Fibers with nanoscale diameters provide benefits due to high surface area for biomaterial scaffolds. In this study electrospun silk fibroin-based fibers with average diameter 700 +/- 50 nm were prepared from aqueous regenerated silkworm silk solutions. Adhesion, spreading and proliferation of human bone marrow stromal cells (BMSCs) on these silk matrices was studied. Scanning electron microscopy (SEM) and MTT analyses demonstrated that the electrospun silk matrices supported BMSC attachment and proliferation over 14 days in culture similar to native silk fibroin (similar to15 mum fiber diameter) matrices. The ability of electrospun silk matrices to support BMSC attachment, spreading and growth in vitro, combined with a biocompatibility and biodegradable properties of the silk protein matrix, suggest potential use of these biomaterial matrices as scaffolds for tissue engineering. (C) 2003 Elsevier Ltd. All rights reserved.