Introduction:

Stem cell research area is not new for researchers but real breakthrough in this industry came when stem cells used as a therapy for heart regeneration. At present, heart failure is amongst one of the major causes of deaths. Scientists are continuously working in this area in collaboration with physicians for the betterment of the patients of heart failure. In past few years, stem cells have shown there marked importance as a therapy for the treatment of conditions like leukaemia. Scientists have explored the potential of stem cells as a therapy for heart diseases and results have shown that they are on the right track. In year 2013, the most read article of the "Cell Press" in 2013 is "Cardiac Stem Cell Therapy and the Promise of Heart Regeneration" by Garbern and Lee. This study has opened up the mind of researchers and scientist in this field towards a new domain of stem cell research. For cardiac disease stem cell therapy is an interesting and exciting research area. Although techniques like cell transplantation strategy and cellular programming have always been attractive approaches but scientists have found some pitfalls in these strategies.

Stem Cells:

Stem cells are those undifferentiated biological cells which are capable of differentiating into specialized cells. Stem cells undergo mitosis to produce daughter stem cells. In mammals the two basic types of stem cells are embryonic stem cells and adult stem cells. In adult organisms stem cells also help progenitor cells to replenish adult tissues. Thus, both progenitor cells and stem cells work as repair and replenishing system of body. Bone marrow, blood and adipose tissues are the three major sources of adult stem cells in humans. In a new born baby stem cells can also be extracted from umbilical cord. Stem cells can be grown artificially and differentiated into specialized cells in vitro using cell cultures. Stem cells have been used in treatment of many diseases like leukaemia by bone marrow transplantation. Use of stem cell as a therapy ranges from wound healing to rheumatoid arthritis to treatment of spinal cord injury to cancer treatment. Stem cells have also been used in treatment of disease of Central nervous systems like Parkinson's disease and Alzheimer's disease. But the major concern regarding stem cell therapy is that if stem cell differentiated in an uncontrollable manner then it can result in the formation of tumours. Another problem associated with stem cell therapy is immune rejection for non native cells.

Role of cardiac stem cell in heart regeneration:

The first ray of hope for the treatment cardiac disease using stem cell therapy has emerged years ago with the identification of stem cells in heart that are capable of generating cardiac tissues and coronary vessels. Endogenous cardiac stem cells (eCSCs) were first discovered in 2003 by Bernardo Nadal-Ginard and team. Before this discovery heart was thought to be a post mitotic organ lacking regenerative capability. The finding that endogenous cardiac stem cells (eCSCs) play an important role in cardiac homeostasis has opened new doors to research for cardiac disease treatment by considering the heart as an organ with regenerative potential. In this new era heart is considered as a self renewing organ. Theories which explained the origin of new cardiac cells in mammals are (a) new cardiomyocytes arises from progenitor or stem cells. (b) This theory suggests that mitosis of mature cardiomyocytes give rise to daughter cells. In addition to these theories, an important role of endogenous c-kitpos cardiac stem cells (eCSCs) has been noted but there significance for the process of regeneration is quite controversial.

What do researchers have to say?

Various research groups all over the world are working in this area. An article published in the well renowned journal "Cell" have mentioned that it is the intrinsic feature of the stem cells to repair the cardiac cells after injury. It has been shown that if stem cells are removed from the cardiac tissue then heart tissues will not be replenished. The study has also revealed the fact that replacement of the cardiac stem cells leads to full anatomical, cellular, and functional heart recovery. Cardiac tissues return to the healthy state and heart start functioning properly. A series of experimentation carried out by one of the leading research groups have established that endogenous cardiac stem cells (eCSCs) play the significant role in cardiac tissue replenishment after injury. In this study, stem cells were removed from cardiac tissue of rodents with heart failure. This removal puts a stop to the regeneration of heart and recovery of the cardiac cells, representing the inherent regenerative ability of stem cells to repair cardiac. Professor Bernardo Nadal-Ginard and Dr Georgina Ellison from the Centre of Human & Aerospace Physiological Sciences and the Centre for Stem Cells and Regenerative Medicine at King's quoted that 'In a healthy heart the quantity of cardiac stem cells is sufficient to repair muscle tissue in the heart. However, in damaged hearts many of these cells cannot multiply or produce new muscle tissue. In these cases it could be possible to replace the damaged cardiac stem cells or add new ones by growing them in the laboratory and administering them intravenously.' It has also been added that currently cells are being injected through coronary vessels (intracoronary) or cardiac muscle wall (intramyocardial) but our study focussed on homing mechanism and to a less invasive procedure where stem cells are injected through a vein present in the skin, i.e., intravenously.

Conclusion:

Stem cell therapy for cardiac regeneration needs further research in this area. After many decades of first heart transplantation we are on a new path for the patients of heart failure. This innovative research is under its clinical trials and everyone is hoping for the positive results. If the results of human trials will favour this technology of heart regeneration then it will be one of the major breakthroughs of all time in stem cell research.

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