Knit A Kidney, Print A Pancreas

Creating a new kidney out of your own cells is not as futuristic as it sounds. Some researchers believe that growing tissues can be as easy as spinning a fabric. T.V. Jayan reports

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Circa 2020. Victims of the 2008 Gurgaon kidney scam are lining up for yet another operation. Not at a remote bungalow that doubles up as a clandestine operation theatre, but before a well-appointed hospital. Also, not for stripping them of the only remaining kidney that helped them survive all these years. They are there for a surgery that would put back a new kidney, grown from their own cells.

Growing a new kidney — for that matter any complex organ — may become a reality by then, largely owing to the work being done today by scientists such as Sri Lanka-born Suwan Jayasinghe.

Jayasinghe, a mechanical engineer specialising in biophysics at the University College London, however, for the time being is concentrating on simple structures of, say, a few million cells per millilitre. Once the technology is proven, the whole organ, however complex it may be, can be attempted, he says.

“Growing tissues for the heart, kidney or the pancreas can be as easy as spinning a fabric,” says Jayasinghe, who got interested in regenerative medicine because his father suffered from a blocked vessel in the brain.

At the heart of the technique his team is pursuing is a borrowed technology — spinning, which has for at least a century helped mankind make textiles.

Jayasinghe’s team pioneered many novel techniques for weaving cells together in a scaffold. The latest among these, pressure-assisted spinning, uses three needles. One sprays cells, another, a viscous polymer and the third, pressurised air, to create a specific structure, much like a hose. Instead of water, living cells and cell media like the collagen which acts as a binder will flow out of the pipe, he says. The cells and polymer mix are put together by the pressurised air

The cells that they intend to use are stem cells from the individual who intends to go in for a transplant and hence there is no question of rejection. As a beginning, the UCL team is trying to develop tubes that can replace damaged blood vessels in the body.

“The techniques once fully developed could be explored for forming biologically viable tissues to possibly fully functional organs,” observes Jayasinghe. “I think we are about 5-10 years away from putting this into practice as we need to first achieve our primary goals which will then see the exploration of such structures in primates,” Jayasinghe told KnowHow.

While Jayasinghe and his collaborators hope to weave complex organs, scientists in the U.S. led by Thomas Boland of Clemson University are trying to print living cells using a machine similar to inkjet printers used in offices.

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In place of ink cartridges, it will use cartridges filled with cells and a biocompatible “crosslinker” which acts as a binding agent.

Boland’s collaborator Vladimir Mironov from the Medical University of South Carolina is heading a team of researchers trying to develop the world’s first bioengineered kidney, using the same technology which is called either bioprinting, or organ printing.

“Bioprinting a kidney is a long term and very ambitious project. We are focusing now on the most essential element of this project — that is printing a branched vascular tree of the organ,”Mironov told KnowHow. A vascular tree is the complete vascular system.

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Suwan Jayasinghe (left); pressure assisted spinning (middle); a diagram depicting the method (right)

Mironov says he is looking forward to some help from Indian scientists adept at modelling and computer simulation. “They can help us with designing virtual bioprinting, a blueprint for organs, mathematical modelling of post-processing and, in general, virtual manufacturing.”

But Jayasinghe believes that organ printing can pose problems. It cannot handle a mixture of cells simultaneously from a single needle, as the size of a printer needle is a limiting factor. For instance, baby cardiac cells can be 100 micrometres across, whereas the size of the needles that printers generally use is 60 micrometres. Squeezing them through an inkjet needle can rupture them, he believes. On the other hand, using their technique they have proven that they can even handle an embryo which is approximately 3 millimetres across, roughly 30 times bigger than baby heart cells.

Jayasinghe’s team is firstly focussing on assessing the biological viability of the treated cells by comparing it with a normal cell at a make-up level (which is the first step for any cell engineering technique). The technique is being applied to as many primary cell types as possible. In a human body, there are more than 200 different cell types. “Our intentions are to investigate and understand if any cellular make-up alterations are taking place when the cells are subjected to these cell spinning techniques,” Jayasinghe says. This is because such inadvertent changes, or damage caused to the cells, at the cellular level can later trigger diseases like cancer.

According to current research publications by the UCL team, it has already crossed this stage. “We have found that post-treated cells are genetically, genomically and physiologically intact,” says Jayasinghe.

The next step is fine tuning these techniques, which would even help control the spacing of cells in a living thread, the number of cells within each droplet and weaving scaffolds for three-dimensional, complex organs.

If all goes well, Gurgaon’s tragic story may well become history.

Sources: The Telegraph (kolkata, India)

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