Stem cell therapy for leukemia

By Jenny Tang

   Stem cells have the ability to dedifferentiate into different types of cells in the body and can be used to replace damaged cells. This theory had led to the creation of stem cell therapies which can, in theory, be used to treat patients who have suffered, for example, spinal cord injuries, or brain ailments such as Alzheimer’s and Parkinson’s disease. 

   Currently, the only established therapy utilizing stem cells is hematopoietic stem cell transplantation, which utilizes bone marrow transplant (though the umbilical cord blood can also be used). It is commonly used in regeneration of damaged cells, tissues and organs.  It is performed most commonly by temporarily removing blood and running it through a machine that separates the stem cells from the blood. Adult stem cells prove to be highly useful for tissue regeneration and may be used in for regeneration after severe injuries (Müller, Huppertz and Henschler, 2016)

   Stem cell therapy is common among individuals that have had high doses of chemotherapy in cancer patients. In chemotherapy, the ability to produce stem cells in patient reduces, and the usage of stem cell transplants assist in the replenishing them. 

Hematopoietic stem cell transplants are used to assist when higher dosages of chemotherapy are used, as to limit the side effects, such as severe damage in the bone marrow which can subsequently damage the production of new blood cells. With higher dosages of chemotherapy, it is much more efficient in killing cancer cells (Schlenk, 2014).

  Leukemia, a form of cancer, originates in the bone marrow and leads to an increase in abnormal blood cells. It is caused through the deregulation of hematopoietic stem cell development, due to a genetic mutation that produces leukemic stem cells. Subsequently it causes several different hematologic disorders such as lymphoma and chronic ML leukemia. However, these two hematologic disorders are currently treated though the usage of hematopoietic stem cells transplantation (Guzman and Allan, 2014).

 The type of stem cell transplant differs depending on where the stem cell comes from. In an allogenic stem cell transplant, the stem cells usually come from a different person rather than the patient themselves. This can be difficult as there may be contrasting tissue types, also known as HLA types. HLA are the proteins located on the surface of white blood cells and are responsible for the regulation of the immune system (Choo, 2007). These stem cells are usually taken from a relative as there is a higher likelihood that the HLA type is compatible, although an unrelated donor is plausible if the HLA type matches. An autologous stem cell transplant can be used instead, which is when the patients stem cells from their own blood or bone marrow is used. 

 Allogenic stem cell transplants are preferred over an autologous stem cell transplant, because although an autologous stem cell transplant lowers the chance of post-transplant complications, it raises the chance of potential of leukemia cells coming back which may potentially induce leukemia once again. Although reducing the number of leukemic cells through a process of purging, which is a process of killing the leukemic cells, there is still a small chance of there still being leukemia cells, causing a potential relapse among patients. The downfall of allogenic stem cells is that the patient may suffer from more complications as the cells are more foreign, leading to potential rejection from the body, or more difficulty to get used to the foreign stem cells (Schlenk, 2014).

    The usage of stem cell therapy fares highly useful among patients with leukemia, as it assists with the stimulation of new bone marrow growth. It also assists with restoring the immune system, after higher doses of chemotherapy is performed on the patient. Although stem cell therapy is a relatively new, it has high implications within the medical field. 

References:

Choo, Sung Yoon. “The HLA System: Genetics, Immunology, Clinical Testing, and Clinical Implications.” Yonsei Medical Journal, vol. 48, no. 1, 2007, p. 11, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2628004/, 10.3349/ymj.2007.48.1.11.

Guzman, Monica L., and John N. Allan. “Concise Review: Leukemia Stem Cells in Personalized Medicine.” STEM CELLS, vol. 32, no. 4, 17 Mar. 2014, pp. 844–851, 10.1002/stem.1597. Accessed 11 June 2020.

Müller, Albrecht M., et al. “Hematopoietic Stem Cells in Regenerative Medicine: Astray or on the Path?” Transfusion Medicine and Hemotherapy, vol. 43, no. 4, 1 July 2016, pp. 247–254, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5040947/, 10.1159/000447748.

“Nine Things to Know about Stem Cell Treatments – a Closer Look at Stem Cells.” Closerlookatstemcells.org, 2019, http://www.closerlookatstemcells.org/stem-cells-medicine/nine-things-to-know-about-stem-cell-treatments/.

Schlenk, R. F. “Post-Remission Therapy for Acute Myeloid Leukemia.” Haematologica, vol. 99, no. 11, 1 Nov. 2014, pp. 1663–1670, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4222459/, 10.3324/haematol.2014.114611.

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