According to British scientists, the prospect of reversing blindness has made a significant leap.
An animal study in the journal Nature Biotechnology showed the part of the eye which actually detects light can be repaired using stem cells.
The team at Moorfields Eye Hospital and University College London say human trials are now, for the first time, a realistic prospect.
Experts described it as a “significant breakthrough” and “huge leap” forward.
Photoreceptors are the cells in the retina which react to light and convert it into an electrical signal which can be sent to the brain.
However, these cells can die off in some causes of blindness such as Stargardt’s disease and age-related macular degeneration.
There are already trials in people to use stem cells to replace the “support” cells in the eye which keep the photoreceptors alive.
Now the London-based team has shown it is possible to replace the light-sensing cells themselves, raising the prospect of reversing blindness.
An animal study in the journal Nature Biotechnology showed the part of the eye which actually detects light can be repaired using stem cells
They have used a new technique for building retinas in the laboratory. It was used to collect thousands of stem cells, which were primed to transform into photoreceptors, and injected them into the eyes of blind mice.
The study showed that these cells could hook up with the existing architecture of the eye and begin to function.
However, the effectiveness is still low. Only about 1,000 cells out of a transplant of 200,000 actually hooked up with the rest of the eye.
Lead researcher Prof. Robin Ali said: “This is a real proof of concept that photoreceptors can be transplanted from an embryonic stem cells source and it give us a route map to now do this in humans.
“That’s why we’re so excited, five years is a now a realistic aim for starting a clinical trial.”
The eye is one of the most advanced fields for stem cell research.
It is relatively simple as the light sensing cells only have to pass their electrical message on to one more cell in order to get their message to the brain, unlike an attempt to reverse dementia which would require cells to hook up with far more cells all across the brain.
The immune system is also very weak in the eye so there is a low chance of the transplant being rejected. A few cells can also make a big difference in the eye. Tens of thousands of stem cells in the eye could improve vision, but that number of stem cells would not regenerate a much larger organ such as a failing liver.
Scientists in the US have created a free swimming artificial jellyfish using silicone as a base on which to grow heart muscle cells that were harvested from rats.
They used an electric current to shock the Medusoid into swimming with synchronized contractions that mimic those of real jellyfish.
The advance, by researchers at Caltech and Harvard University, is reported in the journal Nature Biotechnology.
The finding serves as a proof of concept for reverse engineering a variety of muscular organs and simple life forms.
Because jellyfish use a muscle to pump their way through the water, the way they function – on a very basic level – is similar to that of a human heart.
“I started looking at marine organisms that pump to survive,” said Kevin Kit Parker, a professor of bioengineering and applied physics at Harvard.
“Then I saw a jellyfish at the New England Aquarium, and I immediately noted both similarities and differences between how the jellyfish pumps and the human heart.
“The similarities help reveal what you need to do to design a bio-inspired pump.”
Scientists used an electric current to shock the Medusoid into swimming with synchronized contractions that mimic those of real jellyfish
The work also points to a broader definition of “synthetic life” in an emerging field of science that has until now focused on replicating life’s building blocks, say the researchers.
Prof. Kevin Kit Parker said he wanted to challenge the traditional view of synthetic biology which is “focused on genetic manipulations of cells”. Instead of building just a cell, he sought to “build a beast”.
The two groups at Caltech and Harvard worked for years to understand the key factors that contribute to jellyfish propulsion, including the arrangement of their muscles, how their bodies contract and recoil, and how fluid dynamics helps or hinders their movements.
Once these functions were well understood, the researchers began to reverse engineer them.
They used silicone to fashion a jellyfish-shaped body with eight arm-like appendages.
Next, they printed a pattern made of protein onto the “body” that resembled the muscle architecture of the real animal.
They grew the heart muscle cells on top, with the protein pattern serving as a road map for the growth and organization of the rat tissue. This allowed them to turn the cells into a coherent swimming muscle.
When the researchers set the Medusoid free in a container of electrically conducting fluid, they shocked the Medusoid into swimming with synchronized contractions. The muscle cells even started to contract a bit on their own before the electrical current was applied.
“I was surprised that with relatively few components – a silicone base and cells that we arranged – we were able to reproduce some pretty complex swimming and feeding behaviors that you see in biological jellyfish,” said John Dabiri, professor of aeronautics and bioengineering at Caltech.
“I’m pleasantly surprised at how close we are getting to matching the natural biological performance, but also that we’re seeing ways in which we can probably improve on that natural performance. The process of evolution missed a lot of good solutions.”
Lead author Janna Nawroth from the California Institute of Technology (Caltech) in Pasadena commented that the field of tissue engineering was “still a very qualitative art”.
She said researchers tried to copy a tissue or organ “based on what they think is important or what they see as the major components without necessarily understanding if those components are relevant to the desired function or without analyzing first how different materials could be used”.
The team aims to carry out further work on the artificial jellyfish. They want to make adjustments that will allow it to turn and move in a particular direction.
They also plan to incorporate a simple “brain” so it can respond to its environment and replicate more advanced behaviors like moving towards a light source and seeking energy or food.
