Tissue engineering combines the expertise of several scientific disciplines including biology, medicine and engineering, in order to develop structures outside the human body to replace or support the function of diseased or injured body parts. This process includes developing and manipulating cells, tissues or organs grown in a laboratory to obtain a close likeness of the original body part or even improve on it. The classic 'triad' of tissue engineering is based on the three basic biologic tissue components: a scaffold on which cells are incorporated and signals provided to build and differentiate the tissue - the focus being the prosthesis.