Stem cells relate to biological cells with the capacity to differentiate into various cell types and can divide to generate more forms of stem cells (Chen He, & Lu, 2018). Mammals have two primary forms of stem cells: The adult and the embryonic stem cells. ADCs are usually located in different tissues whereas EMCs are typically separated from the blastocysts’ internal cell mass. In adult organisms, progenitor and stem cells usually function as the body’s repair system, replenishing or restoring adult tissues. Stem cells may differentiate into a variety of specialized cells in a developing embryo and still uphold the standard turnover (rate of replacement) of regenerative body organs, for instance, intestinal, skin, and blood tissues. Examples of these specialized cells include mesoderm, endoderm, and ectoderm. There are three recognized available autologous sources of human somatic stem cells; they include the bone marrow, blood, and adipose tissue (Chen, Hu, & Lu, 2018).
The extraction of somatic stem cells from an individual’s bone marrow is usually done through the harvesting process which involves drilling the iliac crest or femur bone. Liposuction is a procedure used to in the extraction of adult stem cells from the adipose tissue. The apheresis procedure is a process used to extract adult stem cells from the blood (Chen, He, & Lu, 2018). During the process, blood is usually drawn from the donor and passed down a machine used to obtain the adult stem cells. The other blood portions are usually returned to the donor. The extraction of stem cells may also be performed after birth (on the umbilical cord). The risk factor associated with autologous harvesting is significantly low compared to other extraction processes. Adult stem cells are useful in different medical therapies, for instance, bone marrow transplantation. Currently, stem cells may be grown artificially and differentiated (transformed) into different types of specialized cells with features similar to the cells of various body tissues, for instance, nerves or muscles (Manez et al ., 2014). Autologous stem cells (embryonic) and embryonic cell lines produced through the dedifferentiation process or nuclear transfer of somatic cells have been propounded as prospects for future therapies.
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Properties of Stem Cells
Some of the crucial stem cell properties include potency and self-renewal. Potency relates to the stem cells’ capacity to differentiate into different types of specialized cells; this, therefore, requires stem cells to be either pluripotent or totipotent (Manez et al., 2014). However, in various instances, unipotent or multipotent progenitor cells may be categorized as stem cells. The regulation of the functioning of stem cells takes place through a feedback mechanism. Self-renewal underscores the capacity of a stem cell to undergo numerous cell division cycles while maintaining its an undifferentiating state.
Self-Renewal
Two primary mechanisms ensure the maintenance of the stem cell populace: Stochastic differentiation and obligatory asymmetric replication. In stochastic differentiation, a stem cell usually undergoes the process of mitosis to generate two stem cells, similar to the original, following the development of another stem cell into two differentiated daughter cells (Chen, He, & Lu, 2018). Obligatory asymmetric replication is a process which involves a stem cell’s division process into one mother cell which is similar to the original stem cell and the differentiation of another daughter cell (Chen, He, & Lu, 2018). During the self-renewal process, stem cells often divide without disrupting their undifferentiated states. The process requires the cell cycle control process and the upkeep of pluripotency or multipotency which rely on the stem cell.
Potency
Potency stipulates the potential of differentiation in stem cells. Totipotent stem cells are capable of differentiating into extraembryonic and embryonic cell types; these cells can create a complete viable living organism (Chen, He, & Lu, 2018). The production of totipotent cells involves the fusion of a sperm and egg cell. Cells generated during the first fertilized egg divisions are also totipotent. Pluripotent stems cells originate from totipotent cells and are capable of differentiating into almost all cells (cells descended from any of the germ layers). Oligopotent stem cells, on the other hand, can differentiate into a limited cell type, for instance, myeloid and lymphoid stem cells. Unipotent cells are capable of generating only one type of cell but have the self-renewal property (Chen, He, & Lu, 2018). Multipotent stem cells often differentiate into different cell types that are of a closely related cell family.
Comparison, Advantages, and Disadvantages
ESCs (Embryonic stem cells) relate to the cells of the blastocyst’s inner cell mass. In human beings, embryos often advance into the blastocyst phase approximately 4 to 5 days after fertilization (Bhartiya et al ., 2018). During this period, they often contain around fifty to one-hundred and fifty cells. ESCs are pluripotent and often produce all the three key germ cell layers’ derivatives: mesoderm, endoderm, and ectoderm. Adult stem cells, commonly identified as the somatic stem cells often repair and maintain the tissues in which they are located and are found in both adults and children (Monez et al., 2014). Many somatic stem cells are multipotent (lineage-restricted) and are categorized according to their tissue of origin, for example, endothelial stem cells, and adipose-deprived stem cells.
One primary advantage of ESCs is their capacity to offer a variety of medical possibilities. ESCs are usually undifferentiated, and this allows them to be utilized in all body parts. ESCs are, therefore, capable of curing different disorders due to their undifferentiated states. Secondly, ESCs are likely to impact cancer research positively due to their close similarity with cancerous cells (Bhartiya et al., 2018). An improved understanding of the functional, biochemical, and molecular features of cancer stem cells may enhance significant advancements in the attempts to develop effective and accurately targeted treatments. The major disadvantage with ESCs is the process in which they are acquired. During the procedure of harvesting embryonic cells, human embryos are usually destroyed, and this consequently poses significant threats. Another disadvantage of using ESCs is the insufficient or inadequate knowledge concerning the ESCs. Induced pluripotent stem cells and ESCs, may divide uncontrollably in certain instances, forming growths and tumors on unwanted tissues. A study conducted by Dr. David Prentice revealed that ESCs’ effectiveness in treating Parkinson’s disorder in animals was significant; however, it caused the deaths of twenty-percent of the animals with the manifestation of brain tumors triggered by ESCs; this poses a critical risk (Bhartiya et al., 2018). However, with more studies, researchers may get a comprehensive understanding regarding the ESCs and minimize this statistic.
