A method of forming a matrix of aligned nanofibres of elevated pore size and porosity comprises spraying a polymer solution towards a rotating drum so as to form nanofibres which are collected on the drum. The matrix can be used to form artificial tissue by removing the matrix from the drum, depositing cells onto the matrix and allowing the cells to form artificial tissue. Such artificial tissue finds use in the treatment of disease or damaged tissue, and in particular in the treatment of cardiovascular disease.