Prof. Deon Bezuidenhout

Deon Bezuidenhout holds a B.Sc. in Chemistry and Applied Mathematics, and B.Sc. (Hons. cum laude), M.Sc. (cum laude) and Ph.D. degrees in Polymer Science from Stellenbosch University, South Africa. As Associate Professor in the Christiaan Barnard Division of Cardiothoracic Surgery at the University of Cape Town (UCT; leading university in Africa, THE World Ranking = 120th), and Head of Biomaterials Sciences at the Cardiovascular Research Unit, he has more than 20 years experience with teaching and research in the design, synthesis, modification, and processing of synthetic materials and bioprosthetic tissues for use in cardiovascular devices. He specializes in the development of biomaterial scaffolds and biomimetic matrices for tissue engineering and regenerative medicine approaches to vascular graft prostheses and the treatment of myocardial infarction, and in the development of affordable replacement heart valves for the developing world.

He teaches biomaterials and medical device-related courses to undergraduate engineering and medical students, is a member of the Indian Ocean Biomaterials Education Consortium that developed a masters course in Biomaterials at the University of Mauritius, and has established M.Sc. and Ph.D. courses in Biomaterials at the University of Cape Town (the first and only courses of its kind in Africa). He has graduated more than 20 postgraduate students and currently supervises 14 Hons, MSc and PhD students in Biomaterials and related disciplines. He organizes, participates in and convenes numerous short courses, workshops and seminars by international Biomaterials experts, and hosts, supervises and examines graduate studies of students from other South African, African, and European universities.
In the field of vascular grafts, his main contributions are in the development and optimization of porous scaffolds for tissue regeneration, and the application and proof of principal regarding the spontaneous transmural endothelialisation of small diameter synthetic blood vessels made from these scaffolds. The methods for producing the well-defined, angiopermissive, interconnected porosity that is required for full cellular ingrowth, the techniques for covalently attaching active heparin for growth factor delivery and improved vascularization, and isolated rat infrarenal aortic interposition model were developed in his laboratory. A recent and novel highlight of this work is the differentiation between the transanastomotic, transmural, and fallout endothelialisation, and showing that confluent transmural healing is possible in a fully isolated animal model. This work has led to collaboration with two US and a Swedish collaborator(s), as well as funding from NIH/Fogarty and NRF/Sweden in which the model is used for the evaluation of a variety of grafts. The impact of this work lies in his contributions to long-term clinical follow-ups showing the superiority of ePTFE grafts pre-seeded with endothelium, and in the potential to apply the principles of spontaneous endothelialization to small diameter peripheral bypass grafts and arteriovenous shunts (as current synthetic grafts fail to endothelialize due to lack of transmural outgrowth in humans).

He has also been closely involved in the development of external reinforcement methods to prevent excessive dilation and failure of vascular grafts. The one aspect of this work comprises the reinforcement of porous synthetic materials in order to mimic the mechanical compliance of natural blood vessels by using genetic algorithms to optimise the biomechanical properties of reinforced prostheses. The second aspect relates to the reinforcement of natural blood vessels (autologous saphenous veins) for use in coronary artery bypass grafts. The knitted Nitinol reinforcements are the topic of numerous research papers and patents, and are currently undergoing clinical trials by a US device company. The meshes, applied over the ablumenal surfaces of harvested veins, prevent over-dilation when the veins are used in the arterial circulation, and subsequently prevent intimal hyperplasia and resultant occlusion/failure of the grafts.

In the field of replacement heart valves, A/Prof Bezuidenhout has made a significant contribution to the fixation chemistries for xenogeneic tissues used in bioprosthetic heart valves (BPHV), and has published extensively on this topic. The work has led to a better understanding of the mechanisms of crosslinking, degeneration and calcification of BPHV, and he has development extended and improved crosslinking techniques for the abrogation of calcification in pericardial and valvular tissues used in these devices. These treatments are especially needed for the application to patients with rheumatic heart disease, as current commercially available prostheses calcify more rapidly in young recipients. An alternative and novel tissue preservation method, namely the filling the tissues with hydrogels, which leads to marked increased in degradation resistance and decrease in calcification with only minimal increases in tissue crosslink density, was also developed in his group.
He has headed and supported large research projects on device development in collaboration with local and international device companies, and has set up laboratories, methodologies and analytical techniques for prototyping and evaluation of a variety of devices.

A/Prof Bezuidenhout is also co-founder and technical director of Strait Access Technologies (SAT), a company that develops heart valve therapeutic devices, where he contributes his knowledge and expertise in cardiovascular devices in general, and polymeric and bioprosthetic materials in general. The devices are aimed transcatheter techniques for the delivery, replacement and repair of heart valve damaged by rheumatic heart disease (RHD). As such they are designed to be mass produced at low cost (e.g. polymeric valves) and suitable to implantation in secondary hospitals without the need for sophisticated hybrid operating rooms (e.g. via non-occlusive transapical delivery), thereby being applicable to the approximately 70 million of patient with RHD who currently have no access to heart valve surgery in Africa and BRICS nations. Variants of the devices are also suitable for application in developed economies due to their innovative design and unique features that would facilitate transfemoral heart valve replacement and repair therapies.

He further works on the developed of drug eluting polyethylene based hydrogels that are engineered to be either stable, or hydrolytically or enzymatically degradable in the body. The injectable gels can be formed in situ by simple admixture and have been covalently modified to allow cell attachment and ingrowth, and release covalently incorporated drugs at well-defined rates. The method of incorporation of the drugs is such that they are released by hydrolysis in their original form, thus with retained activity. Anti-inflammatory drugs have been successfully incorporated and released with zero-order (constant tempo) kinetics, and enzymatically degradable gels shown to have cell-specific ingrowth due to crosslinking with modified matrix metalloproteinase substrates. The gels have been used in collaboration with local and international colleagues for the treatment of myocardial infarction induced in a rat model, ameliorate pathological remodeling, reduce wall thinning, and improve function (fractional shortening) when the delivery is deferred. Work on these and related gels that are capable of delivering stem cells for improved retention, and adeno-associated viruses for gene delivery has resulted in 6 research papers and a published US patent.

Dr. Bezuidenhout has published 50 papers in international journals (average impact factor > 4; h-index = 24; i-index = 42; citations > 2000) and 10 invited book/encyclopedia chapters, and is inventor on 21 issued, 7 published and 7 pending US and international patents, including 8 patents on the non-occlusive transcatheter heart valves, deployment and related devices for SAT. He is author on 150 conference papers, including mny international, invited, plenary and keynote addresses, is editorial board member/associate editor of 6 international journals, reviewer for 13 journals and member of 9 international academic societies.

He is currently focused on translating his work on spontaneous transmural endothelialization to electrospun grafts and heart valves, the development of heparin based hydrogels for growth factor delivery and the improvement of durability of catheter based polymeric heart valves. Other interests include gene delivery and smart nanomaterials, for which he has attracted additional research funding from the NRF and the Royal Society.