Measurement of extracellular vesicles as biomarkers of consequences or cause complications of pathological states, and prognosis of both evolution and therapeutic safety/efficacy

Measurement of canine blood microparticles by flow cytometry: effect of anticoagulants and staining reagents

Microparticles (MPs) are released from budding plasma membranes into body fluids. The use of flow cytometry for the measurement of MP in canines has not been standardized. In this fundamental study, we compared the effect of anticoagulant agents, such as acid-citrate-dextrose (ACD) and heparin on the measurement of canine MPs in platelet-free plasma (PFP) using flow cytometry. In addition, we used annexin V, carboxyfluorescein succinimidyl ester (CFSE), or calcein tetraacetoxymethyl ester (calcein-AM), and explored the characteristics of the staining reagents in MP detection using flow cytometry. We were able to measure canine MPs in PFP prepared from ACD-anticoagulated blood using flow cytometry, in which the highest positive rate for fluorescent staining was observed when CFSE was used.

A new insight into the cellular mechanisms of envenomation: Elucidating the role of extracellular vesicles in Loxoscelism

Envenomation by the Loxosceles genus spiders is a recurring health issue worldwide and specially in the Americas. The physiopathology of the envenomation is tightly associated to the venom's rich toxin composition, able to produce a local dermonecrotic lesion that can evolve systemically and if worsened, might result in multiple organ failure and lethality. The cellular and molecular mechanisms involved with the physiopathology of Loxoscelism are not completely understood, however, the venom's Phospholipases D (PLDs) are known to trigger membrane injury in various cell types. Here, we report for the first time the Loxosceles venom's ability to stimulate the production of extracellular vesicles (EVs) in various human cell lineages. Components of the Loxosceles venom were also detectable in the cargo of these vesicles, suggesting that they may be implicated in the process of extracellular venom release. EVs from venom treated cells exhibited phospholipase D activity and were able to induce in vitro hemolysis in human red blood cells and alter the HEK cell membranes' permeability. Nonetheless, the PLD activity was inhibited when an anti-venom PLDs monoclonal antibody was co-administered with the whole venom. In summary, our findings shed new light on the mechanisms underlying cellular events in the context of loxoscelism and suggest a crucial role of EVs in the process of envenomation.

Extra cellular vesicles in blood circulation as biomarkers and messengers of patho-hysiological activity and alterations

There is an increasing interest in Extracellular Vesicles released by many cells through membrane shedding. In addition to cell signaling, these particles are true messenger cargos, which can carry cell surface proteins, miRNAs and non-coding RNAs to other and distant cells. They are part of the inter-cellular crosstalk and they contribute to transferring biological messages far away from the triggering event. EVs are biomarkers of many diseases, including thrombo-embolic pathology, infections, neurological or metabolic disorders, and malignancy. Their role and significance are presented and discussed in this short review, as consequences of disease and causes of its progression. But they can also be beneficial for tissue healing or repair, and they can be prepared in vitro to be used for cell- targeted treatments. Many identification and measurement methods for EV's are sophisticated, which restricts their use to research studies, but they have, nevertheless, a high laboratory potential for diagnosis, prognosis and evolution as follow-up of many pathologies. New emerging laboratory tools offer more friendly and easy applications for characterizing EVs and testing their associated activity, especially for the procoagulant ones.

Cell-Derived Microparticles in Blood Products from Thalassemic Blood Donors

OBJECTIVE

To determine the number of cell-derived microparticles (MPs) in blood products obtained from donors who have thalassemia.

METHODS

Packed red blood cells (PRBCs), plasma, and platelet concentrate (PC) were prepared according to routine procedures. We used flow cytometry to quantitate the concentration of MPs.

RESULTS

The results of a comparison of MP levels in unprocessed whole blood showed that the concentration of all MPs in the donors without thalassemia trait (n = 255) was higher than in donors with thalassemia trait (n = 70). After processing, increased concentrations of MPs were documented in both groups. Among the blood components, PRBC showed higher platelet-derived MP concentrations in donors with thalassemia than in donors without thalassemia. However, PC showed higher concentrations of total MPs in donors without thalassemia than in donors with that condition.

