Technology platforms for the delivery of therapies to the mitochondria in our cells are both important and showing signs of progress. There are any number of ways in which we would like to manipulate our mitochondria, most importantly to repair or work around damage to their DNA because that is one of the contributing causes of aging. Given a general method for placing any therapy inside mitochondria we should see more development and experimentation in ways to repair them. Here, researchers "have refined the nanoparticle drug delivery process further by using nanoparticles to deliver drugs to a specific organelle within cells. By targeting mitochondria, 'the powerhouse of cells,' the researchers increased the effectiveness of mitochondria-acting therapeutics used to treat cancer, Alzheimer's disease and obesity in studies conducted with cultured cells. ... The mitochondrion is a complex organelle that is very difficult to reach, but these nanoparticles are engineered so that they do the right job in the right place. [Researchers] used a biodegradable, FDA-approved polymer to fabricate their nanoparticles and then used the particles to encapsulate and test drugs that treat a variety of conditions. ... getting drugs to the mitochondria is no simple feat. Upon entering cells, nanoparticles enter a sorting center known as the endosome. The first thing [researchers] had to demonstrate was that the nanoparticles escape from the endosome and don't end up in the cells' disposal center, the lysosome. The mitochondria itself is protected by two membranes separated by an interstitial space. The outer membrane only permits molecules of a certain size to pass through, while the inner membrane only permits molecules of a given range of charges to pass. The researchers constructed a library of nanoparticles and tested them until they identified the optimum size range - 64 to 80 nanometers, or approximately 1,000 times finer than the width of a human hair - and an optimum surface charge, plus 34 millivolts. ... the components they used to create the nanoparticles are FDA approved and that their methods are highly reproducible and therefore have the potential to be translated into clinical settings. The researchers are currently testing their targeted delivery system in rodents and say that preliminary results are promising."