Regenerative medicine is not an all or nothing field of research. There are many useful waypoints on the road to being able to grow perfectly formed organs, blood vessels, muscle, and other tissues to order and from a patient's own cells. The partial results and half-way houses include a range of potential therapies and technologies that will be a great improvement over the present clinical state of the art.
Roadmaps in this sort of research tend to look like this:
- Gain knowledge of the underlying mechanisms: cell signaling, stem cell life cycles, and so forth.
- Use this new knowledge to better understand the workings of existing therapies, and perhaps optimize them a little.
- Produce new tools for diagnosis and testing procedures based on what is now known.
- Develop a helpful therapy that meets some fraction of the end goal: healing damage in an organ rather than growing a new organ; growing cells to populate a bioartificial system that carries out some of an organ's function, for use in dialysis for example; and so forth.
- Build poor versions of the end goal and find uses for them. The ability to grow small masses of tissue that can carry out some of the functions of a liver or a kidney may be very helpful as implants for those suffering organ failure, for example.
- Finally, the end goal: organs grown from a patient's cells that are good enough for transplant.
Below is an example of one type of waypoint in tissue engineering that is presently under widespread development: the use of cell transplants to spur regeneration and regrowth that would otherwise not have happened. This is a logical application of some of the knowledge gained regarding organ formation and growth; which cells are important, how they work together, and how they signal one another.
[Scientists] have for the first time demonstrated that baboon embryonic stem cells can be programmed to completely restore a severely damaged artery. These early results show promise for eventually developing stem cell therapies to restore human tissues or organs damaged by age or disease.
Researchers completely removed the cells that line the inside surface from a segment of artery, and then put cells that had been derived from embryonic stem cells inside the artery. They then connected both ends of the arterial segment to plastic tubing inside a device called a bioreactor which is designed to grow cells and tissues. The scientists then pumped fluid through the artery under pressure as if blood were flowing through it. The outside of the artery was bathed in another fluid to sustain the cells located there.
Three days later, the complex structure of the inner surface was beginning to regenerate, and by 14 days, the inside of the artery had been perfectly restored to its complex natural state. It went from a non-functional tube to a complex fully functional artery. "Just think of what this kind of treatment would mean to a patient who had just suffered a heart attack as a consequence of a damaged coronary artery. And this is the real potential of stem cell regenerative medicine - that is, a treatment with stem cells that regenerates a damaged or destroyed tissue or organ."