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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.
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Luciferases de Vaga-Lume , Células-Tronco Mesenquimais , Animais , Genes Reporter , Luciferases de Vaga-Lume/genética , Luciferases de Vaga-Lume/metabolismo , Medições Luminescentes/métodos , Células-Tronco Mesenquimais/metabolismo , Camundongos , Distribuição TecidualRESUMO
PURPOSE: To establish high-frequency magnetic resonance electrical properties tomography (MREPT) as a novel contrast mechanism for the assessment of glioblastomas using a rat brain tumor model. METHODS: Six F98 intracranial tumor bearing rats were imaged longitudinally 8, 11 and 14 days after tumor cell inoculation. Conductivity and mean diffusivity maps were generated using MREPT and Diffusion Tensor Imaging. These maps were co-registered with T2 -weighted images and volumes of interests (VOIs) were segmented from the normal brain, ventricles, edema, viable tumor, tumor rim, and tumor core regions. Longitudinal changes in conductivity and mean diffusivity (MD) values were compared in these regions. A correlation analysis was also performed between conductivity and mean diffusivity values. RESULTS: The conductivity of ventricles, edematous area and tumor regions (tumor rim, viable tumor, tumor core) was significantly higher (P < .01) compared to the contralateral cortex. The conductivity of the tumor increased over time while MD from the tumor did not change. A marginal positive correlation was noted between conductivity and MD values for tumor rim and viable tumor, whereas this correlation was negative for the tumor core. CONCLUSION: We demonstrate a novel contrast mechanism based on ionic concentration and mobility, which may aid in providing complementary information to water diffusion in probing the microenvironment of brain tumors.
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Neoplasias Encefálicas , Imagem de Tensor de Difusão , Animais , Encéfalo/diagnóstico por imagem , Neoplasias Encefálicas/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética , Ratos , Tomografia , Microambiente TumoralRESUMO
INTRODUCTION: Type 1 hepatorenal syndrome (HRS) is a fatal complication of cirrhosis. Treatments trend toward HRS reversal, but few show clear mortality benefit. We sought to quantify the progress-or lack thereof-in improving outcomes of type 1 HRS over time. METHODS: We performed a systematic review and meta-analysis for randomized controlled trials (RCTs) comparing type 1 HRS outcomes including (a) overall survival (liver transplant-free survival if reported) and (b) HRS reversal. Each study arm was analyzed separately to look at changes in outcomes over time. RCTs published comparing medical treatments for type 1 HRS were searched using several databases through July 31, 2019. RESULTS: Fourteen RCTs (28 arms) involving 778 participants enrolled between 2002 and 2018 were included. Twelve RCTs measured HRS reversal. In conjunction with albumin (or plasma expander), the most common medications used were terlipressin (13 arms), antibiotics (7), norepinephrine (6), dopamine (4), and midodrine/octreotide (3). Pooled survival rate was 34.6% (95% CI 26.4-43.8), and pooled HRS reversal rate was 42.8% (95% CI 34.2-51.9). Regression analyzing the incremental effect of the year the RCT was initiated showed that more recent studies were not associated with improved survival (OR 1.02, 95% CI 0.94-1.11, p = 0.66) or HRS reversal rates (OR 1.03, 95% CI 0.96-1.11, p = 0.41). There was no survival improvement when RCTs with endpoints assessed ≤ or > 1 month were analyzed separately with respective OR of 1.07 (95% CI 0.95-1.20, p = 0.26) and 0.97 (95% CI 0.85-1.12, p = 0.70). CONCLUSION: Outcomes have not improved for patients with type 1 HRS since 2002. There is a need to improve prevention and treatment of type 1 HRS.
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Síndrome Hepatorrenal/tratamento farmacológico , Síndrome Hepatorrenal/mortalidade , Adulto , Albuminas/uso terapêutico , Antibacterianos/uso terapêutico , Dopamina/uso terapêutico , Quimioterapia Combinada , Feminino , Síndrome Hepatorrenal/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Midodrina/uso terapêutico , Norepinefrina/uso terapêutico , Octreotida/uso terapêutico , Substitutos do Plasma/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Análise de Regressão , Taxa de Sobrevida , Terlipressina/uso terapêutico , Resultado do Tratamento , Vasoconstritores/uso terapêutico , Adulto JovemRESUMO
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.
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Imageamento por Ressonância Magnética , Metástase Neoplásica/diagnóstico por imagem , Metástase Neoplásica/patologia , Animais , Carcinogênese/patologia , Linhagem Celular Tumoral , Embrião de Galinha , Membrana Corioalantoide/patologia , Modelos Animais de Doenças , Desenvolvimento Embrionário , Humanos , Ferro/química , Metástase Neoplásica/diagnóstico , Tamanho da Partícula , Carga TumoralRESUMO
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.
