Stem Cell Therapy
For this paper, I shall explore the possibilities in the use of stem cells in cell-replacement therapy as a possible treatment for many diseases in human life. I am specifically looking at stem cells research over the years and implications of the results of that research.
The thesis I aim to develop is as follows:
Stem cells have unique cellular characteristics that enable them to differentiate into all cell types in the body but only when called upon to. By this I of course mean until they are put in a specific environment of until they are coaxed to. By introduction of these cells into damaged or diseased tissues, this unique characteristic comes into play leading the cells to specialize into the cells of the area they have been exposed to. They specialize and replace the damaged cells thereby offering a therapeutic effect by treating the damaged area. A group of researchersJohn Hopkins University in a series of transplant experiments helped shed light on this ability of neural stem cells to replace cells damaged in the spinal cord, hence treating the condition. This research has the potential to bring about the cure to many life threatening conditions including genetic disorders, cancers and some congenital disorders. When perfected, stem cell research may just become a super cure. I will subsequently direct readers to successes that have been made thus far in this field which include bone marrow transplants.
My inspiration towards this topic comes from the fact that stem cell research has so much potential and yet so little progress has to date been made to fully tap into this potential. It is my hope that my audience will gain insight on the progress that stem cell therapy has had so far and the possibilities that further success in the field hold for modern medicine.
Two properties of stem cells have warranted its use in therapy. One property is self-renewal. This is the ability of stem cells to go through the various changes during cell division and maintain their undifferentiated state. The other equally important property is the potency of stem cells. This is their ability to differentiate into specialized cells. Studies of embryonic stem cells have revealed a lot of useful information about the complexity within human development. (Greer 199
About a quarter of a million people in the U.S live with Spinal cord injuries. Half of these people are quadriplegic. The cost of managing their condition is now up to $ 2-3 million. It may be due to the urgency of dealing with this condition that SCI was the first condition to be attempted in a human clinical trial. Cells used were stem cells of embryonic origin. A lot of the work done by the California stem cell agency is focused on trying to determine which cell types are best for the purpose of transplanting and also deciding which cells are best to be used to make the basis of making those cells. Other goals of the research are aimed at trying to see if the cells transplanted bare fully integrated into the existing nerve system. This would prove useful as it would make new pathways that can transmit nerve signals. Research is also going into ways of facilitating this integration. A major obstacle however in the development of new functional pathways is the capacity of the scar around the area of trauma to block the development of the transplanted cells. One group is trying to overcome this by using scaffold material to place the stem cells into the site of injury. This has really helped to restore the signals. In animal models, the recombination has resulted in increased mobility. Transplantation studies performed on animals have proved that stem cell transplants could have the following effects on spinal cord repair: they could replace the dead nerve cells; the stem cells could generate new cells that could actively participate in the re-sheathing process. The new stem cells also bear within them the ability to protect the site of injury from further damage particularly from secondary processes. The complex processes underlying secondary damage includes soaking up toxins and releasing growth factors. They also suppress the inflammation and therefore stop the inflammation from spreading. Many of the cell types that have been experimented with, none show more that partial recovery of function in the animal. (Nowakowski, et al 88).
Spinal cord injury, SCI is a disorder that is characterized by severe and possibly permanent paralysis due to trauma. After the initial trauma, more damage is incurred through an active secondary process that is complex. Since there is no effective treatment for SCI, more indirect strategies are employed. Such include; rehabilitation therapy, cellular and pharmacological rehabilitation. Spinal injuries are described as either incomplete or complete. This classification depends on the degree of loss of function. Treatment of spinal injuries begins with restraining of the spinal cord and attempted control of inflammation in a bid to prevent further damage. The actual treatment will proceed as dictated by the location of the injury and also its extent. If the injury is as a result of daily activities, spinal injury will call for physical therapy and rehabilitation. It is important to understand spinal injury in order to be able to treat it. Upon spinal injury, nerve fibers at the site of injury may lose the myelination rendering them incapable of transmitting signals along the CNS leading to paralysis. It is unfortunate that the spinal cord locks within itself the ability to restore the lost myelination after trauma. Tissue engineering of the spinal cord involves implanting scaffold material to guide the placement and to foster cell development. To maximize the stem cells regenerative potential, the same scaffold material can be used to deliver the stem cells and the site of trauma.Cell types used in treatment of SCI include; olfactory ensheathing cells, Schwann cells, cells derived from umbilical cord blood and mesenchymal stem cells. It is still unclear as to which adult stem cells are most effective in treatment of SCI. They are able to incorporate themselves into the damaged spinal tissue, to differentiate into their lineages; they exert some neuroprotective effective effects and promote subsequent regeneration of the damaged axons.
Research at John Hopkins University was able to report evidence stem cells of embryonic origin were able to restore movement in an animal model that had amyotrophic lateral sclerosis (ALS). The disorder causes progressive degeneration of special nerves in the central nervous system known as motor neurons. These neurons control movement. Patients with this disease exhibit progressive loss in muscular strength which leads to paralysis or death. There are no effective treatments for this condition. Its cause is also a mystery. A rat models with ALS was used in this study to investigate the possible nerve cell restoration capability of stem cells. The rats were exposed to a virus known as Sindbis which infects the CNS and destroys the motor neurons leaving the organism paralyzed in the rear and with weak hind limbs. The extent of impairment was assessed by measuring the movement of the rat and measuring the electrical activity in the nerves of the hind limbs. The degree of damage to the nerves can also be judged by visually observing the nerves under a microscope.
