I've been a bodybuilder twice in my life, literally and figuratively, and I've always been fascinated by the body's ability to heal itself in even the most extreme circumstances.
I built my own body for athletic competitions back in the day, and rebuilt just about every part of the human body in my days as a reconstructive surgeon. But now, with the help of scientists and doctors around the world, I'm hoping that a much more effective method of building and rebuilidng the human body will emerge as the gold standard for treating injured, damaged, or diseased organs and tissues. The ability to "grow" new body parts has been one of the holy grails in medicine and reconstructive surgery, but now it's not just another episode from a science fiction movie.
A recent article in the New York Times chronicled the story of a 39 year old man whose wind pipe was replaced with a "bioartificial' trachea after a malignant tumor was discovered. Stem cells were harvested from his bone marrow and placed into a specially designed plastic matrix that guided the growth of the cells into a "live" replica of the man's trachea, which was then surgically implanted after the diseased section of his own trachea was removed.
The Times reported this revolutionary procedure as "the first of its kind", and while there is no doubt that it has helped bring the field of tissue regeneration out of the labratory and into the real world, it's actually not the first time tissue regeration has been used in the clinical setting. Plastic surgeons have used cultured human keratinocytes (sheets of skin grown in the lab) for years to treat severe burn injuries, and this research has served as the foundation for several active bioengineering projects today. Believe it or not, tissue regrowth even plays an active role in cosmetic surgery with procedures like fat transfer, stem cell facelifts, and collagen regerating products like Sculptra.
The growth of more complex organs like livers, kidneys, hearts and blood vessels is still in the investigational stage, but with the vast number of physicians and surgeons working on this new biotechnology, it is realistic possiblity that damaged and diseased organs will soon be regenerated instead of transplanted. Several labratories around the world are developing "scaffolds" that guide the growth of harvested cells into new organs and tissues, as well as mechanisms that promote the incorporation of the new organs into the body's natural functioning.
For now, organ transplants and artificial hearts are still the saving grace for many patients, but these procedures necessitate a delicate, and sometimes dangerous, balance between life-long immune suppression and maintaining an acceptable quality of life. When body parts are injured beyond repair in accidents or trauma, plastic surgeons can often reconstruct the injuried part using uninjured parts of the individuals' body, but this rarely leads to a functionally or aesthetically ideal result. The past and present success of tissue engineering may one day mean that cancerous livers will be regrown, slcerotic blood vessels in the heart will be replaced, traumatically amputated limbs will be regenerated, and burned ears and noses will be recreated.
After all, if a starfish can regrow an arm and a crab can regenerate a claw, why can't we?
Nicholas Vendemia, M.D.
But there is one problem to keep in mind. In nature (whether it be the starfish, or salamander, or flatworm, etc.), regeneration (and generation for that matter) is a bottom-up process, where you start with a small group of cells that grows, differentiates, interacts, and organizes based on a defined set of steps in the genetic blueprints AND continual changes to those blueprints following every sequential step (each step dictates the next in the process). Organ bio-printing, or growing stem cells on scaffolds, is trying to approach the problem from top-down perspective, which misses many of the intricacies of organogenesis (like size control, polarity, positional specification, etc. not to mention issues related to vascularization) You couldn't "build a baby" by mixing together a few trillion cells in a bowl... And while top down may work alright for simple tissues in sheets or tubes, it gets much more complex when dealing with the requirements for tissue stability and survival of critical organ systems that need to operate in 3 and technically 4 dimensional space. so in answer to your question "...if a starfish can regrow an arm and a crab can regenerate a claw, why can't we?" - it is because the industry is approaching the problem from the wrong angle (and from one that is way too reductionist), so far... Ira S. Pastor CEO Bioquark Inc.