Mesenchymal stem cells hold promise for regenerative medicine, as the stem cells are capable of differentiating into bone and cartilage, as well as muscle, fat and tendon. So far, small-sized clinical trials using mesenchymal stem cells have shown some early success in cartilage-repair procedures.
A new technique developed by scientists at the Stanford University School of Medicine that tracks stem cells after transplantation may help increase the effectiveness of such procedures.
The technique uses an imaging agent already approved by the FDA for anemia treatment that involves labeling the cells before extraction while they reside in the donor's bone marrow.
Researchers injected ferumoxytol, an FDA-licensed iron supplement made up of iron-oxide nanoparticles, into rats before extracting bone marrow from them. They then enriched the mixture for mesenchymal stem cells and injected it into the sites of knee injuries in rats. The investigators tracked the implanted cells' progress for up to four weeks, comparing the results with those obtained from both cells labeled in laboratory dishes and from unlabeled cells. The research was published online July 12 in the journal Radiology.
Until now, the only ways scientists have been able to label mesenchymal stem cells so that they could be noninvasively imaged have required manipulation in the laboratory. After extracting the stem cells, scientists then must give the cells contrast agents, spin them in a centrifuge, then wash and return the cells to surgeons for transplantation--a process that can raise the risk of contamination, which is a major regulatory concern. However, the new tracking technique allows surgeons to immediately transfer cells from a patient's bone marrow to the site of that patient's own knee injury.
Stanford has filed a provisional patent on the technique, which scientists hope will be adapted for a human trial this fall, in which mesenchymal stem cells will be delivered to the site of patients' knee injuries.
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Special Report: Stem cell research advances in fits and starts