Presentation on theme: "Year 13 –Biotechnology. Learning Intentions Today we will: Define Stem Cell Research, compare with Cloning. Watch a video on Stem Cell Research and complete."— Presentation transcript:
Year 13 –Biotechnology
Learning Intentions Today we will: Define Stem Cell Research, compare with Cloning. Watch a video on Stem Cell Research and complete the guided video sheet Examine the Human need or demand Discuss ethical considerations and examine alternatives. (tomorrow we will focus on process of producing cells and related techniques)
What are Stem Cells? 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... Cells that have not yet become specialized to do particular jobs (undifferientated)
Types 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
Genes 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)
How is this different to cloning? Cloning 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 cells both use SCNT – SOMATIC CELL NUCLEAR TRANSFER as a process and some scientists use term therapeutic cloning to describe their work A clone is an exact copy of a plant/animal/person comes from one parent and has EXACT genes
Dolly – 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 1950s 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
Goals of SCR The 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 often called NUCLEAR TRANSFER to avoid this confusion.
Restrictions on SCR - GERM LINE cells (sperm/eggs) are not modified, only Somatic cells Modifications die with the individual. Somatic cells vs Germ Cells
VIDEO - Rebuilding the Brain. Now that we have defined what Stem Cells are, we will look at video BUILDING THE BRAIN This will look at: 1. Cell types & characteristics 2. Location of cells 3. How they are isolated 4. Problems with culturing cells. Please use the Student Response sheet to guide your note taking during the video. Prepare to discuss.
Applications Skin cells - creating new tissue for burn victims Bone marrow – fighting leukaemia and other cancers (since 70s) Corneas – repairing blindness Heart stem cells – repair damage, heart disease Researching use of nerve cells – treatments for paralysis or brain disorders (Parkinsons, Alzheimers, Multiple Sclerosis) Pancreas cells – produce healthy insulin making pancreas cells to cure diabetes Studying the progression of diseases in cells in vitro and trial drugs Potentially any treatment where cells die or are damaged.
Fighting 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 a supporter of these experiments he urged politicians and others to fund SCR
Using Embryos First frogs/mice, now donated human embryos not implanted in IVF treatments. Discussion between scientists /politicians / the public Many 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.
Ethical Framework 1. Rights and duties 2. Weighing the benefits/harms of the consequences 1. Autonomy and the right to choose 2. Considering whether the outcome is virtuous or not. Revisiting the four commonly used frameworks
High 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
New 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 Bushs 8 year restriction on federal funding March 2009) In New Zealand, strict regulations still govern research into stem cell therapies
Could 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.
Current and Future research Research into turning specialist cells back into ASC (turning back the clock) likened to natural regeneration in animals Nanog – 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
Stem cell breakthrough e.stru.stemcell2/ (5min) e.stru.stemcell2/ Now a revolutionary method of creating stem cells without embryosmay pave the way to swifter progress in the effort to understand and cure diseases.
SC Issues in Organ Transplants Doctors need to be able to: Grow healthy SC in lab Produce 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 transplant Make sure new SC become part of the surrounding tissue after transplant Ensure ES will work properly for the rest of the patients life Make sure the SC will not harm the patient.
Discovery 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 grow bits of muscle, bone, skin and in rare cases even teeth Under the microscope he found a few plain cells in the middle which would later become known as Stem Cells
Fighting for research – M.J.Fox eneric.html?s=frol02n1daeq6c7 (11min) eneric.html?s=frol02n1daeq6c7
Additional resource differences between cloning and SCR fe.gen.cloning/ fe.gen.cloning/ (Interactive, some links to XT and SCR – min)
History 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 /timeline_for_stem_cell_research /timeline_for_stem_cell_research