Drug delivery to the central nervous system (CNS) is limited due to the presence of the blood–brain barrier (BBB), a selective physiological barrier located at the brain microvessels that regulates the flow of cells, molecules and ions between the blood and the brain. Exosomes are nanosized extracellular vesicles expressed by all cell types and that function as cargos, allowing for communication between the cells. The exosomes were shown to cross or regulate the BBB in healthy and disease conditions. However, the mechanistic pathways by which exosomes cross the BBB have not been fully elucidated yet. In this review, we explore the transport mechanisms of exosomes through the BBB. A large body of evidence suggests that exosome transport through the BBB occurs primarily through transcytosis. The transcytosis mechanisms are influenced by several regulators. Inflammation and metastasis also enhance exosome trafficking across the BBB. We also shed light on the therapeutical applications of exosomes for treating brain diseases. Further investigations are essential to provide clearer insights related to trafficking of exosomes across the BBB and disease treatment.

Background: Despite recent advances in perinatal and neonatal care in respiratory distress syndrome (RDS) prevention and treatment, a considerable number of these neonates suffer from acute kidney injury (AKI), and it is associated with poor outcome as an independent risk factor. KIM-1 mRNA and protein are expressed at a low level in normal kidney but are increased in post ischemic kidney. Aim: The aim is to detect the value of urinary KIM-1 measurement as an early predictor marker of acute kidney injury in preterm neonates with respiratory distress syndrome. Patients and methods: The study included 30 preterm newborn with (RDS) ≤36 weeks during the period from October 2014 to March 2015. Also the study included 30 apparently healthy newborn ≤36 weeks as controls. They were selected from NICU of Manshiate Elbakry hospital Cairo, Egypt. uKIM-1 along with serum creatinine levels and eGFR were assessed in days 1 of life for both groups and in day 3 for cases. Results: In day one of life, we found a significant increase in uKIM-1 levels in preterm newborn with RDS compared to their controls (2.88 ± 1.01 ng/ml and 0.95 ± 0.52 ng/ml respectively (p = 0.001)). There is no significant difference between both groups regarding serum creatinine and eGFR. In day 3 of life, preterm with RDS had significant decrease in uKIM-1 levels compared to day 1 of life with significant increase in non-survivor compared to survivor group ( 2.30 ± 1.56 ng/ml and 1.30 ± 0.90 ng/ml respectively (p = 0.03)). The sensitivity and specificity of uKIM-1 and serum creatinine was calculated (100.00%, 86.67% and 33.33%; 95.00%) respectively. Conclusion: Preterm neonate with RDS is at high risk of developing AKI. Early and serial uKIM-1 measurements can be used as a non-invasive indicator of kidney injury in premature newborn with RDS.

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Resistin is a secretory adipocytoine, which is expressed mainly in humans by inflammatory cells especially macrophages. Resistin serum levels are elevated in end-stage renal diseases of people having an increased risk of infections as a result of impaired polymorphonuclear leukocytes (PMNLs) functions. Objectives: To evaluate neutrophil functions (phagocytosis and oxidative burst) in children with end-stage renal disease (ESRD) on regular hemodialysis and to shed light on the contribution of resistin on neutrophil functions. Patients and Methods: The study included 40 children with ESRD on regular hemodialysis. Their ages ranged from 6 to 12 years, and they were selected from children attending the pediatric hemodialysis unit of AL-Zahraa Hospital, Al-Azher University during the period from October 2012 to December 2013. Another group of 40 apparently healthy children with matched age and sex with the patient group served as a control. Serum resistin, phagocytic index and nitro blue tetrazolium test (NBT%) were assessed in both groups. Results: There was a statistically more significant increase in resistin serum levels in cases than in controls; it was (3.25 ± 0.86 ng/ml) and (0.25 ± 0.16 ng/ml) respectively (P < 0.01). On the other hand there was a statistically more significant decrease in neutrophil phagocytic index in cases than in controls; it was (2.57 ± 1.34) and (3.55 ± 0.74) respectively (P < 0.01). Also it showed a statistically more significant decrease in NBT% in cases than in controls; it was (47.98 ± 16.38%) and (61.45 ± 13.17%) respectively (P < 0.01). We found negative correlation between resistin serum level with phagocytic index and NBT%, while we found positive correlation between resistin serum level and hemodialysis duration. Conclusion: High resistin serum level in children with ESRD decreases phagocyte function and oxidative burst of PMNLs, and this is enhanced by the longer duration of hemodialysis.