Nano-medicine - using nano-sized particles to deliver drugs - has the potential to revolutionise the treatment of common maternal and fetal conditions, without side effects or risks to the mother or baby, according to a leading researcher.
Jeff Keelan, principal research fellow in the University of WA's School of Women's and Infants' Health, said nano-technology had the potential to create drugs that "boldly go where no drug has gone before".
"In conventional medicine you take a pill, aspirin say, and it gets dissolved in the stomach, enters the bloodstream and circulates around the body so all of the organs and tissues in your body get exposed to that drug," he said. "It is very non-selective."
Nano-medicine is a bit like adding a postcode to medications - it allows the drugs to be targeted to a specific destination in the body.
Nano-particles, which are the "envelopes" that contain the drugs, are usually made out of a biodegradable polymer and are about the size of a virus, ranging from one to 200 nanometres in diameter. A nanometre is one billionth of a metre.
The "envelope" or shell has a chemical structure that enables it to be targeted to a specific tissue. Once the envelope has reached and entered the target cell, it dissolves and the drug is released.
"Because it goes directly to the cell of interest, the dose you need to give of the drug is much, much smaller, maybe hundreds of times smaller," Professor Keelan said. The average dose of a drug is 10 to 1000mg whereas for nano-drugs the doses would typically be 0.1-10mg.
Professor Keelan is working on nano-particles for pregnancy with three different targets in mind - the mother, the placenta and the baby.
"Sometimes women in pregnancy have to take drugs that might be harmful to the baby," he said. These include drugs for epilepsy, cancer, hypertension and depression. So if you can figure out a way of designing a drug that does not cross the placenta, then you know that the drug is just going to act on the mother without affecting the baby," he said. "I call them 'fetal-friendly' drugs."
It might also be possible to devise therapies that targeted the fetus only; for example, if a test during pregnancy showed that the fetus had a genetic or metabolic defect, gene therapy could be delivered directly to the fetus using nano-delivery. Cystic fibrosis was an example of a genetic disorder that potentially could be treated with nano-medicine.
The placenta was another target and was particularly attractive because it was readily accessed via the mother's blood. In cases where the baby was not growing properly - so-called intra-uterine growth restriction - a "cocktail" of growth factors, nutrients or an enzyme that made a nutrient, could be delivered to the placenta.
"Inflammation and infection in the placenta is one of the major causes of preterm birth and in this case, nano-particles could deliver anti-inflammatory drugs and antibiotics to the tissues," Professor Keelan said.
"Really, the possibilities are limitless."
The particles that Professor Keelan and his team are working with have a fluorescent tag and can be tracked within the body to ensure they are reaching their target.Professor Keelan said it was expected that within one or two years, nano-particles for pregnancy would have been designed that were effective, safe and well tolerated with no side effects. The next stage would be clinical trials. The first of the nano-drugs were now coming on to the market and were treating diseases such as cancer.
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