Health BiotechnologyStem Cell

LECTURE 20:

Biotechnology; 3 Credit hours

Atta-ur-Rahman School of Applied Biosciences (ASAB)

National University of Sciences and Technology (NUST)

What are Stem cells

• Unspecialised cells lacking any tissue-specific structure

• Can give rise to specialised cells through the process of differentiation

• Stem cells are the raw material from which all of the body’s mature, differentiated cells are made.

• Stem cells give rise to brain cells, nerve cells, heart cells, pancreatic cells, etc.

Stem Cells !!!

stem cell

stem cell

SELF-RENEWAL

(copying)

specialized celle.g. muscle cell, nerve cell

DIFFERENTIATION

(specializing)

Stem Cell Definition

• A cell that has the ability to continuously divide and differentiate (develop) into various other kind(s) of cells/tissues

• Stem Cell

Kinds of Stem Cells

Cell type Description Examples

Totipotent Each cell can develop into a new individual

Cells from early (1-3 days) embryos

Pluripotent* Cells can form any (over 200) cell types

Some cells of blastocyst (5 to 14 days)

Multipotent*Cells differentiated, but can form a number of other tissues

Fetal tissue, cord blood, and adult stem cells

*The pluripotent stem cells are in fact derived from totipotent stem cells. The pluripotent stem cells can develop into any cell type except for the extra-embryonic tissue. *Multipotent progenitor cells can give rise to many but limited types of cell. For example, a hematopoietic cell can give rise to several types of blood cells (i.e. red blood cells, white blood cells, platelets, etc.)

Day 1Fertilized egg

Day 1Fertilized egg

Day 22-cell embryo

Day 22-cell embryo

Day 3-4Multi-cell embryo

Day 3-4Multi-cell embryo

Day 5-6BlastocystDay 5-6

BlastocystDay 11-14Tissue Differentiation

Day 11-14Tissue Differentiation

Totipotent Stem Cells

Multipotent Stem Cells

Stem Cell types: Origin

Stem Cells comprise the following Types1. Embryonic Stem Cells2. Fetal Stem Cells3. Umbilical Stem Cells4. Adult Stem Cell

A human embryo is considered fetus 8 weeks after the egg is fertilized

1- Embryonic Stem Cells

• Usually they are pluripotent cells• Most valuable can become into any type • 1998 first human embryonic cell was grown• In invitro fertilization (IVF) • Extra embryo that are not implanted are

frozen

Embryonic Stem Cells

2- Fetal Stem Cells

• These are also pluripotent• Fetus brain tissue• They are excellent source of cells for adults

with Parkinson’s disease

3- Umbilical Stem Cells

• The cells from cord blood are multipotent stem cell.• They can naturally develop into blood cells and

immune cells• Cord blood cells are highly suitable because they

have less rejection.• They also lack mature immune cells that can attack

the recipient body.• Cord cells can be store and it can be denoted by

woman after giving birth.• Cord blood bank

4- Adult Stem Cell

• Numerous multipotent adult stem exist in body

• Can develop into cells of specific types of the tissue

• These are least plastic in term of differentiation

• Much research is focused in this area

Application of Stem Cells

Induced pluripotent stem cells (iPS cells)

adult cell

‘genetic reprogramming’= add certain genes to the cell

induced pluripotent stem (iPS) cellsbehave like embryonic stem cells

Advantage: no need for embryos!

all possible types ofspecialized cells

culture iPS cells in the lab

differentiation