Presentation on theme: "Stem Cell Research Applications"— Presentation transcript:
1Stem Cell Research Applications Year 13 –Biotechnology
2Learning Intentions Today we will: Define Stem Cell Research, compare with Cloning.Watch a video on Stem Cell Research and complete the guided video sheetExamine the Human need or demandDiscuss ethical considerations and examine alternatives.(tomorrow we will focus on process of producing cells and related techniques)
3What are Stem Cells?Cells that have not yet become specialized to do particular jobs (undifferientated)At birth we have approx 20 billion cells, as an adult we have trillion!Most are specialised in shape and function - i.e nerve, blood, muscle, liver, skin, brain etc...Red blood cdells have no nucleus adn this gives them a sunken appearence, red colour is from haemoglobin.Nerve cells – message is sent along from cell body – along axon (some up to 1meter in length) towards the dendrites. Message is then passed to neigbhouring nerve cells.
4Types of Stem Cells There are several types of stem cells. Two categories EMBRYONIC or ADULT.Embryonic cells are found within embryos.The stem cells are pluripotent at 4-8 days old(capable of becoming many different cell types). They are removed during this stage.Stem cells can divide and produce copies of themselves again and again, this continues throughout the life of the organism
6Genes ‘on’ or ‘off’DNA in unspecialized cell is the same is specialised cells.Some genes are switched on or off (nerve cells diff to liver cells)The active genes are those needed for cell function (i.e to express proteins etc)
7How is this different to cloning? A clone is an exact copy of a plant/animal/person comes from one parent and has EXACT genesCloning is not new – vegetative propagation (i.e. tubers, runners), asexual reproduction in micro-organisms, identical twins (natural clones)They have different goals, but are sometimes confused. Modern techniques:both use embryonic stem cellsboth use SCNT – SOMATIC CELL NUCLEAR TRANSFER as a processand some scientists use term therapeutic cloning to describe their workClone – Greek word for clone is twigMicro-organisms reproduce this way when conditions are ideal, plenty of food.
8Dolly – Dorset Ewe Clone First cloning of Adult Cell – udder cell from one sheep was modified and inserted into empty ovum, transplanted to surrogate – 1996 (died 2004)Dolly identical to donor of udder cell.Concern – DNA age, reduced lifespan (Dolly started with 6 year old donor DNA). High mortality rate of clones – possibly tiny changes to genes effect essential proteins.Early clone research 1950’s using frog eggs/DNA from tadpoles – no success with cells from adult frog.The goal of this project was to create clones of transgenic animal to produce drugs for human use. The techniques lead to great progress in Stem Cell Research
9Goals of SCRThe goal of cloning is to use Somatic Cell Nuclear Transfer to create a new person/animal (reproductive cloning)The goal of SCR is to use Somatic Cell Nuclear Transfer to create ESC and tissues to cure diseases and disorders.Therapeutic cloning is now oftencalled NUCLEAR TRANSFER toavoid this confusion.
10Somatic cells vs Germ Cells Restrictions on SCR - GERM LINE cells (sperm/eggs) are not modified, only Somatic cellsModifications die with the individual.
11VIDEO - Rebuilding the Brain. Now that we have defined what Stem Cells are, we will look at video BUILDING THE BRAINThis will look at:Cell types & characteristicsLocation of cellsHow they are isolatedProblems with culturing cells.Please use the Student Response sheet to guide your note taking during the video. Prepare to discuss.Discuss Michael J Fox, advocate for Parkinsons
12Applications Skin cells - creating new tissue for burn victims Bone marrow – fighting leukaemia and other cancers (since 70’s)Corneas – repairing blindnessHeart stem cells – repair damage, heart diseaseResearching use of nerve cells – treatments for paralysis or brain disorders (Parkinson’s, Alzheimer’s, Multiple Sclerosis)Pancreas cells – produce healthy insulin making pancreas cells to cure diabetesStudying the progression of diseases in cells in vitro and trial drugsPotentially any treatment where cells die or are damaged.In Parkinsons, the brain cells stop producing dopamine – chemical that helps the body control muscles (tremours and shaking) – 1million Americans suffer from this disease. Michael J Fox strong advocate for SCR.(sheet of cells is dropped on eye, held in place, dissolves away - Presence of stem cells on cornea triggers the eye to repair itself.
13Fighting paralysis Repairing spinal cord injuries. In 2000, John Hopkins experimented with paralysed mice/rats, injected A.S.C into spinal fluid, over half showed functional improvement (5-7% cells appeared to differentiate into Nerve Cells)Christopher Reeve was asupporter of these experimentshe urged politicians andothers to fund SCRChristopher Reeve was a supporter of these experiments, he was paralyzed after falling from a horse in 1995.He frequently urged politicians and others to fund stem cell research.
