Most stem cell research is focused on finding ways to make stem cells become particular cell types to treat different diseases. Scientists at the UCLA Samueli School of Engineering, however, have found an atypical use for blood stem cells: delivery vehicles.
Zhen Gu’s group wanted to test a new way to treat acute myeloid leukemia (AML). AML, one of the most common types of leukemia in adults, is tricky to treat because cancerous cells can remain in the bone marrow hidden from chemotherapy drugs. This reserve population can reactivate and cause cancer that is much more difficult to control than the initial manifestation.
To solve this problem, the scientists hooked up the cancer treatment molecule (a protein that turns immune cells on to fight cancer cells) to blood stem cells and platelets. Because blood stem cells are naturally able to enter the bone marrow (this is where blood stem cells become the many different types of cells of the immune system), the investigators reasoned that this system would deliver the cancer drug to the quiescent cancer cells. Platelets were utilized in the system to aid delivery to the correct cells.
Indeed, when they tested this system in AML mice, 87.5% of them survived for over two months, whereas the mice that were given the cancer drug without the complete delivery system survived less than half of that time. In addition, the drug delivery complex made the mice more resistant to becoming sick when they were artificially injected with leukemia cells. The complete results of their study were published in the journal Nature Biomedical Engineering.
This approach is particularly exciting because although bioengineered cells have been used in drug delivery, this is the first time that two different cell types have been using in conjunction to achieve this goal.
There are certainly many steps before this type of treatment can be used in patients, but Gu is optimistic that this treatment will be successfully expanded to humans. In an article, he also states his hope that this strategy can be incorporated into existing treatment options:
“We can package medicines or immune system boosters on the cell surface of platelets, and have them activated to unload once at the target site inside the body.”