Transarterial embolization of the external carotid artery in the treatment of life-threatening haemorrhage following blunt maxillofacial trauma.

Background Severe bleeding after blunt maxillofacial trauma is a rare but life-threatening event. Non-responders to conventional treatment options with surgically inaccessible bleeding points can be treated by transarterial embolization (TAE) of the external carotid artery (ECA) or its branches. Case series on such embolizations are small; considering the relatively high incidence of maxillofacial trauma, the ECA TAE procedure has been hypothesized either underused or underreported. In addition, the literature on the ECA TAE using novel non-adhesive liquid embolization agents is remarkably scarce. Patients and methods PubMed review was performed to identify the ECA TAE literature in the context of blunt maxillofacial trauma. If available, the location of the ECA injury, the location of embolization, the chosen embolization agent, and efficacy and safety of the TAE were noted for each case. Survival prognostic factors were also reviewed. Additionally, we present an illustrative TAE case using a precipitating hydrophobic injectable liquid (PHIL) to safely and effectively control a massive bleeding originating bilaterally in the ECA territories. Results and conclusions Based on a review of 205 cases, the efficacy of TAE was 79.4-100%, while the rate of major complications was about 2-4%. Successful TAE haemostasis, Glasgow Coma Scale score ≥ 8 at presentation, injury severity score ≤ 32, shock index ≤ 1.1 before TAE and ≤ 0.8 after TAE were significantly correlated with higher survival rate. PHIL allowed for fast yet punctilious application, thus saving invaluable time in life-threatening situations while simultaneously diminishing the possibility of inadvertent injection into the ECA-internal carotid artery (ICA) anastomoses.

Effect of shear stress in the flow through the sampling needle on concentration of nanovesicles isolated from blood.

During harvesting of nanovesicles (NVs) from blood, blood cells and other particles in blood are exposed to mechanical forces which may cause activation of platelets, changes of membrane properties, cell deformation and shedding of membrane fragments. We report on the effect of shear forces imposed upon blood samples during the harvesting process, on the concentration of membrane nanovesicles in isolates from blood. Mathematical models of blood flow through the needle during sampling with vacuumtubes and with free flow were constructed, starting from the Navier-Stokes formalism. Blood was modeled as a Newtonian fluid. Work of the shear stress was calculated. In experiments, nanovesicles were isolated by repeated centrifugation (up to 17,570×g) and washing, and counted by flow cytometry. It was found that the concentration of nanovesicles in the isolates positively corresponded with the work by the shear forces in the flow of the sample through the needle. We have enhanced the effect of the shear forces by shaking the samples prior to isolation with glass beads. Imaging of isolates by scanning electron microscopy revealed closed globular structures of a similar size and shape as those obtained from unshaken plasma by repetitive centrifugation and washing. Furthermore, the sizes and shapes of NVs obtained by shaking erythrocytes corresponded to those isolated from shaken platelet-rich plasma and from unshaken platelet rich plasma, and not to those induced in erythrocytes by exogenously added amphiphiles. These results are in favor of the hypothesis that a significant pool of nanovesicles in blood isolates is created during their harvesting. The identity, shape, size and composition of NVs in isolates strongly depend on the technology of their harvesting.

Suppression of membrane vesiculation as anticoagulant and anti-metastatic mechanism. Role of stability of narrow necks.

Nanovesicles that are pinched off from biological membranes in the final stage of budding constitute a cell-cell communication system. Recent studies indicate that in vivo they are involved in blood clot formation and in cancer progression. The bud is connected to the mother membrane by a thin neck so it dwells close to the mother membrane. Using the electron microscopy we have observed in blood cells that adhesion between the membrane of the bud and of the mother cell in the vicinity of the neck took place and prevented the bud to pinch off from the mother vesicle. The same effect was observed in giant phospholipid vesicles (GPVs) due to attractive interaction between the bud and the mother vesicle mediated by the plasma protein beta-2-glycoprotein I. The stability of the neck is important for this process. By using Fourier method we analyzed thermal fluctuations of a GPV while a protrusion composed of beads connected by thin necks was spontaneously integrated into the mother GPV. Stepwise change of Fourier coefficients indicates an increased stability of necks which contributes to the retention of buds by the mother membrane and promotes anticoagulant and anti-metastatic mechanism by suppression of nanovesiculation.

Isolated microvesicles from peripheral blood and body fluids as observed by scanning electron microscope.

Microvesicles are sub-micron structures shed from the cell membrane in a final step of the budding process. After being released into the microenvironment they are free to move and carry signaling molecules to distant cells, thereby they represent a communication system within the body. Since all cells shed microvesicles, it can be expected that they will be found in different body fluids. The potential diagnostic value of microvesicles has been suggested, however, a standardized protocol for isolation has not yet been agreed upon. It is unclear what is the content of the isolates and whether the isolated microvesicles were present in vivo or-have they been created within the isolation procedure. To present evidence in this direction, in this work we focus on the visualization of the material obtained by the microvesicle isolation procedure. We present scanning electronic microscope images of microvesicles isolated from blood, ascites, pleural fluid, cerebrospinal fluid, postoperative drainage fluid and chyloid fluid acquired from human and animal patients. Vesicular structures sized from 1microm downto 50nm are present in isolates of all considered body fluids, however, the populations differ in size and shape reflecting also the composition of the corresponding sediments. Isolates of microvesicles contain numerous cells which indicates that methods of isolation and determination of the number of microvesicles in the peripheral blood are to be elaborated and improved.