A modified reconstituted extracellular matrix composition is provided herein. The composition includes an extracellular matrix and at least one exogenous component selected from heparin, fibronectin and laminin. The composition may have a basic pH. Additionally, provided herein is a cell culturing system including a substrate and a coating thereon of the composition to assess potential stimulators and/or inhibitors for their effects on various cell cultures while increasing the signal dynamic range.