Professor Rein V. Ulijn, of the University of New York’s Hunter College, says the idea of trapping cells with molecular cells is inspired by nature. Many somatic cells are in the extracellular matrix. Extracellular matrix is a complex network of biomolecules, can provide structure for the organization, promote the transmission of information between cells, the collection of nutrients. Scientists are developing molecules that can be spontaneously assembled into simple external substrates to provide the growth medium for cells, especially in biological tissue engineering.
Research in this area has focused on self-assembling peptides. In a recent study, Dr. Losser of the University of Brandeis Unuiversity and colleagues designed a non-nurturing peptide that agglomerates and engulfs cancer cells after removal of the phosphate group. Phosphopeptides have both hydrophilic and hydrophobic ends, which allow them to be assembled in a manner similar to lipids on the cell membrane. The negative charge on the phosphoric acid group produces electrostatic repulsion between molecules, which prevents the self-assembly process. Because some types of cancer cells overexpress alkaline phosphatase, an enzyme used to cleave phosphate groups, the presence or absence of phosphate groups is highly beneficial for targeting cancer cells.
Uljin and his colleagues, including Iva Pashkuleva of the University of Minho, think they can make carbohydrate-type molecules behave in the same way. Uljin said, compared with peptides, carbohydrates can generate a richer structure, open up new applications. In order to synthesize web-like molecules, the researchers added hydrophobic aromatic groups to a hydrophilic carbohydrate glucosamine to synthesize self-assembling molecules, and then added a phosphoric acid group group.
The researchers added molecules to cancer cells and normal chondrocyte media to test the anticancer properties of synthetic molecules. Compared to cancer cells, only about 5% of alkaline phosphatase activity was observed in the normal cell group. Seven hours later, about 95% of bone cancer cells died, and chondrocyte cell death rate was 15%.
According to the imaging of cells under scanning electron microscopy, the surface of bone cancer cells formed a cage-like hydrogel. Although the mechanism of cell death has not been elucidated, Uljin is suspected to be caused by nanofibers with asphyxial cells: neither nutrient entry nor cell waste efflux.
Dr. Losser believes that this study shows that high enzyme activity can be a method of positioning cancer cells. Xu also believes that the team needs to use higher than conventional drug concentration of molecules tested. For patients, high concentrations tend to correspond to larger doses, which means that there may be a higher risk of side effects. Uljin also believes that his team needs to carry out some research on the possible side effects of self-assembling carbohydrate-type molecules.