Stem Cells, Cloning, Genetically Modified Organisms and Gene

Therapy…

Thirty-eight-year-old Marc Bergeron was diagnosed with Parkinson's Disease four years ago. The disease, which usually strikes people over 60, is slowly taking control of his body.

Currently, there is no way to predict who the disease will hit, there is no way to prevent it, and there is no cure.

But all that could change.

Scientists have found something they believe could revolutionize medicine by giving them the power to repair tissue damaged by disease or injury.

Stem CellsThe promise and the protestDocumentary: Leslie MacKinnonOnline: Owen WoodJune 5, 2001

"Stem cells… are going to usher in a new phase in medical research and treatment," says Roger Gosden, a research scientist at the Royal Victoria Hospital in Montreal.They're called stem cells. Essentially, stem cells are cells that haven't matured. This means they are just waiting to become any type of cell in the body – skin, bone, brain tissue.The promise of stem cells is that if doctors can harvest enough of them, they could grow new skin for burn victims or treat neurological diseases or repair spinal injuries or do a whole bunch of things that are only a dream today. The possibilities seem endless. But there's a catch.

What are stem cells?• Cells that can differentiate (evolve) into many

different types of cells• Some stem cells are totipotent: can transform into

many different types of cells

How can we use stem cells?

• To repair damaged tissue, ex. Neural injury

• Instead of transplants

Where are stem cells present?

• …in the bone marrow of adults• …in the adult brain• …the catch: in embryo tissue

WORKER CELL: An adult stem cell, collected from human bone marrow. It can replace blood cells killed by cancer or by cancer treatments like radiation and chemotherapy.

To produce large numbers of stem cells…

• It is necessary to clone embryos

• Stem cells are collected when embryo is 5 days old and contains nearly 150 cells

• The rest of the embryo is DESTROYED!!

(The ethical dilemma!!!)

Cloning Embryonic Stem Cells

• Nucleus from an adult body cell is transferred into an empty unfertilised egg cell.

• The embryo grows and the stem cells are taken and induced to differentiate into the cells that are needs (ie: insulin producing cells, muscle cells, cardiac cells).

How can we avoid dealing with embryonic stem cells but still use

stem cells?

• Harvest from adults

• Grow in Petri plates

• Use for therapy not for cloning people!!!

Induced pluripotent stem cells… a new hope???

• Scientists have recently made a break through in stimulating adult mouse cells to revert back into pluripotent cells (Cells that have the ability to give rise to any type of cell in an organisms body.).

• Scientists in Japan have introduced genes into adult cells that are normally only active in embryos. The result was that these cells were `reprogrammed` into pluripotent cells.

Therapeutic cloning

• Used to produce tissue that is identical to the donor, to prevent rejection

Reproductive Cloning• Creates an organism with the same

genetic material (DNA) as the original organism – an EXACT COPY of the donor

Dolly the Sheep

• The first cloned sheep

Cloning Genetically Modified Organisms

• Biotechnology has given scientists the ability to alter the genetic material in an organism.

• Genetically modified organisms can carry genes from other species.

• IE: Insulin is produced by bacteria and yeast that have been genetically modified to contain copies of the human gene that codes for insulin.

• Scientists at the University of Calgary recently inserted the human insulin gene into a safflower plant.

• It is a very cost effective way to mass produce insulin.

• The entire world’s supply of insulin could be produced on 65 square km of prairie farmland.

The desired gene is inserted into a cells nucleus using a retrovirus as a carrier

The defective gene is replaced by functional gene

Gene therapy

Gene Therapy … use to correct defective genes??

• Successes:– Restoring vision in patients with inherited

retinal disease– Repairing the gene responsible for Duchenne

Muscular Dystrophy– Restore hearing in Guinea Pigs

– Video…

Plenary• 1. What are stem cells?• 2. What is the difference between therapeutic cloning

and reproductive cloning?• 3. In the video clip at the beginning of class, what type

of cloning were scientists interested in?• 4. What are genetically modified organisms and how are

they being used today? • 5. What is gene therapy and what are some success

associated with it?• 6. What is the big deal with cloning embryos? Why are

some people up in arms about it?