2022 Summer Studentship winner Khush Saba studying at Aston University, was awarded £3,125 for her project to identify material for an in vitro human blood vessel model to study heart disease.

Khush Saba has just completed the second year of her 4 year BEng Mechanical Engineering degree at Aston University, Birmingham. Her project aims to identify ideal materials for use in an in vitro human blood vessel model, that can then be used for future vascular graft development and testing. Her project is being overseen by Dr Laura Leslie, Head of School (Engineering and Technology) at Aston University.

Development of a non-animal vascular model for medical device testing – Materials Selection and Testing

Cardiovascular diseases, diseases of the heart or blood vessels which are sometimes referred to as heart disease, contributed to 32% of global deaths in 2019. Treatment is often in the form of a vascular graft, which is where blood vessels from the patient, another person, or an animal are used to patch an injured or diseased section of an artery or replace diseased tissue entirely. These can be limited in availability (of healthy blood vessels in the patient), or have a high failure rate if coming from another individual or animal. Artificial grafts and tissue-engineered grafts have also been developed. Tissue-engineered grafts in particular hold a lot of potential for the future as they can be grown from the patient’s own cells.

As with all new medical devices and drugs, biomaterials that can be used in surgical treatments have to be tested to ensure they are safe. The regulators that oversee these safety tests currently require data to show this. Whilst modern computer simulations are capable of modelling the behaviour of the human body in great detail, the data they provide on the mechanics and physiology of our blood vessels and blood flow is not sufficient to meet current regulatory standards. This therefore often still requires the use of animals to provide data for regulatory purposes. For the testing of new vascular graft developments, the animals (mostly large mammals) must undergo surgery and ultimately euthanasia. Whilst animals allow whole-body responses to be monitored, they have different anatomy, metabolism and physiology to people, meaning responses are not always comparable. Animal models are also expensive and results can be difficult to replicate due to differences within, and between, species.

In her application, Khush highlighted a review paper by Mufty et al (2021) that explored in vivo models used for evaluating the coating of vascular grafts to prevent infection. They found 94 papers reporting studies on dogs, rabbits, sheep etc, which used between five and 528 animals per study.

Human-relevant in vitro models play an important role in improving our knowledge without the use of animals, but also provide more relevant avenues for studying human diseases and testing experimental treatments and interventions.

As Khush explains “Understanding the fluid mechanics within an artery, both with and without a vascular graft, is key to predicting key markers for health, good fluid flow and the risk of blockage. The only models available for visualising and/or measuring vascular fluid mechanics are either unvalidated computational models, limited experimental setups or in vivo animal models.”

In this Summer project, Khush is reviewing and identifying different materials and their potential to be used in in vitro models of human arteries. She will be researching and identifying different materials, assessing their different properties, such as stiffness, strength, hardness and other parameters that need considering when developing an in vitro blood flow model of a healthy, diseased or repaired human artery. She will need to research and review available materials and processing routes including exciting new technologies in 3D printing. Her findings will have the potential to help researchers select the most appropriate materials for blood vessel models.