A chemical 鈥楾rojan horse鈥� developed in the US may lead to a host of
new therapies against many diseases 鈥� from cancer to diabetes 鈥� by ushering
drugs and other biological substances directly into living cells. This breaks
new ground in medicine because cells will not normally admit large molecules
such as proteins, monoclonal antibodies and enzymes, many of which have
therapeutic potential.
Philip Low and colleagues at Purdue University in West Lafayette, Indiana,
have overcome this problem by tacking large molecules onto folic acid, a
member of the vitamin B family which is vital to the survival of cells.
Like other vitamins, folic acid is readily admitted into cells. 鈥楾he vitamin
opens the door for the protein,鈥� he says.
Low鈥檚 team attached a chemical grouping to folic acid that can act as
a 鈥榟ook鈥� for other molecules. So far though, his team has only succeeded
in delivering enzymes to cells in culture. 鈥業t鈥檚 very much in the basic
science stage,鈥� he says.
Advertisement
But the potential is huge if Low鈥檚 team can achieve its goal of scaling
up the process to deliver drugs to animals and, ultimately, people. For
example, in some cancerous cells certain proteins are overabundant and may
contribute to the growth of the cells. Low says a combination of folic acid
with an antibody against the protein could disarm the cancer cells by disrupting
the production of the protein. In normal cells, the protein would be present
in much smaller amounts or absent altogether, so the antibody would remain
inert and leave the cell unharmed.
Low says that biologists have attempted to deliver drugs into cells
with hormones, which also have a 鈥榢ey鈥� to enter cells. However, the hormones
are directed into the 鈥榮tomachs鈥� of cells, known as lysosomes, and are rapidly
digested along with any other material. In contrast, the folic acid and
its passenger reach the cell鈥檚 cytoplasm, where they remain unharmed. 鈥業n
practice, (our method) is the only way to deliver things nondestructively
into the cell,鈥� says Low.
