If you wind back the clock on the different cells in our bodies, they'd all start life as one of just a few types of stem cells. Now, researchers from the University of Queensland have wound back the clock even further, and discovered a new type of dual stem cell that can produce certain tissues with built-in blood vessels.

Originally, the scientists set out to isolate endothelial progenitors – cells that give rise to blood vessel cells – from the placenta. But when the team tried to grow these specialized placental cells, they soon realized they weren't alone. Mesenchymal cell types, those that lead to bone, cartilage and fat cells, were also appearing in the mix.

"We first thought it was a mistake and our isolation process was not pure enough and somehow our endothelial cells were getting contaminated by mesenchymal cells," Kiarash Khosrotehrani, corresponding author of the study, tells New Atlas. "But despite our best efforts in cleaning up the isolation we noticed that some endothelial progenitors were also giving rise to mesenchymal cells. Finally to have definitive proof that this was not contamination, we isolated and observed placental cells one by one. In this single cell environment there is no contamination."

Sure enough, even without the possibility of contamination, both types of stem cells still arose. The placental cells were producing both mesenchymal stem cells and endothelial progenitors, leading the researchers to name them "meso-endothelial stem cells." This newly-identified type of cell appears to be essentially the root of the two other stem cell types, meaning in practice it could perform two functions for the price of one.

"In the past, each of these stem cells would have been harvested and spun together and then given to the patient," says Abbas Shafiee, co-author of the study. "Now it is just a dual cell, which means the cell has two specific functions at the same time."

The researchers say the meso-endothelial stem cells could eventually find use in many of the same applications as other mesenchymal stem cells, which may include repairing bone fractures, damaged cartilage or blood vessels. The advantage of the new cell type is that it can build both blood vessels and surrounding tissue together.

"We're focusing our efforts on their cardiovascular benefits: blood vessels are made of both endothelial cells and surrounded by mesenchymal cells," Khosrotehrani tells us. "The contact between the two cell types is essential in the maintenance of the blood vessel. Having a single bipotential stem cell type that can give rise to both constituents is likely to be advantageous."

Unfortunately, the scientists don't yet know how to create the right culture to keep the cells alive in vitro for very long, so the cells need to be used shortly after isolation from the placenta. For now, the UQ researchers are working on using meso-endothelial cells to grow new blood vessels for newborns suffering cerebral ischema, a condition where blood flow to the brain is reduced.

The research was published in the journal Stem Cell Reports.