![Oxford scientists have identified ways to dramatically improve a technique for isolating cells by magnetic sorting. This technique uses a tiny magnetic bead coated in […]](/wp-content/uploads/2013/02/NEWSICON2-620x300.png "Oxford scientists pave way for new method of detecting cancer cells")
Oxford scientists have identified ways to dramatically improve a technique for isolating cells by magnetic sorting. This technique uses a tiny magnetic bead coated in an antibody against a certain cell surface molecule to bind cells expressing that marker. The bead-cell complex is then separated from the sample by applying a magnetic field. This approach can be used as a diagnostic tool to detect circulating tumour cells (CTC), which are thought to be present in the blood before metastasis – and possibly even malignancy – occur.
Dr Mark Howarth and colleagues in the Department of Biochemistry used an antibody against the HER2 protein, expressed on certain tumour cells, to study factors that affect the efficiency and specificity of cell isolation. They found that cellular cholesterol level is important, as cholesterol depletion inhibited isolation, while pre-loading the cells with cholesterol improved separation of cells.
In addition, they compared the efficiency of cell isolation when different methods were used for attaching the antibodies to the magnetic beads. This revealed that linking a biotinylated antibody to the bead via streptavidin produced a highly stable bridge that greatly enhanced the sensitivity of the isolation. The group also showed that increasing the antibody’s affinity for the target protein improved cell isolation.
Finally, they verified that these effects also apply to cell isolation when EpCAM – a common protein marker of CTCs – is targeted by the antibodies instead.
Published recently in Cancer Research, this work has important implications for cancer diagnostics as it could allow early detection of CTCs, which express relatively low levels of markers like EpCAM, in a simple blood sample. While magnetic isolation techniques are already used in the US to spot recurrence of cancers, Dr Howarth emphasised that there are still issues that must be resolved before the technique could be used clinically to provide a primary diagnosis.