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Proteínas de Bactérias/farmacologia , Proteínas de Transporte de Cátions/farmacologia , Genes Reporter , Imageamento por Ressonância Magnética/métodos , Células-Tronco Mesenquimais/efeitos dos fármacos , Animais , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Meios de Contraste , Células HEK293 , Humanos , Ferro/metabolismo , Células-Tronco Mesenquimais/citologia , CamundongosRESUMO
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.
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Rastreamento de Células/métodos , Meios de Contraste/química , Imageamento por Ressonância Magnética/métodos , Nanopartículas de Magnetita/química , Polímeros , Células-Tronco/citologia , Animais , Meios de Contraste/toxicidade , Desenho de Fármacos , Humanos , Nanopartículas de Magnetita/toxicidade , Polietilenoglicóis/química , Polímeros/síntese química , Polímeros/química , Polissacarídeos/químicaRESUMO
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.
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Apoferritinas/genética , Ferro/metabolismo , Receptores da Transferrina/genética , Animais , Apoferritinas/metabolismo , Linhagem Celular , Embrião de Galinha , Galinhas , Genes Reporter , Vetores Genéticos/genética , Vetores Genéticos/metabolismo , Lentivirus/genética , Imageamento por Ressonância Magnética , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Camundongos , Microscopia de Fluorescência , Fenótipo , Receptores da Transferrina/metabolismoRESUMO
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.
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Meios de Contraste/química , Nanopartículas/química , Rastreamento de Células , Diagnóstico por Imagem , Ouro/química , Humanos , Nanopartículas de Magnetita/química , Pontos Quânticos , Fatores de TempoRESUMO
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.
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DEAE-Dextrano , Células-Tronco Mesenquimais , Humanos , Transdução Genética , DEAE-Dextrano/metabolismo , Lentivirus/genética , Vetores Genéticos/genética , Fenótipo , Proliferação de Células , Diferenciação Celular , Células CultivadasRESUMO
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. In this study, we (i) compare the long-term fate and safety of umbilical cord (UC-)MSCs administered to immunocompetent and immunocompromised (severe combined immunodeficient (SCID) and non-obese diabetic (NOD)/SCID) animals, and (ii) investigate the immunological response of the host to the administered cells. Intravenous administration of firefly luciferase expressing UC-MSCs revealed that the cells get trapped in the lungs of both immunocompetent and immunocompromised animals, with > 95% of the cells disappearing within 72 h after administration. In 27% of the SCID and 45% of the NOD/SCID, a small fraction of the cells lived up to day 14 but in most cases they all disappeared earlier. One NOD/SCID mouse showed a weak signal up to day 31. Immunocompetent mice displayed elevated percentages of neutrophils in the lungs, the blood, and the spleen 2 h after the administration of the cells. The concentration of neutrophil chemoattractants (MCP1, CCL7, Gro-α and IP-10) were also increased in the plasma of the animals 2 h after the administration of the MSCs. Our results suggest that although the UC-MSCs are short-lived in mice, they still result in an immunological response that might contribute to a therapeutic effect.
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Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Animais , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Cordão Umbilical , Sistema Imunitário , Células-Tronco Mesenquimais/fisiologiaRESUMO
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.
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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-A165 on normal human dermal fibroblasts (NHDFs) for a 7-day period. The co-culture with GFP-MCs had a positive effect on branch point formation indicating that the cells supported endothelial tube formation. We interrogated the molecular response of the GFP-MCs to the angiogenic co-culture by qRT-PCR and found that the pericyte marker Ng2 was upregulated when the cells were co-cultured with HDMECs on NHDFs, indicating a change towards a perivascular phenotype. When GFP-MCs were cultured on the NHDF feeder layer, they upregulated the epithelial-mesenchymal transition marker Zeb1 and lost their circularity while increasing their size, indicating a change to a more migratory cell type. We analyzed the pericyte-like behavior of the GFP-MCs in a 3D cardiac microtissue (spheroid) with cardiomyocytes, cardiac fibroblasts and cardiac endothelial cells where the mesothelial cells showed alignment with the endothelial cells. These results indicate that mesothelial cells have the potential to adopt a perivascular phenotype and associate with endothelial cells to potentially support angiogenesis.
