Hi,
Just read an article in Science Translation Medicine, where researchers have used nanofibers to repair heart. Here is what they did:
Currently, there are no approved therapies in regenerative
medicine for heart failure. In this work, scientists have used nanotechnology
materials to repair vital tissues damaged by heart attacks in animals. The experiments, done in rats and pigs, led to the
growth of fresh blood vessels and improved heart function without harmful side
effects.
To promote blood-vessel growth in the heart, a protein
called vascular endothelial growth factor, or VEGF was delivered. Previously
this method hasn't worked well because the heart's blood circulation tends to
rapidly wash away the VEGF. In this work the researchers developed an
engineering fix for the problem. They made fibers from bits of protein and then
assembled them into a lattice-like structure. Each fiber is just five
nanometers wide and 100 nanometers long. The
lattice structure is in the form of a sticky gel. The scientists mixed it with
the VEGF and injected the combination into the hearts of two groups of test
animals, rats and pigs, in which they had induced heart attacks. (Pig hearts
bear significant similarities to human ones.) In both cases, instead of being
washed away, the VEGF stayed on the lattice and slowly got released over
several weeks.
Source: WSJ
Bone-marrow stem cells normally circulate in the blood and
are part of the "repair crew" for damaged tissue. In the animal
experiments, when those cells sensed the release of VEGF, they relocated to the
heart and began to grow tiny blood vessels known as capillaries. The nanofibers create a special microenvironment in
the heart for recruiting stem cells. However, fresh
capillary formation isn't enough to help a failing heart. For regeneration to
continue, stem cells from both the bone marrow and the heart itself must be
coaxed to grow a second layer of tissue that is necessary for the formation of
arteries, which are bigger and thicker than capillaries.
To the scientists'
surprise, the prolonged release of VEGF achieved that result. The researchers also
detected the creation of fresh heart muscle. This, too, is significant because
the "scarring" tissue that naturally forms after a heart attack is
thin and can get stretched in ways that alter the shape of the heart. In the
latest experiments, the nanofiber gel appeared to strengthen these weak areas
of the heart.
While the beneficial
results in pig hearts were particularly important due to their resemblance to
human ones, two challenges remain before the same technique can be safely
attempted in people:
1. long-term effect
in animals, and
2. determine the optimal time window" when the VEGF
nanofibers need to be administered
Long live science...
A
