Autologous Endothelial Progenitor Cell-Seeding Technology and Biocompatibility Testing For Cardiovascular Devices in Large Animal Model

Implantable cardiovascular devices are manufactured from artificial materials (e.g. titanium (Ti), expanded polytetrafluoroethylene), which pose the risk of thromboemboli formation1,2,3. We have developed a method to line the inside surface of Ti tubes with autologous blood-derived human or porcine endothelial progenitor cells (EPCs)4. By implanting Ti tubes containing a confluent layer of porcine EPCs in the inferior vena cava (IVC) of pigs, we tested the improved biocompatibility of the cell-seeded surface in the prothrombotic environment of a large animal model and compared it to unmodified bare metal surfaces5,6,7 (Figure 1). This method can be used to endothelialize devices within minutes of implantation and test their antithrombotic function in vivo

Parallel-plate Flow Chamber and Continuous Flow Circuit to Evaluate Endothelial Progenitor Cells under Laminar Flow Shear Stress

The overall goal of this method is to describe a technique to subject adherent cells to laminar flow conditions and evaluate their response to well quantifiable fluid shear stresses1. Our flow chamber design and flow circuit (Fig. 1) contains a transparent viewing region that enables testing of cell adhesion and imaging of cell morphology immediately before flow (Fig. 11A, B), at various time points during flow (Fig. 11C), and after flow (Fig. 11D). These experiments are illustrated with human umbilical cord blood-derived endothelial progenitor cells (EPCs) and porcine EPCs2,3. This method is also applicable to other adherent cell types, e.g. smooth muscle cells (SMCs) or fibroblasts. The chamber and all parts of the circuit are easily sterilized with steam autoclaving In contrast to other chambers, e.g. microfluidic chambers, large numbers of cells (> 1 million depending on cell size) can be recovered after the flow experiment under sterile conditions for cell culture or other experiments, e.g. DNA or RNA extraction, or immunohistochemistry (Fig. 11E), or scanning electron microscopy5. The shear stress can be adjusted by varying the flow rate of the perfusate, the fluid viscosity, or the channel height and width. The latter can reduce fluid volume or cell needs while ensuring that one-dimensional flow is maintained. It is not necessary to measure chamber height between experiments, since the chamber height does not depend on the use of gaskets, which greatly increases the ease of multiple experiments. Furthermore, the circuit design easily enables the collection of perfusate samples for analysis and/or quantification of metabolites secreted by cells under fluid shear stress exposure, e.g. nitric oxide (Fig. 12)6

A Comparison Between the Teg 6s and Teg 5000 Analyzers to Assess Coagulation in Trauma Patients

BACKGROUND Trauma-induced coagulopathy is a major driver of mortality following severe injury. Viscoelastic goal-directed resuscitation can reduce mortality after injury. The TEG 5000 system is widely used for viscoelastic testing. However, the TEG 6s system incorporates newer technology, with encouraging results in cardiovascular interventions. The purpose of this study was to validate the TEG 6s system for use in trauma patients. METHODS Multicenter noninvasive observational study for method comparison conducted at 12 US Levels I and II trauma centers. Agreement between the TEG 6s and TEG 5000 systems was examined using citrated kaolin reaction time (CK.R), citrated functional fibrinogen maximum amplitude (CFF.MA), citrated kaolin percent clot lysis at 30 minutes (CK.LY30), citrated RapidTEG maximum amplitude (CRT.MA), and citrated kaolin maximum amplitude (CK.MA) parameters in adults meeting full or limited trauma team criteria. Blood was drawn ≤1 hour after admission. Assays were repeated in duplicate. Reliability (TEG 5000 vs. TEG 6s analyzers) and repeatability (interdevice comparison) was quantified. Linear regression was used to define the relationship between TEG 6s and TEG 5000 devices. RESULTS A total of 475 patients were enrolled. The cohort was predominantly male (68.6%) with a median age of 49 years. Regression line slope estimates (ß) and linear correlation estimates (p) were as follows: CK.R (ß = 1.05, ρ = 0.9), CFF.MA (ß = 0.99, ρ = 0.95), CK.LY30 (ß = 1.01, ρ = 0.91), CRT.MA (TEG 6s) versus CK.MA (TEG 5000) (ß = 1.06, ρ = 0.86) as well as versus CRT.MA (TEG 5000) (ß = 0.93, ρ = 0.93), indicating strong reliability between the devices. Overall, within-device repeatability was better for TEG 6s versus TEG 5000, particularly for CFF.MA and CK.LY30. CONCLUSION The TEG 6s device appears to be highly reliable for use in trauma patients, with close correlation to the TEG 5000 device and equivalent/improved within-device reliability. Given the potential advantages of using the TEG 6s device at the site of care, confirmation of agreement between the devices represents an important advance in diagnostic testing. LEVEL OF EVIDENCE Diagnostic test, level II

Topical haemostatic agents for skin wounds: a systematic review

Background: Various agents and techniques have been introduced to limit intra-operative blood loss from skin lesions. No uniformity regarding the type of haemostasis exists and this is generally based on the surgeon's preference. To study the effectiveness of haemostatic agents, standardized wounds like donor site wounds after split skin grafting (SSG) appear particularly suitable. Thus, we performed a systematic review to assess the effectiveness of haemostatic agents in donor site wounds. Methods. We searched all randomized clinical trials (RCTs) on haemostasis after SSG in Medline, Embase and the Cochrane Library until January 2011. Two reviewers independently assessed trial relevance and quality and performed data analysis. Primary endpoint was effectiveness regarding haemostasis. Secondary endpoints were wound healing, adverse effects, and costs. Results: Nine relevant RCTs with a fair methodological quality were found, comparing epinephrine, thrombin, fibrin sealant, alginate dressings, saline, and mineral oil. Epinephrine achieved haemostasis significantly faster than thrombin (difference up to 2.5 minutes), saline or mineral oil (up to 6.5 minutes). Fibrin sealant also resulted in an up to 1 minute quicker haemostasis than thrombin and up to 3 minutes quicker than placebo, but was not directly challenged against epinephrine. Adverse effects appeared negligible. Due to lack of clinical homogeneity, meta-analysis was impossible. Conclusion: According to best available evidence, epinephrine and fibrin sealant appear superior to achieve haemostasis when substantial topical blood loss is anticipated, particularly in case of (larger) SSGs and burn debridement

A Novel Microwave Sensor to Detect Specific Biomarkers in Human Cerebrospinal Fluid and Their Relationship to Cellular Ischemia During Thoracoabdominal Aortic Aneurysm Repair

Thoraco-abdominal aneurysms (TAAA) represents a particularly lethal vascular disease that without surgical repair carries a dismal prognosis. However, there is an inherent risk from surgical repair of spinal cord ischaemia that can result in paraplegia. One method of reducing this risk is cerebrospinal fluid (CSF) drainage. We believe that the CSF contains clinically significant biomarkers that can indicate impending spinal cord ischaemia. This work therefore presents a novel measurement method for proteins, namely albumin, as a precursor to further work in this area. The work uses an interdigitated electrode (IDE) sensor and shows that it is capable of detecting various concentrations of albumin (from 0 to 100 g/L) with a high degree of repeatability at 200 MHz (R2 = 0.991) and 4 GHz (R2 = 0.975)