Magnetic Beads The key to an efficient and effective blood-test
Many different blood tests have to be performed for MS to be confirmed and this is a lengthy process, as well as often being inconclusive as symptoms come and go. Additionally, NHS doctors, who have to assess the cost-benefit relationship very critically, are unwilling to send off more than one test when the negative result of one may make the other useless. Patients can also only give a certain volume of blood for testing before it becomes dangerous. The tests use immunomagnetic separation, which involves binding the targeted cells to a specific magnetic complex in order to extract and then isolate the cells with powerful magnets. The target cells are then transferred to a system using chips for identification, counting and studying. These microfluidic chipscannot process large volumes of fluid quickly because they rely on extremely narrow channels which restrict fluid flow. Because of the large volumes being processed on the industrial scale, this means doctors and patients have to wait longer for the results: typically 2 weeks. The Current System
All the steps can be performed at once, rapidly speeding up the process. • The mesh can be re-used for further experiments, so it is more efficient. • Using this method we can screen and process very low quantities of particular cells by using a high concentration of magnetic beads. • If needed, the cells can be returned for further analysis by turning off the magnetic field. • More than one type of cell can be tested for at once. Especially as symptoms and the patient’s body chemistry are fluctuating, this gives a better overall impression of the patient’s state and makes detection of the disease more likely (please see diagram below) How does our solution improve on this? This diagram is for illustration only and is not accurate. As you can see, if the test was only able to detect one symptom-causing molecule (e.g. “Symptom 2”) and was performed at Point 4, MS might be dismissed as a possibility. However, if our method was being used, it would be clear that the patient could still be suffering from lupus and that “Symptom 2” is just at a temporary low.
Our idea was inspired by research detailed on www.theengineer.com which describes early advances in detecting cancer in the blood. Magnetic beads about a micron in diameter are coated with antibodies that recognise and attach to antigens on the surface of target cells. Different batches of magnetic beads can be coated with different antibodies so that different cells that might indicate lupus can all be collected in the same test. The beads are directed by a magnetic field to a silicon mesh containing holes eight microns in diameter. Beads that have not bound to cells pass through the silicon mesh and can be re-used. The beads that have attached to cells are too large to pass through and can be analysed. By using beads with different strengths of magnetism, we could also separate different target cells by increasing or decreasing the strength of the magnetic field so that only some are collected. OUR SOLUTION Imagine a giant sieve to help you understand how the silicon mesh works..
As well as combining the current blood tests for lupus into one test, we propose to test for another factor as well – high levels of B-cell activating factor in the blood, a cytokine that regulates the survival, growth and function of B cells. Recent research has shown that overexpression of BAFF in mice led to their developing an SLE-like disease, and that BAFF was elevated in the serum of patients suffering from SLE. The first and only drug to be approved by the FDA specifically for lupus treatment, Belimumab, also works by inhibiting B-cell activating factor. Although there is not yet enough research to show that high levels of BAFF cause lupus, this test could contribute towards a better diagnosis of the disease. Adding another test
The beads could detect the presence of the CD257 antigen on the surface of BAFF. Data was gathered on the levels of BAFF in serum of healthy patients and those with Sjogren’s syndrome, another autoimmune condition. We estimate the interquartile range for healthy subjects was roughly 700-1100 pg/mL (our estimate based on the graph and the median of 983pg/mL, range of 600-1564pg/mL.) whereas the median for Sjogren’s patients was 1277pg/mL. Based on this data, we propose that a test result of higher concentrations of BAFF than 1100pg/mL in the blood should be considered a positive test result for high levels of BAFF. The research which indicates our solution would be effective: http://ard.bmj.com/content/72/1/146.extract How the new test would work