15Using EmbryosFirst frogs/mice, now donated human embryos not implanted in IVF treatments.Discussion between scientists /politicians / the publicMany concerns about ethics of this work such as rights of the embryo – protection/rights of an individual, should not be destroyed solely for medical research.Recent research now points towards removal of stem cells without destroying blastocyst/ embryo.Growing SC in the lab reduces need to use embryos.Twinning can still occur at this stage – interesting point – the blastocyst is not yet an ‘individual’ as could be twins.Is it ethical to allow an embryo to be destroyed if the stem cells gained from it could help another person already in existance?Some cultures/religions find ESC research permissable, i.e place emphasis on finding cures and easing pain and suffering. ‘’The salient principle of Jewish Law is that life is precious and that any action that will protect life is permissable. Some cultures do not believe an embryo is a human before 40 days old.Is it ethical to destroy IVF embryos and NOT use them for research? Waste? It is estimated there are up to 400,000 frozen stored surplus embryos in the US.
16Ethical Framework Rights and duties Weighing the benefits/harms of Revisiting the four commonly used frameworksRights and dutiesWeighing the benefits/harms ofthe consequencesAutonomy and the right to chooseConsidering whether theoutcome is “virtuous” or not.AutonomyThe ability to make decisions for oneself. A person acts autonomously when such decisions can be put into effect.DutiesThings each of us ought to do. For example, if you have a baby, you have the duty to look after it.A virtue is something that the community accepts as being “good” or “right”. For example, honesty is a virtue.
17High potential..Hope for the medical potential of this research is high...it may provide cures to any number of diseases and disorders that are currently intractable to other forms of treatment...stem cells may produce revolutionary changes in medicine seen only rarely in human history’’David E Newton (Science writer)These tiny cells, hold the promise to treat and potentially cure diseases and disorders that have troubled all of our lives”Christopher Reeve
18New laws UK Government passed law to regulate use of SC. Embryos can be used up to 14 days old, then must be destroyed, Law does allow researchers to produce embryos for specific projects (although majority are still from IVF)In other European countries, they cannot produce embryos for research - Avoiding these laws – using ASC or umbilical cord cells.In America, government funding was not approved for any research involving destroying human embryos (Obama lifted Bush’s 8 year restriction on federal funding March 2009)In New Zealand, strict regulations still govern research into stem cell therapies
19Could stem cells cause cancer? Like cancer cells, SC divide repeatedly, but SC divide in a controlled way.There is concern that something may go wrong and SC may start causing cancer in a patient.Observations in the lab show that SC gradually gain abnormal chromosomes (over long period of time).Care must be taken to ensure normal cells are injected.
20Current and Future research Research into turning specialist cells back into ASC (turning back the clock) likened to natural regeneration in animalsNanog – protein found in ESC in mice.Role - keep SC dividing, this is not found in ASC. It is suspected that this may be one of the reasons why ASC do not divide as such as ESC.Some scientists believe this may help them understand the process of aging in the body - prolong life/treat elderly.Research around the world is edging towards using ESC in Humans
21Stem cell breakthrough (5min)Now a revolutionary method of creating stem cells—without embryos—may pave the way to swifter progress in the effort to understand and cure diseases.
22SC Issues in Organ Transplants Doctors need to be able to:Grow healthy SC in labProduce sufficient quantities for tissues/transplant etc (alternative transgenesis/cloning/XT)Control growth of SC so they produce the right kind of cell.Ensure that SC survive in the patient after transplantMake sure new SC become part of the surrounding tissue after transplantEnsure ES will work properly for the rest of the patients lifeMake sure the SC will not harm the patient.
23Discovery of Stem Cells For more than a 100 years, scientists had wondered how cells in an embryo could give rise to all the specialized cells in the body.In 1953 Roy Stevens discovered SC in cancerous growths on mice (called Terotoma)Terotomas are tumours that can growbits of muscle, bone, skin and inrare cases even teethUnder the microscope he found a fewplain cells in the middle which wouldlater become known as Stem Cells
25Additional resource differences between cloning and SCR (Interactive, some links to XT and SCR – min)
26History 1953 - Evidence of stem cells in mice (Roy Stevens) 1981 – Evidence of E.S.C in Mice (Uni California & Uni Cambridge)1988 – Isolated A.S.C in mice (Irving Weissman -Stanford Uni)1992 – Isolated A.S.C in human blood (Stanford Uni)1998 – Major breakthrough - E.S.C removed from embryo and grown in lab (James Thomson – Uni of Wisconsin)Since this time there have been many breakthroughs in labs around the world