Stem cells

What are stem cells?

unspecialized cells from which other types of cells can develop

Where are stem cells found?

In early human embryos, umbilical cord blood, placenta, amniotic fluid or the bone marrow, brain, blood and fat of adults

stem cell potency

The potential capacity of a stem cell to differentiate

3 stem cell types

totipotent, pluripotent, multipotent

totipotent stem cells

Stem cells that can differentiate into any type of specialised cells found in organisms of that species.

pluripotent stem cells

Stem cells that can become almost all types of tissues and cells in the body, except foetal membranes

multipotent stem cells

stem cells that can become a limited number of types of tissues and cells in the body

What determines the potency of stem cells?

Epigenetic factors, metabolic states of stem cells, environmental factors and where they are found

What potency do adult stem cells have?

multipotency

What potency do placental stem cells have?

Totipotency

What potency do embryonic stem cells have?

pluripotency

What potency to umbilical cord stem cells have?

Pluripotency

How are embryonic stem cells harvested?

Human ES cells are derived from 4-5 day old blastocyst (destroys the embryo)

How are adult stem cells harvested?

Harvested from tissues via brain biopsy or bone marrow extraction etc

How are umbilical cord and placental stem cells harvested?

They are harvested at birth from the umbilical cord blood and placental tissues

How are embryonic stem cells cultured?

cells from the inner cell mass are removed and cultured in vitro

therapeutic cloning

The cloning of human cells by nuclear transplantation for therapeutic purposes, such as the generation of embryonic stem cells to treat disease.

Focus areas of stem cells research

Regenerative medicine - preparing or replacing damaged tissues (spinal cord, diabetes, blood regeneration)

Clinical use - Bone marrow transplants

Reprogramming adult cells into pluripotent forms

Ethical considerations of stem cells

destroys embryos, general medical procedure ethics

Unproven treatments (some clinics offer stem cells therapies with little evidence, concerns about exploitation)

Stem cell laws

Prohibition of cloning Act 2002 - ban on reproductive cloning

Research involving human embryos Act 2002 - strict regulations on embryonic research. Only excess embryos can be used under a license