Keeping track of white blood cell levels in chemotherapy patients is an involved but crucially important task. The treatment can lead to suppression of the immune system, a decline in white blood cell count, which in turn can give rise to infections and other serious complications. As things stand, patients are subjected to regular blood tests as a means of keeping an eye on things, but an international team of scientists has a less invasive alternative in the works. With the ability to tally up white blood cells through the skin in real time, the new testing device can simply be stuck onto a fingertip to help clinicians tailor personalized and more timely treatments.
The biggest advantage of the new testing device – dubbed a leukometer – over the current method of blood sampling is its immediacy. The researchers point out that it is simply not realistic to be carrying out blood tests on chemotherapy patients every hour, while it doesn't always take long for things to take a turn for the worse. If a drop in white blood cell count can be picked up early on, drugs can be prescribed to return it to safe levels and allow the body to better fight off infection. Additionally, if a patient is recovering from immunosuppression faster than expected, medication could be adjusted accordingly to cut the overall recovery time.
The leukometer works in a similar way to a pulse oximeter, a device that measures blood oxygen levels through the skin using light. With an array of LEDs and a small lens, the device projects light and gathers images of capillaries just under the surface. As light at certain frequencies is absorbed by the blood's hemoglobin (a protein that carries oxygen around the body) but not by the white cells, they show up as small transparent particles moving through the capillary.
The device then uses algorithms to analyze these images and give an estimation of the white blood cell concentration in the blood. According the researchers, all of this culminates in a portable, user-friendly device that could see patients monitor their own white blood cell counts at home, something that could prove particularly valuable in rural areas or developing countries.
"It would also be possible to perform measurements on a continuous basis, opening up treatment options that were previously not possible," says Carlos Castro, biomedical engineer at MIT and member of the research effort.
Castro and his team, which includes researchers from Boston University, the Universidad Politécnica de Madrid and the Spanish National Cancer Research Centre (CNIO), have developed three prototypes for the leukometer device. The first was a portable microscope that is placed on the patient's fingertip, while the second saw improvements made to the microscope that resulted in better image quality. The third works with a mobile phone camera and sends images to a server for analysis.
The researchers are hopeful that a beta product will become available for testing in 2017, with a market ready product to follow in 2019 if they can gather enough funding.