Cancerous growths that arise from the supportive tissue of the brain, known as gliomas, account for around 30 percent of all brain tumors and carry an average survival rate of just 14 months. These aggressive tumors are difficult to detect through MRI, largely due to the the protective blood-brain barrier that stops contrast agents from entering and lighting them up. But a new type of engineered fat cell could make them more treatable, by penetrating the barrier and revealing their presence at a much earlier stage of development.
A patient diagnosed with a cancerous glioma often survives the primary tumor after having it treated through surgical removal or radiation therapy. But this process generally gives rise to recurring, more resistant tumors that pop up in other parts of the brain. These fresh gliomas don't respond to further treatment, as they are derived from cancer cells that already endured the initial therapy.
To complicate things further, gliomas don't show up on an MRI until they are already well developed, as a result of the contrasting agents that would reveal them earlier being unable to penetrate the blood-brain barrier. This protective membrane surrounds vessels in the brain to stop 98 percent of therapeutic molecules from entering. Only when a tumor has reached a certain size will it disrupt the blood-brain barrier enough to allow the contrast agent through.
Unfortunately, this comes too late for the second, deadly wave of gliomas to be caught before causing irreparable damage. But researchers at Penn State College of Medicine are claiming to have found an early route through the blood-brain barrier. They have developed a new type of fat cell that contains a commonly used contrast agent called Magnevist, and embedded on its surface proteins that target receptors on glioma cells.
The researchers found that the engineered fat cell was able to penetrate the blood-brain barrier in mice and seek out early stage tumors. The researchers are not yet clear on how exactly the cell is able to sneak through the barrier, but claim that it does so in a safe manner, with the mice showing no harm from the treatment.
If it is proven safe, the stealthy fat cell could hold some advantages over using ultrasound to penetrate the blood-brain barrier, a technique used to prise the membrane open and deliver chemotherapy drugs to a human subject in a world first last month. Though that procedure was hailed a success, in temporarily tearing apart the barrier's tightly woven cells, some hold concerns over the lingering medical effects that may result.
"Ultrasound, with all of its good qualities, is disruptive to the blood-brain barrier, whereas we can get an agent to cross it without causing disruption," says James Connor, professor of neurosurgery at Penn State.
The research was published in the journal Neuro-Oncology.
Source: Penn State College
