Injuries can result in devastating consequences that may change a person’s life. Injuries that result from car accidents can affect a person’s spine, making them immobile. Recently, people who suffered from car accidents were forced to change their lives to accommodate living with spinal cord injuries. To offer accident victims another chance at enjoying their lives, doctors and other medical professionals have continuously tested the practicality of using stem cells to alleviate spinal cord injuries.
Stem cells are unspecialized cells that can transform into any cell in the body; thus, they can recreate functional tissues. These cells can differentiate into specialized cells that form the heart, brain, liver, bones, or blood cells. Additionally, stem cells can self-replicate; thereby, they can regenerate into other stem cells. Stem cells exist as adult and embryonic stem cells, with each category having its range of potency. Adult stem cells generally have a lower range of potency, with most of these cells being unipotent. On the other hand, embryonic stem cells have a higher degree of potency as most of these cells are totipotent.
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Stem cells have varying degrees of potency. When stem cells differentiate, they become more specialized at each step. Differentiation reduces the stem cell’s potency. Stem cells are generally classified into three categories unipotent, pluripotent, and totipotent. Pluripotent cells have a higher degree of differentiation than unipotent cells, although their differentiation range is lower when compared to that of totipotent cells. A unipotent stem cell has a lower degree of differentiation as these cells cannot differentiate into as many types of cells as a pluripotent stem cell. Totipotent cells have the highest differentiation rate; this allows them to differentiate into any cell in the body.
There exist varying types of stem cells, with each type of cell grouping having its own set of differentiating characteristics and sources. Embryonic stem cells come from the inner cell mass (ICM) of a blastocyst (Tewarie et al., 2009). A week after the fertilization of an ovum by a sperm, the fused cells develop into a blastocyst, a hollow ball of cells that comprises the ICM and the trophoblast. The ICM develops in an embryo while the trophoblast forms the placenta.
Adult stem cells are found in different tissues of an adult’s body. These cells are generally few in the body. Scientists previously believed that adult stem cells were only capable of differentiating into similar types of cells. E.g., adult stem cells found in the liver are only capable of generating other liver cells. Laboratory tests conclude that adult cells also can form other types of cells despite their origins. E.g., adult stem cells extracted from bone marrow can differentiate into brain cells.
Induced pluripotent stem(iPS) cells are adult stem cell that are genetically reprogrammed to exhibit properties similar to embryonic stem cells. Researchers obtain iPS cells from adult somatic cells (Sheth et al., 2008). Scientists forcefully introduce reprogramming genes into the adult somatic cells during the reprogramming process to maintain the defining properties similar to embryonic stem cells. Perinatal stem cells are the final and most recently discovered types of stem cells. These cells are found in amniotic fluids and umbilical cord blood. Additionally, the cells can change into specialized cells. Currently, there exists a void in the knowledge related to these types of cells.
Each type of cell has its share of advantages and disadvantages. Some of the advantages of embryonic stem cells (ESC) include they are pluripotent, thus can differentiate into any specialized cell in the body. Additionally, the ESCs have a longer life span when grown and maintained in culture (Zeng & Rao, 2007) . Scientists have found that ESCs can stay for up to a year in a culture without degrading. Lastly, there are established and well-defined protocols and regulations that govern studies around ESCs.
Despite the advantages that surround ESCs, the cells also have several disadvantages. Most of the therapies that utilize ESCs are new and unrefined, thus creating the need for more research on the sector. Also, there is a degree of uncertainty surrounding the acceptability rate of ESCs by the body after a transplant. Scientists have not yet confirmed if the body’s immune system will reject ESCs and treat these cells as intruders in the body. Another disadvantage is the process of regenerating ESCs is inefficient, thus requiring more studies and tests. Lastly, there remains a risk of developing tumors and cancer after using ESCs in a patient (Zeng & Rao, 2007). Research into ESCs shows that if the cells are used directly from undifferentiated cultures, they may cause the development of cancers and tumors in a patient.
