Introduction

Stem cells are unspecialized cells found in the human body with the potential to become specialized. Stem cells have the ability to become and replace any cell in the body. This characteristic ability of stem cells has “great potential for future therapeutic uses in tissue regeneration and repair” (Biehl and Russell, 2009). In addition, stem cells can be directed to differentiate into different cells and used to treat diseases including macular degeneration, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis (“Stem Cell Basics IV.”, 2016). These diseases are hard to cure and potentially life-threatening with a bleak outlook. Thankfully, after decades of research, doctors, and scientists can finally improve their patient’s conditions with stem cell therapy. Stem cell therapy is an umbrella term and refers to a wide variety of different treatments. However, stem cell therapy is relatively unexplored and still needs an enormous amount of additional research before the true potential and safe application of stem cells is discovered. The three most viable stem cell therapies are autogenic and allogeneic transplant, mesenchymal stem cells therapy, and therapeutic cell cloning.

Stem Cells Types

  The term “stem cells” collectively refer to all the different types of stem cells found in the human body. The two main categories of stem cells are adult stem cells and embryonic stem cells. As the name suggests, embryonic stem cells are found in embryos and adult stem cells are found in adults. Embryonic stem cells are significantly more powerful than adult stem cells, being able to form nearly any cell in the body. Stem cells can also be categorized by the ability they have. Stem cells with the ability to replace any cell in the body are referred to as totipotent. These stem cells can develop into a fully functioning body. These cells are briefly present in the early stages of the zygote. Stem cells with the ability to replace most, but not all, cells in the body is referred to as pluripotent. Pluripotent cells are found in the inner mass cells of the blastocyst. Stem cells with the ability to replace a limited number of cells are referred to as multipotent. An example of multipotent stem cells is mesenchymal stem cells (MSCs). MSCs can differentiate into many different cells such as osteoblasts, chondrocytes, and myocytes.

Autogenic and Allogenic Transplant

Autogenic and allogeneic transplant has been around for nearly three decades and is an approved stem cell therapy. Allogeneic stem cell transplantation involves transferring the stem cells to a patient after high-intensity chemotherapy or radiation. Here lies the difference in an allogenic and autogenic transplant. In allogeneic stem cell transplant, the stem cells, specifically bone marrow stem cells, come from a donor but holds the risk of transplant rejection. In allogeneic stem cell transplant, the stem cells are harvested from the patient’s body and therefore free of any risk of transplant rejection. This treatment is often used for patients suffering from leukemia and other related diseases. When doctors use chemotherapy with or without radiation to kill cancerous cells, the blood-forming stem cells in your bone marrow also dies. To alleviate this, doctors usually add the collected stem cells into the patient’s bloodstream a day or two after the chemotherapy. The stem cells are added in the same way as a blood transfusion. As the days go by, the transplanted stem cells move to the marrow space in the bones where they gradually start to produce new blood cells. After a few weeks, newly formed blood cells such as red blood cells, white blood cells, and platelets should appear in the patient’s bloodstream.

Mesenchymal Stem Cells Therapy

MSCs are the major stem cells for stem cell therapy and is particularly effective in the treatment of tissue injury and degenerative diseases. Mesenchymal stem cells (MSCs) “exist in almost all tissues” (Wei, X., Yang, X., Han, Z., Qu, F., Shao, L., and Shi, Y., 2013). They can be easily isolated from the bone marrow, umbilical cord, fetal liver, muscle, and lung and can be successfully divided in laboratory settings. Despite its lack of cell variety when compared to ESC and iPS, MSCs hold one clear advantage over them. One key characteristic of ESC cells and iPS cells is their high potential for teratoma formation. A teratoma is an uncontrolled tumour made out of multiple tissues. MSCs, on the other hand, have nearly no chance of a teratoma formation. In nearly all of the clinical studies, “the engraftment of MSCs into damaged tissues via migration to enhance tissue repair/regeneration is a crucial process for clinical efficacy”, regardless of the type of organ or specific disease (Wei, X., Yang, X., Han, Z., Qu, F., Shao, L., and Shi, Y., 2013). Another key characteristic of MSC is that they have a tendency to travel towards to damaged tissue and inflammation. This allows for the continual repair of damaged tissue throughout the body. Although the treatment model is in place, product quality standards, and safety controls are still not available in most countries.

