Scientists have successfully used an injectable gel to “turn back on” heart cells that had been injured during a heart attack and stopped working.
This new technique addresses one of the biggest issues with heart attacks - that the sudden trauma to the organ leaves scarring on the cells that enable the heart to beat, and do not regenerate again.
The dramatic loss of heart muscle obviously makes patients more susceptible to long-term cardiovascular disease and increased mortality.
The reasons why these heart cells (cardiomyocytes) do not regenerate is not fully understood, but the team at the University of Pennsylvania wanted to target the ‘stop’ signal pathways that prohibit them from automatically switching on.
They were convinced they should invest their efforts in ‘fixing’ these cells, rather than trying to introduce new replacement cells.
Previous studies have tried to do this using short gene sequences, known as microRNAs, to do this, but delivering the right dose to the right place has been a consistent challenge.
What is RNA?
If DNA is the master copy of code in the human body, responsible for storing and transferring genetic information, RNA is a secondary copy that directly codes for individual amino acids and is a necessary middle-man for any cell to use the instructions in the DNA.
One of the biggest problems has been the time frame these treatments work to.
Professor Edward Morrisey, said: “The microRNAs that we used last less than eight hours in the bloodstream.”
And having such a short lifespan meant patients were needed large doses, but because these microRNAs are designed to promote cell proliferation, there would be a risk of tumor-producing, off-target effects.
But the new study, which used a mouse model, used an injectable gel that slowly releases the microRNAs into the heart muscle, rather than flooding it all at once.
“The most important traits of this gel are that it’s shear-thinning and self-healing. Shear-thinning means it has bonds that can be broken under mechanical stress, making it more fluid and allowing it to flow through a syringe or catheter.
“Self-healing means that when that stress is removed, the gel’s bonds re-form, allowing it to stay in place within the heart muscle.”
Mice treated with this gel after a heart attack showed improved recovery in key clinically relevant categories.
Professor Jason Burdick, said: “We’re seeing a change in approaches for regenerative medicine, using alternatives to stem cell delivery.”