There is a form of stem cell in the human body that can chase cancer cells. Now a new study from the US suggests brain cancer patients’ own fat may provide the best source of these mesenchymal stem cells (MSCs) for delivering treatments directly into the brain after the surgical removal of glioblastoma, the most common and deadliest type of brain tumor.
Study leader Alfredo Quinones-Hinojosa and colleagues, from the Johns Hopkins University School of Medicine in Baltimore, Maryland, write about their findings in the 12 March issue of the online open access journal PLOS ONE.
Glioblastoma is the most common and most aggressive malignant primary brain tumor in humans, and each year around 10,000 individuals in the US are diagnosed with the disease.
The current standard treatments are chemotherapy, radiation and surgery, but even when patients receive all three they rarely live more than 18 months after diagnosis.
Glioblastomas are not easy to remove. While the surgeon may remove as much of the tumor as possible, there is a risk that some stray cancer cells are left behind in areas that are difficult to reach.
These particularly nimble cancer cells migrate across the entire brain and form new tumors. This ability to migrate rapidly to other parts of the brain is thought to be the main reason for the low rate of cure in this type of cancer.
In a 2012 issue of PloS Biology, researchers report finding a protein that may reveal how glioblastoma moves and invades nearby healthy brain tissue.
“The biggest challenge in brain cancer is the migration of cancer cells. Even when we remove the tumor, some of the cells have already slipped away and are causing damage somewhere else,” says Quinones-Hinojosa, who is a professor of neurosurgery, oncology and neuroscience.
“Building off our findings, we may be able to find a way to arm a patient’s own healthy cells with the treatment needed to chase down those cancer cells and destroy them. It’s truly personalized medicine,” he adds.
Mesenchymal stem cells (MSCs) can be harvested from bone marrow and adipose (fat) tissue. As stem cells they have the ability to differentiate into several types of cell, for instance to make bone, cartilage and fat tissue.
But MSCs also have an unexplained ability to seek out damaged cells, such as glioblastoma cells. Quinones-Hinojosa says they appear to have a natural affinity for sites of damage in the body, such as wounds.
MSCs, both from bone marrow and fat, have been investigated in animal studies for their potential to treat trauma, and diseases like Parkinson’s and amyotrophic lateral sclerosis (ALS or motor neurone disease).
In a recent study, researchers describe how they used mesenchymal cells from mice, combined with cells taken from human gum tissue, to grow new bioengineered teeth.
Human MSCs are known as hMSCs. The researchers in this study worked with hMSCs.
In their study background, they explain that while the potential for using hMSCs in cancer treatments has been extensively investigated, nobody has yet compared whether bone marrow or fat tissue is the best source of hMSCs for treating gliomas.
For their lab study, Quinones-Hinojosa and colleagues created three hMSC cell lines in “test tubes”. One was derived from bought MSCs (extracted from fat and bone marrow), and the other two were harvested from fat taken from two patients.
They found all three hMSC cell lines performed equally well in the test tube: they stayed alive, they proliferated, migrated, and kept their ability to differentiate into other cells.
Quinones-Hinojosa says the results of their “proof of principle” study are important because they suggest patients’ own fat tissue may be as good a source of viable hMSCs as any other.
Because of their ability to target and find cancer cells, hMSCs are being put forward as a possible delivery mechanism for new cancer treatments. For instance, they could transport drugs or nanoparticles or some other treatment directly to the cancer cells.
Such a “sniper” method, because it leaves healthy cells alone, has huge attraction compared to the “shotgun” approach of many chemotherapies that target all growing cells, for instance.
If further studies show that hMSCs do what researchers hope, it may one day be possible to take some fat tissue from the brain cancer patient (from any number of places in the body), shortly before surgery.
The hMSCs would then be taken to a lab and adapted to carry drugs or other treatments. Then, after removing the brain tumor, the surgeon could deposit the altered hMSCs and leave them to hunt down and destroy any rogue cancer cells that escaped the knife.
Quinones-Hinojosa likens the adapted hMSCs to “smart” devices that “track cancer cells”.
But, while this study raises hope, and further studies are now under way, he says we are talking years before we see human trials using MSC delivery systems.
Funds from the National Institutes of Health’s National Institute of Neurological Disorders and Stroke, the Maryland Stem Cell Research Fund and the Howard Hughes Medical Institute, helped finance the study.
Written by Catharine Paddock PhD