A family of cell-adhesive peptides homologous to sequences on different chains of fibrinogen was investigated. These homologous peptides, termed Haptides, include the peptides c beta, preC gamma, and C alpha E, corresponding to sequences on the C-termini of fibrinogen chains beta, gamma, and alpha E, respectively. Haptides do not affect cell survival and rate of proliferation of the normal cell types tested. The use of new sensitive assays of cell adhesion clearly demonstrated the ability of Haptides, bound to inert matrices, to mediate attachment of different matrix-dependent cell types including normal fibroblasts, endothelial, and smooth muscle cells. Here we present new active Haptides bearing homologous sequences derived from the C-termini of other proteins, such as angiopoietin 1&2, tenascins C&X, and microfibril-associated glycoprotein-4. The cell adhesion properties of all the Haptides were found to be associated mainly with their 11 N-terminal residues. Mutated preC gamma peptides revealed that positively charged residues account for their attachment effect. These results suggest a mechanism of direct electrostatic interaction of Haptides with the cell membrane. The extended Haptides family may be applied in modulating adhesion of cells to scaffolds for tissue regeneration and for enhancement of nanoparticulate transfection into cells. (C) 2010 Elsevier Inc. All rights reserved.