Biology subjects

Poptani, H.

Publications and source records attributed to Poptani, H..

8 recordsLinked to original sources

bioRxiv2026

Lysosomal abundance in young and aged mouse hearts assessed by In Vivo Imaging Systems (IVIS) Lysotracker imaging and autophagy-related gene expression

Lysosomal function is essential for cardiac proteostasis and cellular health, yet its regulation during ageing remains poorly defined. We hypothesised that ageing alters both the abundance of acidic organelles and the machinery supporting their acidification. Using fluorescence-based In Vivo Imaging Systems (IVIS) with Lysotracker Red in young (2-4 months) and aged (18 months) mouse hearts, we quantified whole-heart acidic-vesicle signals and assessed expression of lysosomal and autophagy-related genes (Lamp2, Atp6v1a, Sqstm1, Cd63, Atg12, Nfe2l2, M6pr) by RT-qPCR. Whole-heart labelled Lysotracker fluorescence did not differ significantly between age groups, indicating preservation of the total acidic-vesicle pool. No changes in Atp6v1a and Lamp2 expression suggest acidification capacity and structural stability are maintained, whereas the minor, upregulation of Sqstm1 might indicate increased autophagic demand and altered vesicle trafficking, which warrants further investigation. No statistical significant changes in M6pr, Atg12, or Nfe2l2 were detected, suggesting transcriptional stability in enzyme trafficking, core autophagy, and oxidative stress pathways. Regionally, atria showed higher Lysotracker signal than ventricles, consistent with known enrichment of acidic vesicular stores in atrial physiology. These findings highlight the utility of IVIS imaging of Lysotracker-labelled hearts, providing rapid whole-organ assessment of acidic vesicle distribution, albeit with limited depth resolution. Complementary techniques such as RT-qPCR analysis is essential to interpret IVIS findings, enabling insight into underlying molecular changes in lysosomal and autophagy pathways during cardiac ageing.

physiology↗

bioRxiv2025

Evaluating Labelling Efficiency of Commercial SPIONs in Mesenchymal Stem/Stromal Cells for Magnetic Particle Imaging Applications

Magnetic Particle Imaging (MPI) is a state-of-the-art, highly sensitive modality for non-invasive cell tracking. This study evaluated labelling efficiency, biocompatibility, intracellular localization, and MPI detection sensitivity of four commercial superparamagnetic iron oxide nanoparticles (SPIONs)--ProMag, VivoTrax, SynoMag-D, and Ferumoxytol--in mouse mesenchymal stem/stromal cells. SPION labelling efficiency and cytotoxicity was assessed at varying concentrations and incubation times using Prussian blue staining and ATP-based viability assays, respectively. MPI characterization and transmission electron microscopy (TEM) evaluations were performed for cells labelled for two-hour with ProMag or VivoTrax. For >90% labelling efficiency, ProMag required 20{square}{micro}g Fe/mL across all time points. VivoTrax, however, required [≥]240{square}{micro}g Fe/mL, reducing cell viability by >20% necessitating a reduction to 120 {micro}g/mL for further analyses. Transfection agents improved SynoMag-D and Ferumoxytol labelling but compromised viability. MPI analysis revealed linear dependence of signal intensity on labelled cell numbers for ProMag and VivoTrax (r2=0.99). ProMag yielded higher signal intensity due to greater iron uptake, although VivoTrax exhibited higher signal per unit iron. TEM confirmed intracellular SPION localization, with ProMag present as individual particles and VivoTrax as aggregates within endocytic vesicles. Low-temperature assays confirmed energy-dependent endocytosis as the primary uptake mechanism. Despite ProMags stronger MPI signals and lower detection threshold (12,500 cells), VivoTraxs superior magnetization per iron suggests its potential following further optimization of cell uptake. Overall, ProMag and VivoTrax emerged as optimal candidates for MPI-based stem cell tracking. These findings underscore the importance of optimizing both nanoparticle selection and labelling protocols to maximize MPI performance and inform future in vivo applications.

cell biology↗

bioRxiv2024

Inhibition of glioblastoma cell proliferation and invasion by the choline-kinase inhibitor JAS239 varies with cell type and hypoxia

