Dolly1st experimentally cloned animal

QuickTime™ and aH.263 decompressorare needed to see this picture.

Microinjection of nuclei into eggs

Reproductive cloning requires epigenetic modifications to be reset to state in fertilized egg.

But, this doesn’t work perfectly.

Not yet clear what health problems may arise due to misexpression of many genes.

Reproductive Cloning:

Remove nucleus from egg cell. Replace it with nucleus from somatic cell (e.g., skin cell)Stimulate cell to divide (like a fertilized egg).Implant embryo into surrogate mother.

Therapeutic Cloning (Nuclear Transplantation):Start the same, but stop development at blastocyst stage.Remove inner cell mass cells and use to create embryonic stem cell line.

Clones = Genetically identical individuals

Two Kinds of Animal Cloning

Stem CellsUnspecialized cells that renew themselves by dividing an unlimited number of times.

Under certain conditions they can give rise to cells with specialized functions.

Embryonic Stem Cells:

Derived from undifferentiated cells from early-stage embryos (blastocyst stage).

Pluripotent: Have the potential to give rise to any kind of cell in the body.

Therapeutic Cloning

1. Make embryonic stem cell line from patient

2. Induce cells to develop into specific cell type that patient needs

Use to treat diseases such as Parkinsons or diabetes (right)

Mature neurons (red) and glial cells (green)derived from human embryonic stem cells

Blood cells (red) derived from human embryonicstem cells

Can combine stem cell & gene therapy

Replace bad copy of gene with good one

Make embryonic stem cells from “patient”

Stem CellsUnspecialized cells that renew themselves by dividing an unlimited number of times.

Under certain conditions they can give rise to cells with specialized functions.

Embryonic Stem Cells:Derived from undifferentiated cells from early-stage embryos (blastocyst stage).

Pluripotent: Have the potential to give rise to any kind of cell in the body.

Adult Stem Cells:Found in a variety of tissues and organs.

Multipotent: Able to give rise to a limited range of cell types.

Adult Stem Cells

Blood stem cells

Stromal stem cells

Bone marrow

Multipotent

Some adult stem cells may be pluripotent

This potential ability to differentiate into wider array of cells is called plasticity.

How may plasticity be regulated???

Potential Uses:Bone marrow transplants.

Hope to be able to get adult stem cells to differentiate into wider range of cell types.

May be able to regenerate tissues using cells from one’s own body, avoiding tissue rejection problems.

Limitations:May be limited in range of cells they can give rise to. e.g., Blood stem cells may be able to produce blood cells, but not brain cells.

Can only obtain a relatively small number of cells from an individual & they don’t grow well in culture.

Adult Stem Cells

Challenges in stem cell therapy

Learn what causes stem cells to become distinct kinds of specialized cells, such as insulin-producing pancreatic cells or nerve cells, and how to more precisely control this process.

Demonstrate plasticity of adult stem cells and learn how to control this.

Overcome technical (& political) barriers for working with

human embryonic stem cells.