We have recently reported on a bench-top approach for isolating extracellular matrix (ECM) from pure populations of cells grown in culture using sacrificial, open-celled foams to concentrate and capture the ECM. To increase both the accumulation and the strength of the ECM harvested, cell-seeded polyurethane (PU) foams were cultured in media supplemented with either transforming growth factor beta-1 (TGF beta 1) or hepatocyte growth factor (HGF). At the end of a 3-week culture period, ECM yield was significantly increased for samples conditioned in supplemented media. Control foams yielded 48 +/- 12 mg of material for every gram of PU foam seeded. Yield values increased to 102 +/- 21 and 243 +/- 25 mg for HGF and TGF beta 1-treated samples, respectively. HGF supplementation increased the modulus by 59%, while TGF beta 1 treatment increased the elastic modulus by 204%. TGF beta 1-stimulated material was organized into a network that was markedly denser than control material, with HGF-stimulated network density intermediate to TGF beta 1 and controls. Our study showed that TGF beta 1-treated samples were collagen enriched while HGF samples had an increased gylcosaminoglycan concentration. The results demonstrate that growth factor supplementation, particularly with TGF beta 1, can significantly alter the biomechanical properties of cell-derived ECM that may be used for therapeutic applications. (C) 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012