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Células-Tronco Mesenquimais , Pericitos , Humanos , Células Endoteliais/metabolismo , Células Epiteliais , Técnicas de CoculturaRESUMO
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. Lack of standard procedures hinders inter-study comparability and delays the progression of the field. The aim of this study was A- to assess the impact on MSC characteristics when different laboratories, performed analysis on the same MSC material using harmonised culture conditions and B- to understand source-specific differences. METHODS: Three independent institutions performed a head-to-head comparison of human-derived adipose (A-), bone marrow (BM-), and umbilical cord (UC-) MSCs using harmonised culture conditions. In each centre, cells from one specific tissue source were isolated and later distributed across the network to assess their biological properties, including cell expansion, immune phenotype, and tri-lineage differentiation (part A). To assess tissue-specific function, angiogenic and immunomodulatory properties and the in vivo biodistribution were compared in one expert lab (part B). RESULTS: By implementing a harmonised manufacturing workflow, we obtained largely reproducible results across three independent laboratories in part A of our study. Unique growth patterns and differentiation potential were observed for each tissue source, with similar trends observed between centres. Immune phenotyping verified expression of typical MSC surface markers and absence of contaminating surface markers. Depending on the established protocols in the different laboratories, quantitative data varied slightly. Functional experiments in part B concluded that conditioned media from BM-MSCs significantly enhanced tubulogenesis and endothelial migration in vitro. In contrast, immunomodulatory studies reported superior immunosuppressive abilities for A-MSCs. Biodistribution studies in healthy mice showed lung entrapment after administration of all three types of MSCs, with a significantly faster clearance of BM-MSCs. CONCLUSION: These results show the heterogeneous behaviour and regenerative properties of MSCs as a reflection of intrinsic tissue-origin properties while providing evidence that the use of harmonised culture procedures can reduce but do not eliminate inter-lab and operator differences.
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Técnicas de Cultura de Células , Células-Tronco Mesenquimais , Humanos , Animais , Camundongos , Células Cultivadas , Distribuição Tecidual , Diferenciação Celular , Técnicas de Cultura de Células/métodos , Células-Tronco Mesenquimais/metabolismo , Proliferação de Células , Células da Medula Óssea , Cordão UmbilicalRESUMO
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. The only FDA-approved material for clinical use is indocyanine green (ICG). ICG can be used for both fluorescence and photoacoustic imaging, but is prone to photodegradation, and at higher concentrations, undergoes quenching and can adversely affect cell health. We have developed novel near-infrared imaging probes comprising conjugated polymer nanoparticles (CPNs™) that can be fine-tuned to absorb and emit light at specific wavelengths. To compare the performance of the CPNs™ with ICG for in vivo cell tracking, labelled mesenchymal stromal cells (MSCs) were injected subcutaneously in mice and detected using fluorescence imaging (FI) and a form of photoacoustic imaging called multispectral optoacoustic tomography (MSOT). MSCs labelled with either ICG or CPN™ 770 could be detected with FI, but only CPN™ 770-labelled MSCs could be detected with MSOT. These results show that CPNs™ show great promise for tracking cells in vivo using optical imaging techniques, and for some applications, out-perform ICG.
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To investigate the utility of DCE-MRI derived pharmacokinetic parameters in evaluating tumour haemodynamic heterogeneity and treatment response in rodent models of glioblastoma, imaging was performed on intracranial F98 and GL261 glioblastoma bearing rodents. Clustering of the DCE-MRI-based parametric maps (using Tofts, extended Tofts, shutter speed, two-compartment, and the second generation shutter speed models) was performed using a hierarchical clustering algorithm, resulting in areas with poor fit (reflecting necrosis), low, medium, and high valued pixels representing parameters Ktrans, ve, Kep, vp, τi and Fp. There was a significant increase in the number of necrotic pixels with increasing tumour volume and a significant correlation between ve and tumour volume suggesting increased extracellular volume in larger tumours. In terms of therapeutic response in F98 rat GBMs, a sustained decrease in permeability and perfusion and a reduced cell density was observed during treatment with JAS239 based on Ktrans, Fp and ve as compared to control animals. No significant differences in these parameters were found for the GL261 tumour, indicating that this model may be less sensitive to JAS239 treatment regarding changes in vascular parameters. This study demonstrates that region-based clustered pharmacokinetic parameters derived from DCE-MRI may be useful in assessing tumour haemodynamic heterogeneity with the potential for assessing therapeutic response.
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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. However, a problem with animal studies is that there is a lack of standardisation in the models and MSC therapy regimes used; there appears to be publication bias towards studies reporting positive outcomes; and the reproducibility of results from animal experiments tends not to be confirmed prior to clinical translation. A further problem is that while some progress has been made towards investigating the mechanisms of action (MoA) of MSCs, we still fail to understand how they work. To make progress, it is important to ensure that prior to clinical translation, the beneficial effects of MSCs in animal studies are real and can be repeated by independent research groups. We also need to understand the MoA of MSCs to assess whether their effects are likely to be beneficial across different species. In this review, we give an overview of the current clinical picture of MSC therapies and discuss what we have learned from animal studies. We also give a comprehensive update of what we know about the MoA of MSCs, particularly in relation to their role in immunomodulation.