BackgroundElevated choline kinase alpha (ChoK) is observed in most solid tumours including glioblastomas (GBM), yet until recently, inhibitors of ChoK have demonstrated limited efficacy in GBM models. Given that hypoxia is associated with GBM therapy resistance, we hypothesised that tumour hypoxia could be responsible for such limitations. We therefore evaluated in GBM cells, the effect of hypoxia on the function of JAS239, a potent ChoK inhibitor. MethodsRodent (F98 and 9L) and human (U-87 MG and U-251 MG) GBM cell lines were subjected to 72 hours of hypoxia conditioning and treated with JAS239 for 24 hours. NMR metabolomic measurements and analyses were performed to evaluate the signalling pathways involved. In addition, cell proliferation, cell cycle progression and cell invasion were measured in cell monolayers and 3D spheroids, with or without JAS239 treatment in normoxic or hypoxic cells to assess how hypoxia affects JAS239 function. ResultsHypoxia and JAS239 treatment led to significant changes in the cellular metabolic pathways, specifically the phospholipid and glycolytic pathways associated with a reduction in cell proliferation via induced cell cycle arrest. Interestingly, JAS239 also impaired GBM invasion. However, JAS239 effects were variable depending on the cell line, reflecting the inherent heterogeneity observed in GBMs. ConclusionOur findings indicate that JAS239 and hypoxia can deregulate cellular metabolism, inhibit proliferation and alter cell invasion. These results may be useful for the design of new therapeutic strategies based on ChoK inhibition that can act on multiple pro-tumorigenic features.

cancer biology↗

bioRxiv2023

Microcephaly with a disproportionate hippocampal reduction, stem cell loss and neuronal lipid droplet symptoms in Trappc9 KO mice

Mutations of the human TRAFFICKING PROTEIN PARTICLE COMPLEX SUBUNIT 9 (TRAPPC9) cause a neurodevelopmental disorder characterised by microcephaly and intellectual disability. Trappc9 constitutes a subunit specific to the intracellular membrane-associated TrappII complex. The TrappII complex interacts with Rab11 and Rab18, the latter being specifically associated with lipid droplets (LDs). Here we used non-invasive imaging to characterise Trappc9 knock-out (KO) mice as a model of the human hereditary disorder. KOs developed postnatal microcephaly with many grey and white matter regions being affected. In vivo MRI identified a disproportionately stronger volume reduction in the hippocampus, which was associated with a significant loss of Sox2-positive neural stem and progenitor cells. Diffusion Tensor imaging indicated a reduced organisation or integrity of white matter areas. Trappc9 KOs displayed behavioural abnormalities in several tests related to exploration, learning and memory. Trappc9-deficient primary hippocampal neurons accumulated a larger LD volume per cell following Oleic Acid stimulation, and the coating of LDs by Perilipin-2 was much reduced. Additionally, Trappc9 KOs developed obesity, which was significantly more severe in females than in males. Our findings indicate that, beyond previously reported Rab11-related vesicle transport defects, dysfunctions in LD homeostasis might contribute to the neurobiological symptoms of Trappc9 deficiency.

neuroscience↗

bioRxiv2023

Pleiotropic effects of trisomy and pharmacologic modulation on structural, functional, molecular, and genetic systems in a Down syndrome mouse model

Down syndrome (DS) is characterized by skeletal and brain structural malformations, cognitive impairment, altered hippocampal metabolite concentration and gene expression imbalance. These alterations were usually investigated separately, and the potential rescuing effects of green tea extracts enriched in epigallocatechin-3-gallate (GTE-EGCG) provided disparate results due to different experimental conditions. We overcame these limitations by conducting the first longitudinal controlled experiment evaluating genotype and GTE-EGCG prenatal chronic treatment effects before and after treatment discontinuation. Our findings revealed that the Ts65Dn mouse model reflected the pleiotropic nature of DS, exhibiting brachycephalic skull, ventriculomegaly, neurodevelopmental delay, hyperactivity, and impaired memory robustness with altered hippocampal metabolite concentration and gene expression. GTE-EGCG treatment modulated most systems simultaneously but did not rescue DS phenotypes. On the contrary, the treatment exacerbated trisomic phenotypes including body weight, tibia microarchitecture, neurodevelopment, adult cognition, and metabolite concentration, not supporting the therapeutic use of GTE-EGCG as a prenatal chronic treatment. Our results highlight the importance of longitudinal experiments assessing the co-modulation of multiple systems throughout development when characterizing preclinical models in complex disorders and evaluating the pleiotropic effects and general safety of pharmacological treatments.

