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A patient with myocardial
infarction has been treated with cell grafting. These are really
wonderful news, but have received little attention by the mass
media. Let's see why this is so important according to me.
What happens during a myocardial infarction? A partial or
complete occlusion in a cardiac vessel is the main event and
produces an adverse effect on oxygen delivery. The heart depends
on an adequate supply of oxygen for all the vital processes. This
results in the damage and death of the cells at the infarcted
area. The myocardial cells, which are highly specialized, do not
regenerate, so, if the patient survives, the healing takes place
by the replacement of the infarcted myocardium by scar tissue,
whose cells do not exhibit the contractile properties of the
normal myocardial cells. As a result, the infarcted area
1) fails to contract and
2) may also diminish the conduction of an impulse through
segments of the myocardium. Because of that the infarcted area
may decrease the effectiveness of the contraction of the normal
muscle by bulging outward while the remaining myocardium is
contracting.
If the contraction of the myocardial cells isn't simultaneous, the myocardium looses its ability to pump an adequate quantity of blood to the periphery. This is what occurs in patients with the disease called fibrillation. We can imagine, for example, that we have to push a Fiat 500 with a friend of us, who is as strong as we are. In order to move it we have to unit our forces and push it in the same direction. On the other hand, if our friend pushes in the opposite direction, even if the force we use is the same, we won't be able to move it. So, which are the problems that produces a myocardium infarction? Decreased ability to pump an adequate quantity of blood but, most of all, diminished conduction of an impulse.
In order to understand better the extraordinary achievement of the French group we must explain that there are three types of human muscle cells (fibers). There are the smooth muscular cells that form the involuntary muscles, for example the gastrointestinal muscles that allow the propulsion of the food along the gastrointestinal tract. These are muscles that undergo contraction without our will (although we sometimes hear that for some Indian guru thinks are different). There are also the striated muscles that form our voluntary muscles, as those of the arts, the face muscles, etc. Finally we have the myocardial cells, which are involuntary and have the properties of the striated muscles but form a particular unit, which has as a goal the most effective conduction of an impulse. These particular cells exist only in the heart. Although a muscular cell of the leg is the same as a muscular cell of the face, the myocardial cells are characteristic of the heart.
From the muscle of the patient's thigh have been taken muscular cells that have afterwards been cultivated at the laboratory. After a month's time they have been placed with an injection series at the infarcted area. This procedure has taken place June the 30th, 2000 but the doctors have distributed the news only when they verified that there has been achieved a better efficiency of the heart (greater than what they expected), but most of all a new electrical activity, an event that suggests that these cells have differentiated so as to have a function very similar as the true myocardial cells. Who could be glad to hear these news? Without doubt, all the patients with a heart failure, including those that for years live, or we can better say survive waiting for an implant.
Equipe:
Philippe Menasché et Marcio Scorsin (Hôpital Bichat), Albert
Hagège et Michel Desnos (Hôpital Georges Pompidou), Denis Duboc
(Hôpital Cochin et CEA), André Syrota (CEA), Ketty Schwartz et
Jean-Thomas Vilquin (Groupe hospitalier Pitié-Salpêtrière),
Jean-Pierre Marolleau (Hôpital Saint-Louis).
20/03/2001 Dott. Domenico Alfieri