Researchers aiming to explore the mitochondria of an individual cell traditionally had to settle for a method that involves breaking open groups of cells and studying the mitochondria in a sort of cellular soup. From that mix, however, it is nearly impossible to link a particular mitochondrion with its cell of origin.
A team of biologists and physicists at the National Institute of Standards and Technology and Gettysburg College has developed a new method to surgically remove individual mitochondria using lasers and a tiny pipette with a tip less than a micrometer wide. Their approach, which uses a combination of existing techniques — including a protocol for parsing out single chromosomes from isolated rice cells with a laser pulse to make an incision into a cell's outer membrane — allows researchers to place the isolated mitochondrion into a small test tube where its genetic makeup can more reliably be analyzed.
The team's initial findings using this laser tweezers approach confirmed that a mutation present throughout an entire cell was also present within an individual mitochondrion. The group says this method has wide- ranging implications for investigators looking to study diseases related to mitochondrial DNA, such as early-onset blindness, seizures, dementia, and hearing loss. "Detecting differences between single cells and sub-cellular organelles may allow doctors to diagnose diseases long before symptoms present themselves," says Joseph Reiner, a physicist at NIST. "One can imagine treating and preventing a disease at an extremely early stage of development by performing analysis on single cells or single organelles."
Reiner and his colleagues are hoping to further develop their extraction method to facilitate single organelle studies, which could be used to detect mtDNA changes following exposure to environmental toxins or radiation. "Overall, having the tools to isolate a single mitochondrion from a specific cell will benefit many cellular and sub-cellular studies," Reiner says. "Using [cells that have been depleted of their mitochondrial DNA], mitochondria dynamics, replication, mtDNA propagation, and nucleoid formation can be studied more systematically. Mitochondrial metabolomics — in other words, metabolic production within a single mitochondrion — could also be attempted."