CONCLUSIONS

Our results suggest little influence of thalassemia-trait status on changes in MP concentrations in blood components.

Walking speed decline in older adults is associated with elevated pro-BDNF in plasma extracellular vesicles

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is produced by cleavage of proBDNF, and BDNF and proBDNF may play antagonistic roles in nervous system development, learning, memory and neuronal stress resistance. BDNF and proBDNF are present in blood, but the origin and relative contributions of soluble and extracellular vesicle (EV)-associated levels are unknown.

METHODS

In this study we used validated immunoassays to measure proBDNF and BDNF levels in plasma, total plasma EVs and a subpopulation of EVs enriched for neuronal origin (expressing the neuronal marker L1CAM) in 150 Baltimore Longitudinal Study of Aging participants with and without decline in walking speed (reflecting aging-associated motor decline).

RESULTS

Levels of BDNF and proBDNF were highest in L1CAM+ EVs. Participants with walking speed decline had higher levels of proBDNF in L1CAM+ EVs compared to non-decliners, but no differences in proBDNF levels in plasma and total EV.

CONCLUSIONS

Our findings suggest that levels of proBDNF and BDNF in circulating L1CAM+ EVs might be used as biomarkers for conditions involving altered BDNF signaling.

Blood derived products in pediatrics: New laboratory tools for optimizing potency assignment and reducing side effects

Neonates and children can develop rare bleeding disorders due to congenital/acquired coagulation Factor deficiencies, or allo-immune/autoimmune complications, or can undergo surgeries at high haemorrhagic risk. They then need specialized transfusion of blood components/products, or purified blood extracted products or recombinant proteins. Blood-derived therapies conventionally used for management of affected infants with genetic/acquired deficiencies, bleeding problems (coagulation Factor reduced or missing) or thrombotic disorders (reduced or missing anticoagulant proteins) pose some additional risks. These remedial therapies can cause tolerance when used very early in life and, sometimes needed, repeatedly. The introduction of recombinant proteins has allowed manufacturers to produce large amounts of the proteins usually present at very low concentration in blood. This has also changed the risk pattern of plasma-extracted products, especially in terms of continual reduction of viral transmission. Many efforts have been made over these past decades to reduce the risks associated with the use of all these products in terms of viral and bacterial safety, as well as immune disorders but they are not the objective of this article. Other associated side effects are the presence of undesired activities in blood products, which can produce thrombotic events or adverse reactions. The progressive introduction of blood derived products has greatly improved the prognosis and quality of life of affected patients. This concerns whole blood, but also blood cell concentrates, mainly platelets and red blood cells, plasma, while the blood extracted products are increasingly replaced by recombinant proteins. All these therapeutic products, i.e. blood extracted drugs, improve health and quality of life for hemophiliac's A or B, or patients with auto/allo-immune thrombocytopenias or with rare bleeding disorders, and those with thrombotic events occurring in childhood, which are mainly due to Protein C or Protein S deficiencies (congenital or acquired). Progress in analytical methods and biotechnology allow better control of the manufacturing processes for all blood derived or plasma extracted products and recombinant proteins, and contribute to improved manufacturing processes to minimize the occurrence of side effects. These adverse events can be due to the aging of the blood cell concentrate with release of their granule content, and generation of EVs, which can produce anaphylactic reactions and risk of thrombosis, but also to the presence of activated coagulation Factors in purified products, such as Factor Xia as recently identified in immunoglobulin concentrates. Characterization and measurement of contaminant products is of special usefulness during product preparation and for optimization of manufacturing processes for purified extracted products, but also for recombinant proteins. The pharmaceutical industry introduces these new methods for validating manufacturing processes, or for quality control assessments. The objective is first to warrant the full quality and safety of the lots produced, and assure the highest efficacy with the lowest risks when used in patients. For cell concentrates and fresh blood, storage conditions are critical and measurement of analytes such as EVs or Annexin V allows evaluation of quality of each individual transfused pouch. In addition to all the rules around viral and bacterial transmission risk, and immune tolerance, our available laboratory methods contribute to reducing the side effects of blood cell concentrates and derived plasma products, as well as those of the therapeutic recombinant proteins.