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. The bioluminescence of AkaLuc+ and FLuc+ cells was assessed both in vitro (emission spectra, saturation kinetics and light emission per cell) and in vivo (substrate kinetics following intraperitoneal and subcutaneous administration and biodistribution of the cells up to day 7). RESULTS: Introduction of the reporter genes has no effect on MSC phenotype. For BLI, the FLuc system is superior to AkaBLI in terms of (i) light output, producing a stronger signal after subcutaneous substrate delivery and more consistent signal kinetics when delivered intraperitoneally; (ii) absence of hepatic background; and (iii) safety, where the AkaLuc substrate was associated with a reaction in the skin of the mice in vivo. CONCLUSION: We conclude that there is no advantage in using the AkaBLI system to track the biodistribution of systemically administered cell-based regenerative medicine therapies in vivo.

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. Thus, we compared three optical tissue-clearing protocols (Clear, Unobstructed Brain/Body Imaging Cocktails and Computational analysis (CUBIC), modified stabilised 3D imaging of solvent-cleared organs (s-DISCO) and ethyl cinnamate (ECi)) to evaluate their potential to track the biodistribution of human umbilical cord MSCs expressing the tdTomato fluorescence reporter and investigate how they interact with host cells in the mouse lung. The results showed that although CUBIC clearing is the only method that enables direct imaging of fluorescently labelled MSCs, combining s-DISCO or ECi with immunofluorescence or dye labelling allows the interaction of MSCs with endothelial and immune cells to be studied. Overall, this comparative study offers guidance on selecting an optical tissue-clearing method for cell tracking applications.

Preschool autism services: A tale of two Canadian provinces and the implications for policy.

For children with autism spectrum disorder (ASD), a lifelong neurodevelopmental condition, assessment and treatment services vary widely across Canada-potentially creating inequities. To highlight this, the Preschool Autism Treatment Impact study compared children's services and outcomes in New Brunswick (NB) and Nova Scotia (NS). Diagnostic practices, service delivery models, wait times, and treatment approaches differed, as did children's 1-year outcomes and costs for families and the public sector. Considering NB and NS strengths, we suggest that an optimal system would include: rapid access to high-quality diagnostic and intervention services; adherence to research-informed practice guidelines; interventions to enhance parents' skills and self-efficacy; and measures to minimize financial burdens for families. Our results also suggest that provinces/territories must do more to ensure equitable access to effective services, including sharing and reporting on national comparative data. Canadian children with ASD deserve access to effective and consistent services, no matter where they live.

In Vitro Determination of the Immunogenic Impact of Nanomaterials on Primary Peripheral Blood Mononuclear Cells.

Investigation of the potential for nanomaterials to generate immunogenic effects is a key aspect of a robust preclinical evaluation. In combination with physicochemical characterization, such assessments also provide context for how material attributes influence biological outcomes. Furthermore, appropriate models for these assessments allow accurate in vitro to in vivo extrapolation, which is vital for the mechanistic understanding of nanomaterial action. Here we have assessed the immunogenic impact of a small panel of commercially available and in-house prepared nanomaterials on primary human peripheral blood mononuclear cells (PBMCs). A diethylaminoethyl-dextran (DEAE-dex) functionalized superparamagnetic iron oxide nanoparticle (SPION) generated detectable quantities of tumor necrosis factor α (TNFα), interleukin-1ß (IL-1ß), and IL-10, the only tested material to do so. The human leukemia monocytic cell line THP-1 was used to assess the potential for the nanomaterial panel to affect cellular oxidation-reduction (REDOX) via measurement of reactive oxygen species and reduced glutathione. Negatively charged sulfonate-functionalized polystyrene nanoparticles demonstrated a size-related trend for the inhibition of caspase-1, which was not observed for amine-functionalized polystyrene of similar sizes. Silica nanoparticles (310 nm) resulted in a 93% increase in proliferation compared to the untreated control (p < 0.01). No other nanomaterial treatments resulted in significant change from that of unstimulated PBMCs. Responses to the nanomaterials in the assays described demonstrate the utility of primary cells as ex vivo models for nanomaterial biological impact.

The ZT Biopolymer: A Self-Assembling Protein Scaffold for Stem Cell Applications.

