American scientists have found that a molecule called SleX can help restore an important biological function of stem cells, in case they have lost such surface proteins as are crucial to their therapeutic potential.
Once the molecule has been added to the surface of the cells, according to the researchers, it takes just 45 minutes to show its effect.
"Delivery remains one of the biggest hurdles to stem cell therapy. The blood stream offers a natural delivery vehicle, but stem cells don't move through blood vessels normally after being expanded in culture. Our procedure promises to overcome this obstacle," says senior author Jeffrey Karp, an instructor at the Harvard-MIT Division of Health Sciences and Technology.
In order for cells injected into the blood stream to be therapeutically useful, they need to take initiative to reach target tissues.
However, cultured stem cells go with the flow, move through the body quickly carried by the current, and seldom contact the sides of blood vessels.
A doctoral student postdoctoral fellow in Karp's lab, Debanjan Sarkar, simply flooded a dish of cells with three molecules-biotin, streptavidin, and SLeX-one after the other. The biotin and streptavidin anchored SLeX to the cell surface.
Sarkar fine-tuned the concentrations of each molecule to maximize the cell's ability to roll along the interior of the blood vessel, instead of getting lost in the flow.
He also confirmed that the altered cells were still viable.
"The method is very simple. Plus, biotin and streptavidin work with many molecules, so labs can use this universal anchor we discovered to tackle other problems. They're not limited to sticking SLeX on cells," says Sarkar, who is first author on the paper.
The study was conducted using human cells extracted from the bone marrow.
Karp, however, cautions that his lab's discovery must be validated in animals, before doctors can apply it in the clinic.
He also revealed that his team would work in collaboration with researchers elsewhere to conduct studies on mice, so as to ensure whether or not their findings are actually promising.
"We need to confirm that this rolling behavior translates into increased homing and tissue repair. We may need to tweak the cells further," says Karp.
Pamela Robey, chief of the Craniofacial and Skeletal Diseases Branch of the National Institute of Dental and Craniofacial Research, says: "This is definitely an approach that should be tried. Jeff hasn't tested the altered MSCs inside animals, and that's really the gold-standard, but his in vitro data looks promising."
The findings have been reported online in the journal Bioconjugate Chemistry.