Biology subjects

Tirelli, V.

Publications and source records attributed to Tirelli, V..

5 recordsLinked to original sources

bioRxiv2024

STANDARDISED FLOW CYTOMETRIC PROCEDURE FOR DEEP CHARACTERIZATION OF NANOPARTICLES

In recent years, there has been a notable increasing interest surrounding the identification and quantification of nanosized particles, including extracellular vesicles (EVs) and viruses. The challenge posed by the nano-sized dimension of these particles makes precise examination a significant undertaking. Among the different techniques for the accurate study of EVs, Flow cytometry (FCM) stands out as the ideal method. It is characterized by high sensitivity, low time consumption, non-destructive sampling, and high throughput. In this article, we propose the optimization of FCM procedures to identify, quantify, and purify EVs and virus like particles (VLPs). The protocol aims to reduce artifacts and errors in nano-sized particles counting, overall caused by the swarming effect. Different threshold strategies were compared to ensure result specificity. Additionally, the critical parameters to consider when using conventional FCM outside of the common experimental context of use have also been identified. Finally, fluorescent-EVs sorting protocol was also developed with highly reliable results using a conventional cell sorter.

cell biology↗

bioRxiv2024

Complementary methods for the study of interactions between eosinophils and cancer cells.

Eosinophils are a rare immune cell subset with important roles in Th2 immunity and, recently, in cancer. Interleukin IL-33 (IL-33) is well recognized for its important roles in the activation of eosinophils in Th2 immunity. On the other hand, IL-33 has been recently discovered to play central roles in cancer, in particular by activating eosinophils and increase their degranulation consequent to an intrinsic tumor cell killing function. We propose a dual approach methodology to extrapolate functional interactions of eosinophils with tumor cells, as a result of eosinophil stimulation. Human eosinophils (Eos) isolated from the blood of healthy donors by dextran sedimentation followed by magnetic sorting are exposed to IL-33 (Eos33) or IL-5 (Eos5, control) for 18 h. These pre-conditioned cells are then co-cultured with A375P melanoma cells to monitor cell-cell interactions. Acoustic focusing flow cytometry analysis is employed to evaluate the presence of Eos-tumor cell conjugates after 1h incubation of human eosinophils and A375P melanoma cells. Moreover, a 24 h time-lapse video recording approach is employed to obtain single cell tracking Eos profiles. This allows to quantitatively determine the interaction extent of Eos33, as opposed to Eos5 (control condition), with tumor cells. In conclusion, our protocols easily and quickly allow the extrapolation of relevant kinematic and biologically relevant parameters for tumor reactive eosinophils. Furthermore, these methods are adaptable to various models with other types of immune cell subsets and cancer cells and can be implemented on different video microscopy platforms and advanced flow cytometry systems.

cancer biology↗

bioRxiv2024

Combined in vitro differentiation and cell sorting-based isolation of highly pure mouse bone marrow-derived basophils.

Basophils constitute a rare population of granulocytes with key functions in allergies, immunodeficiencies and cancer. The scarcity of basophils in the human blood and tissues constitutes a considerable limit for the study of these cells. Interleukin-3 (IL-3) is a cytokine that stimulates both the differentiation and the expansion of basophils from bone marrow (BM) precursors by positively regulating the expression of the IL3Ra receptor. We have standardized an in vitro differentiation protocol of mouse basophils (mBaso) from BM precursors through culture in presence of IL-3 for 10 days followed by cell sorting. At the end of the 10-day differentiation, a considerable number of mBaso can be obtained and cell sorting procedures further improved the isolation of an extraordinarily pure (>98%) and vital Fc{varepsilon}R1+ CD11c- c-kit- mBaso population. Phenotypic analysis revealed that terminally differentiated (day 10) unsorted mBaso cultured for 24 hours showed a decrease in basophilic lineage (c-kit-) and an increase of mastocytic lineage (c-kit+) and reduced the expression of basophil markers Fc{varepsilon}RI, CD49b and CD200R either in absence of stimuli or following activation with the alarmin IL-33, indicating cell dedifferentiation. In contrast, terminally differentiated and Fc{varepsilon}R1+ CD11c- c-kit- sorted mBaso do not dedifferentiate in mast cells when placed in culture, and responded to IL-33 stimulation by up-regulating the activation marker CD63 without down-modulation of Fc{varepsilon}RI and CD200R3. These evidences highlight that in vitro differentiation followed by cell sorting is a useful method to obtain elevated numbers of highly pure mBaso that preserve their lineage markers and thus are suitable for conducting the desired functional studies.

cell biology↗

bioRxiv2021

A cytofluorimetric analysis of a Saccharomyces cerevisiae population cultured in a fed-batch bioreactor

The yeast Saccharomyces cerevisiae is a reference model system and one of the widely used microorganisms in many biotechnological processes. In industrial yeast applications, combined strategies aim to maximize biomass/product yield, with the fed-batch culture being one of the most frequently used. Flow cytometry (FCM) is widely applied in biotechnological processes and represents a key methodology to monitor cell population dynamics. We propose here an application of FCM in the analysis of yeast cell cycle along the time course of a typical S. cerevisiae fed-batch culture. We used two different dyes, SYTOX Green and SYBR Green, with the aim to better define each stage of cell cycle during S. cerevisiae fed-batch culture. The results provide novel insights in the use of FCM cell cycle analysis for the real-time monitoring of S. cerevisiae bioprocesses.

cell biology↗

bioRxiv2020

Peptide-based Inhibitors of Protein-Protein Interactions of Src Homology 2 Domain-Containing Phosphatase 2

We developed a new class of inhibitors of protein-protein interactions of the SHP2 phosphatase, which is pivotal in multiple signaling pathways and a central target in the therapy of cancer and rare diseases. Currently available SHP2 inhibitors target the catalytic site or an allosteric pocket but lack specificity or are ineffective on disease-associated SHP2 mutants. Based on the consideration that pathogenic lesions cause signaling hyperactivation due to increased SHP2 association with cognate proteins, we developed peptide-based molecules with low nM affinity for the N-terminal Src homology domain of SHP2, good selectivity, stability to degradation and an affinity for pathogenic variants of SHP2 up to 20 times higher than for the wild-type protein. The best peptide reverted the effects of a pathogenic variant (D61G) in zebrafish embryos. Our results provide a novel route for SHP2-targeted therapies and a tool to investigate the role of protein-protein interactions in the function of SHP2.

biophysics↗