The development of cell culture systems for the naturalistic propagation, self-renewal and differentiation of cells ex vivo is a high goal of molecular engineering. Despite significant success in recent years, the high cost of up-scaling cultures, the need for xeno-free culture conditions, and the degree of mimicry of the natural extracellular matrix attainable in vitro using designer substrates continue to pose obstacles to the translation of cell-based technologies. In this regard, the ZT biopolymer is a protein-based, stable, scalable, and economical cell substrate of high promise. ZT is based on the naturally occurring assembly of two human proteins: titin-Z1Z2 and telethonin. These protein building blocks are robust scaffolds that can be conveniently functionalized with full-length proteins and bioactive peptidic motifs by genetic manipulation, prior to self-assembly. The polymer is, thereby, fully encodable. Functionalized versions of the ZT polymer have been shown to successfully sustain the long-term culturing of human embryonic stem cells (hESCs), human induced pluripotent stem cells (hiPSCs), and murine mesenchymal stromal cells (mMSCs). Pluripotency of hESCs and hiPSCs was retained for the longest period assayed (4 months). Results point to the large potential of the ZT system for the creation of a modular, pluri-functional biomaterial for cell-based applications.

Magnetic Resonance Imaging for Characterization of a Chick Embryo Model of Cancer Cell Metastases.

Metastasis is the most common cause of death for patients with cancer. To fully understand the steps involved in metastatic dissemination, in vivo models are required, of which murine ones are the most common. Therefore, preclinical imaging methods such as magnetic resonance imaging (MRI) have mainly been developed for small mammals and their potential to monitor cancer growth and metastasis in nonmammalian models is not fully harnessed. We have here used MRI to measure primary neuroblastoma tumor size and metastasis in a chick embryo model. We compared its sensitivity and accuracy to end-point fluorescence detection upon dissection. Human neuroblastoma cells labeled with green fluorescent protein (GFP) and micron-sized iron particles were implanted on the extraembryonic chorioallantoic membrane of the chick at E7. T2 RARE, T2-weighted fast low angle shot (FLASH) as well as time-of-flight MR angiography imaging were applied at E14. Micron-sized iron particle labeling of neuroblastoma cells allowed in ovo observation of the primary tumor and tumor volume measurement noninvasively. Moreover, T2 weighted and FLASH imaging permitted the detection of small metastatic deposits in the chick embryo, thereby reinforcing the potential of this convenient, 3R compliant, in vivo model for cancer research.

Functionalized superparamagnetic iron oxide nanoparticles provide highly efficient iron-labeling in macrophages for magnetic resonance-based detection in vivo.

BACKGROUND AIMS: Tracking cells during regenerative cytotherapy is crucial for monitoring their safety and efficacy. Macrophages are an emerging cell-based regenerative therapy for liver disease and can be readily labeled for medical imaging. A reliable, clinically applicable cell-tracking agent would be a powerful tool to study cell biodistribution. METHODS: Using a recently described chemical design, we set out to functionalize, optimize and characterize a new set of superparamagnetic iron oxide nanoparticles (SPIONs) to efficiently label macrophages for magnetic resonance imaging-based cell tracking in vivo. RESULTS: A series of cell health and iron uptake assays determined that positively charged SPIONs (+16.8 mV) could safely label macrophages more efficiently than the formerly approved ferumoxide (-6.7 mV; Endorem) and at least 10 times more efficiently than the clinically approved SPION ferumoxytol (-24.2 mV; Rienso). An optimal labeling time of 4 h at 25 µg/mL was demonstrated to label macrophages of mouse and human origin without any adverse effects on cell viability whilst providing substantial iron uptake (>5 pg Fe/cell) that was retained for 7 days in vitro. SPION labeling caused no significant reduction in phagocytic activity and a shift toward a reversible M1-like phenotype in bone marrow-derived macrophages (BMDMs). Finally, we show that SPION-labeled BMDMs delivered via the hepatic portal vein to mice are localized in the hepatic parenchyma resulting in a 50% drop in T2* in the liver. Engraftment of exogenous cells was confirmed via immunohistochemistry up to 3 weeks posttransplantation. DISCUSSION: A positively charged dextran-coated SPION is a promising tool to noninvasively track hepatic macrophage localization for therapeutic monitoring.

Assessing the Effectiveness of a Far-Red Fluorescent Reporter for Tracking Stem Cells In Vivo.

