What are the potential uses of stem cells in research and medicine? (WHAT…
What are the potential uses of stem cells in research and medicine?
WHAT ARE THE STEM CELLS?
cells that are undifferentiated, and don't have a specific job or function or structure.
have the potential to become almost any other kind of cell
body uses stem cells to replace worn out cells when they die
e.g. replacing lining of intestine every 4 days. stem cells replace the cells as they worn out.
stem cells are used in the blood system and live in the bone marrow/ every time daughter cells are produced they could be new cells or specialised cells.
internal and external signals provided by the body are used to guide stem cells. signals are replicated in labs in an attempt to impose the direction on the system for the cells.
THE TREATMENT OF NEUROLOGICAL CONDITIONS SUCH AS ALZHEIMER'S AND PARKINSON'S
a chronic disease defined by high blood sugar levels because there is not enough insulin. Insulin is produced by beta cells in the pancreas. Transplantations of those cells are isolated by donor organs
obstacle = shortage of donor cells
BENEFITS AND RISKS
poop guarantee of success in the therapies, for example, the use of stem cells in replacing nerve cells lost in Parkinson's disease patients
difficulty finding suitable stem cell donors
difficulty in obtaining and storing a patient's embryonic stem cells. these would have to be collected before birth - some clinics offer to store blood from the umbilical cord when a person is born.
mutations have been observed in stem cells cultured for numbers of generations, and some mutated stem cells have been observed to behave like cancer cells
cultured stem cells could be contaminated with viruses which would be transferred to a patient
Source of embryonic stem cells is unused embyro's produced by in vitro fertilisation fertilisation
Is it ethical to create embryos for therapy and destroy them in the process?
embryos could come to be viewed as a commodity, and not as an embryo that could develop into a person
does life begin at conception?
educating the public about what stem cells can and cannot do is crucial
do the benefits of stem cell use outweigh the objections
lots of the research for stem cells are carried out by commercial clinics, so reported successes are not subject to peer review
stem cell therapies are expensive and only in their developmental stages. can also give patients false hope for their cure.
A disease when people don't have enough dopamine (a chemical that allows messages to be sent to the part of the brain that control movement and some forms of thinking). When nerve cells dies, patients develop tremors and sometimes dementia in later stages. People develop abnormally large clumps in the brain made of a protein called "Alpha-synuclein"
Embyrynic stem cells can be directed to make dopamine-producing neurones which could be transplanted into patients. Dopamine-producing neurones have been made from both mouse and human embryonic stem cells in the lab --> human cells have recently been shown to have similar affects as the fetal cells in a rat model ofParikinson's diease.
INDUCED PLURIPOTENT STEM CELLS can be made from patient's adult skin ells in the lab and then used to make dopamine-producing neurones. Recent studies in rat and monkey models of PD show that dopamine-producing neurones survive with good outcomes.
THE REPAIR OF DAMAGED TISSUES e.g. severe burns, type I diabetes
replacing damaged bodily tissue
e.g. stem cells being used for treating patients with leukemia (cancer that effects bone marrow)
cells in bone marrow grow uncontrollably in bone marrow and crowd healthy stem cells that form blood cells.
stem cell transplant creates the blood cells needed by patient body.
Sample is taken from unburnt area, cells taken out, cells are seeded and fed with a protein and sugar substance. Cells will eventually divide and cover entire flask. Cells are removed using a special chemical and the sheet of cells are transplanted into patient. The epidermis layer can be replaced in this way but glands and follicles can not be altered (so they have no hair and don't sweat)
can be used in type I diabetes, multiple sclerosis (Which can lead to paralysis), in cases of spinal cord or brain injury, that have led to paralysis.
WHAT ARE THE DIFFERENT TYPES?
2) embryonic cells
created from left over embyros
can be grown into any kind of tissue in the body
comes from blastocyst = stage of development before implantation in the uterus. Blastocysts are produced in fertility labs and some are donated for research. Can give rise to all the tissues in the body. Grown in culture and maintained in a state where they can be transferred.
cells have to be isolated by removing the trophectoderm cells (outer) so that you're left with inner cell mass. grow in culture and they will grow and multiply. they can become heart, blood, brain and skin cells depending on how they are grown.
immortal in culture and maintained for several hundred passaged in the undifferentiated state. they also maintain a normal chromosomal composition.
1) adult stem cells / tissue specific
found in small numbers in most of the body tissues
replace existing cells in tissue as they wear out and die
muscle / skin / liver / nerve / blood
attractive to clinical therapy because of easy in vitro expansion and their ability to differentiate into a variety of tissues, provision of trophic support, and modulation of immune responses.
3) induced pluripotent skin cells
regular skin/fat/liver/ other cells that scientists have changed to behave like embyronic stem cells
can become any other cell in the body
there are 8 different types of specialised cells; including in the skin, brain and more.
stem cells also take place in plants after cell division takes place in regions called meristems. The cells inside divide by mitosis and produce unspecialised cells which can differentiate to produce all types of plant cells at any time during the life of the plant.
RESEARCH INTO DEVELOPMENTAL BIOLOGY: HOW ORGANS AND TISSUES FORM AND HOW THEY WORK
e.g. stem cells for the brain from embryonic stem cells : neural stem cells can only make 3 types of cells (3 that exist in the brain)
lab grown human cells provide models for testing and screening medical treatments and resist animal testing.
regeneration for most animals is restricted to certain tissues and different cells have different turnover rates. Recent progress has enabled the ability to reprogram adult somatic cells to embryonic stem cells in culture - this has solved concerns regarding ethics of use of ESC's and also reduced immunorejection.
This means that scientists are able to use natural / synthetic molecules to reprogram adult somatic cells in vitro to adult stem cells to stimulate resident pre-existing adult stem cells in the body.