Gene therapy and hematopoietic stem cell (HSC) research are among the most fascinating areas of contemporary biology. Results of the clinical trials, performed in these areas provide promise for the treatment of different humain disorders in the near future. This essay will show several data, regarding advances and current issues in the mentioned areas. Current Advances and Issues In the Gene Therapy and Stem Cell Research What is gene therapy?
Cavazzana-Calvo & Fischer (2007) describe it as “a form of molecular medicine based on the addition of a corrected copy of a gene to the somatic cells of an individual in order to cure or to alleviate his/her disease” (p. 1456). Two types of cells: accessible stem cell and terminally differentiated, postmitotic, long-lived cells are currently used in gene therapy (Cavazzana-Calvo & Fischer, 2007). As further described by Cavazzana –Calvo & Fischer (2007), stem cells in the hematopoietic system and those in the skin are optimal for the gene therapy purpose.
Their ability to survive in ex vivo has enabled rapid progress in the gene therapy research during the last 20 years. Results in gene therapy and stem cell research provide evidence supporting their use and positive effect in the treatment of inherited and acquired diseases of the hematopoietic system (Cavazzana-Calvo & Fischer, 2007) as well as vascular diseases, patients with diabetes and critical limb ischemia (Kolvenbach, Kreissig, Ludwig, & Cagiannos, 2007).
We could find more detailed overview of the gene therapy research for the treatment of severe combined immunodeficiency (SCID), based on the results of Phase II clinical trial – SCDI- X1. As described by Cavazzana-Calvo & Ficher (2007), SCIDs are different disorders where the block in T cell differentiation together with the impairment of B cells immunity occur. Clinically, SCIDs are characterized by the early onset of recurrent and severe infections, caused by opportunistic organisms. These infections, if not treated, lead to death within the first year of life.
In the above mentioned clinical trial, 10 children under the age of 1year were enrolled. 9 patients have developed T cells, and in 7 out of these nine, T cell counts reached normal levels within 3 months and have remained so ever since (Cavazzana-Calvo & Fischer, 2007). Along with the positive outcomes, several limitations of gene therapy have been pointed out. Firstly, it is difficult to define an upper threshold for reducing the risk of insertional mutagenesis, thus associated with the oncogenic risk, and secondly, there is an age limit for success (Cavazzana-Cavalo & Fischer, 2007).
Patients, who participate in the clinical trials, especially in pase II, are hoping for a benefit that cannot be guaranteed, but they are facing safety issues (Robertson, 2006). It is important to point out, as with any existing treatment, implementation of clinical trials needs specific evaluation of the risk /benefit ratio and several groups are working in seeking to make safer the already existing vectors (Cavazzana-Calvo & Fischer, 2007). Conclusions Cavazzan-Cavalo & Fischer (2007) made the following conclusion:
“Continuing technological progress in gene targeting and stem cell manipulation should improve safety and efficacy and thus prompt a significant extension of the application of gene therapy as a treatment for inherited diseases and notably those of the hematopoietic system and the skin” (p. 1463). Kolvenbach et al. ( 2007) suggest to standardise the outcome measures for future trials so that comparisions can be made. References Cavazzana-Calvo, M. , & Fischer A. (2007, Jun. ).
Gene therapy for severe combined immunodeficiency: are we there yet? Journal of Clinical Investigation, 117(6), 1456- 1465. Kolvenbach, R. , Kreissig, C. , Ludwig, E. , & Cagiannos, C. (2007, Feb. ). Stem cell use in critical limb ischemia. Journal of Cardiovascular Surgery, 48(1), 39-44. Retrieved from ProQuest database. Robertson, J. A. (2006, Nov. , Dec. ). Controversial Medical Treatment and the Right to Health Care. The Hastings Center Report, 36(6), 15-21. Retrieved from ProQuest database.