due to entrapment in the lungs. The immunomodulatory properties of MSCs are thought to underlie their therapeutic effects, irrespective of whether they are sourced from bone marrow, adipose tissue, or umbilical cord.

Quantifying acute kidney injury in an Ischaemia-Reperfusion Injury mouse model using deep-learning-based semantic segmentation in histology.

This study focuses on ischaemia-reperfusion injury (IRI) in kidneys, a cause of acute kidney injury (AKI) and end-stage kidney disease (ESKD). Traditional kidney damage assessment methods are semi-quantitative and subjective. This study aims to use a convolutional neural network (CNN) to segment murine kidney structures after IRI, quantify damage via CNN-generated pathological measurements, and compare this to conventional scoring.

Multispectral optoacoustic tomography is more sensitive than micro-computed tomography for tracking gold nanorod labelled mesenchymal stromal cells.

Tracking the fate of therapeutic cell types is important for assessing their safety and efficacy. Bioluminescence imaging (BLI) is an effective cell tracking technique, but poor spatial resolution means it has limited ability to precisely map cells in vivo in 3D. This can be overcome by using a bimodal imaging approach that combines BLI with a technique capable of generating high-resolution images.

Harmonised culture procedures minimise but do not eliminate mesenchymal stromal cell donor and tissue variability in a decentralised multicentre manufacturing approach.

Background: Mesenchymal stromal cells (MSCs), commonly sourced from adipose tissue, bone marrow and umbilical cord, have been widely used in many medical conditions due to their therapeutic potential. Yet, the still limited understanding of the underlying mechanisms of action hampers clinical translation. Clinical potency can vary considerably depending on tissue source, donor attributes, but importantly, also culture conditions.

VEGF Stimulates Activation of ERK5 in the Absence of C-Terminal Phosphorylation Preventing Nuclear Localization and Facilitating AKT Activation in Endothelial Cells.

Extracellular-signal-regulated kinase 5 (ERK5) is critical for normal cardiovascular development. Previous studies have defined a canonical pathway for ERK5 activation, showing that ligand stimulation leads to MEK5 activation resulting in dual phosphorylation of ERK5 on Thr218/Tyr220 residues within the activation loop. ERK5 then undergoes a conformational change, facilitating phosphorylation on residues in the C-terminal domain and translocation to the nucleus where it regulates MEF2 transcriptional activity.

Fate of intravenously administered umbilical cord mesenchymal stromal cells and interactions with the host's immune system.

Mesenchymal stromal cells (MSCs) are multipotent cells showing promise in pre-clinical studies and currently used in many clinical trials. The regenerative potential of MSCs is mediated, at least in part, by direct and indirect immunomodulatory processes. However, the mechanism of action is not fully understood yet, and there are still concerns about possible undesired negative effects associated with the administration of living cells.

The transition zone in Hirschsprung's bowel contains abnormal hybrid ganglia with characteristics of extrinsic nerves.

The aganglionic bowel in short-segment Hirschsprung's disease is characterized both by the absence of enteric ganglia and the presence of extrinsic thickened nerve bundles (TNBs). The relationship between the TNBs and the loss of enteric ganglia is unknown. Previous studies have described decreasing numbers of ganglia with increasing density of TNBs within the transition zone (TZ) between ganglionic and aganglionic gut, and there is some evidence of spatial contact between them in this region.

Extracellular Vesicles from Human Umbilical Cord-Derived MSCs Affect Vessel Formation In Vitro and Promote VEGFR2-Mediated Cell Survival.

Mesenchymal stromal cell (MSC)-derived extracellular vesicles (EVs) have emerged as novel tools in regenerative medicine. Angiogenesis modulation is widely studied for the treatment of ischaemic diseases, wound healing, and tissue regeneration. Here, we have shown that EVs from human umbilical cord-derived MSCs can affect VEGFR2 signalling, a master regulator of angiogenesis homeostasis, via altering the phosphorylation of AKT.

Optical Tissue Clearing to Study the Intra-Pulmonary Biodistribution of Intravenously Delivered Mesenchymal Stromal Cells and Their Interactions with Host Lung Cells.

Mesenchymal stromal cells (MSCs) injected intravenously are trapped in the capillaries of the lungs and die within the first 24 h. Studying the biodistribution and fate of labelled therapeutic cells in the 3D pulmonary context is important to understand their function in this organ and gain insights into their mechanisms of action. Optical tissue clearing enables volumetric cell tracking at single-cell resolution.

Mesenchymal stromal cells: what have we learned so far about their therapeutic potential and mechanisms of action?

Mesenchymal stromal cells (MSCs) have been found to be safe and effective in a wide range of animal models of human disease. MSCs have been tested in thousands of clinical trials, but results show that while these cells appear to be safe, they tend to lack efficacy. This has raised questions about whether animal models are useful for predicting efficacy in patients.

Restricted differentiative capacity of Wt1-expressing peritoneal mesothelium in postnatal and adult mice.

