How to catch cancer cells
Despite the fact that the vast majority of malignant cells freely moving through the body do not form new tumors, their appearance in the bloodstream is considered a harbinger of the development of metastases. Experts believe that accurately determining the number of such cells, known as circulating tumor cells, can be a useful method for tracking the effectiveness of therapy, as well as preventive screening.
However, searching for these cells among millions of blood cells can be compared to searching for a needle in a haystack. The development of methods for their selective concentration and capture turned out to be a difficult task from a technical point of view. Existing methods for detecting freely circulating cancer cells from the blood of patients are very few and are under development.
Based on the results of several years of work, researchers at the University of Wisconsin-Madison have created CapioCyte technology, which allows detecting large numbers of circulating tumor cells by slowing their movement and molecular binding to specific molecules.
A schematic representation of the binding process, in which circulating tumor cells (orange) and leukocytes (white) roll over a surface covered with "sticky" proteins, imitating the surface of the inner wall of the vessel.
The authors took advantage of the behavior of these cells, which attach to the inner walls of blood vessels and look for sites suitable for insertion. They have developed a surface covered with "sticky" proteins, upon contact with which tumor cells begin to "roll" over the surface, which slows down their movement. After that, they bind with three specific antibodies. To increase the binding force, the researchers developed a branching nanostructure, each branch of which ends with an antibody. A tumor cell can bind to several branches at the same time, which ensures binding strength.
This approach allowed the authors to bind an average of 200 circulating tumor cells in each milliliter of patient's blood, which is many times greater than the capabilities of earlier methods. Cancer cells were detected in samples of all 24 study participants undergoing therapy for head and neck, prostate, rectum and cervical cancer. Despite the fact that the number of cells did not correlate with the stage and, accordingly, with the severity of the disease, its decrease was observed with successful radiotherapy. In two out of three patients with recurrent or resistant forms of the disease, the number of circulating tumor cells increased again after the end of the course of standard therapy.
A prototype device based on CapioCyte technology, inside which a small amount of the patient's blood flows through a chamber whose surface is covered with proteins binding tumor cells.
According to the head of the group, the absolute number of circulating tumor cells does not matter much because of the high individual variability of the indicator. More important is the tendency to change their number, as it reflects the reaction of the tumor to treatment.
Article by Ja Hye Myung et al. Multivalent binding and biomimetic cell rolling improves the sensitivity and specificity of circulating tumor cell capture published in the journal Clinical Cancer Research.
Evgenia Ryabtseva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of the University of Wisconsin–Madison: Improved capture of cancer cells in blood could help track disease.