Introduction to Stem Cells

By

AMAR DEEPPh. D. Scholar

Department of Zoology

University of Lucknow

Lucknow – 226007 (India)

A Life Story…

Embryonic Stem Cells

blastocyst - a very early

embryo

Tissue Stem Cells

fetus, baby and

throughout life

Stem cells are unspecialized cells that are thought to be

able to reproduce themselves indefinitely and under the

right conditions, to develop into a wide variety of

mature cells with specialized functions.

What are Stem Cells?

Stem cells can:

• Self-renew to make more stem

cells.

• Differentiate into a specialized cell

type.

Definitions:

Totipotent:Able to give rise to all type of differentiated cells including

placenta. eg. Single cell embryo.

Multipotent:Stem cells that can become only a few types of cells are called

multipotent. eg. Fetal tissue, Cord blood, Adult stem cells.

Pluripotent:Stem cells that can become many types of cells in the body are called

pluripotent. Undifferentiated inner cell mass of the blastocyst.

Type of Stem Cells

Embryonic stem cells

Adult stem cells

Pluripotent stem cells

Embryonic Stem Cells

Where do embryonic stem cells come from?

8-cell blastocystfertilised egg

2-cellegg

Day 0 Day 1 Day 2 Day 3 Day 6

Inner cell mass

Advantages of E.S. Cell

1. Flexible-have the potential to make any cell.

2. Immortal-can provide an endless supply to cells.

3. Availability-embryos from in vitro fertilization

clinics.

neurons

Embryonic stem (ES) cells:

Challenges

embryonic stem cells

skin

blood

liver?

Disadvantage of E.S. Cell1. Difficulty to differentiate uniformly into a target

tissue.

2. Immunogenic ie. cells from a random embryo

donor may be rejected after transplantation.

3. Tumorigenic ie. capable of forming tumors.

4. Destruction of developing human life.

Tissue Stem Cells: Adult Stem Cells

• Adult stem cell is an undifferentiated (unspecialized) cellie. found in differentiated (specialized) tissue.

• Also includes stem cells isolated from fetal and cordblood.

• Reside in most tissues of the body where they areinvolved in repair and replacement

Adult Stem Cells

Brain Skeletal

Muscle

Liver, Skin,

GIT &

Pancreas

Bone Marrow &

Blood Stream

Eye dental pulp

& Eye

Sources of Adult Stem Cells

Disadvantage of Adult Stem Cell• Limited quantity- can sometimes be difficult

to obtain in large numbers.

• Finite- may not live as long as embryonic stemcell in culture.

• Less flexible- may be more difficult toreprogram to form other tissue type.

Why are adult stem cells preferable to embryonic stem cells ?

• Adult stem cells are naturally exist in our bodies and they provide a natural repair mechanism for many tissue. eg. hematopoietic stem cells.

• They belong in the microenvironment of an adult body, where they never cause tumors and immune system reactions.

• Adult stem cells have already been successfully used in human therapies.

Pluripotent Stem Cells• Pluripotent Stem Cells are descendants of the

totipotent stem cells of the embryo.

• Similar properties to embryonic stem cells as candifferentiate into many different tissue types.

• Terminally differentiated cells induced to becomepluripotent with in vitro manipulation k/a inducedpluripotent stem (iPS) cells.

Induced pluripotent stem cells (iPS cells)

cell from the body

‘genetic reprogramming’= add certain genes to the cell/culture condition

induced pluripotent stem (iPS) cellbehaves like an embryonic stem cell

Advantage: no need for embryos!all possible types of

specialized cells

culture iPS cells in the lab

differentiation

• Apoptosis

No apoptosis in stem cells

• Telomere

No shortening of telomere in stem cells

• DNA Methylation

Minimum DNA methylation in stem cells

Stem cells specialty

Identification of stem cells

• Cell morphology

• Expression of unique cell surface antigens

• Characterization of biochemical markers such as tissue

specific enzymatic activity

• Expression of genes that are unique to a particular cell

type

• Nuclear chromosomal karyotype to access genetic

stability

Applications of Stem Cell Research

Animal model testing for pharmaceutical research

Use of stem cells in transplantation and cellreplacement therapy

Conservation of endangered species

Understanding fundamental events in embryonicdevelopment

Therapeutic delivery system

To resolve mysteries of developmental biology

To investigate genes involved in differentiation anddevelopment

Cell banking for research applications

Applications of Stem Cell Research

Study cell

differentiation

Drug screening

&

Toxicity testing

Bone Marrow

for leukemia &

chemotherapty

Nerve cells for

Neurodegener-

ative disorders

Heart muscle

cells for heart

disease

Pancreatic

islet cells for

diabetes

Pluripotent

Stem Cells

Cell replacement therapy

Therapeutic Use

Thank You