Stem Cell Techniques
Manjusha P. Yeole*, Shailju G. Gurunani, Yogesh N. Gholse
J. L. Chaturvedi College of Pharmacy (Degree), Electronic Zone Bldg., MIDC, Hingna Road, Nagpur-16
*Corresponding Author E-mail: mp_yeole@rediffmail.com
ABSTRACT:
Stem cells are biological cells found in all multicellular organisms, that can divide (through mitosis) and differentiate into diverse specialized cell types and can self-renew to produce more stem cells. Stem cell therapy encompasses new technologies and therapies that aim to replace damaged cells with healthy new ones. In mammals, there are two broad types of stem cells: embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues. There are three accessible sources of autologous adult stem cells in humans: Bone marrow, (typically the femur or iliac crest), Adipose tissue (lipid cells), Blood, which requires extraction through pheresis. Stem cells can also be taken from umbilical cord blood just after birth.Cells may be dysfunctional due to any number of reasons such as genetics, disease, injury or aging. Currently, stem cells offer the potential to treat cancer, Parkinson's disease, spinal cord injuries and diabetes, among other serious diseases. There are several types of techniques for harvesting, altering and using stem cells to treat persons afflicted with conditions or diseases. Some of these techniques are simple chemistry operations that have been done for years and other techniques have controversial processes that demand extension of research and reform. New harvesting techniques are crucial to successful stem cell research because they provide greater opportunities to treat diseases in a more unique case-by-case basis. They also provide ways to overcome challenges with current techniques as well as extending stem cell therapies to diseases that may otherwise have been untreatable by current therapies.
KEYWORDS: Stem cells, blastocysts, Parkinson's disease, spinal cord injuries, stem cell therapies
INTRODUCTION:
Stem cells are biological cells found in all multicellular organisms, that can divide (through mitosis) and differentiate into diverse specialized cell types and can self-renew to produce more stem cells for example, nerve cell, blood cell, liver cell. Stem cells removed from embryos are known to be pluripotent whereas stem cells from adults have been considered to only have the potential to become certain cell types. Human embryos reach the blastocyst state 4-5 days post fertilization at which time they consist of 50-150 cells Embryonic stem cells retain the character of embryo founder cells ,even after prolonged culture and extensive manipulation.1 In mammals, there are two broad types of stem cells: embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues.
However, recent advances have suggested that adult stem cells may also be successfully "reprogrammed" to grow into any tissue type. The allure of stem cell research is the potential to manipulate these cells to grow into any transplantable tissue or organ2.
There are three accessible sources of autologous adult stem cells in humans:
1. Bone marrow, which requires extraction by harvesting, that is, drilling into bone (typically the femur or iliac crest),
2. Adipose tissue (lipid cells), which requires extraction by liposuction, and
3. Blood, which requires extraction through pheresis, wherein blood is drawn from the donor (similar to a blood donation), passed through a machine that extracts the stem cells and returns other portions of the blood to the donor.
Stem cells can also be taken from umbilical cord blood just after birth
Fig. 1: Stem Cells
Highly plastic adult stem cells are routinely used in medical therapies, for example in bone marrow transplantation. Stem cells can now be artificially grown and transformed (differentiated) into specialized cell types with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture. Embryonic cell lines and autologous embryonic stem cells generated through therapeutic cloning have also been proposed as promising candidates for future therapies. Research into stem cells grew out of findings by Ernest A. McCulloch and James E. Till at the University of Toronto in the 1960s.
Embryos used for Research:
Discussions of human embryo research usually refer to the use of "spare" embryos, those that were destined only to be discarded after no longer being required for in vitro fertilization or other reproductive techniques. Many scientists claim that embryos are never produced specifically for research purposes. This distinction, however, is suggested by some to be quite artificial. They point out that it is a simple thing to "overproduce" embryos for assisted fertility with the intention of having many remaining for stem cell research
Harvesting Techniques cell:
New harvesting techniques are crucial to successful stem cell research because they provide greater opportunities to treat diseases in a more unique case-by-case basis. They also provide ways to overcome challenges with current techniques as well as extending stem cell therapies to diseases that may otherwise have been untreatable by current therapies. Perhaps even more important they offer a possible solution to the ethical conundrum that continues to plague stem cell research
1. Altered Nuclear Transfer:
Altered nuclear transfer (ANT) may make it feasible for stem cells to be removed from embryos without destroying the embryo itself in the process Traditionally, embryonic stem cells were harvested by destroying the human embryo in a process called somatic cell nuclear transfer (SCNT). A somatic cell is simply a body cell that is neither an egg nor a sperm cell. In this procedure, the nucleus is removed from a somatic cell and it is then implanted into a donor egg that first had its nucleus removed. The egg cell is essentially fooled into thinking it has been fertilized. It has its own DNA and after stimulation, it divides just as a normally fertilized egg would, before forming an embryo. Cells from the inner cell mass are extracted and cultured to provide embryonic stem cells but the technique destroys the embryo.
