If you lose or damage an organ due to disease or injury, typically your only option is to get an artificial organ or a transplant. Unfortunately, artificial organs and other implanted devices often fail over time, partly due to being funkified with biofilms, dense coatings of drug-resistant bacteria or fungi.
On the other hand, a successful transplant requires a compatible and willing donor. If you can't wait at least a few months for the new organ, you're probably out of luck.
How about designing an artificial organ?
It would be much better if a new organ could be grown in a laboratory. Certain classes of stem cells show promise for this goal, at least those that can be grown into a wide range of cell types as needed.
Living cells are genetically programmed to assemble themselves into tissue and organs. However, scientists are still in the early stages of understanding how this works.
If an artificial organ is to assemble and work properly, specific cells must be directed to specific locations at a specific time, forming patterns of cells with a defined function. This is a fundamental feature of tissue and organ assembly in all living organisms.
A major challenge is figuring out not only how to fabricate such patterns of cells, but also how to control protein synthesis within the patterns. The proteins in cells are the direct actors in cell (and ultimately organ) function.
Previous research in this area suffers from insufficient cellular responses to some stimulus (usually light) intended to control protein synthesis. John Koh (University of Delaware, United States) and coworkers have addressed this limitation.
Their research has shown how to use light to spatially pattern genetically engineered cells (in the absence of physical restraints), and to utilize these patterns to define the function of cells within these patterns, thereby fabricating primitive "artificial tissue." Their research is complimentary to that of other scientists who have used DNA to assemble cells into specific three-dimensional arrangements for the facilitation of cell-cell communication.
Fabricating primitive artificial tissue.
The scientists genetically engineered their cells to quickly synthesize a fluorescent protein after brief illumination with UVA light. Impressively, fluorescent protein synthesis in response to brief illumination (a stimulus that can be quickly turned on and off) was comparable to that of two hours of direct chemical treatment (a stimulus than cannot be quickly turned on and off).
Obvious cell patterns were observed four or six hours after briefly, selectively illuminating a group of cells. A cell pattern is a group of cells that were producing large quantities of protein, more than their nonilluminated neighboring cells.
Maximum protein production was observed after 26 hours. The cells that had been illuminated with UVA light (i.e. those within the pattern, over 70% of which were active) were producing on average nearly five times the amount of protein as the cells that had not been illuminated (i.e. those outside the pattern).
Cellular response time was limited only by the cells' speed of protein synthesis. Patterns were still visible after four days, far longer than that reported by other scientists using different approaches to cell patterning, at least those that do not utilize physical restraints to immobilize their cells.
Approximately 20% to 30% of the cell patterns were sharply defined, while the remainder possessed regions of low levels of protein production surrounding the region of intended patterning. The scientists were able to fabricate well-defined cell patterns down to a width of approximately 300 micrometers.
Controlling the biological function of primitive artificial tissue.
Up to this point, the scientists have demonstrated that they can control protein synthesis by cells arranged within defined patterns through brief illumination with UVA light. Next, they demonstrated that patterned cellular assemblies can exhibit a biological function.
The scientists genetically engineered their cells to synthesize a protein that enables them to adhere to a second type of cell. Using a similar protocol as previously described, they fabricated patterns of cells, and observed an almost 100% increase in adhesion to this second type of cell, relative to cells that were not a part of the defined pattern.
A third type of cell was studied that was designed to be repelled by the genetically engineered original cells. Repulsion was over 100 times as effective within the cell patterns, relative to cells that were not a part of the defined pattern.
This demonstrates a biological function of the cell patterns. The cellular assemblies can therefore be classified as a primitive "artificial tissue."
These scientists were clearly able to fabricate patterns of cells, without specifically immobilizing the cells onto some surface. Most importantly, they were able to utilize these patterns to control the function of the cells with a mild stimulus, thereby fabricating primitive "artificial tissue."
In the short term, their research will be very useful for studying the biochemical consequences of cellular arrangement into patterns for functional coordination, a phenomenon that is fundamental to tissue and organ assembly in all living organisms. In the longer term, this is an important step towards fabricating artificial tissues and organs from the bottom up.
for more information:
Sauers, D. J., Temburni, M. K., Biggins, J. B., Ceo, L. M., Galileo, D. S., & Koh, J. T. (2010). Light-Activated Gene Expression Directs Segregation of Co-cultured Cells in Vitro ACS Chemical Biology, 5 (3), 313-320 DOI: 10.1021/cb9002305