Far-red fluorescent reporter genes can be used for tracking cells non-invasively in vivo using fluorescence imaging. Here, we investigate the effectiveness of the far-red fluorescent protein, E2-Crimson (E2C), for tracking mouse embryonic cells (mESCs) in vivo following subcutaneous administration into mice. Using a knock-in strategy, we introduced E2C into the Rosa26 locus of an E14-Bra-GFP mESC line, and after confirming that the E2C had no obvious effect on the phenotype of the mESCs, we injected them into mice and imaged them over nine days. The results showed that fluorescence intensity was weak, and cells could only be detected when injected at high densities. Furthermore, intensity peaked on day 4 and then started to decrease, despite the fact that tumour volume continued to increase beyond day 4. Histopathological analysis showed that although E2C fluorescence could barely be detected in vivo at day 9, analysis of frozen sections indicated that all mESCs within the tumours continued to express E2C. We hypothesise that the decrease in fluorescence intensity in vivo was probably due to the fact that the mESC tumours became more vascular with time, thus leading to increased absorbance of E2C fluorescence by haemoglobin. We conclude that the E2C reporter has limited use for tracking cells in vivo, at least when introduced as a single copy into the Rosa26 locus.

MS-1 magA: Revisiting Its Efficacy as a Reporter Gene for MRI.

Bacterial genes involved in the biomineralization of magnetic nanoparticles in magnetotactic bacteria have recently been proposed as reporters for magnetic resonance imaging (MRI). In such systems, the expression of the bacterial genes in mammalian cells purportedly leads to greater concentrations of intracellular iron or the biomineralization of iron oxides, thus leading to an enhancement in relaxation rate that is detectable via MRI. Here, we show that the constitutive expression of the magA gene from Magnetospirillum magnetotacticum is tolerated by human embryonic kidney (HEK) cells but induces a strong toxic effect in murine mesenchymal/stromal cells and kidney-derived stem cells, severely restricting its effective use as a reporter gene for stem cells. Although it has been suggested that magA is involved in iron transport, when expressed in HEK cells, it does not affect the transcription of endogenous genes related to iron homeostasis. Furthermore, the magA-induced enhancement in iron uptake in HEK cells is insignificant, suggesting this gene is a poor reporter even for cell types that can tolerate its expression. We suggest that the use of magA for stem cells should be approached with caution, and its efficacy as a reporter gene requires a careful assessment on a cell-by-cell basis.

Design considerations for the synthesis of polymer coated iron oxide nanoparticles for stem cell labelling and tracking using MRI.

Iron oxide nanoparticles (IONPs, sometimes called superparamagnetic iron oxide nanoparticles or SPIONs) have already shown promising results for in vivo cell tracking using magnetic resonance imaging (MRI). To fully exploit the potential of these materials as contrast agents, there is still a need for a greater understanding of how they react to physiological conditions. A key aspect is the specific nature of the surface coating, which can affect important properties of the IONPs such as colloidal stability, toxicity, magnetism and labelling efficiency. Polymers are widely used as coatings for IONPs as they can increase colloidal stability in hydrophilic conditions, as well as protect the iron oxide core from degradation. In this tutorial review, we will examine the design and synthesis approaches currently being employed to produce polymer coated IONPs as cell tracking agents, and what considerations must be made. We will also give some perspective on the challenges and limitations that remain for polymer coated IONPs as MRI contrast agents for stem cell tracking.

Overexpression of the MRI Reporter Genes Ferritin and Transferrin Receptor Affect Iron Homeostasis and Produce Limited Contrast in Mesenchymal Stem Cells.

Imaging technologies that allow the non-invasive monitoring of stem cells in vivo play a vital role in cell-based regenerative therapies. Recently, much interest has been generated in reporter genes that enable simultaneous monitoring of the anatomical location and viability of cells using magnetic resonance imaging (MRI). Here, we investigate the efficacy of ferritin heavy chain-1 (Fth1) and transferrin receptor-1 (TfR1) as reporters for tracking mesenchymal stem cells. The overexpression of TfR1 was well tolerated by the cells but Fth1 was found to affect the cell's iron homeostasis, leading to phenotypic changes in the absence of iron supplementation and an upregulation in transcript and protein levels of the cell's endogenous transferrin receptor. Neither the sole overexpression of Fth1 nor TfR1 resulted in significant increases in intracellular iron content, although significant differences were seen when the two reporter genes were used in combination, in the presence of high concentrations of iron. The supplementation of the culture medium with iron sources was a more efficient means to obtain contrast than the use of reporter genes, where high levels of intracellular iron were reflected in transverse (T2) relaxation. The feasibility of imaging iron-supplemented cells by MRI is shown using a 3R-compliant chick embryo model.

