Stem Cell ResearchApplications

Year 13 –Biotechnology

Learning IntentionsToday 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)

What are Stem Cells?

At birth we have approx 20 billion cells, as an adult we have 70-100 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 CellsThere 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

http://upload.wikimedia.org/wikipedia/commons/6/65/Human_embryonic_stem_cells.png

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 cellsboth use SCNT – SOMATIC CELL

NUCLEAR TRANSFER as a processand 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 CloneFirst 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

Goals 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 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 BRAINThis will look at:

1. Cell types & characteristics 2. Location of cells 3. How they are isolated4. Problems with culturing cells.

Please use the Student Response sheet to guide your note taking during the video. Prepare to discuss.

ApplicationsSkin cells - creating new tissue for

burn victimsBone 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 diabetes

Studying the progression of diseases in cells in vitro and trial drugs

Potentially any treatment where cells die or are damaged.

Fighting paralysisRepairing 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 experimentshe urged politicians andothers to fund SCR

http://southdakotapolitics.blogs.com/.a/6a00d8341c046f53ef0115702a5e42970b-pi

Using 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.

Ethical Framework

1. Rights and duties 2. Weighing the benefits/harms of

the consequences 3. Autonomy and the right to choose 4. 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 lawsUK 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

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 researchResearch 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 breakthroughhttp://www.teachersdomain.org/resource/nsn

08.sci.life.stru.stemcell2/ (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.

SC Issues in Organ TransplantsDoctors 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.

Discovery of Stem CellsFor 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 inrare 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.Foxhttp://www.pbs.org/wgbh/pages/frontline/vide

o/flv/generic.html?s=frol02n1daeq6c7 (11min)

Additional resource differences between cloning and SCR

http://www.teachersdomain.org/resource/biot09.sci.life.gen.cloning/

(Interactive, some links to XT and SCR – 10- 15 min)

History1953 - 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

http://www.biotechlearn.org.nz/themes/biotech_therapies/timeline_for_stem_cell_research