Adult stem cells are advantageous because they have a higher chance of being accepted by the body. Thus, increasing the likelihood ness of transplant success. Another advantage is these cells can be reprogrammed and differentiated with ease in a laboratory. A disadvantage of these cells is they cannot survive for a longer time in cultures. Another shortcoming is there is little knowledge of the potency of these cells, although current research proves that the cells may only be unipotent or multipotent. Furthermore, the cells are scarce in the body, making them hard to find and study.
Induced pluripotent stem cells are beneficial because scientists can use abundant somatic cells to generate the cells. Also, iPS cells have a higher chance of being accepted by the body because they can be generated from the somatic cells of a patient’s body. Lastly, iPS cells are beneficial because they can be used in drug development and testing. Some of the drawbacks of iPS cells are during the reprogramming process. Scientists use viruses to introduce modifying genes into a somatic cell (Park et al., 2008). Mouse studies have shown that these viruses may cause cancer or other unpreferred consequences.
The unique characteristics exhibited by stem cells in their ability to regenerate themselves or into other body cells make them useful for the treatment of injuries like spinal cord injuries (SCI). After a spinal cord injury, the body of the affected organism initiates endogenous regenerative events. During these events, Tewarie et al. (2009) states that “the spinal cord tries to restore itself as the Schwann cells, myelinating and regeneration-inducing cells in the peripheral nervous system, the division of nerves that lie outside the central nervous system, travel from spinal roots into the injured spinal tissues”. Although, as the body tries to repair itself, growth inhibitors present in the cells that create scar tissue and failure of the new stem cells to integrate functionally into the injured stem cells result in failure of the endogenous regenerative events in repairing the spinal cord.
Stem cells can be used to treat spinal cord injuries in a variety of ways. The cells can be used in neuroprotective procedures, where they limit secondary tissue loss that results in loss of functionality. By performing a neuroprotective strategy on an SCI patient, doctors can prevent loss of functionality that results from injury-induced tissue loss (Ohta, 2004) . Studies conducted on injured adult rats showed that stromal cells extracted from bone marrow and introduced into the injured area of the rat’s spine resulted in tissue-sparing causing the injured rat to become more functional.
Stem cells can also be used in axonal regeneration. Scientists have found that Stem cells that differentiated into neural progenitor secrete a permissive guiding substrate that promotes axon regeneration after an SCI. Additionally, stem cells that regenerated into stem cell-like olfactory unsheathing cells barred the axons from recognizing growth inhibitors, allowing these axons to elongate (García et al., 2004).
Despite the few uncertainties in using stem cells to treat SCI patients, the available treatment alternatives show promising results. Scientists have conducted trials and tests on people and other animals like rats. The possibility of improving sensory function through stem cell therapies or even reducing the adverse effects that result after a spinal cord injury sounds better than failing to undergo the stem cell therapies. Additionally, scientists have conducted extensive research to improve the available stem cell treatments, thereby reducing the risks related to SCI treatments. I view the available stem cell treatment as the best alternative that my friend should undergo to relieve the adverse effects of his spinal cord injury.
References
García, R., Aguiar, J., Alberti, E., K., & Pavón, N. (2004). Bone marrow stromal cells produce nerve growth factor and glial cell line-derived neurotrophic factors. Biochem Biophys Res Commun , 316(3): pp 753–754.
Ohta, M. S. (2004). Bone marrow stromal cells infused into the cerebrospinal fluid promote functional recovery of the injured rat spinal cord with reduced cavity formation. Experimental neurology , 187(2), pp.266-278.
Park, I., Zhao, R., & West, J. (2008). Reprogramming of human somatic cells to pluripotency with defined factors. Nature , 451(7175): pp 141–146.
Sheth, R., Manzano, G., Xiuming, L., & Levi, A. (2008). Transplantation of human bone marrow–derived stromal cells into the contused spinal cord of nude rats. Journal of Neurosurgery: Spine SPI , 8(2), pp 153-162.
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): pp 105–114.
Zeng, X., & Rao, M. (2007). Human embryonic stem cells: long term stability, absence of senescence and a potential cell source for neural replacement. Neuroscience , 145(4): pp 1348–1358.
