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.
Matters of the heart not simple. The dozens of clinical trials using various types of stem cells to repair hearts after a heart attack have produced some encouraging and some discouraging results. Trials using a type of cell called a c-kit positive progenitor cells have generally produced the more positive changes in patients. But no one is completely sure why.
The Scientist used a recent publication in Circulation Research to review the various beliefs about what these heart-derived cells do. The recent paper by University of Louisville’s Roberto Bolli confirmed what several other studies had found: the cells do not create new heart muscle themselves but do release various proteins that seem to direct natural healing. These signals, called paracrine effects, seem to last for many months even if the transplanted cells themselves don’t stick around.
The article quotes a member of a CIRM funded team using c-kit+ cells in a phase 2 clinical trial that published a paper on the paracrine effect a couple years ago:
“They’re just confirming a paradigm we and others established years ago,” said Eduardo Marban, of Cedars-Sinai hospital in Los Angeles.
The author of The Scientist piece also brings in one of the more controversial characters in the field, Piero Anversa, who while at Harvard produced a paper that suggested the c-kit+ cells could produce heart muscle, but that paper was later retracted and led Anversa to move to Switzerland from where he told the writer not all c-kit+ cells are the same. He still maintains some of the cells can produce heart muscle. This is one intrigue of the heart to be continued.
Hearts respond to ultrasound. One theory on what the factors released by implanted stem cells do suggests they enlist the few cardiac stem cells we all have in our hearts. Those cells naturally try to repair the damage after a heart attack, but there just are not enough of them to be very effective. So, the paracrine factors released by donor stem cells may prod them to do a better job. Now a team in Spain suggests ultrasound treatment may do the same thing.
The researchers at the Universidad Politecnica de Madrid applied low-intensity pulsed ultrasound in mice with damaged hearts and found improved performance of the heart stem cells. Laboratory tests suggested the ultrasound treatment improved the cells mobility, in effect made them better able move to the site of damage. MedicalNews.net picked up a piece from the university on the research.
Give those cells a hug. Most of you have seen the many colorful images we post of stem cells with various parts of the cells glowing in different colors. These fluorescent tags on specific proteins in the cells help scientists identify and track cellular bits of interest. They sometimes introduce the tags genetically during development of the cells, but if they want to introduce them into living tissue after the fact, they have trouble getting the often large fluorescent tags into cells in a way that maintains a living cell’s normal function.
Now teams working at MIT and Goethe University in Frankfurt have refined a technique that squeezes living cells and creates temporary pores that lets the tags into the cells. The teams published their work in Nature Communications and a press release from MIT picked up by Phys.Org offered a quote from one of the authors, Armon Sharei, on the value of the work to the field in general:
“Basically everything that happens in your cells is mediated by proteins. You can start to learn a lot about the basic biology of how a cell works, how it divides, and what makes the cancer cell a cancer cell, as far as what mechanisms go awry and what proteins are responsible for that.”
Another mini-organ, the pituitary. The list of miniature organs created in the lab has grown to at least a dozen with the creation of pituitary glands by a team at Japan’s RIKEN Center, where some of the other “organoids” have been made. Because the pituitary is tiny, the lab grown version comes closer to the size of the natural one, and may be ready for clinical consideration sooner.
The pituitary gland secretes several hormones that control bodily functions, and when it is out of whack, you really know it. So a replacement would be a boon for patients, who now receive hormone replacement therapy that is not fully effective.
SciCasts wrote a story on the research that provides a nice narrative of the various steps the researchers took to get to a functional mini-organ that worked to correct hormone level when implanted in mice. It ends with a quote from Takashi Tsuji the head of the appropriately named Laboratory for Organ Regeneration:
“This is an exciting step forward toward our ultimate goal, which is to be able to regrow fully functioning organs in the laboratory. We will continue to push ahead with experiments to grow other parts of the body.”