systems biology↗

bioRxiv2018

In vivo fate of free and encapsulated iron oxide nanoparticles after injection of labelled stem cells

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.

biochemistry↗

bioRxiv2017

Magnetic resonance imaging for characterization of a chick embryo model of cancer cell metastases

BackgroundMetastasis is the most common cause of death for cancer patients, hence its study has rapidly expanded over the past few years. To fully understand all the steps involved in metastatic dissemination, in vivo models are required, of which murine ones are the most common. Therefore pre-clinical imaging methods have mainly been developed for small mammals. However, the potential of preclinical imaging techniques such as magnetic resonance imaging (MRI) to monitor cancer growth and metastasis in non-mammalian in vivo models is not commonly used. We have here used MRI to measure primary neuroblastoma tumour size and presence of metastatic dissemination in a chick embryo model. We compared its sensitivity and accuracy to end-point fluorescence detection.\n\nMethodsHuman neuroblastoma cells were labelled with GFP and micron-sized iron particles (MPIOs) and implanted on the extraembryonic chorioallantoic membrane of the chick embryo at E7. T2 RARE, T2 weighted FLASH as well as time-of-flight MR angiography imaging was applied at E14. Primary tumours as well as metastatic deposits in the chick embryo were dissected post imaging to compare with MRI results.\n\nResultsMPIO labelling of neuroblastoma cells allowed in ovo observation of the primary tumour and tumour volume measurement non-invasively over time. Moreover, T2 weighted and FLASH imaging permitted the detection of very small metastatic deposits in the chick embryo.\n\nConclusionsThe use of contrast agents enabled the detection of metastatic deposits of neuroblastoma cells in a chick embryo model, thereby reinforcing the potential of this cost efficient and convenient, 3R compliant, in vivo model for cancer research.

cancer biology↗

bioRxiv2017

Non-invasive imaging platform reveals a potential tumourigenicity hazard of systemically administered cells

BackgroundCell-based regenerative medicine therapies are now frequently tested in clinical trials. In many conditions, cell therapies are administered systemically, but there is little understanding of their fate, and adverse events are often under-reported. Currently, it is only possible to assess safety and fate of cell therapies in preclinical studies, specifically by monitoring animals longitudinally using multimodal imaging approaches. Here, using a suite of in vivo imaging modalities to explore the fate of a range of human and murine cells, we investigate how route of administration, cell type and host immune status affect the fate of administered cells.\n\nMethodsWe applied a unique imaging toolkit combining bioluminescence, optoacoustic and magnetic resonance imaging modalities to assess the safety of different human and murine cell types by following their biodistribution and persistence in mice following administration into the venous or arterial system. Results: Longitudinal imaging analyses (i) suggested that the intra-arterial route may be more hazardous than intravenous administration for certain cell types; (ii) revealed that the potential of a mouse mesenchymal stem/stromal cell (MSC) line to form tumours, depended on administration route and mouse strain; and (iii) indicated that clinically tested human umbilical cord (hUC)-derived MSCs can transiently and unexpectedly proliferate when administered intravenously to mice.\n\nConclusionsIn order to perform an adequate safety assessment of potential cell-based therapies, a thorough understanding of cell biodistribution and fate post administration is required. The non-invasive imaging toolbox used here can expose not only the general organ distribution of these therapies, but also a detailed view of their presence within different organs and, importantly, tumourigenic potential. Our observation that the hUC-MSCs but not the human bone marrow (hBM)-derived MSCs persisted for a period in some animals, suggests that therapies with these cells should proceed with caution.

cell biology↗