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Heart surgery is delicate, costly and, when it comes to valve reconstruction, not often a long-term fix – but that could be changing.
Contemporary approaches to heart valve surgery often see artificial or fixed animal prosthetics used as replacement parts.
Both approaches are positive, in that they act as successes in the immediate environment; and negative, in that they are tricky to build, they degrade and they don’t grow with the patient – the latter a problem with children’s surgery.
Your health is your wealth
Scientists have been investigating new approaches, ones that match incredible medical advances in other parts of the body.
For example, this year alone we have seen new tools to manipulate organs during surgery and 3D-printed material that mimics cartilage for knees. This latest development, however, seems to be the most impressive.
A team lead by Kevin Kit Parker, of Harvard’s Wyss Institute for Biologically Inspired Engineering, developed a construct to achieve all that contemporary approaches cannot.
Tested in vitro, Parker’s team came up with a way to build valve replacements that can grow with the patient, and provide for a potentially safer surgical process in future.
In a paper published in Biomaterials, a valve-shaped nanofibre network that mimics the mechanical and chemical properties of the human valve is detailed, with its speedy construction the main appeal.
Cotton candy set-up
“Our set-up is like a very fast cotton candy machine that can spin a range of synthetic and [naturally] occurring materials,” said Parker.
“We used a combination of synthetic polymers and valve extracellular matrix (ECM) proteins to fabricate biocompatible ‘JetValves’ that are haemodynamically competent upon implantation, and support cell migration and repopulation in vitro.
“Importantly, we can make human-sized JetValves in minutes - much faster than possible for other regenerative prostheses,” he said.
Parker linked up with a team from the University of Zurich, headed by Simon Hoerstrup, who had developed his own regenerative heart prostheses.
This approach sees human cells directly deposit a regenerative layer of complex ECM on biodegradable scaffolds shaped as heart valves and vessels.
By combining Parker’s approach of fast, mass production, and Hoerstrup’s cell-packed structures, the new valves were trialled in sheep.
Safer and faster results
“In our previous studies, the cell-derived ECM-coated scaffolds could recruit cells from the receiving animal’s heart and support cell proliferation, matrix remodelling, tissue regeneration and even animal growth.
“While these valves are safe and effective, their manufacturing remains complex and expensive as human cells must be cultured for a long time under heavily regulated conditions.
“The JetValve’s much faster manufacturing process can be a game-changer in this respect. If we can replicate these results in humans, this technology could have invaluable benefits in minimising the number of paediatric re-operations,” he said.
Through the keyhole
Earlier this year, a University College Cork spin-out, SecuRetract, was released onto the market, allowing surgeons to manipulate organs that obscure and limit the ability to perform keyhole surgery.
Developed through the work of dozens of surgeons over four years of research, the prize-winning device uses clever engineering to improve the surgical process.
Inflated inside the 5mm surgical incision used in laparoscopic surgery, it keeps the bowels from obstructing surgeons’ views.
Take a knee
Elsewhere, a cartilage-mimicking material created by researchers at Duke University is paving the way for custom-built, replacement knee parts.
The hydrogel-based material, according to the researchers, is the first to match human cartilage in strength and elasticity, while also remaining 3D-printable and stable inside the body.
Human knees come with a pair of built-in shock absorbers called the menisci. This cartilage cushions our knees, but wear and tear can be telling.
A key concern is how little the menisci heal after humans reach adulthood, meaning synthetic substitutes are often needed.
“We’ve made it very easy now for anyone to print something that is pretty close in its mechanical properties to cartilage, in a relatively simple and inexpensive process,” said Benjamin Wiley, author of the paper.
