C-src Enriched Serum Microvesicles Are Generated in Malignant Plasma Cell Dyscrasia

Plasma cell dyscrasias are immunosecretory disorders that can lead to hematological malignancies such as Multiple Myeloma (MM). MM accounts for 15% of all hematologic cancers, and those diagnosed with MM typically become severely ill and have a low life expectancy. Monoclonal immunoglobulin Free Light Chains (FLC) are present in the serum and urine of many patients with plasma cell diseases. The biological differences between monoclonal FLCs, produced under malignant or benign dyscrasias, has not yet been characterized. In the present study, we show that endothelial and heart muscle cell lines internalize kappa and lambda FLCs. After internalization, FLCs are rerouted in the extracellular space via microvesicles and exosomes that can be re-internalized in contiguous cells. Only FLCs secreted from malignant B Lymphocytes were carried in Hsp70, annexin V, and c-src positive vesicles. In both MM and AL Amyloidosis patients we observed an increase in microvesicles and exosomes production. Isolated serum vesicles from MM, AL Amyloidosis and monoclonal gammopathy of undetermined significance (MGUS) patients contained FLCs. Furthermore MM and AL amyloidosis vesicles were strongly positive for Hsp70, annexin V, and c-src compared to MGUS and control patients. These are the first data implying that FLCs reroute via microvesicles in the blood stream, and also suggest a potential novel mechanism of c-src activation in plasma cell dyscrasia

Comparison of Hevylite™ IgA and IgG assay with conventional techniques for the diagnosis and follow-up of plasma cell dyscrasia

Background: Heavy/light chain assay allows the characterization and quantification of immunoglobulin light chains bound to heavy chains for each Ig’k and Ig’ immunoglobulin class, discriminating between the involved/uninvolved isotypes in plasma cell dyscrasia. The Ig’k/Ig’ ratio (heavy/light chain ratio) enables to monitor the trend of monoclonal component during therapy and disease evolution. Objective: In this study, we evaluate the impact of the heavy/light chain assay in monitoring multiple myeloma patients in comparison with conventional techniques. Methods: Serum samples of 28 patients with IgG or IgA monoclonal component were collected for a mean of 109 days and analyzed. The heavy/light chain assay was compared with classical immunoglobulin quantification (Ig’Tot), serum immunofixation electrophoresis, serum protein electrophoresis, and serum-free light chains quantification. Serum samples from 30 healthy patients were used as control (polyclonal). Results: Heavy/light chain ratio and serum immunofixation electrophoresis were comparable in 86% of the cases, and free light chain ratio and heavy/light chain ratio in 71.8%. Heavy/light chain assay and Ig’Tot measurements showed a concentration-dependent agreement in monoclonal patients. The heavy/light chain assay was able to quantify the monoclonal component migrating in SPE b region: this occurred in 10% of our IgG and 50% of our IgA patients. Conclusions: The concordance scores indicate that heavy/light chain and Ig’Tot assays show differences at high monoclonal component values. The heavy/light chain ratio, serum immunofixation electrophoresis, and free light chain ratio showed partial concordance. Our study confirmed that, in the context of heavy/light chain assay, heavy/light chain Ig’k and Ig’ absolute values and heavy/light chain ratio are both important tools to monitor the presence of monoclonal component that are difficult to be identified in SPE

Active antithrombin glycoforms are selectively physiosorbed on plasma extracellular vesicles

Antithrombin (AT) is a glycoprotein produced by the liver and a principal antagonistof active clotting proteases. A deficit in AT function leads to AT qualitative deficiency,challenging to diagnose. Here we report that active AT may travel physiosorbed on thesurface of plasma extracellular vesicles (EVs), contributing to form the “EV-proteincorona.” The corona is enriched in specific AT glycoforms, thus suggesting glycosyla-tion to play a key role in AT partitioning between EVs and plasma. Differences in ATglycoform composition of the corona of EVs separated from plasma of healthy andAT qualitative deficiency-affected subjects were also noticed. This suggests deconstructing the plasma into its nanostructured components, as EVs, could suggest noveldirections to unravel pathophysiological mechanisms

Immunoglobulin free light chains and GAGs mediate multiple myeloma extracellular vesicles uptake and secondary NfkB nuclear traslocation

Multiplemyeloma(MM) is a hematological malignancy caused by a microenviromentally aided persistence of plasmacells in the bone marrow. Monoclonal plasmacells often secrete high amounts of immunoglobulin free light chains(FLCs)that could induce tissue damage. Recently, we showed that FLCs are internalized in endothelial and myocardial cell lines and secreted in extracellular vesicles(EVs). MM serum derived EVs presented phenotypic differences if compared with monoclonal gammopathy of undetermined significance (MGUS)serum derived EVs suggesting their involvement in MM pathogenesis or progression. To investigate the effect of circulating EVs on endothelial and myocardial cells, we purified MM and MGUS serum derived EVs with differential ultracentrifugation protocols and tested their biological activity. We found that MM and MGUS EVs induced different proliferation and internalization rates in endothelial and myocardial cells, thus we tried to find specific targets in MM EVs docking and processing. Pre-treatment of EVs withanti-FLCs antibodies or heparin blocked the MM EVs uptake, highlighting that FLCs and glycosaminoglycans are involved. Indeed, only MM EVs exposure induced a strong nuclear factor kappa B nuclear translocation that was completely abolished afteranti-FLCs antibodies and heparin pre-treatment. The protein tyrosine kinase c-src is present on MM circulating EVs and redistributes to the cell plasma membrane after MM EVs exposure.The anti-FLCs antibodies and heparin pre-treatments were able to block the intracellular redistribution of the c-src kinase and the subsequent c-src kinase containing EVs production. Our results open new insights in EVs cellular biology and in MM therapeutic and diagnostic approaches

