Inkjet bioprinting opens cells to new possibilities
With a little ingenuity, office equipment can be used in surprising ways. Old inkjet printers are an important tool for bioprinting (the old models have larger droplet size, which makes a more comfortable fit for cells to pass through undamaged). By emptying out the ink cartridges and refilling with a cargo of cells in a carrier fluid, researchers have printed patterns of cell-packed droplets to create living tissue. Recently researchers from Clemson University discovered that inkjet bioprinting disrupts the membranes of the cells being printed, leaving them open to having proteins inserted ... and opening up new avenues of research in the field.
The goal of bioprinting is to eventually grow new body parts for transplant. This video by Christopher Barnatt provides a good overview of the bioprinting process and where it could lead us.
It turns out that inkjet bioprinting does more than simply deposit living cells. Using a modified HP DeskJet 500 printer, Dr. Delphine Dean and researchers from Clemson University have found a useful side-effect to the bioprinting process.
The printer was modified by removing the paperfeed mechanism and adding a 3D stage with which to move the slides on which cellular patterns are to be printed. The ink was replaced with a cell solution and the cells printed in linear strips directly on to the slides. By moving the slides back and forth and in height, 3D bioprinting is made possible.
Dr. Dean's group only recently discovered that the stress of droplet ejection and impact disrupts cell walls creates temporary holes in the membranes of live cells. These pores allow researchers to put molecules inside of cells that wouldn’t otherwise fit, and study how the cells react.
“We first had the idea for this method when we wanted to be able to visualize changes in the cytoskeleton arrangement due to applied forces on cells,” said Dr. Dean.
The team achieved this goal by using the holes to introduce fluorescent molecules that illuminate the cytoskeleton of the cell.
“We are actually interested in the cell mechanics of compressed cells," said Dr. Dean. "This method allows us to push on the cells and watch the response easily. We are interested in cardiovascular cells, and how they respond to mechanical force.”
At present the size of the holes (10 nm) limits what proteins can be inserted into the cells, but refinement of the process may well extend this range.
The new technique also holds promise for introducing proteins into mature cells that reprogram those cells to revert to pluripotent stem cells as a part of the bioprinting process. This capability would allow a large range of bodily tissues to be printed from one easy to maintain feed stock.
Details of the method were published in JoVE, the Journal of Visualized Experiments, on March 16.
“The authors have used an extremely innovative approach for bioprinting cells. Moreover, this approach can be used for applications other than cell printing,” said JoVE Science Editor, Dr. Nandita Singh. “Matrix proteins can be printed onto substrates with this technique for cell patterning.”