Therapeutic Cell Cloning and Drug Testing

Therapeutic cloning produces stem cells with the same DNA as the patient. To achieve this, the nucleus of the donor stem cells are removed and the patient’s nucleus is injected into them. With the transfer of the patient’s own cell nucleus, the issue of immunocompatibility and transplant rejection of human ESC cells would thereby be solved. Furthermore, stem cells are also expected to significantly shorten the time drug companies take to test new drugs for side effects. Modern drug testing involves extensive animal trials and even after animal trials, there is no guarantee that the drug will be safe for humans. However, using human tissue grown with stem cells to test drugs would be much more accurate. The genetic makeup of the grown tissue would be the exact same as the patient. Since the most prominent drug side effects affect the heart, liver, and kidney, doctors will grow large amounts of these tissues to test with.  This would significantly lower the testing costs and decrease the time it takes to develop a new drug. Another benefit of therapeutic cloning is the introduction of personalized medicine. Therapeutic cloning will allow drug companies to develop and tailor drugs that are safe and effective for the patient’s needs and specifications. However, Article 18 of The Convention on Human Rights and Biomedicine or the Oviedo Convention declare that “the creation of human embryos for research is prohibited.” There is also a blanket ban on human cloning. These bans severely limiting the research capabilities of scientists around the world.

Current and Future Research

Naturally “much more research is needed to understand the full nature and potential of stem cells as future medical therapies”  (Stem Cell Basics, 2015). Scientists still do not know how many kinds of adult stem cells exist, how they interact, and how they evolve. Current research is focused on the application of induced pluripotent stem cells (iPSCs) in an attempt to treat age-related macular degeneration, a common cause of blindness in older people. This small scale research is designed to analyze the safety of iPSCs transplantation into patients’ eyes. In addition, scientists are also focused on finding new methods of acquiring new stem cells. Future research is focused on the negation of iPSCs ability to promote tumour growth and metastasis. iPSCs have a tendency to form tumours in vivo because using viruses to genetically alter the cells can trigger the expression of cancer-causing genes or oncogenes. These are just a few of the many formidable hurdles that researchers still face. Researching the characteristics of stem cell is difficult and elusive and researching the safe application of stem cells are even more so. “Those are things we have to continually learn about and try to address. It will take time to understand them better,” Dr. Owens says. With all the scientific, regulatory, and financial challenges that lie ahead, “It’s unlikely that one entity could do it all alone. Collaboration is essential” (Stem Cell Basics, 2015).

Conclusion

All in all, there is a range of stem cell treatments ranging from allogeneic stem cell transplant and autologous stem cell transplant to mesenchymal stem cells therapy to therapeutic cell cloning. Despite the over exaggerated and often times completely false promises about stem cell therapy, there truly is great undiscovered potential for stem cell research and stem cell therapy to cure hard-to-cure diseases such as macular degeneration, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis (“Stem Cell Basics IV.” , 2016). In order to ensure further progress in the field of stem cells, more funding must be dedicated to its research. Additionally, the public must be informed and familiarized with stem cells in order to alleviate the ongoing ethical debate over stem cells. Hopefully, in the future, stem cell research and therapies will be widely accepted by all, ensuring the advancement of research and enabling doctors to cure difficult diseases. Knowing that stem cells exist is different from knowing how to use them safely. 

  Biehl, J. K., & Russell, B. (2009, March 24)              Biehl, J. K., & Russell, B. (2009, March 24)

(Wei, X., Yang, X., Han, Z., Qu, F., Shao, L., & Shi, Y., 2013)          (“What Are Stem Cells?”, 2019)

References

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