stem cell therapy and heart

Stem cell therapy in heart diseases
Stem cell therapy is upcoming form of treatment which holds great promise
Stem cells are the cells which have the capacity to regenerate and proliferate in an unlimited fashion, provided that suitable substrate for growth and cell division is available. The growth can be of the extent that you can regenerate the entire organ, or the organism itself, if you the methods to control and regulate the growth.
Can stem cells be used to treat heart diseases? Dose stem cells exist in heart? Can heart regenerate following an injury? Can we apply stem cells to regenerate heart?
For last 30 years medical science believed that heart is post mitotic organ (an organ which has completed its cell division reserves and can not regenerate now). “you have so many beats of your heart, so use it wisely”
This concept has changed recently.
• It was a chance discovery: Observation of male cells in female hearts transplanted into
a male patient (cells came either from bone marrow or were produced from remaining cardiac structures of the male patient). This led to intense search for the source of these cells and ultimately led to discovery of ‘cardiac stem cells’. Yes the Heart can regenerate itself. This has been a major change in medical concept and has the potential to revolunize medical treatment
 Heart is now viewed as a self-renewing organ
 Cardiac stem cells are clustered in atria, apex & throughout ventricular myocardium
 Stem cells within damaged area also die
 Do not migrate from healthy myocardium to damaged area, to replace dead cells
Yes the heart divides and repairs itself. It is a constant process. Yes repair goes on in heart as any other organ in the body. It is not a terminally differentiated organ, as believed previously.
But why does this repair process fail in patients with heart disease?
Are there ways by which we can increase this repair process?





 In a typical myocardial infarct (heart attack) it is estimated that one billion cardiac cells are lost.
 A decline in regenerative capacity is also observed with increasing age, in that cardiomyocyte (heart cells) turn over ranged from a rate of 1%/year in young adults to 0.5%in elderly2.
 Myocardial aging – genes which regulate cell division gets dysfunctional, decrease pool of competent stem cells.
 View of cardiac aging & heart failure from perspective of stem cell disorder.
 New paradigm sees heart as a highly dynamic organ in which old, poorly functioning myocytes & vascular smooth muscle cells replaced by activation & commitment of resident Cardiac Stem Cells






Sources of stem cell

Stem cell potency Derived from Can regenerate
Totipotent Fertilized eggs All cell types
Pluripotent Early embroys Most cell types, but not germ cell lines
Multipotent Embroys/bone marrow Multiple cell types
Oligopotent Adult tissues Several cell types
Monopotent Adult tissues Only one cell type







Potential source their advantages and limitations for cardiac repair.


Different cell types have been studied in different patients with cardiac diseases.
There have been extensive animal studies and several early human studies.
Almost all animal studies have shown great improvement in cardiac function with stem cells.
Many of the stem cell trials in humans have shown benefit, some have not shown benefit.
Initially stem cells of muscles from body were isolated and injected in heart with a concept that they could regenerate cardiac muscles. Unfortunately they did not regenerated the heart muscles, instead they formed skeletal muscles in the heart. These fail to establish electrical connections with the heart cells and lead to increased cases of ventricular arrthymia (VT)
Till now bone marrow stem cells have been used most extensively. It has shown extensive safety records and modest benefit in all trials so far. But it has been shown that even these cells do not generate cardiac cells. But they produces benfit form some other mechanisms which we don’t know yet.

Recently cardiac stem cells have been isolated from cardiac biopsy.
Now clinical trials are underway with use of these cardiac stem cells in patients with heart attack and patients with heart failure. First patient undergo cardiac biopsy, their cardiac stem cells are isolated and grown in culture. Then these cells are injected in their heart. Will this approach give more promising results!!! Only time will tell.