Biogenesis and delivery of extracellular vesicles: harnessing the power of EVs for diagnostics and therapeutics

Extracellular vesicles (EVs) are membrane-enclosed particles secreted by a variety of cell types. These vesicles encapsulate a diverse range of molecules, including proteins, nucleic acids, lipids, metabolites, and even organelles derived from their parental cells. While EVs have emerged as crucial mediators of intercellular communication, they also hold immense potential as both biomarkers and therapeutic agents for numerous diseases. A thorough understanding of EV biogenesis is crucial for the development of EV-based diagnostic developments since the composition of EVs can reflect the health and disease status of the donor cell. Moreover, when EVs are taken up by target cells, they can exert profound effects on gene expression, signaling pathways, and cellular behavior, which makes these biomolecules enticing targets for therapeutic interventions. Yet, despite decades of research, the intricate processes underlying EV biogenesis by donor cells and subsequent uptake by recipient cells remain poorly understood. In this review, we aim to summarize current insights and advancements in the biogenesis and uptake mechanisms of EVs. By shedding light on the fundamental mechanisms governing EV biogenesis and delivery, this review underscores the potential of basic mechanistic research to pave the way for developing novel diagnostic strategies and therapeutic applications.

Neurological impact of emboli during adult cardiac surgery

Objectives

This study draws on advances in Doppler ultrasound bubble sizing to investigate whether high volumes of macro-bubbles entering the brain during cardiac surgery increase the risk of new cerebral microbleeds (CMBs), ischemic MR lesions, or post-operative cognitive decline (POCD).

Methods

Transcranial Doppler (TCD) ultrasound recordings were analysed to estimate numbers of emboli and macrobubbles (>100 μm) entering the brain during cardiac surgery. Logistic regression was used to explore the hypothesis that emboli characteristics affect the incidence of new brain injuries identified through pre- and post-operative MRI and neuropsychological testing.

Results

TCD, MRI, and neuropsychological test data were compared between 28 valve and 18 CABG patients. Although valve patients received over twice as many emboli per procedure [median: 1995 vs. 859, p = .004], and seven times as many macro-bubbles [median: 218 vs. 28, p = .001], high volumes of macrobubbles were not found to be significantly associated with new CMBs, new ischaemic lesions, or POCD. The odds of acquiring new CMBs increased by approximately 5% [95% CI: 1 to 10%] for every embolus detected in the first minute after the release of the aortic cross-clamp (AxC). Logistic regression models also confirmed previous findings that cardiopulmonary bypass time and valve surgery were significant predictors for new CMBs (both p = .03). Logistic regression analysis estimated an increase in the odds of acquiring new CMBs of 6% [95% CI: 1 to 12%] for every minute of bypass time over 91 mins.

Conclusions

This small study provides new information about the properties and numbers of bubbles entering the brain during surgery, but found no evidence to substantiate a direct link between large numbers of macrobubbles and adverse cognitive or MR outcome.

Clinical Trial Registration URL - http://www.isrctn.com. Unique identifier: 66022965.

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Higher numbers of macrobubbles enter the brain during valve surgery compared to bypass graft surgery.

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Macrobubbles did not appear to be linked to new cerebral microbleeds, ischemic lesions, or cognitive decline.

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Emboli received following release of the aortic cross-clamp predicted new cerebral microbleeds.

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Other factors predicting new microbleeds included cardiopulmonary bypass duration and surgery type.

Biomarker Predictors of Adverse Acute Kidney Injury Outcomes in Critically Ill Patients: The Dublin Acute Biomarker Group Evaluation Study

BACKGROUND

The Dublin Acute Biomarker Group Evaluation (DAMAGE) Study is a prospective 2-center observational study investigating the utility of urinary biomarker combinations for the diagnostic and prognostic assessment of acute kidney injury (AKI) in a heterogeneous adult intensive care unit (ICU) population. The objective of this study is to evaluate whether serial urinary biomarker measurements, in combination with a simple clinical model, could improve biomarker performance in the diagnostic prediction of severe AKI and clinical outcomes such as death and need for renal replacement therapy (RRT).

