Syndecan-4 functionalization of tissue regeneration scaffolds improves interaction with endothelial progenitor cells

Abstract

Key to most implanted cell free scaffolds for tissue regeneration is the ability to sequester and retain undifferentiated mesenchymal stem cells at the repair site. In this report, syndecan-4, a heparan sulfate containing proteoglycan, was investigated as a unique molecule for use in scaffold functionalization. An electrospun hybrid scaffold comprised of poly (glycerol) sebacate (PGS), silk fibroin and type I collagen (PFC) was used as a model scaffold to develop a procedure and test the hypothesis that functionalization would result in increased scaffold binding of endothelial progenitor cells (EPCs). For these studies both Syndecan-4 and stromal derived factor-1α (SDF-1α) were used in functionalization PFC. Syndecan-4 functionalized PFC bound 4.8 fold more SDF-1α compared to nonfunctionalized PFC. Binding was specific as determined by heparin displacement studies. After culture for 7 days, significantly, more EPCs were detected on PFC scaffolds having both syndecan-4 and SDF-1α compared to scaffolds of PFC with only syndecan-4, or PFC adsorbed with SDF-1α, or PFC alone. Taken together, this study demonstrates that EPCs can be bound to and significantly expanded on PFC material through syndecan-4 mediated growth factor binding. Syndecan-4 with a multiplicity of binding sites has the potential to functionalize and expand stem cells on a variety of scaffold materials for use in tissue regeneration.

Syndecan‐4 and stromal cell‐derived factor‐1 alpha functionalized endovascular scaffold facilitates adhesion, spreading and differentiation of endothelial colony forming cells and functions under flow and shear stress conditions

“…22 We have also found in a previous study that syndecan-4 and SDF-1α functionalized PFC (fPFC) significantly facilitated the binding of ECFCs compared with syndecan-4 fPFC, SDF-1α fPFC or non-fPFC. 25 In the current study, we confirmed and extended these findings to demonstrate more extensive cell spreading and differentiation of ECFCs if PFC was functionalized with syndecan-4 and SDF-1α. While only SDF-1α was the exogenous growth factor used, the presence of syndecan-4 on PFC may facilitate growth, spreading, and differentiation of ECFCs in multiple and versatile ways (see Figure 1).…”

“…Previous studies have shown that PFC is compositionally and mechanically similar to native vascular tissue and supports endothelial cell growth in culture 22 . We have also found in a previous study that syndecan‐4 and SDF‐1α functionalized PFC (fPFC) significantly facilitated the binding of ECFCs compared with syndecan‐4 fPFC, SDF‐1α fPFC or non‐fPFC 25 . In the current study, we confirmed and extended these findings to demonstrate more extensive cell spreading and differentiation of ECFCs if PFC was functionalized with syndecan‐4 and SDF‐1α.…”

“…The ultrastructure of cell–material interaction was evaluated by SEM to evaluate ECFCs interaction and spreading on thick mats of materials. The mats had the same structural properties as PFC described in previous reports from our laboratory 22,25 . After ECFCs were cultured for 7 days on PFC and fPFC electrospun mats, ECFCs were tightly associated with the nanofibers and covered the surface of PFC as well as fPFC electrospun mats (Figure 6).…”

“…Then the material was treated with 1.5% glutaraldehyde vapor overnight to crosslink the proteins. PFC was then functionalized with syndecan‐4 and SDF‐1α and termed fPFC 25 . Briefly, PFC was saturated with 0.8 μg syndecan‐4/cm 2 PFC using the two‐step NHS/EDC method and rinsed with Na 2 HPO 4 and PBS 25 .…”

Stereo Coverage and Overall Stiffness of Biomaterial Arrays Underly Parts of Topography Effects on Cell Adhesion

“…The extracellular signals are transduced via the cytoskeleton to regulate transcription in nuclei, resulting in the change of cell behaviors such as adhesion, migration, differentiation, and so forth, which is known as mechanotransduction . Mechanotransduction is influenced by cell–material interactions and its insight is helpful for the design of biomedical materials. − …”