Go to the NIH site on stem cells: http://stemcells.nih.gov/index.asp and click on the Info Center link “Stem Cell Basics.” Starting with the “Introduction” section, read the information presented.
Use the site’s glossary to find definitions for these important terms:
Cell-based therapies: Treatment in which stem cells are induced to differentiate into the specific cell type required to repair damaged or destroyed cells or tissues.
Differentiation: The process whereby an unspecialized embryonic cell acquires the features of a specialized cell such as a heart, liver, or muscle cell. Differentiation is controlled by the interaction of a cell's genes with the physical and chemical conditions outside the cell, usually through signaling pathways involving proteins embedded in the cell surface.
Embryonic stem cell line: Embryonic stem cells, which have been cultured under in vitro conditions that allow proliferation without differentiation for months to years.
Proliferation: Expansion of the number of cells by the continuous division of single cells into two identical daughter cells.
Plasticity: the capacity for continuous alteration of the neural pathways andsynapses of the living brain and nervous system in response to experience or injury that involves the formation of new pathways and synapses and the elimination or modification of existing ones
Pluripotent: The state of a single cell that is capable of differentiating into all tissues of an organism, but not alone capable of sustaining full organismal development.
Answer the following questions:
1. What are the unique properties of all stem cells? Explain in your own words what each property means.
a. All stem cells have three general properties:
i. they are capable of dividing and renewing themselves for long periods
1. stem cells are able to replicate themselves numerous times
ii. they are unspecialized
1. a stem cell does not have any tissue-specific structures that allow it to perform specialized functions
iii. they can give rise to specialized cell types
1. come from unspecialized cells the process is called differentiation. While differentiating, the cell usually goes through several stages, becoming more specialized at each step. The internal signals are controlled by a cell’s gene which are interspersed across long strands of DNA, and carry coded instructions for all cellular structures and functions. The external signals for cell differentiation include chemicals secreted by other cells, physical contact with neighboring cells, and certain molecules in the microenviroment.The interaction of signals during differentiation causes the cell's DNA to acquire epigentic marks that restrict DNA expression in the cell and can be passed on through cell division.
2. What are the two main kinds of stem cells used by researchers? What are the major differences between the two types in terms of their sources and usefulness to researchers? Give examples for each type of stem cell.
b. differences
i. their different abilities in the number and type of differentiated cell types they can become.
2. "adult" stem cells are thought to be limited to differentiating into different cell types of their tissue of origin.
ii. embryonic stem cells can be grown relatively easily in culture
iii. Adult stem cells are rare in mature tissues, so isolating these cells from an adult tissue is challenging
iv. tissues derived from embryonic and adult stem cells may differ in the likelihood of being rejected after transplantation
3. List some of the diseases that scientists think may be treated using stem cell research and suggest how stem cells might be used to treat each disease.
a. Type 1 Diabetes
i. it may be possible to direct the differentiation of human embryonic stem cells in cell culture to form insulin-producing cells that eventually could be used in transplantation therapy for persons with diabetes.
b. Heart Disease
i. generate healthy heart muscle cells in the laboratory and then transplant those cells into patients with chronic heart disease.
4. What are the necessary characteristics that laboratory-manipulated stem cells will need to have in order to be successfully used in cell-based therapies.
a. To realize the promise of novel cell-based therapies for such pervasive and debilitating diseases, scientists must be able to manipulate stem cells so that they possess the necessary characteristics for successful differentiation, transplantation, and engraftment. The following is a list of steps in successful cell-based treatments that scientists will have to learn to control to bring such treatments to the clinic. To be useful for transplant purposes, stem cells must be reproducibly made to:
i. Proliferate extensively and generate sufficient quantities of tissue.
ii. Differentiate into the desired cell type(s).
iii. Survive in the recipient after transplant.
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