ABSTRACT
In virtually all tissue engineering approaches, an exogenous three-dimensional polymer matrix is critical to the success of the approach. The material should perform as a vehicle to transport the cells and bioactive molecules to the desired sites in the body, a synthetic extracellular matrix (ECM) to regulate the function of cells, and a template to
guide the growth of new tissues. For this purpose, a variety of biodegradable synthetic or naturally derived polymers have been employed to date [22]. For example, synthetic polyesters [e.g., poly(glycolic acid)] have found utility due to their FDA approval in a number of medical applications [23]. The materials utilized in tissue engineering can be processed into various physical forms, including a nonwoven mesh or fibrils, porous scaffolds, and hydrogels. Cells are seeded onto the nonwoven or porous scaffold followed by implantation (Fig. 2). Alternatively, if a hydrogel is the desired form, the cells are often mixed with polymer solutions prior to gelling, followed by injection into the body.
