Speaker
Description
"Introduction
As one of the most outstanding technology, cardiac patches hold the potential to restore cardiac function clinically. Many biomaterials used to fabricate cardiac patches have emerged during the last decade. Synthetic polymers can be tailored on a molecular level to fit any requirement that should be met to function as an integral part of a beating heart.
A facile method was found to incorporate a mussel inspired adhesive moiety into polyurethanes to develop a tissue engineered electrospun cardiac patch.
Methodology
The polyurethanes were synthetized through a step growth polymerization based on 1,4-butanediol (BDI) as hard segment, triblock copolymers PCL-PEG-PCL as soft segments, and lysine-dopamine as chain extender.
The triblock copolymers PCL-PEG-PCL were synthetized by Ring Opening Polymerization, setting two molar ratios between ε-caprolactone and Polyethylenglicole equal to 30 and 50 respectively.
Lysine-dopamine LDA was synthetized from L-Lysine and dopamine-HCl as reported in literature.
Products were characterized by FTIR, 1HNMR, SEC, DSC and UV-Vis confirming the success of the synthesis reactions.
To characterize intrinsic properties of the polymer like cytocompatibility, adhesiveness after melting and degradation rate, the polyurethanes were processed by film casting. The synthetized polyurethanes were then dispersed in HFIP and processed through electrospinning to obtain a three-dimensional scaffold that mimic as closely as possible the structure of healthy native myocardium. SEM was adopted as investigation method to study the morphology of the fibers.
Results
Two triblock copolymers were synthetized and used to obtain different polyurethanes composition and properties. Lysine was used as chain extender alone or linked with dopamine to create a new type of mussel mimetic polyurethanes. The successful combination of the unique mussel-inspired adhesive moiety with a tunable polyurethane structure can increase cells adhesion and proliferation and tissue adhesion.
The DSC analysis showed two different melting temperature inside the polyurethane. The first one at 38°C is correlated to the PEG block ed the other at 56°C is due to the PCL. This result, combined with the observed adhesiveness after melting, could allow the safely attachment of the scaffold to the heart’s wall when the temperature is increased locally.
The degradation test underlines the remarkable hydrolytic resistance of the synthetized PU which is a fundamental design requirement for cardiac patches to maintain structure and function over time. Its properties and degradation profile could be controlled during the manufacturing process to provide the best outcomes for ECM synthesis and tissue regeneration.
Fiber deposition was macroscopically smooth and homogeneous along the metal rod, without any spikes. An almost linear relation between the thickness of the electrospun layer and the deposition time was observed.
Conclusions
The aim of this work is to develop a fully integrated cardiac patch begins with materials that support biological activity while minimizing the risk of additional injury for the patient, caused by the conventional stitching methods, and withstand the dynamic forces of the heart.
Conductive polymers may integrate more successfully since they are able to participate in the pumping of the heart. Indeed, we are currently working on electroactive components integration inside the fibrous scaffold."
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