Senior Lecture University of Edinburgh Edinburgh, Scotland, United Kingdom
Introduction: There are currently a variety of vascular tissue engineering approaches used to treat arterial disease [1]. These range from scaffold materials that mimic the native extracellular matrix (ECM) to materials designed to promote angiogenesis [2,3]. However, native autologous vessels used as implants still outperform these novel materials [4]. Therefore, trying to find solutions that promote vascular regeneration leading to fully functional tissues is of crucial importance for the advancement of this field. Herein, we investigated the effects of fiber diameter and composition of electrospun polymer scaffolds and their effects on the performance of human umbilical vein endothelial cells (HUVECs) and human umbilical aorta smooth muscle cells (HUVSMCs).
Materials and
Methods: Scaffolds were electrospun using varying electrospinning parameters in order to achieve fibers of different diameters. Briefly, 8% and 12% w/v polycaprolactone (PCL) solutions in Hexafluoro-2-propanol (HFIP); and 14% and 19% w/v PCL solutions in 5:1 chloroform:methanol were electrospun at 250 RPM mandrel speed, resulting in four randomly aligned PCL scaffolds with different fiber diameters: small (S), medium (M), large (L) and extra-large (XL). Scaffold composition was further optimized through the addition of decellularized vascular ECMs at a concentration of 0.25% by weight. All scaffolds were mechanically characterised by tensile testing. Scaffolds were either seeded with HUVECs or HUVSMCs. Various quantification methods were performed at time points of 1 day, 6 days and 12 days, including cell viability, Real-time quantitative polymerase chain reaction (RT-qPCR).
Results, Conclusions, and Discussions: Fiber diameter and pore size analysis showed that four unique architectures were created, with incrementally increasing diameters/widths ranging from approximately 1μm to 5μm. We noted increased cellular infiltration in the largest fibre scaffold. Furthermore, interesting trends in gene expression were noted suggesting that altering the morphology of the scaffold had beneficial effects on the seeded cells. Decellularized ECM was successfully incorporated into the scaffold and confirmed using Fourier Transform Infrared analysis (Figure 1. A, B). This systematic study has shown that cellular performance and gene expression can be modulated through altering the fibre diameter and composition of the scaffold. We found increase infiltration with the largest fibre, which lead to positive changes in gene expression. These results highlight the potential of these approaches in vascular tissue engineering.
Acknowledgements (Optional): This work is funded by an Engineering & Physical Sciences Research Council [EPSRC] doctoral training partnership studentship ESPRC no. EP/N509644/1 and MRC grant MR/L012766/1 References:
References: [1]. Ravi S et al. Regen Med. 2010 5:1-21. [2]. Reid J et al. J Biomed Mater Res B. 2019:1-15. [3]. Reid J et al. J Appl Poly Sci. 2019 136:48181. [4]. Pashneh-Tala S et al. Tissue Eng Part B Rev. 2016 22(1):68-100.
