Polycaprolactone-Chitosan Nanofibers Electrospun on Decellularized Bovine Pericardium as a Regenerative Biomaterial for Heart Valve Tissue Replacement
Jahnavi Mudigonda, Muralidhar Padala.
Emory University, Atlanta, GA, USA.
Objective: Glutaraldehyde (GA) fixation is a crucial step in preparing decellularized bovine pericardium (BP) for use in bioprosthetic heart valves (HVs). GA crosslinks collagen and imparts substantial mechanical strength to the tissue, that is lost during decellularization. However, GA is cytotoxic, pro-calcific and often leads to accelerated degeneration and failure of bioprosthetic HVs. In this study, we sought to develop a new strategy by electrospinning polycaprolactone-chitosan nanofibers (PCL-CH-NF) onto the decellularized BP to obtain the same mechanical strength as GA treated tissue, but without the use of cytotoxic agents. We demonstrate that this strategy results in a material that has equivalent mechanical strength to fresh BP, and could potentially enable cellular infiltration and material regeneration.
Methods: Fresh BP was decellularized with 1% sodium deoxycholate, and analyzed for acellularity (DNA estimation and presence of nuclei on H&E stain) and extracellular matrix (ECM) damage (histology and scanning electron microscopy-SEM). PCL-CH-NF were electrospun onto the decellularized BP, along the native collagen fibers in the BP. Nanofiber attachment to the decellularized tissue was analyzed with SEM, and tensile testing was performed to compare the stiffness and yield strength of fresh BP, decellularized BP and PCL-CH-NF electrospun decellularized BP.
Results: En face SEM images of fresh BP, decellularized BP and PCL-CH-NF covered decellularized BP are shown in (Figure A1-A3). The nanofiber layer thickness was 70±10 nm, with good attachment of the nanofibers to the underlying matrix and without delamination. H&E, DAPI and trichrome staining demonstrated acellularity in the decellularized BP and PCL-CH-NF covered decellularized BP, with preserved ECM architecture (Figure B1-B3). The yield stress was 31.25 + 8.53 MPa for fresh BP, 20.75 + 2.98 MPa for decellularized BP and 48.75 + 14.36 MPa for PCL-CH-NF covered decellularized BP, indicating that the electrospun nanofibers restored the mechanical strength after decellularization (Figure C1-C3).
Conclusion: Electrospinning polymeric nanofibers onto decellularized BP can reliably increase the mechanical strength of the tissue, without the cytotoxic effects of GA and thus lower risk of degradation.
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