The present work together with our previous

The present work, together with our previous study, offers a means of conferring collagen-binding integrin-, VWF- and DDR-reactivity upon an inert substrate. GPRGQOGVNleGFO is known to bind not only VWF and DDR2, but also DDR1 and SPARC (Secreted Protein Acidic and Rich in Cysteine) [20,52]. We therefore expect this ion channels peptide to be able to promote DDR1 and SPARC recruitment to crosslinked films, increasing the restoration of physiological function to cross-linked collagens in tissue engineering. The scope of the method developed here can also be extended to include three-dimensional matrices [10] and to other inert substrates, not necessarily collagen-based [53], due to the broad reactivity of the diazirine group. Other collagen motifs for other receptors, for example for GPVI or OSCAR, are currently being studied in order to broaden the methodology further to allow enhancement of reactivity beyond that of native collagen. A wider range of THP ligands will allow us to adjust cell activity for different cell types to particular applications in tissue engineering.
Conclusion Our objective is to promote cell activity on biomaterials, especially for use in regenerative medicine, by grafting THPs containing collagen-binding sites onto inert substrates. We have previously reported a methodology to derivatize EDC/NHS crosslinked films with photoreactive THPs. This resulted in increased cell reactivity towards the collagen substrate, illustrated by cell binding and spreading, after attaching a GFOGER-containing THP that supports the attachment of collagen-binding integrins. Here, we diversified our range of photoreactive ligands to address different collagen-binding receptors for a wider range of applications. Of particular interest is Diaz-ES-VWFIIINle, containing the GPRGQOGVNleGFO active sequence, which targets both DDR1 and DDR2, and VWF. DDRs have been implicated in wound healing and cell migration, and DDR2 has been reported in epicardium-derived cardiac fibroblasts [29] and cardiac mesenchymal stem cells [28]. The proper regulation of these receptors is likely to be important to direct cell behavior and regeneration in several tissue engineering settings. VWF can equally present multiple interests in vascular repair, as it is a key factor in platelet thrombus formation in flowing blood. We have demonstrated that Diaz-ES-VWFIIINle-derivatised films had an increased affinity for recombinant DDR2 and VWF A3. Beyond simple binding activity, we have shown that receptors could be activated by our THPs covalently bound to collagen films, which was highlighted by tyrosine phosphorylation of DDR2 in transfected cells, and platelet deposition in human blood. Finally, we have demonstrated that derivatised collagen films could support HUVECs activity, a key step towards the production of collagen-based structures promoting angiogenesis. In this way, we have overcome the loss of reactivity that occurs when collagen is crosslinked to enhance its mechanical properties, paving the way for the construction of collagen scaffolds and other biomaterials for diverse applications.