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Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Animais , Humanos , Imunidade , Imunomodulação , Transplante de Células-Tronco Mesenquimais/métodos , Reprodutibilidade dos TestesRESUMO
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. The effect of administration route (venous or arterial) on the ability of MSCs to home to injured renal tissue, and persist there, was assessed in a glomerular injury model (induced by the nephrotoxicant, Adriamycin) and a tubular injury model induced by ischaemia-reperfusion injury (IRI). Exogenous macrophages were used as a positive control because these cells are known to home to injured mouse kidneys. To assess whether the homing capacity of MSCs can be influenced by the presence of exogenous macrophages, we used a dual-bioluminescence strategy that allowed the whole-body biodistribution of the two cell types to be monitored simultaneously in individual animals. RESULTS: Following intravenous administration, no MSCs were detected in the kidneys, irrespective of whether the mice had been subjected to renal injury. After arterial administration via the left cardiac ventricle, MSCs transiently populated the kidneys, but no preferential homing or persistence was observed in injured renal tissue after unilateral IRI. An exception was when MSCs were co-administered with exogenous macrophages; here, we observed some homing of MSCs to the injured kidney. CONCLUSIONS: Our findings strongly suggest that MSCs do not home to injured kidneys.
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Rim/diagnóstico por imagem , Rim/lesões , Macrófagos/patologia , Células-Tronco Mesenquimais/patologia , Imagem Multimodal , Animais , Sobrevivência Celular , Rastreamento de Células , Modelos Animais de Doenças , Feminino , Fígado/diagnóstico por imagem , Medições Luminescentes , Imageamento por Ressonância Magnética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos SCID , Células RAW 264.7 , Traumatismo por Reperfusão/diagnóstico por imagem , Traumatismo por Reperfusão/patologiaRESUMO
Due to their particular magnetic properties, nanoparticles of metallic iron are promising candidates for magnetic fluid hyperthermia when compared to the commonly used iron oxides. However, the difficulty of handling these structures in ambient conditions without oxidation hinders its practical application. In this work, iron filled carbon nanotubes non-covalently functionalized by human serum albumin are studied as potential agents for hyperthermia. Here the iron is encapsulated inside of the carbon shells and protected from reactions with its environment. Besides protecting the iron and biological environment against each other, the carbon shells can also work as an interface for conjugation with other biological molecules of interest. In order to assess if such structures could induce any toxic effect in human cell cultures, we have probed its biocompatibility on a dosage and time dependent manner by measuring metabolic activity, cell proliferation, cell cycle distribution and apoptosis. Our results have shown that those nanotubes strongly associate with cells within a short incubation period and do not pose any significant toxic effect. The magnetic properties of iron filled carbon nanotubes in biological environment, i.e., associated to cells, have been studied and a possible rotation as a function of the applied magnetic field is discussed. Our initial findings encourage the further study of these structures as potential hyperthermia agents.
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Materiais Biocompatíveis , Ferro , Nanotubos de Carbono , Albumina Sérica/administração & dosagem , Apoptose , Ciclo Celular , Linhagem Celular Tumoral , Proliferação de Células , Febre/terapia , Humanos , Técnicas In Vitro , Magnetismo , Masculino , Microscopia Eletrônica de TransmissãoRESUMO
Nanoparticle contrast agents are useful tools to label stem cells and monitor the in vivo bio-distribution of labeled cells in pre-clinical models of disease. In this context, understanding the in vivo fate of the particles after injection of labelled cells is important for their eventual clinical use as well as for the interpretation of imaging results. We examined how the formulation of superparamagnetic iron oxide nanoparticles (SPIONs) impacts the labelling efficiency, magnetic characteristics and fate of the particles by comparing individual SPIONs with polyelectrolyte multilayer capsules containing SPIONs. At low labelling concentration, encapsulated SPIONs served as an efficient labelling agent for stem cells. The bio-distribution after intra-cardiac injection of labelled cells was monitored longitudinally by MRI and as an endpoint by inductively coupled plasma-optical emission spectrometry. The results suggest that, after being released from labelled cells after cell death, both formulations of particles are initially stored in liver and spleen and are not completely cleared from these organs 2 weeks post-injection.
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AIM: To develop a 3D neural cell construct for encapsulated delivery of transplant cells; develop hydrogels seeded with magnetic nanoparticle (MNP)-labeled cells suitable for cell tracking by MRI. MATERIALS & METHODS: Astrocytes were exogenously labeled with MRI-compatible iron-oxide MNPs prior to intra-construct incorporation within a 3D collagen hydrogel. RESULTS: A connective, complex cellular network was clearly observable within the 3D constructs, with high cellular viability. MNP accumulation in astrocytes provided a hypointense MRI signal at 24 h & 14 days. CONCLUSION: Our findings support the concept of developing a 3D construct possessing the dual advantages of (i) support of long-term cell survival of neural populations with (ii) the potential for noninvasive MRI-tracking of intra-construct cells for neuroregenerative applications.