Using stem and progenitor cells to recapitulate kidney development and restore renal function.

PURPOSE OF REVIEW: There is considerable interest in the idea of generating stem and precursor cells that can differentiate into kidney cells and be used to treat kidney diseases. Within this field, we highlight recent research articles focussing on mesenchymal stem cells (MSCs), embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and kidney-derived stem/progenitor cells (KSPCs). RECENT FINDINGS: In preclinical studies, MSCs ameliorate varied acute and chronic kidney diseases. Their efficacy depends on immunomodulatory and paracrine properties but MSCs do not differentiate into functional kidney epithelia. iPSCs can be derived from healthy individuals and from kidney patients by forced expression of precursor genes. Like ESCs, iPSCs are pluripotent and so theoretically they have the potential to form functional kidney epithelia when used therapeutically. KSPCs, existing as cell subsets within adult and developing kidneys, constitute attractive future therapeutic agents. SUMMARY: Results from preclinical studies are encouraging but caution is required regarding potential human therapeutic applications because molecular, morphological and functional characterization of 'kidney cells' generated from ECSs, iPSCs, KSPCs have not been exhaustive. The long-term safety of renal stem and precursor cells needs more study, including potential negative effects on renal growth and their potential for tumor formation.

Modification of nanodiamonds for fluorescence bioimaging.

Non-invasive bioimaging is essential in enhancing pre-clinical diagnosis and therapy. Developing efficient imaging probes with high stability, low toxicity, and the potential of offering high resolution images is a very important aspect of developing non-invasive bioimaging techniques. Fluorescent nanodiamonds, which are produced by high energy beam irradiation and high temperature/pressure treatment, have been extensively investigated. In this study, we report the chemical modification of common nanodiamonds (prepared by detonation and high-pressure high-temperature milling) using a stable fluorophore (perylene diimide derivative) via carbodiimide coupling. The resulting nanodiamonds show good biocompatibility, cellular uptake and fluorescent imaging potential with mesenchymal stromal cells. This method provides an efficient alternative approach to the preparation and the use of fluorescent nanodiamonds for bioimaging, with the potential benefit of chemically adjusting the structure of perylene diimide for optimized emission/absorbance wavelength.

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. We used longitudinal, multi-parametric magnetic resonance imaging (MRI) employing arterial spin labelling (ASL), diffusion weighted imaging (DWI), and dynamic contrast enhanced (DCE)-MRI to assess IRI induced changes in both the injured and healthy contralateral kidney, in a unilateral IRI mouse model (n = 9). Multi-parametric MRI demonstrated significant differences in kidney volume (p = 0.001), blood flow (p = 0.002), filtration coefficient (p = 0.038), glomerular filtration rate (p = 0.005) and apparent diffusion coefficient (p = 0.048) between the injured kidney and contralateral kidney on day 1 post-IRI surgery. Identification of the injured kidney using principal component analysis including most of the imaging parameters demonstrated an area under the curve (AUC) of 0.97. These results point to the utility of multi-parametric MRI in early detection of IRI-induced kidney damage suggesting that the combination of various MRI parameters may be suitable for monitoring the extent of injury in this model.

Integration potential of mouse and human bone marrow-derived mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are a multipotent cell population which has been described to exert renoprotective and regenerative effects in experimental models of kidney injury. Several lines of evidence indicate that MSCs also have the ability to contribute to nephrogenesis, suggesting that the cells can be employed in stem cell-based applications aimed at de novo renal tissue generation. In this study we re-evaluate the capacity of mouse and human bone marrow-derived MSCs to contribute to the development of renal tissue using a novel method of embryonic kidney culture. Although MSCs show expression of some genes involved in renal development, their contribution to nephrogenesis is very limited in comparison to other stem cell types tested. Furthermore, we found that both mouse and human MSCs have a detrimental effect on the ex vivo development of mouse embryonic kidney, this effect being mediated through a paracrine action. Stimulation with conditioned medium from a mouse renal progenitor population increases the ability of mouse MSCs to integrate into developing renal tissue and prevents the negative effects on kidney development, but does not appear to enhance their ability to undergo nephrogenesis.

Long-term tracking of cells using inorganic nanoparticles as contrast agents: are we there yet?

