Patent GB-1052589-A (GB)
IPC: A61L27/36
Abstract: 1,052,589. Artificial veins, arteries &c. H. THIELE. July 26, 1965 [July 25, 1964], No. 31863/65. Heading A5R. The invention relates to a process in which a natural vein or like vessel is dissolved and an artificial vein or like vessel is subsequently reconstituted from solution. The term "like vessel" is defined to include arteries, for example aortas, and other blood vessels, tracheae and like tubular body parts. The invention comprises, in one aspect, producing a series of solutions, in each of which is dissolved a histologically defined layer of a natural body vessel and from which may be prepared artificial body vessels, by the steps of causing a natural vessel to swell, mechanically separating the swollen vessel into layers according to the histological structure of the vessel, and separately dissolving each layer in a solvent without affecting the protein components of the layer. Advantageously, the vessel is separted into extema, media and intima layers from which layers three solutions may be obtained. The solvent for the layers may be a weak organic acid, for example pyruvic, lactic, tartaric or citric acid, or an alkaline solution, for example a solution of an alkali metal hydroxide such as sodium hydroxide, or of urea or a derivative of urea, or a solution of an alkali metal thiocyanate, for example lithium thiocyanate. The layers preferably are dissolved at a temperature not greater than 27‹C. to minimise physiological damage. Prior to being caused to swell, the natural vessel may be treated with a defattening agent, for example methanol, ethanol or acetone, either alone or mixed with dimethoxy methane; a suitable agent comprises a mixture of 4 volumes methanol and 1 volume dimethoxy methane. After being defatted, the natural vessel may be treated with an agent to dissolve out the mucopolysaccharides and uronic acids that are present; this agent, which may be an aqueous acid or alkaline solution, for example aqueous sodium hydroxide, may also be capable of swelling the natural vessel so that such dissolution and swelling occur simultaneously. By successively causing a series of solutions, prepared as above, to gel and precipitate around a mould of the desired shape, there may be obtained an artificial body vessel constituted by superposed layers of the gel's formed from each solution and having a histological structure corresponding to that of the original natural vessel. If mucopolysaccharides and uronic acids were removed from the natural vessel after defattening, these substances are added to the series of solutions prior to the gelling and precipitation stress. The superposed layers of the gel may subsequently be immersed in blood serum to absorb serum components. The solutions may be caused to gel and precipitate by allowing gel-forming ions, for example hydrogen ions or multivalent metal cations (calcium, copper, cadmium, aluminium and lantharum cations are specified), to diffuse into the solutions, or by suitably adjusting the pH of the solutions, or by electrophoresis using the mould as a membrane in an electrodialyzer. After gelling and precipitation have been effected the metal cations may be exchanged with hydrogen ions by treatment with, for example, dilute acetic acid; excess hydrogen ions may be removed by dialysis.