METHODS

Urine was collected daily from patients admitted to the ICU, for a total of 7 post-admission days. Urine biomarker concentrations (neutrophil gelatinase-associated lipocalin [NGAL], α-glutathione S-transferase [GST], π-GST, kidney injury molecule-1 [KIM-1], liver-type fatty acid-binding protein [L-FABP], Cystatin C, creatinine, and albumin) were measured. Urine biomarkers were combined with a clinical prediction of AKI model, to determine ability to predict AKI (any stage, within 2 days or 7 days of ICU admission), or a -30-day composite clinical outcome (RRT - or death).

RESULTS

A total of 257 (38%) patients developed AKI within 7 days of ICU admission. Of those who developed AKI, 106 (41%) patients met stage 3 AKI within 7 days of ICU admission and 208 patients of the entire study cohort (31%) met the composite clinical endpoint of in-hospital mortality or RRT within 30 days of ICU admission. The addition of urinary NGAL/albumin to the clinical model modestly improved the prediction of AKI, in particular severe stage 3 AKI (area under the curve [AUC] of 0.9 from 0.87, p = 0.369) and the prediction of 30-day RRT or death (AUC 0.83 from 0.79, p = 0.139).

CONCLUSION

A clinical model incorporating severity of illness, patient demographics, and chronic illness with currently available clinical biomarkers of renal function was strongly predictive of development of AKI and associated clinical outcomes in a heterogeneous adult ICU population. The addition of urinary NGAL/albumin to this simple clinical model improved the prediction of severe AKI, need for RRT and death, but not at a statistically or clinically significant level, when compared to the clinical model alone.

Prophylactic perioperative sodium bicarbonate to prevent acute kidney injury following open heart surgery: a multicenter double-blinded randomized controlled trial

BACKGROUND

Preliminary evidence suggests a nephroprotective effect of urinary alkalinization in patients at risk of acute kidney injury. In this study, we tested whether prophylactic bicarbonate-based infusion reduces the incidence of acute kidney injury and tubular damage in patients undergoing open heart surgery.

METHODS AND FINDINGS

In a multicenter, double-blinded (patients, clinical and research personnel), randomized controlled trial we enrolled 350 adult patients undergoing open heart surgery with the use of cardiopulmonary bypass. At induction of anesthesia, patients received either 24 hours of intravenous infusion of sodium bicarbonate (5.1 mmol/kg) or sodium chloride (5.1 mmol/kg). The primary endpoint was the proportion of patients developing acute kidney injury. Secondary endpoints included the magnitude of acute tubular damage as measured by urinary neutrophil gelatinase-associated lipocalin (NGAL), initiation of acute renal replacement therapy, and mortality. The study was stopped early under recommendation of the Data Safety and Monitoring Committee because interim analysis suggested likely lack of efficacy and possible harm. Groups were non-significantly different at baseline except that a greater proportion of patients in the sodium bicarbonate group (66/174 [38%]) presented with preoperative chronic kidney disease compared to control (44/176 [25%]; p = 0.009). Sodium bicarbonate increased urinary pH (from 6.0 to 7.5, p<0.001). More patients receiving bicarbonate (83/174 [47.7%]) developed acute kidney injury compared with control patients (64/176 [36.4%], odds ratio [OR] 1.60 [95% CI 1.04-2.45]; unadjusted p = 0.032). After multivariable adjustment, a non-significant unfavorable group difference affecting patients receiving sodium bicarbonate was found for the primary endpoint (OR 1.45 [0.90-2.33], p = 0.120]). A greater postoperative increase in urinary NGAL in patients receiving bicarbonate infusion was observed compared to control patients (p = 0.011). The incidence of postoperative renal replacement therapy was similar but hospital mortality was increased in patients receiving sodium bicarbonate compared with control (11/174 [6.3%] versus 3/176 [1.7%], OR 3.89 [1.07-14.2], p = 0.031).

