A Study of Unidirectionally Aligned Collagen-silk Composite E-spun Fibers and the Application In Stem Cell Differentiation

Abstract: Tissue engineering that involves matrix-specified differentiation of stem cells provides new approaches for tissue regeneration. In our preliminary study, collagen type I, as an important extracellular matrix (ECM) component, was found able to support cell proliferation and promote neuroectodermal commitment in stem cell differentiation. Other studies also showed aligned matrices can provide guidance for neural cell migration and directional axonal regeneration across the glial scar and lesion site, which is a promising tissue engineering strategy for neural repair. In order to make more suitable biological scaffolds, we used electrospinning technique to fabricate well-aligned collagen fibers mimicking the native ECM, and incorporated synthetic spider silk proteins into collagen to enhance mechanical properties of e-spun fibers. In this study, we examined physical properties of collagen-silk composite e-spun matrices, as well as their biological performance on facilitating neural differentiation of human decidua parietalis placental stem cells (hdpPSCs).

Results from Instron tests and AFM elasticity measurements showed that as silk protein content increased, both mechanical strength and matrix stability of e-spun fibers increased significantly. On the other hand, hdpPSCs had higher expression levels of neural markers when cultured on collagen dominant composite e-spun fibers. The accelerated neural development on collagen dominant metrices may arise from higher integrin binding that causes cell polarization along the fiber direction. To further investigate the collagen-integrin interaction, we will apply an AFM affinity measurement to quantify cell adhesion forces and to explore the distribution and potential structural changes of collagen within composite fibers. Taken together, collagen dominant composite fibers are mechanically strong, stable and provide excellent cell adhesion to promote stem cell differentiation. The aligned fibers can accelerate neural differentiation of stem cells, and promote 1D development of neural filaments which can be potentially utilized in future nano-bio-devices.