The Role of Stem Cells in Regenerative Medicine

Introduction

Generally, stem cells are defined as antecedent cells that possess the ability to renew themselves and produce numerous matured cell types. Based on the role they play in the body of a person or an animal, stem cells are defined as cells that have an incredible potential for limitless self-renewal, in addition to a useful ability to generate one or more types of matured and specialized cells (Chagastelles & Nardi, 2011). The ability to self-renew and generate different cell types in the body enables the stem cells to serve as some kind of internal restoration system in the body of a living person or animal. The cells basically divide limitlessly to replace other worn out or dysfunctional cells. After the stem cells have divided, the newly formed cells can either remain stem cells or develop into a differentiated cell with a particular function such as a red blood cell, brain cell, or a muscle cell.

Main Features of Stem Cells

There are two essential features of the stem cells that differentiate them from other types of cells. First, stem cells are unspecialized and have the capability of self-renewal through the process of cell division regardless of how long they have been sedentary, an ability that is not present in the other normal body cells. The stem cells frequently divide to mend and replace worn out and dysfunctional tissues and cells in organs such as the bone marrow and the gut. In other organs, such as the heart and pancreas, the cells divide only under unusual circumstances. Additionally, stem cells—under certain investigational or physiological conditions—can be cultured to become organ-specific or tissue-specific cells with explicit functions.

Categories of Stem Cells

Stem cells can be categorized into three main groups: embryonic stem cells, tissue-specific/somatic/adult stem cells, and induced pluripotent stem (iPS) cells. Embryonic stem cells are obtained from the embryo. These cells are normally derived from the interior cell mass of the blastocyst in embryos developing from in vitro fertilized eggs after which they are donated for research with the permission of the donors. Embryonic stem cells are pluripotent: when these cells are not interrupted, they have the ability to develop and give rise to every type of differentiated cells (except the umbilical cord and the placenta) in the fully formed body of a person or an animal (Biswas & Hutchins, 2007). However, when scientists extract the embryonic stem cells from the blastocyst and culture them under laboratory conditions, the cells retain their embryonic stem cell properties. In culture, the embryonic stem cells self-renew easily thereby providing a renewable resource for studying disease and ordinary development, in addition to drug and therapy testing (Chagastelles & Nardi 2011). Although these stem cells are very useful tools for scientists, their mode of acquisition remains a major disadvantage. In the acquisition of human embryonic stem cells, for instance, human embryos are damaged thereby making the process unacceptable among people who hold the opinion that life starts at conception. On the other hand, tissue-specific stem cells are found in specific tissues or organs in the body and tend to be more differentiated relative to embryonic stem cells. Unlike the embryonic stem cells that can generate virtually all types of cells in the body, tissue-specific stem cells typically create different types of cells for the particular organ or tissue in which they are found (Brack & Rando, 2012). Also, tissue-specific stem cells can be difficult to locate in the body and they self-renew less easily in culture as compared to embryonic stem cells.

Application of Stem Cells

The final category of the stem cells is the induced pluripotent stem cells. These are cells that have been engineered in the laboratories by scientists. The creation of these cells involves the conversion of tissue-specific stem cells into cells that exhibit the features of embryonic stem cells (Chagastelles & Nardi, 2011). Even though they are not exactly similar, the IPS cells and the embryonic stem cells share numerous common features; therefore, the IPS cells are normally used for the same purposes as the embryonic stem cells: the study of normal growth and progression and disease onset and development, as well as the development and trial of new therapies and drugs.

Advantages of Stem Cell Therapy

Although donated tissues and organs are frequently used to replace sickly or damaged tissues and organs in the contemporary world, it is apparent that the demand for such organs and tissues is gradually outweighing the supply. Therefore, there is an urgent need of alternatives. One potential alternative is the application of human stem cells to generate tissues and organs which can then be used to replace the worn out or dysfunctional organs or tissues in the body. By guiding stem cells to differentiate into particular types of cells, we can create a constant supply of replacement tissues and cells for the treatment of diseases such as stroke, heart disease, burns, macular degeneration, spinal cord injury, rheumatoid arthritis, and diabetes.

Stem Cell Therapy for Spinal Cord Injury

In spinal cord injury, for instance, there is a loss of nervous tissue which results in the loss of sensory and motor functions. Since no treatment is currently available that can restore the loss of sensory and motor function in spinal cord injury, the use of stem cells may help repair the damaged cells and tissues (Nandoe Tewarie et al., 2009). Since stem cells can renew themselves and become any cell in a living organism, they can be guided to specialize into glia or neurons in vitro. The newly generated neurons can then be used to replace the damaged neural cells in the spine thus restoring the sensory and motor functions. A clinical trial of the spinal cord injury cell-based therapy was conducted on 25 patients in Guayaquil, Ecuador by a biotechnology company based in California. The trial indicated positive outcomes as the patients reported improved perception of the sensory and motor functions (Nandoe Tewarie et al., 2009). The encouraging results obtained from the trial suggest that the application of stem cells for the treatment of injuries and diseases could be very beneficial.

Conclusion

In conclusion, the clinical application of stem cells for the treatment of various diseases and injuries has great potential for transforming thousands of lives. As scientists continue to explore ways of how to safely incorporate cell-based therapy into health systems, we also need to address the ethical hurdles that surround stem cells and their applications, especially the conflict over the acquisition of the embryonic stem cells. Unless a majority of the people are convinced of the benefits of cell-based therapy, the success of this approach is ever going to be limited.

References

Biswas, A., & Hutchins, R. (2007). Embryonic stem cells. Stem cells and development, 16(2), 213-222.

Brack, A. S., & Rando, T. A. (2012). Tissue-specific stem cells: lessons from the skeletal muscle satellite cell. Cell stem cell, 10(5), 504-514.

Chagastelles, P. C., & Nardi, N. B. (2011). Biology of stem cells: an overview. Kidney international supplements, 1(3), 63-67.

Nandoe Tewarie, R. S., Hurtado, A., Bartels, R. H., Grotenhuis, A., & Oudega, M. (2009). Stem cell-based therapies for spinal cord injury. The journal of spinal cord medicine, 32(2), 105-114.