In recent years scientists have made synthetic versions of key parts of the cell, such as chromosomes and ribosomes. Now researchers have developed the first working artificial prototype of an “organ” of a human cell—the Golgi apparatus.
Made up of a network of sacs piled together like a stack of pancakes, the Golgi apparatus chemically modifies proteins to help make them stable and functional, and it helps to manufacture complex sugars. But it remains one of the most poorly understood organelles. “The sacs are fluid and constantly change shape, so it’s difficult to get a handle on,” explains Robert Linhardt, a chemist at Rensselaer Polytechnic Institute. “And while we know the general direction of the flow of vesicles between stacks, we don’t really know what cargoes they’re carrying.”
To better dissect how the Golgi apparatus works, Linhardt and his colleagues created a synthetic version of it, designing a square-millimeter-size lab-on-a-chip to mimic the assembly line of enzymes that modify a biomolecule within the Golgi apparatus. The sample molecules are attached to magnetic particles suspended in a watery droplet 300 billionths of a liter in size and placed on the chip. When the desired location on the chip for those molecules is electrically charged, it attracts the droplet and causes it to flow there. A larger magnet under that spot can keep in place the magnetic particles attached to the biomolecules. In this way, the drop can be moved through chambers loaded with an assembly line of enzymes, sugars and other raw materials.
In experiments with an inactive precursor of heparin, a widely used blood thinner, the scientists discovered their device could quickly and efficiently modify the anticoagulant to make it functional, findings they detail in the August 12 Journal of the American Chemical Society. The researchers suggest that an artificial Golgi could lead to a faster, safer method of producing heparin than current techniques, which employ animal tissue.
Scientists have experimented with building up cells piece by piece for decades, including the creation of simple artificial cells in the form of bubbles made of synthetic cell membranes, to better understand how life on earth might have began. In 1997 researchers devised the first artificial human chromosome. And earlier this year molecular technologist George Church of Harvard University and his colleagues developed artificial ribosomes—bodies inside each cell that make proteins based on instructions from DNA—that functioned under cell-like conditions.
Linhardt and his co-workers plan on creating a synthetic endoplasmic reticulum (ER) as well, the organelle into which ribosomes are studded and where protein synthesis and folding take place. “We’d even like to integrate an artificial Golgi and ER together,” Linhardt says. “We’re basically taking pieces of a cell and making them on electronic chips,” with the hope of moving to even more complex systems.
Note: This article was originally printed with the title, "Going with Golgi."