The scientists had difficulties with sustaining stem cells derived from rat embryos;they therefore used germ cells that the university students had extracted from human fetal tissues. The tissues are capable of dividing and remain undifferentiated forming embryoid bodies. When subjected to certain laboratory conditions, the cells were even seen to look and act like functional neurons. The researchers thought that the unspecialized cells would become specialized and would replace the neurons in the area that was damaged. They therefore injected the prepared stem cells into the cerebral spinal fluid surrounding the area in the spinal cord that was damaged. Just three months after the injection, many of the rats that were treated exhibited increased movement in their hind limbs. Others could even walk, while those that received no treatment remained paralyzed. An autopsy carried out reviled that the cells of human fetal origin migrated into the CNS and continued to develop to resemble mature motor neurons both in shape and molecular markers. The scientists were quick to say that the results were preliminary as they were not sure that the treatment was successful because the new stem cells replaced the old damaged cells or because the trophic factors from the injected cells caused the injured rats to recover the ability to use their limbs. They were also unsure of whether the same treatment could work on humans. (Kerr et al 2001).
Tendon injury is another major cause of lameness and reduces performance, especially in athletic equines. Though many therapies of said tendonitis have been researched on, none of the methods described involve tissue regeneration. In an experiment, the researcher introduced a lesion in the collagenase gel in the digital flexor tendon in the metacarpal region of some eight equines with a lesion. Two weeks later, the lesion in both treated and control animals were treated with mesenchymal stem cells that were of adipose origin in a platelet concentrate. Ultra sounds were then performed every two weeks for sixteen weeks. A biopsy was carried out on the sixteenth week. Improvement was noted in the treated organisms. This improvement however did not involve a difference in gene expression levels but were in the line of evolution that was clearly histopathological. It was concluded that the treatment prevented the progression of the lesion in the treated animals, there was less inflammation and some organization of collagen. (Worster vet al p. 128).
Conclusion
Diseases of the central nervous system, cancers, congenital disorders and degenerative diseases affect tens of millions of people around the world. Congenital diseases are as a function of the brain and spinal cord’s failure to form well during development. Cancers of the CNS result from uncontrolled spread of aberrant cells. (Hayat108) Degenerative diseases result from loss of function of nerve cells. All the above named disorders can be potentially traded using stem cells. However, most of the research involving stem cell therapy is currently directed towards the degenerative diseases.
From the results of the above experiment, the researchers atJohn Hopkins University have given hope to those suffering from neural conditions. The potential of germ cells to regenerate damaged tissue could mean the end to many diseases. There are studies in place that look to stem cells a possible cure to tumors. Other treatments focus on limiting the amount and extent of damage. Stem cell therapy enthusiasts believe that said damage can actually be reversed by replacing the damaged and dead cells with new cells; neural stem cells that will mature into cells of the CNS. Research that uses stem cells to treat the disorders of the CNS shows a lot of promise and it aims at demonstrating that cell-replacement therapy through use of stem cells can restore lost function. Researchers are applying this new found knowledge on stem cells in two ways. They are trying to use their knowledge of normal development of the brain to moderate the stem cells they are growing in culture. When translated into the brain of a model, the cells will be allowed to be differentiated by the brain’s signals into glia and neurons. (Zigova 201). The cells can also be caused to differentiate into neurons and glia while still in the culture dish before translation into the model. Progress has been made using embryonic stem cells that can differentiate into all types of cells in the body. They can be retained in culture for long without differentiating they usually need certain amount of coaxing to differentiate into the desired product. Recent studies have come to show that embryonic stem cell differentiation into neurons is more straight-forward than its differentiation into other cell types. (Shamblott et al 199).
References
- Kerr, D.A., Llado, J., Shamblott, M., Maragakis, N., Irani, D.N., Dike, S., Sappington, A., Gearhart, J., and Rothstein, J. (2001). Human embryonic germ cell derivatives facilitate motor recovery of rats with diffuse motor neuron injury.
- Hayat, M. A. (2012).Stem cells and cancer stem cells: Therapeutic applications in disease and injury. Dordrecht: Springer.
- Shamblott, M.J., Axelman, J., Wang, S., Bugg, E.M., Littlefield, J.W., Donovan, P.J., Blumenthal, P.D., Huggins, G.R., and Gearhart, J.D. (1998). Derivation of pluripotent stem cells from cultured human primordial germ cells. Natl. Acad. Sci. U. S. A
- Nowakowski, R. S., & Bhide, P. G. (2004).Stem and progenitor cells in the central nervous system. New York.
- Potten, C. S. (1997).Stem cells. London: Academic Press.
- Greer, E. V. (2006). Stem cell therapy. New York: Nova Science Publishers.
- Zigova, T. (2010).Neural Stem Cells for Brain and Spinal Cord Repair. Gardeners Books.
- Worster, Allison, A. In-vitro studies of Equine Mesenchymal Stem Cell Chondrogenic Capacity after Treatment with Transforming Growth Factor-B and Insulin-Like Growth Factor-1. Thesis (M.S)—Cornell University, Jan., 2000, 2000.