The use of inorganic nanoparticles as probes to label and track cells in vivo is already a reality. While superparamagnetic nanoparticles have been the subject of clinical studies involving magnetic resonance imaging, quantum dots and gold nanoparticles are starting to be explored for similar goals in pre-clinical studies involving fluorescence and photoacoustic imaging. Although exciting results have been obtained from in vivo investigations, there appears to be a general lack of understanding on the effects of physicochemical properties on the labelling efficiency and toxicity of those nanoparticles, as well as on their stability in the intracellular microenvironment; essential requirements for using them as probes for cellular tracking. In this tutorial review, we look at what the current literature can teach us in respect to cell interactions with these nanoparticles, with the perspective of using them as probes for cell labelling. We also examine the findings obtained in pre-clinical studies that expose potential misinterpretation that can occur when using inorganic nanoparticles for in vivo imaging.

DEAE-Dextran Enhances the Lentiviral Transduction of Primary Human Mesenchymal Stromal Cells from All Major Tissue Sources Without Affecting Their Proliferation and Phenotype.

Genetic engineering of mesenchymal stromal cells (MSCs) is a tool widely used to explore MSC properties in vitro and in vivo. Lentiviral infection with the use of polycations as an adjuvant is a method that is commonly used to generate stably transduced cells. However, it is known that some polycations can negatively affect primary MSCs and to date, no study has explored the effect of different polycations on the transduction efficiency and properties of all main types of MSCs, namely those derived from umbilical cord, bone marrow and adipose tissue. Here we explore a range of polycations, using transduction protocols with and without spinoculation, to produce stably transduced MSCs from these three tissue sources. We identified that an overnight incubation with diethylaminoethyl-dextran (DEAE-Dextran) is the protocol associated with the best transduction efficiency without compromising the viability of the cells, and which worked consistently with lentiviral particles encoding for different transgenes. Transduced and sorted MSC populations revealed no significant changes in proliferation, morphology and expression of MSC markers compared to naïve MSCs. Following this study, we conclude that DEAE-Dextran is a polycation that can be successfully used to enhance the transduction of MSCs from all major tissue sources.

Describing Self-Advocacy in Underrepresented Women With Advanced Cancer.

PURPOSE: To describe the self-advocacy experiences of women from underrepresented groups who have advanced breast or gynecologic cancer. PARTICIPANTS & SETTING: To be eligible for the study, participants had to self-identify as vulnerable, which was defined as a member of a group considered at risk for poor cancer outcomes and underrepresented in clinical research. METHODOLOGIC APPROACH: This descriptive, longitudinal, qualitative study consisted of one-on-one interviews of women within three months of an advanced breast or gynecologic cancer diagnosis. FINDINGS: 10 participants completed 25 interviews. The average age of participants was 60.2 years (range = 38-75 years). Three major themes emerged: (a) speaking up and speaking out, (b) interacting with the healthcare team, and (c) relying on support from others. IMPLICATIONS FOR NURSING: Women with advanced cancer who are from underrepresented groups self-advocated in unique ways, learning over time the importance of how to communicate their needs and manage their healthcare team. Future research should incorporate these findings into tailored self-advocacy interventions.

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. To better understand how MSCs affect innate immune cell populations in the lung, we evaluated the distribution and phenotype of neutrophils, monocytes, and macrophages by flow cytometry and histological analyses after delivering human umbilical cord-derived MSCs (hUC-MSCs) IV into immunocompetent mice. After 2 hr, we observed a significant increase in neutrophils, and proinflammatory monocytes and macrophages. Moreover, these immune cells localized in close proximity to the MSCs, suggesting an active role in their clearance. By 24 hr, we detected an increase in anti-inflammatory monocytes and macrophages. These results suggest that the IV injection of hUC-MSCs leads to an initial inflammatory phase in the lung shortly after injection, followed by a resolution phase 24 hr later.

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. Here we compared the effectiveness of combining either multispectral optoacoustic tomography (MSOT) or micro-computed tomography (micro-CT) with BLI for tracking the fate of luciferase+ human mesenchymal stromal cells (MSCs) labelled with gold nanorods. Following subcutaneous administration in mice, the MSCs could be readily detected with MSOT but not with micro-CT. We conclude that MSOT is more sensitive than micro-CT for tracking gold nanorod-labelled cells in vivo and depending on the route of administration, can be used effectively with BLI to track MSC fate in mice.