Biomedical engineering researchers have developed an anti-cancer drug
delivery method that essentially smuggles the drug into a cancer cell
before triggering its release. The method can be likened to keeping a
cancer-killing bomb and its detonator separate until they are inside a
cancer cell, where they then combine to destroy the cell.
The technique uses nanoscale lipid-based capsules, or liposomes, to
deliver both the drug and the release mechanism into cancer cells. One
set of liposomes contains adenosine-5’-triphosphate (ATP), the so-called
"energy molecule." A second set of liposomes contains an anti-cancer
drug called doxorubicin (Dox) that is embedded in a complex of DNA
molecules. When the DNA molecules come into contact with high levels of
ATP, they unfold and release the Dox.
The surface of the liposomes is integrated with positively charged lipids or peptides, which act as corkscrews to introduce the liposomes into cancer cells.
As the liposomes are absorbed into a cancer cell, they are sealed off from the rest of the cell in an endosome - a compartment that walls off all foreign material that gets into a cell.
The environment inside an endosome is acidic, which causes the Dox liposomes and ATP liposomes to fuse together, as well as to the wall of the endosome itself.
Meanwhile, two other things are happening simultaneously. First, the ATP liposomes spill their ATP into the Dox liposomes, releasing the Dox from its DNA cage. Second, the walls of the Dox liposomes create an opening in the endosome, spilling their Dox-rich contents into the surrounding cell - leading to cell death.
In a mouse model, the researchers found that the new technique significantly decreased the size of breast cancer tumors compared to treatment that used Dox without the nanoscale liposomes.
The surface of the liposomes is integrated with positively charged lipids or peptides, which act as corkscrews to introduce the liposomes into cancer cells.
As the liposomes are absorbed into a cancer cell, they are sealed off from the rest of the cell in an endosome - a compartment that walls off all foreign material that gets into a cell.
The environment inside an endosome is acidic, which causes the Dox liposomes and ATP liposomes to fuse together, as well as to the wall of the endosome itself.
Meanwhile, two other things are happening simultaneously. First, the ATP liposomes spill their ATP into the Dox liposomes, releasing the Dox from its DNA cage. Second, the walls of the Dox liposomes create an opening in the endosome, spilling their Dox-rich contents into the surrounding cell - leading to cell death.
In a mouse model, the researchers found that the new technique significantly decreased the size of breast cancer tumors compared to treatment that used Dox without the nanoscale liposomes.
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