Immunoglobulin free light chains and GAGs mediate multiple myeloma extracellular vesicles uptake and secondary NfkB nuclear traslocation

Multiplemyeloma(MM) is a hematological malignancy caused by a microenviromentally aided persistence of plasmacells in the bone marrow. Monoclonal plasmacells often secrete high amounts of immunoglobulin free light chains(FLCs)that could induce tissue damage. Recently, we showed that FLCs are internalized in endothelial and myocardial cell lines and secreted in extracellular vesicles(EVs). MM serum derived EVs presented phenotypic differences if compared with monoclonal gammopathy of undetermined significance (MGUS)serum derived EVs suggesting their involvement in MM pathogenesis or progression. To investigate the effect of circulating EVs on endothelial and myocardial cells, we purified MM and MGUS serum derived EVs with differential ultracentrifugation protocols and tested their biological activity. We found that MM and MGUS EVs induced different proliferation and internalization rates in endothelial and myocardial cells, thus we tried to find specific targets in MM EVs docking and processing. Pre-treatment of EVs withanti-FLCs antibodies or heparin blocked the MM EVs uptake, highlighting that FLCs and glycosaminoglycans are involved. Indeed, only MM EVs exposure induced a strong nuclear factor kappa B nuclear translocation that was completely abolished afteranti-FLCs antibodies and heparin pre-treatment. The protein tyrosine kinase c-src is present on MM circulating EVs and redistributes to the cell plasma membrane after MM EVs exposure.The anti-FLCs antibodies and heparin pre-treatments were able to block the intracellular redistribution of the c-src kinase and the subsequent c-src kinase containing EVs production. Our results open new insights in EVs cellular biology and in MM therapeutic and diagnostic approaches

Residual matrix from different separation techniques impacts exosome biological activity

Exosomes are gaining a prominent role in research due to their intriguing biology and several therapeutic opportunities. However, their accurate purification from body fluids and detailed physicochemical characterization remain open issues. We isolated exosomes from serum of patients with Multiple Myeloma by four of the most popular purification methods and assessed the presence of residual contaminants in the preparations through an ad hoc combination of biochemical and biophysical techniques - including Western Blot, colloidal nanoplasmonics, atomic force microscopy (AFM) and scanning helium ion microscopy (HIM). The preparations obtained by iodixanol and sucrose gradients were highly pure. To the contrary, those achieved with limited processing (serial centrifugation or one step precipitation kit) resulted contaminated by a residual matrix, embedding the exosomes. The contaminated preparations showed lower ability to induce NfkB nuclear translocation in endothelial cells with respect to the pure ones, probably because the matrix prevents the interaction and fusion of the exosomes with the cell membrane. These findings suggest that exosome preparation purity must be carefully assessed since it may interfere with exosome biological activity. Contaminants can be reliably probed only by an integrated characterization approach aimed at both the molecular and the colloidal length scales

Surface functionalization of extracellular vesicle nanoparticles with antibodies: a first study on the protein corona "variable"

To be profitably exploited in medicine, nanosized systems must be endowed with biocompatibility, targeting capability, the ability to evade the immune system, and resistance to clearance. Currently, biogenic nanoparticles, such as extracellular vesicles (EVs), are intensively investigated as the platform that naturally recapitulates these highly needed characteristics. EV native targeting properties and pharmacokinetics can be further augmented by decorating the EV surface with specific target ligands as antibodies. However, to date, studies dealing with the functionalization of the EV surface with proteins have never considered the protein corona "variable", namely the fact that extrinsic proteins may spontaneously adsorb on the EV surface, contributing to determine the surface, and in turn the biological identity of the EV. In this work, we explore and compare the two edge cases of EVs modified with the antibody Cetuximab (CTX) by chemisorption of CTX (through covalent binding via biorthogonal click-chemistry) and by formation of a physisorbed CTX corona. The results indicate that (i) no differences exist between the two formulations in terms of binding affinity imparted by molecular recognition of CTX versus its natural binding partner (epidermal growth factor receptor, EGFR), but (ii) significant differences emerge at the cellular level, where CTX-EVs prepared by click chemistry display superior binding and uptake toward target cells, very likely due to the higher robustness of the CTX anchorage

Large-scale production of extracellular vesicles: Report on the “massivEVs” ISEV workshop

Extracellular vesicles (EVs) large-scale production is a crucial point for the translation of EVs from discovery to application of EV-based products. In October 2021, the International Society for Extracellular Vesicles (ISEV), along with support by the FET-OPEN projects, “The Extracellular Vesicle Foundry” (evFOUNDRY) and “Extracellular vesicles from a natural source for tailor-made nanomaterials” (VES4US), organized a workshop entitled “massivEVs” to discuss the potential challenges for translation of EV-based products. This report gives an overview of the topics discussed during “massivEVs”, the most important points raised, and the points of consensus reached after discussion among academia and industry representatives. Overall, the review of the existing EV manufacturing, upscaling challenges and directions for their resolution highlighted in the workshop painted an optimistic future for the expanding EV field

Minimal information for studies of extracellular vesicles 2018 (MISEV2018):a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points