Optimists like myself don't like speculating on the limitations of technologies. Being somewhat of a scientist as well as a doctor, my ethos is to exhaust all areas in order to give somebody in need a hand.

Putting my personal sentiments aside, stem cell technologies in the future will have the ability to reverse most disease states, cure or combat conditions and rebuild injured tissues.

There are, however, some limitations that I can see both now and in the future, regardless of how far stem cell therapies progress. And that is in regards to certain genetic conditions.

When we arrive at a point in stem cell technology where we can inject or implant stem cell loads directly into the area of damaged tissue, we have to ask ourselves, "What if the complete nervous system is damaged?"

If that were myself, then my answer would be, "Let's treat the whole nervous system, a bit at a time, starting with the parts that need it the most (ie, nerves that supply vital functions, and so on...)".

The problem is that some genetic conditions proceed rapidly. Thankfully, all do not and are usually progressively slow. However, unfortunate as it may be, some progress more rapidly. Do we simply continually treat different areas? As I've said, if it were myself, I'd take a stab at it, provided the safety was there and the benefits outweighed the risks.

Let's say for example, we advance stem cell therapies to such a level, whereby we can grow a complete clone our ourselves and simply transplant the brain into the new body, reconnecting the cranial nerves to the new body with stem cells as well. Sounds like sci-fi, I know, but I believe this will be easily done in the future once the technology is there.

But my point is this: Even at this level of technology, there are some genetic conditions that affect ONLY the brain. And this is also what I'm refering to in regards to limitations. In some respects, we will even be able to treat the entire brain with stem cell implants - and even continually replace genetically faulty neurons and supporting tissue in the brain, even as it begins to become damaged, as is the case with some inherited lipid metabolism disorders.

The effects of replacing cells will delve into areas of actually replacing cells that are part of a memory, a reflex, or a vital function. This will be interesting medicine, but as I am hoping, will be aimed at helping people to live better quality lives.

But until we develop these levels of technology, even if we do, what can we do now?

It doesn't mean that for these conditions there is less hope of a cure. If genetic engineering research (gene therapy) parallels other areas of medical research, I believe treatments will be on par with each other.

As you may know, using gene therapy, a defective gene can be replaced with functionally correct gene. Of course, gene therapy has its risks as well, but it's getting better as well. With the combination of stem cells to replace damaged cells, and gene therapy to replace defective genes, the future looks bright. But always keep in mind the limitations we face along the way...

Understanding, will help each of us cope with our situation to the best of our ability while we tackle these conditions.