One primary advantage associated with somatic stem cells is that they can be extracted from one’s bone marrow, fat, or blood with little impact on the person; this subsequently eliminates controversies concerning the destruction of life (Chen, He, & Lu, 2018). The cells may be extracted directly from their respective tissues, and the human embryo is not usually destroyed during the process. Secondly, somatic stem cells are not usually rejected by the immune system of the body, and this enhances the capacity to perform autologous transplants. Thirdly, somatic stem cells effective in various treatment procedures, for instance, the regeneration of bones utilizing cells obtained from the bone marrow stroma, development of insulin-generation cells in individuals diagnosed with type 1 diabetes, and repairing of destroyed heart muscles after a heart attack involving cardiac muscle cells. Lastly, Somatic stem cells may be divided into pluripotent stem cells; this allows them to possess advantages similar to ESCs, without the attempt to destroy human embryos. One main disadvantage associated with adult stem cells is that they have a specific cell type and therefore, the incapacity to change them into tissues which differ from their original tissue; this subsequently restricts their particular use in treatment (Chen, He, Lu, 2018). Secondly, the process of transforming these cells into induced pluripotent cells is significantly difficult compared to harvesting ESCs. Thirdly, the stem cells’ culture in-vitro procedure is considerably difficult and impossible for specific cell types and their harvesting procedure is significantly difficult using other methods.
Effectiveness in the Treatment of an Injured Spinal Cord
With the effective integration of growth factors or elements, ESCs may be used to acquire glial cells and neurons. ES-obtained neurons are capable of surviving and integrating after its administration to the injured spinal cord of a rat (Bhartiya et al., 2018). Additionally, rat ESCs grafted into a rat’s damaged spinal cord enhanced its functional recovery significantly. Human ESCs may be administered to oligodendrocyte progenitor cells, motor neurons, and multipotent neural precursors (Chen He, & Lu, 2018). These cells indicate their capacity to myelinate axons following spinal cord transplantation in myelin-deficient adult rats and shiverer mice (Chen, He, & Lu, 2018). The neural progenitor cells in humans may be extracted from blastocysts and manipulated to produce functional glia and neurons. In a study, the grafting of neural progenitor cells from humans into the rat’s injured spinal cord enhanced the differentiation of the cells into oligodendrocytes (Monez et al., 2014). The study’s findings were associated with improved functional sequels. Neural progenitor cells may also offer protection against excitotoxicity. These cells also secrete various molecules, capable of protecting neural cells other death mechanisms. These cells’ transplantation into a damaged spinal cord may enhance neuroprotective impacts. Promoting axon development in a damaged spinal cord may improve the restoration of its functions.
The neural progenitor cells’ capacity to generate various neurotrophic elements underscores their capacity to promote the development of damaged axons. Somatic neural progenitor cells can also secrete a permissive-guiding substrate for corticospinal axon’s regeneration process after spinal cord injuries. Stem cells obtained from the bone marrow’s Mesenchyme tissue have therapeutic prospects for SCI (Monez et al ., 2014). Monez et al., (2014) reveal the stem cells’ capacity to differentiate effectively into cartilage, tendon, fat, and bone cells. These stem cells can undergo transdifferentiation in vitro into the cardiac, skeletal, and liver muscle cells and CNS cells. However, the effectiveness of this process is still debatable and subjected to additional research. The implantation of stromal cells from the bone marrow exhibits neuroprotective impacts since the grafting process into a rat’s injured spinal cord enhanced tissue sparing. Autologous stem cells extracted from the bone marrow have been used in Guayaquil, Ecuador in the treatment of damaged spinal cords of twenty-five patients. PrimeCell Therapeutics supported this trial (Chen, He, & Lu, 2018).
In conclusion, stem cells hold success prospects in the treatment of injured spinal cords and cancer treatment. Additional studies associated with the analysis of the effectiveness of stem cells in these treatment procedures should be emphasized. The government should also direct sufficient funds to enhance these studies.
References
Bhartiya, D., Patel, H., Ganguly, R., Shaikh, A., Shukla, Y., Sharma, D., & Singh, P. (2018). Novel Insights into Adult and Cancer Stem Cell Biology. Stem Cells & Development , 27 (22), 1527–1539.
Chen, X., He, Y., & Lu, F. (2018). Autophagy in Stem Cell Biology: A Perspective on Stem Cell Self-Renewal and Differentiation. Stem Cells International , 1–12.
Menezes, K., Nascimento, M. A., Gonçalves, J. P., Cruz, A. S., Lopes, D. V., Curzio, B. Coelho-Sampaio, T. (2014). Human Mesenchymal Cells from Adipose Tissue Deposit Laminin and Promote Regeneration of Injured Spinal Cord in Rats. PLoS ONE , 9(5), 1–15.
