Modeling of the Hemodynamics of Vascular Prostheses "Kemangiprotez" in Silico

The paper describes aspects of the application of numerical simulation of fluid flows in clinical medicine with interventions on the human vascular system. The modeling method used in the study is verified using the data of the doppler sonography of the patient underwent vascular replacement. It was shown that the deviation between the numerical experiment and the clinical data - pressure curves at the inlet and outlet of the studied vessel, is 20%. The obtained quantitative characteristics of the flow: peak systolic velocity, final diastolic velocity, minimum diastolic velocity, resistivity index, pulsatility index, systole/diastole index are comparable between verification and experimental data. Thus, for the proximal site of the clinical vessel the corresponding indices were 96.5 cm/s; 4.5 cm/s; 36.2 cm/s; 1.05; 11.5; 21.3. For simulation, 107.9 cm/s; 4.44 cm/s; 43.9 cm/s; 1.05; 12.0; 24.3. In addition, the work describes the application of tested method in two clinical vascular prostheses "KemAngioprotez" for the assessment of zones of increased shear stress and, thus, the risk of thrombus formation. It is shown that the distribution of critical zones corresponds to zones of anastomosis between prosthesis segments, which may be a potential location for optimization of the device.

Bioengineered hemodialysis access grafts

There is a need for bioengineered therapies to improve the overall health of the growing and aging world population. Patients with renal failure have a life-long requirement for a durable form of hemodialysis vascular access. In this article, we review the history of tissue engineering as it pertains to bioengineered grafts and vessels for hemodialysis access. Over the years, various strategies have been utilized to develop ideal, humanized vessels for vascular replacement such as fixation of animal or human vessels, cell seeding of synthetic materials, and the synthesis of completely autologous or allogeneic bioengineered vessels. Tissue engineering technologies from two companies have progressed to reach phase 2 and phase 3 clinical trials, but the prospect of newer strategies on the horizon may offer improved manufacturing efficiency, a greater variety of conduit size and length, and reduce the cost to produce.

Mass spectrometric imaging of in vivo protein and lipid adsorption on biodegradable vascular replacement systems

Cardiovascular diseases present amongst the highest mortality risks in Western civilization and are frequently caused by arteriosclerotic vessel failure.

Collagen-Silk Fibroin Fibers: A Promising Scaffold for Vascular Tissue Engineering

Small caliber vascular replacement (<4 mm) still remains a challenge for medical and research teams, as no available vascular substitutes (VS) are suitable for small diameter bypass. Vascular engineering proposes new models of small diameter VS but rare are those that meet the biocompatibility and mechanical criteria. In this study, we developed a new scaffold made by the combination of two natural biomacromolecules: collagen and silk fibroin. The scaffold was further cellularised with porcine smooth muscle cells. First, the behavior of cells in the collagen-fibroin constructs was verified in order to evaluate the biocompatibility of the scaffold with the cells. Then, gel mass loss and cellular attachment, morphology, spreading and viability were analysed. The results showed an excellent interaction and biocompatibility between collagen, silk fibroin fibers and cells. Thus, the collagen-fibroin construct appears to be a very attractive material for vascular tissue engineering.

Experimental results and clinical impact of using autologous rectus fascia sheath for vascular replacement

Vascular complications are major causes of graft failure in liver transplantation. The use of different vascular grafts is common but the results are controversial. The aim of this study was to create an ‘ideal’ arterial interponate for vascular replacements in the clinical field. An autologous, tubular graft prepared from the posterior rectus fascia sheath was used for iliac artery replacement in dogs for 1, 3, 6 and 12 months. Forty-one grafts were implanted and immunosuppression was used in separate groups. The patency rate was followed by Doppler ultrasound. Thirty-seven grafts remained patent, 2 cases with thrombosis and 2 cases with stenosis occurred. There was no evidence of necrosis or aneurysmatic formation. The histological analysis included conventional light microscopic and immunohistochemical examinations for CD34 and factor VIII. The explanted grafts showed signs of arterialisation, appearance of elastin fibres, and smooth muscle cells after 6 months. Electron microscopy showed intact mitochondrial structures without signs of hypoxia. In conclusion, the autologous graft presents acceptable long-term patency rate. It is easy to handle and the concept of beneficial presence of the anti-clot mesothelium until endothelialisation seems to work. The first clinical use was already reported by our group with more than 2 years survival.