CONCLUSIONS

Urinary alkalinization using sodium bicarbonate infusion was not found to reduce the incidence of acute kidney injury or attenuate tubular damage following open heart surgery; however, it was associated with a possible increase in mortality. On the basis of these findings we do not recommend the prophylactic use of sodium bicarbonate infusion to reduce the risk of acute kidney injury. Discontinuation of growing implementation of this therapy in this setting seems to be justified.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00672334 Please see later in the article for the Editors' Summary.

The risks of transmission of acute hepatitis A and B virus infection in an urban centre

In a large urban centre of a developed nation, 63 household contacts of 20 index cases with acute hepatitis A virus infection and 95 household contacts of 29 index cases with acute hepatitis B virus infection were prospectively followed for 2 years to document the risk of acquiring acute hepatitis from the index case. Twenty-one of 63 (33%) hepatitis A virus household contacts had serologic evidence of previous hepatitis A virus infection on the initial serum sample. Of the remaining 42 susceptible individuals, 22 (52%) were or became IgM anti-HAV positive within 6 months of the diagnosis in the index case. With respect to hepatitis B virus infection, 18/95 (17%) household contacts had serologic evidence of previous hepatitis B virus infection on the initial serum sample. Of the remaining 77 susceptible individuals, four (5%) had or developed serologic evidence of acute hepatitis B virus infection (IgM anti-hepatitis B core antigen positive) during the 2 years of follow up. In three of these four individuals, acquisition of hepatitis B virus was apparent within 6 months of the diagnosis in the index case. The results of this study indicate that in this urban centre, the risk of acquiring acute hepatitis A virus infection from index cases within the household is approximately 10 times greater than that for acute hepatitis B virus infection. These results support the need for continued passive and/or active immunization against hepatitis A and B virus infection in susceptible household contacts.

A phase II study of crisnatol mesylate in patients with ovarian carcinoma

Fourteen patients with advanced ovarian cancer received a 72 hour infusion of a new DNA intercalator, crisnatol mesylate, administered intravenously. There was no evidence of antitumor efficacy. A syndrome of nausea and vomiting associated with vertigo, dizziness and ataxia was observed in nearly all patients. Two of the patients developed severe CNS toxicity manifested in one by a grand-mal seizure and in the other by peripheral neuropathy. Further explorations into the potential efficacy of crisnatol mesylate administered intraperitoneally are underway.

Iatrogenic disease in hospitalized elderly veterans

To help determine whether or not the elderly are at unusually high risk for hospital-related complications, a study was made of consecutive admissions involving 48 patients less than 65 years old (mean 50.3 years) and 174 patients more than 65 years old (mean 73.1 years). They were prospectively followed during their hospital stays, and were monitored daily. According to admission data, they were classified as : Group 1, likely to die soon after admission; Group II, likely to die within a year; Group III, likely to live longer than a year. Complications were listed under the causal factors: trauma, infection, hospital procedures, drugs, and miscellaneous. About 90 per cent of all 222 patients in both age categories were in Group III. The overall complication rates were 29 per cent for patients under 65, and 45 per cent for those over 65 (P less than 0.05). For the under-65 Group III patients, the rates were 17 per cent and 42 per cent for medical and surgical patients, respectively; for the over-65 patients, the rates were 40 per cent (medical) and 43 per cent (surgical). This indicated a major increase in complications among medical patients more than 65 years old. Procedure-related problems were most common among surgical patients under 65. For over-65 patients, the complication rates for procedure-related, trauma, miscellaneous, infection, and drug toxicity categories were fairly evenly distributed within the range of 16.8-12.8 per cent, in that order. Major psychiatric deterioration was observed in 10.7 per cent of patients over 65, but in none of the younger subjects. Drug toxicity and traumatic complications were also more common in the older patients. These data confirm the disproportionately high incidence of iatrogenic diseases in hospital patients over the age of 65. Several of these complications are amenable to control.