A simplified fabrication technique for cellularized high-collagen dermal equivalents

Human autologous bioengineered skin has been successfully developed and used to treat skin injuries in a growing number of cases. In current clinical studies, the biomaterial used is fabricated via plastic compression of collagen hydrogel to increase the density and stability of the tissue. To further facilitate clinical adoption of bioengineered skin, the fabrication technique needs to be improved in terms of standardization and automation. Here, we present a one-step mixing technique using highly concentrated collagen and human fibroblasts to simplify fabrication of stable dermal equivalents. As controls, we prepared cellularized dermal equivalents with three varying collagen compositions. We found that the dermal equivalents produced using the simplified mixing technique were stable and pliable, showed viable fibroblast distribution throughout the tissue, and were comparable to highly concentrated manually produced collagen gels. Because no subsequent plastic compression of collagen is required in the simplified mixing technique, the fabrication steps and production time for dermal equivalents are consistently reduced. The present study provides a basis for further investigations to optimize the technique, which has significant promise in enabling efficient clinical production of bioengineered skin in the future

Designing a Power Tool to Show the Potentials of Additive Manufacturing - Effects of Additive Manufacturing on the Product Development Process

Today Additive Manufacturing (AM) is mainly used for rapid prototyping and specialized parts for industrial and end-user applications. To communicate the design potentials of AM to a general audience it is useful to demonstrate it with a visionary product, similar to the concept cars of the automotive industry. We have redesigned a power tool to show the benefits of AM on an end-user product. This paper describes the Concept Tool, its different sub-systems and highlights the range of AM’s applications. Furthermore we present our observations and findings during the product development process. Based on these findings a design supporting system is suggested to improve the development process for additive manufactured products.Mechanical Engineerin

Evaluation of a novel flow-controlled syringe infusion pump for precise and continuous drug delivery at low flow rates: a laboratory study

Syringe infusion pumps are used for the administration of short-acting drugs in anaesthesia and critical care medicine, but are prone to flow irregularities at low flow rates. A flow-controlled syringe infusion pump using an integrated flow sensor for feedback control represents a new approach to overcoming these limitations. This study compares the performance of a prototype flow-controlled syringe pump both at start-up, and during vertical displacement manoeuvres, with that of a standard infusion syringe pump. The novel pump almost completely eliminated delays at start-up and flow irregularities during hydrostatic pressure changes. Related fluctuations in plasma drug concentration were minimised and the known disadvantages of standard syringe infusion pumps currently used in clinical practice were reduced. Besides providing fast start-up to steady-state flow and precise continuous drug delivery at low flow rates during hydrostatic pressure changes, the new pump offers the potential for the development of target-controlled infusion algorithms for short-acting cardiovascular and other drugs

Transcatheter Mitral Valve Repair Simulator Equipped with Eye Tracking Based Performance Assessment Capabilities: A Pilot Study

Background The increase in cardiovascular disease cases that require minimally invasive treatment is inducing a new need to train physicians to perform them safely and effectively. Nevertheless, adaptation to simulation-based training has been slow, especially for complex procedures. Objectives We describe a newly developed mitral valve repair (MVR) simulator, equipped with new objective performance assessment methods, with an emphasis on its use for training the MitraClip™ procedure. Methods The MVR contains phantoms of all anatomical structures encountered during mitral valve repair with a transvenous, transseptal approach. In addition, several cameras, line lasers, and ultraviolet lights are used to mimic echocardiographic and fluoroscopic imaging and with a remote eye tracker the cognitive behaviour of the operator is recorded. A pilot study with a total of 9 interventional cardiologists, cardiac surgeons and technical experts was conducted. All participants performed the MitraClip procedure on the MVR simulator using standard interventional tools. Subsequently, each participant completed a structured questionnaire to assess the simulator. Results The simulator functioned well, and the implemented objective performance assessment methods worked reliably. Key performance metrics such as x-ray usage were comparable with results from studies assessing these metrics in real interventions. Fluoroscopy imaging is realistic for the transseptal puncture but reaches its limits during the final steps of the procedure. Conclusion The functionality and objective performance assessment of the MVR simulator were demonstrated. Especially for complex procedures such as the MitraClip procedure, this simulator offers a suitable platform for risk-free training and education.ISSN:1869-408XISSN:1869-409

Evaluation of a novel flow‐controlled syringe infusion pump for precise and continuous drug delivery at low flow rates: a laboratory study

Syringe infusion pumps are used for the administration of short-acting drugs in anaesthesia and critical care medicine, but are prone to flow irregularities at low flow rates. A flow-controlled syringe infusion pump using an integrated flow sensor for feedback control represents a new approach to overcoming these limitations. This study compares the performance of a prototype flow-controlled syringe pump both at start-up, and during vertical displacement manoeuvres, with that of a standard infusion syringe pump. The novel pump almost completely eliminated delays at start-up and flow irregularities during hydrostatic pressure changes. Related fluctuations in plasma drug concentration were minimised and the known disadvantages of standard syringe infusion pumps currently used in clinical practice were reduced. Besides providing fast start-up to steady-state flow and precise continuous drug delivery at low flow rates during hydrostatic pressure changes, the new pump offers the potential for the development of target-controlled infusion algorithms for short-acting cardiovascular and other drugs

Blood Pump Design Variations and Their Influence on Hydraulic Performance and Indicators of Hemocompatibility

Patients with ventricular assist devices still suffer from high rates of adverse events. Since many of these complications are linked to the flow field within the pump, optimization of the device geometry is essential. To investigate design aspects that influence the flow field, we developed a centrifugal blood pump using industrial guidelines. We then systematically varied selected design parameters and investigated their effects on hemodynamics and hydraulic performance using computational fluid dynamics. We analysed the flow fields based on Eulerian and Lagrangian features, shear stress histograms and six indicators of hemocompatibility. Within the investigated range of clearance gaps (50-500 µm), number of impeller blades (4-7), and semi-open versus closed shroud design, we found association of potentially damaging shear stress conditions with larger gap size and more blades. The extent of stagnation and recirculation zones was reduced with lower numbers of blades and a semi-open impeller, but it was increased with smaller clearance. The Lagrangian hemolysis index, a metric commonly applied to estimate blood damage, showed a negative correlation with hydraulic efficiency and no correlation with the Eulerian threshold-based metric