Bio artificial surfaces - Blood surface interaction

Contact between blood and an artificial surface is a well known problem in medicine.Endothelial cells cover the whole circulatory system in a single layer. They are, besides many other systemic hemodynamic functions, responsible for keeping the balance between blood coagulation and blood flow. In case of trauma, the deficit of endothelial cells and the loss of endothelial cell function, in combination with other factors, are responsible for the activation of the coagulation cascade. This also happens in disease of arteriosclerosis, when plugs cover the inner surface of blood vessels, disrupting the continuous layer of endothelial cells.So far, it was not possible to create an artificial surface covering all these functions. The requirements we have to artificial surfaces is that they should be as inert as possible, i.e. not activate the platelets and the coagulation cascade on the one hand and allow a turbulence free blood flow on the other hand.What are the problems resulting from the contact between artificial surface and human blood?The first problem is thrombosis. The activation of the platelets and the coagulation cascade result in small blood clots. Adhering to the surface, these clots will occlude artificial vessels. In case of embolism, the consequence is very often a cerebral insult.The second is infection: in the case of systemic infection, bacteria can be detected in blood culture. Some of them have a high affection to artificial surfaces. Attached to the surface, even systemic antibiotic therapy becomes inadequate. Thrombus and pannus formation are the consequences and the replacement of the vascular prostheses or the artificial heart valve is the only therapy possible.In modern medical practice, blood can be in contact with synthetic materials and metal for a short time, such as only some hours, or for some months or even permanently, i.e. for the rest of the patient's life.