Biodegradable electrospun cardiovascular prosthesis: accelerated degradation and mechanical characterization in vitro

Background

The approach of in situ tissue engineering is built on the notion that the natural inflammatory response can be harnessed to induce endogenous tissue regeneration. It is hypothesized that, upon implantation, the scaffold provides support for mature tissue formation and adequate mechanical properties to withstand the hemodynamic loads. Over time, the scaffold should slowly degrade, ultimately resulting in a purely biological structure which has the ability to repair, remodel, and grow. The mechanical investigation of electrospun scaffolds as well as the scaffold degradation over time are instructive tests for the design and manufacturing of replacements for load-bearing cardiovascular tissues.

Objective

This project intends to characterize PCL-based materials for cardiovascular implants, and measure some of their most relevant mechanical properties according to the international standards ISO 7198:2016. Tests will be performed before and after accelerated degradation in vitro. Particularly, the followings will be evaluated:

1. The porosity of the constructs, via gravimetric approach
2. The suture retention (SR) of the constructs, via uniaxial tensile test
3. The burst strength (BS) of the constructs, via burst pressured test

The students will learn how to perform accelerated degradation tests in vitro, build up simple mechanical apparatus, conduct mechanical tests according to ISO standards, and evaluate the obtained results with some limited data analysis work. Ultimately, the students will learn the fundamentals of cell culture and cell analysis when measuring:

4. The cytotoxicity levels of the degraded constructs, via viability assays on seeded blood-derived cells and saphenous vein-derived cells

Methods and project outline

Accelerated degradation in vitro will be induced via lipase incubation.

1. For gravimetric determination of the porosity, a high accuracy balance and a high resolution microscope will be used.
2. To test the SR of the constructs, the Biaxial Tensile Tester will be used (in uniaxial configuration).
3. To measure the BS, pressure will be applied to tubular constructs via a Harvard pump and the pressure rise and burst pressure will be measured via a pressure sensor.
4. To evaluate the cytotoxicity levels of the degraded constructs, blood-derived cells and saphenous vein-derived cells will be seeded, and the viability monitored over time via propidium iodide staining.