Stem cell stories that caught our eye: heart repair, epilepsy and comparing cloned and reprogrammed cells

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

Reminding broken hearts how to mend them selves.
After years of tracking down the right genetic buttons a team at the Salk Institute in La Jolla has taught a mammal to do what zebra fish do naturally, repair a severely damaged heart. While all our cells have the genetic code for building whole organs those genes seem to be switched off in all higher animals, but active in some more primitive species like zebra fish and salamanders.

New cells (red) repairing injury in a zebra fish heart.

New cells (red) repairing injury in a zebra fish heart.

Starting a decade ago the researchers measured the gene activity during heart repair in the fish. They found many genes that had their on-off status change during repair. They then looked to see which of those genes had been preserved during evolution to mammal species. They found four genes that were turned off during repair in the fish but were turned on in the mice they were using.

When, with CIRM funding, they inserted genetic signals to turn off those genes in the mice, they saw significant repair of the damaged heart. There are many steps between this advance and getting human hearts to repair them selves—notably finding a way to introduce the genetic signals without using the virus used in this study. HealthCanal picked up the institute’s press release.

Cloned stem cells pretty much like reprogrammed stem cells. In the early days of stem cell research there was a great deal of excitement about the possibility of creating stem cells that genetically match a patient by a process commonly called cloning. This process of taking the genetic storehouse of a cell, the nucleus, and inserting it into a donor egg had been relatively easy in mice. But it turned out quite difficult in humans and was only accomplished last year.

During the years of failed attempts at this process known as nuclear transfer in humans an alternative came into the field. The Nobel prize-winning discovery that you can reprogram any adult cell to act like an embryonic stem cell gave us a new way to create personalized stem cells that genetically match a patient. But ever since that 2008 advance, the research community has fretted over whether those new stem cells called iPS cells really match embryonic stem cells. The iPS cells came from older cells that had lived through many opportunities for mutation and the genetic factors used to reprogram them added further opportunities for mutation.

Researchers at the New York Stem Cell Foundation’s in house lab have now compared the two types of cells with several layers of genetic analysis. They found the same level of mutation in the iPS cells and the cells from nuclear transfer lending some reassurance to the use of iPS cells going forward. HealthCanal ran the foundation’s press release.

A more efficient way to make cloned stem cells. Even though a team in Oregon overcame the obstacles to creating stem cells by nuclear transfer last year, and the feat has been repeated by the New York team above and others, it remains terribly inefficient. So, several groups are working on better ways to make these potentially valuable cells.

A former colleague now at Children’s Hospital, Boston wrote a nice explanation of how researchers are going about making these cloned cells easier in the hospital’s blog, Vector.

Stem cells reduced seizures.
The seizures endured by people with many forms of epilepsy originate from genetic defects in their nerves. So, a team at McClean Hospital outside of Boston implanted healthy nerves grown from embryonic stem cells in mice with genetically linked seizures. Half the mice no longer had seizures and the other half had their seizure frequency reduced.

The type of nerves transplanted are called interneurons, which are known to be the nerves that reduce firing of signals. In epilepsy nerve signals are hyperactive. The team is now working on methods to mature the stem cells into purer populations of just the desired interneurons. ClinicalSpace picked up the hospital’s press release.

Don Gibbons

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