Previously, genetic lineage tracing based on the mesothelial marker Wt1, appeared to show that peritoneal mesothelial cells have a range of differentiative capacities and are the direct progenitors of vascular smooth muscle in the intestine. However, it was not clear whether this was a temporally limited process or continued throughout postnatal life. Here, using a conditional Wt1-based genetic lineage tracing approach, we demonstrate that the postnatal and adult peritoneum covering intestine, mesentery and body wall only maintained itself and failed to contribute to other visceral tissues.

Firefly luciferase offers superior performance to AkaLuc for tracking the fate of administered cell therapies.

Introduction: A novel, red-shifted bioluminescence imaging (BLI) system called AkaBLI has been recently developed for cell tracking in preclinical models and to date, limited data is available on how it performs in relation to existing systems.

Purpose: To systematically compare the performance of AkaBLI and the standard Firefly luciferase (FLuc) systems to monitor the biodistribution and fate of cell therapies in rodents.

Methods: Umbilical cord mesenchymal stromal cells (MSCs) were transduced to produce two genetically engineered populations, expressing either AkaLuc or the engineered FLuc luc2.

Post-Surgical Peritoneal Scarring and Key Molecular Mechanisms.

Post-surgical adhesions are internal scar tissue and a major health and economic burden. Adhesions affect and involve the peritoneal lining of the abdominal cavity, which consists of a continuous mesothelial covering of the cavity wall and majority of internal organs. Our understanding of the full pathophysiology of adhesion formation is limited by the fact that the mechanisms regulating normal serosal repair and regeneration of the mesothelial layer are still being elucidated.

Regenerative medicine therapies: lessons from the kidney.

We focus on three strategies for renal regenerative medicine; administering cells to replace damaged tissue, promoting endogenous regeneration, and growing stem cell-derived organs. Mouse kidney regeneration can be promoted by stem cells injected into the circulation which do not become new kidney tissue but seem to secrete regeneration-promoting humoral factors. This argues against direct replacement but encourages developing pharmacological stimulators of endogenous regeneration.

Perylene Diimide Nanoprobes for In Vivo Tracking of Mesenchymal Stromal Cells Using Photoacoustic Imaging.

Noninvasive bioimaging techniques are critical for assessing the biodistribution of cellular therapies longitudinally. Among them, photoacoustic imaging (PAI) can generate high-resolution images with a tissue penetration depth of ∼4 cm. However, it is essential and still highly challenging to develop stable and efficient near-infrared (NIR) probes with low toxicity for PAI.

Multimodal Imaging Techniques Show Differences in Homing Capacity Between Mesenchymal Stromal Cells and Macrophages in Mouse Renal Injury Models.

Purpose: The question of whether mesenchymal stromal cells (MSCs) home to injured kidneys remains a contested issue. To try and understand the basis for contradictory findings reported in the literature, our purpose here was to investigate whether MSC homing capacity is influenced by administration route, the type of injury model used, and/or the presence of exogenous macrophages.

Procedures: To assess the viability, whole-body biodistribution, and intra-renal biodistribution of MSCs, we used a multimodal imaging strategy comprising bioluminescence and magnetic resonance imaging.

Measuring Kidney Perfusion, pH, and Renal Clearance Consecutively Using MRI and Multispectral Optoacoustic Tomography.

To establish multi-modal imaging for the assessment of kidney pH, perfusion, and clearance rate using magnetic resonance imaging (MRI) and multispectral optoacoustic tomography (MSOT) in healthy mice. Kidney pH and perfusion values were measured on a pixel-by-pixel basis using the MRI acidoCEST and FAIR-EPI methods. Kidney filtration rate was measured by analyzing the renal clearance rate of IRdye 800 using MSOT.

A Noninvasive Imaging Toolbox Indicates Limited Therapeutic Potential of Conditionally Activated Macrophages in a Mouse Model of Multiple Organ Dysfunction.

Cell-based regenerative medicine therapies require robust preclinical safety, efficacy, biodistribution, and engraftment data prior to clinical testing. To address these challenges, we have developed an imaging toolbox comprising multispectral optoacoustic tomography and ultrasonography, which allows the degree of kidney, liver, and cardiac injury and the extent of functional recovery to be assessed noninvasively in a mouse model of multiorgan dysfunction. This toolbox allowed us to determine the therapeutic effects of adoptively transferred macrophages.

Multicolour In Vivo Bioluminescence Imaging Using a NanoLuc-Based BRET Reporter in Combination with Firefly Luciferase.

The ability to track the biodistribution and fate of multiple cell populations administered to rodents has the potential to facilitate the understanding of biological processes in a range of fields including regenerative medicine, oncology, and host/pathogen interactions. Bioluminescence imaging is an important tool for achieving this goal, but current protocols rely on systems that have poor sensitivity or require spectral decomposition. Here, we show that a bioluminescence resonance energy transfer reporter (BRET) based on NanoLuc and LSSmOrange in combination with firefly luciferase enables the unambiguous discrimination of two cell populations with high sensitivity.