The Bush embryonic stem cell funding limitations will be histoire as of January 20, 2009. But the advances in ethical stem cell research, that I believe his policy did much to promote, will not abate. Now, umbilical cord blood stem cells have been used to create rudimentary heart valves. From the story:
Lest we hype the science like the ESCR advocates have so shamelessly, it is important to understand there is much work to do with no guarantees:Stem cells collected at birth from the umbilical cord may help doctors fashion new heart valves for children born with heart valve defects.
The tissue-engineered valves would have the advantage of growing with the child, the German researchers said. “If we replace a valve in a child, they will need surgery several times in their lifetime, because they will grow out of the devices, so the ultimate goal is to have a construct which is able to grow with the child and only have to do the surgery once,” said study author Dr. Ralf Sodian, a cardiac surgeon at University Hospital of Munich. “Earlier is better, if it’s possible.”
Presenting Monday at the American Heart Association’s annual scientific sessions in New Orleans, Sodian reported that his team took stem cells from umbilical cord blood, stored them for 12 weeks, then seeded them on to eight heart valve scaffolds.
The stem cells went on to form a layer of tissue which included several characteristics of the “extracellular matrix,” or the section of tissue outside of cells.The engineered valves had almost 78 percent as much collagen as human tissue from pulmonary heart valves; 85 percent as much glycosaminoglycan as human tissue; and 67 percent as much elastin. Collagen and elastin are proteins in connective tissue, and glycosaminoglycan is a carbohydrate in connective tissue.
“I don’t think anyone has any idea if [these valves] would grow,” Luepker said. “One may not know until it is put into a child, and the child grows. There are obviously a lot of hurdles to overcome.”...There is also a possibility that the child’s body will reject the artificial valve, although this is not so common, Luepker said.This much is sure: The old meme that “embryonic stem cells are the only hope” for regenerative treatments is as dead as the Bush funding policy.
A bigger issue is the sheer work that a heart valve has to perform. “The stresses on a heart valve are enormous,” Luepker said. “They have to hold the blood back with each beat. The wear and tear on them which we see with metal and plastic valves is an issue, and those are fairly hard substances.”
