One of the challenges with testing stem cells as treatments is that they are hard to track in the body, to clearly determine if they've survived implantation, reached where they were supposed to go or strayed somewhere else. University of Liverpool researchers in the U.K. believe that they've solved the problem, and their breakthrough study is published in the journal ACS Nano.
A partial solution is already in use. According to the researchers, the scientists use superparamagnetic iron oxide nanoparticles (SPION) to tag the cells when injecting them into a patient, and then MRI scans pick them up, creating some way to track the cells to see if they reach their goal. But the body's cells can degrade the SPIONs and make it harder for them to be tracked, the researchers explain.
The Liverpool scientists' solution includes developing ways to visualize SPIONs in the cells before they enter the body. That way, the idea is to both track where they go within a given stem cell, and also predict their behavior over a longer period once injected into the body. What's more, they've developed a photothermal technique that improves the SPION labeling, thereby boosting their survival time and minimizing how they affect the transplanted stem cells.
Losing the ability to track the progress of stem cell implants could harm patients who are being treated for leukemia or testing new treatments for a variety of diseases, University of Liverpool researcher Lara Bogart noted in a statement. Bogart, who performs her work at the university's Institute of Integrative Biology, explained that stem cells could cause inflammation if they migrate beyond their target organ or tissue site, or reach the circulatory system.
An Israeli company, Pluristem Therapeutics ($PSTI), is trying to address the tracking issue with its stem cell treatment by injecting it into muscle rather than intravenously. The company says using muscle appears to generate a stronger systemic response and the cells remain in muscle. Pluristem's cells are made from discarded placentas. In a recent test, they spurred hematopoietic stem cells already in the body to grow bone marrow in mice.
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