Fabrication of an electrospun biomaterial with potential use in cardiac heart valve leaflet replacements: a proof of concept study
Valvular heart disease (VHD) is a serious health burden affecting morbidity and mortality worldwide. The prevalence of VHD is expected to grow along with the global rise in population. VHD is characterized by the stiffening of the valve leaflets, resulting in stenosis (incomplete opening), or regurgitation (incomplete closing) of valve leaflets. Sustained VHD can lead to hypertrophy of the heart and heart failure. Despite advances in treatments for VHD, current treatments are limited by the lack of durability and growth capability of prosthetic valves. Therefore, an alternative approach to addressing these issues is required. Tissue engineering is gaining momentum due to its ability to design and fabricate tissue substitutes in vitro suitable for replacement in the human body. For heart valve leaflet tissue engineering, either natural polymeric or/and synthetic polymeric biomaterials can be processed via various fabrication techniques such as electrospinning. The primary aim of the current study was to investigate the ability to use biomaterials PCL, SF, and PVA for bioscaffold that could potentially be used for heart tissue such as heart valve. To fulfill the aim of the current study, nanofibrous scaffolds were fabricated using 10 % (w/v) Polycaprolactone (PCL), 30 % (w/v) silk fibroin (SF) and 10 % (w/v) poly vinyl alcohol (PVA) via dual syringe electrospinning in different ratios of PCL/SF/PVA, 100:20:80, 100:30:70, 100:40:60, 100:50:50. The generated scaffolds were characterized chemically through Fourier-transform infrared spectroscopy (FTIR), morphologically through Scanning Electron Microscopy (SEM) and physically through the hydrolytic biodegradation test, to ensure their suitability for heart valve leaflet engineering applications. Then, cardiac stem cells (CSCs) were cultured and seeded onto the nanofibrous scaffolds, in order to test their biocompatibility. For biological assessment of the scaffolds, 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay and immunofluorescence (IF) were performed. The PCL/SF/PVA nanofibrous bioscaffold was electrospun successfully and the presence of all functional groups of PCL, SF and PVA were identified by FTIR. Analysis of the SEM images demonstrated an increasing porosity and pore sizes with a higher ratio of SF, while a decreasing fiber size correlated with a higher ratio of SF in the nanofibrous scaffolds. The hydrolytic degradation test demonstrated a significant increase in mass loss only on day 1 but no significant loss was demonstrated over a further period of 7 days. The MTT assay showed that CSCs seeded on the bioscaffold with the 100:50:50 ratios showed significantly increased cell viability compared to the control and the other groups. The IF showed positive staining of alpha smooth muscle actin (α-SMA) in all bioscaffold groups with the 100:50:50 group showing more expression compared to the other groups, which was consistent with the results from the MTT assay. This current study demonstrates that the electrospun PCL/SF/PVA nanofibrous bioscaffold is biocompatible. Furthermore, the ratio of PCL/SF/PVA;100:50:50 may have the most superior biocompatibility compared to the other four groups (100:20:80, 100:30:70, 100:40:60, 100:50:50). Therefore, this compound has the potential to be applied as a heart tissue such as heart valves.
Advisor: Ali, Azam; Milburn, Krys; Katare, Rajesh
Degree Name: Master of Science
Degree Discipline: Food Science
Publisher: University of Otago
Keywords: Valvular heart disease; Heart valve tissue engineering; Electrospinning, Polycaprolactone; Silk fibroin; Poly vinyl alcohol; Cardiac stem cells.
Research Type: Thesis