Back in 2011, researchers at the Icahn School of Medicine at Mount Sinai generated excitement in the cardiology community when they announced they had used placental stem cells to regenerate damaged hearts in pregnant mice. Now, they’ve taken that research a step further, isolating the precise population of cells that can regenerate healthy heart cells after heart attack due to proteins that give them the ability to travel directly to the injury site.
The Mount Sinai team discovered that Cdx2 cells (stem cells derived from the placenta) of mice can migrate through the circulatory system and target heart injuries. Once there, the cells transform into beating heart cells and start the repair process.
The researchers knew from their previous study that a mixed population of placental stem cells could help repair injuries that would normally lead to heart failure in pregnant mice. They zeroed in on Cdx2 cells because they were the most prevalent cells in that mixed population, containing 40 percent of the cells that seemed to be promoting heart repair.
Three months after the treatment, the stem cells had formed new blood vessels and beating heart muscles cells called cardiomyocytes. There were no signs of regeneration in the other two groups
To test the Cdx2 cells’ regenerative properties, the researchers tested cells in three different mouse models of heart attack, (all male): one group received Cdx2 stem cell treatments derived from end-gestation mouse placenta, one group received placental cells that did not express Cdx2, and the third group received a saline control. The team used magnetic resonance imaging to analyse how the animals’ hearts were responding throughout the study.
The Mount Sinai team observed that all of the mice in the Cdx2 group experienced regeneration of healthy heart tissue. Three months after the treatment, the stem cells had formed new blood vessels and beating heart muscles cells called cardiomyocytes. There were no signs of regeneration in the other two groups.
“[…] we are now hopeful that we can design a better human stem cell treatment for the heart than we have seen in the past,” explained Dr. Chaudhry, MD, Director of Cardiovascular Regenerative Medicine at the Icahn School of Medicine at Mount Sinai
The results are exciting for a number of reasons. Alongside all the regenerative abilities of embryonic stem cells, the team found that placental stem cells have additional proteins, giving them the ability to travel directly to the injury site, which is something embryonic stem cells cannot do, and they appear to avoid the host immune response. The immune system did not reject these cells when administered from the placenta to another animal.
“These properties are critical to the development of a human stem cell treatment strategy, which we have embarked on, as this could be a promising therapy in humans. We have been able to isolate Cdx2 cells from term human placentas also; therefore, we are now hopeful that we can design a better human stem cell treatment for the heart than we have seen in the past,” explained Dr. Chaudhry, MD, Director of Cardiovascular Regenerative Medicine at the Icahn School of Medicine at Mount Sinai.
They published their findings in the journal Proceedings of the National Academy of Sciences.
This post was written by Samantha Billups and edited by Karolina Zieba.