2. Blastomere Extraction:
This technique is one potential way around the ethical concerns that result from the destruction of an embryo. It is performed on a two-day old embryo, following the division of the fertilized egg into eight blastomeres, or cells. Previously, the techniques used for harvesting involving the derivation of embryonic stem cells at a later developmental stage, when the embryo is made up of approximately 150 cells. When these cells were harvested, the embryo was destroyed.
Another technique is called therapeutic cloning or somatic cell nuclear transfer. This process involves taking a woman's egg and removing the nucleus. Then, the nucleus of an adult cell is put into that same woman's egg. The result is something resembling an embryo but without the use of sperm; stem cells can be harvested from the mass of cells3.
There is a technique that is easier than nuclear transfer. It was attempted on mice It involves taking four genes from a tissue cell and inserting them into a special skin cell called an induced pluripotent stem (iPS) cell. This stem cell is derived from skin; no eggs or sperm are joined and none are used. This is a technique that has Nucleofection promise for generating new, healthy cells, tissue or organs for the body.
A new technique for researching stem cell activities is called nucleofection. Tiny holes are perforated through the cell layer by electrical pulses. Then DNA can be inserted through the holes and a special light x-ray illuminates the DNA and tracks its movements and processes. This helps scientists understand which techniques are working and which ones do not work4.
Some techniques involve taking damaged parts of DNA from skin cells and inserting healthy DNA parts from IPS cells. This technique has helped cure sickle cell anemia in mice, has grown healthy bone marrow cells and also encouraged multiplication of normal blood cells. These are promising steps in the field of stem cell research and implementation that will serve to relieve human suffering.
7. Peripheral Blood Stem Cell:
A peripheral blood stem cell harvest is a technique used to restore a person's blood cells after they have been damaged by chemotherapy or radiation. The procedure is often used to treat patients with either leukaemia or lymphoma cancer. Because the chemotherapy or radiation treatment damages healthy cells alongside cancer cells a patient requires a viable source of blood-forming cells. Stem cells are able to generate the white blood cells, platelets and red blood cells that are important for functions such as oxygen transport, clotting and immunity
Cardiomyocytes, the workhorse cells that make up the beating heart, can now be made cheaply and abundantly in the laboratory The capacity to make the heart cells using induced pluripotent stem cells, which can come from adult patients with diseased hearts, means scientists will be able to more readily model those diseases in the laboratory. Such cells contain the genetic profile of the patient, and so can be used to recreate the disease in the lab dish for study. Cardiomyocytes are difficult or impossible to obtain directly from the hearts of patients and, when obtained, survive only briefly in the laboratory
CONCLUSION:
The pursuit and production of knowledge through scientific research is an undertaking that offers enormous intellectual rewards for researchers while also performing a important social function.
The advancement of science has transformed our lives in ways that would have been unpredictable just a half-century ago. Whether stem cell research will have a similar effect remains to be determined, but the promise is so great that it seems wise to consider seriously how best to further such research in a manner that is sensitive to public sensibilities.
SUMMARY:
Recent developments in human stem cell research have raised hopes that new therapies will become available that will serve to relieve human suffering.
Stem cells made by reprogramming patients' own cells might one day be used as therapies for a host of diseases, but scientists have feared that dangerous mutations within these cells might be caused by current reprogramming techniques. A sophisticated new analysis of stem cells' DNA finds that such fears may be unwarranted.
REFERENCES:
1. Ray A “Scope of embryonic stem cells in research” Asian Journal of Nursing Education & Research(AJNER) ,2 (2); 2012; 51
2. Tuch BE “Stem cells—a clinical update". Australian Family Physician, 35 (9): 2006; 719–21.
3. Becker AJ, McCulloch EA, Till JE "Cytological demonstration of the clonal nature of spleen colonies derived from transplanted mouse marrow cells". Nature, 197 (4866): 1963; 452–4. Siminovitch L, McCulloch EA, Till JE "The distribution of colony-forming cells among spleen colonies". Journal of Cellular and Comparative Physiology, 62 (3): 1963; 327–36.
Received on 03.01.2013 Modified on 13.01.2013
Accepted on 04.02.2013 © RJPT All right reserved
Research J. Pharm. and Tech. 6(3): March 2013; Page 304-306