Stem cells

By: Dr SM Koruji, Ph.D

What are Stem Cells?

Stem Cells are extraordinary because: They can divide and make identical copies ofthemselves over and over again (Self-Renewal) Remain Unspecialized with no ‘specific’

function or become . . . . Specialized (Differentiated) w/ the potential

to produce over 200 different types of cells in the body.

Diagram of stem cells to differentiated cells

Description: A colony of embryonic stem cells. 10X. Image in the Public Domain.

Description: (A) Human ESCs; (B) Neurons derived from Human ESCs. Images courtesy of Nissim Benvenisty.

Caption: This image depicts a colony of human embryonic stem cells grown over a period of 10 months in the absence of mouse feeder cells. The cell nuclei are stained green; the cell surface in red.

Photo Credit: Courtesy Ren-He Xu/University of Wisconsin

The Major Types of Stem Cells

A.Embryonic Stem Cells

• From blastocysts left over from In-Vitro Fertilization in the laboratory

• From aborted fetuses

B. Adult Stem Cells

• Stem cells have been found in the blood, bone marrow, liver, kidney, cornea, dental pulp, umbilical cord, brain, skin, muscle, salivary gland, testis . . . .

Embryonic Stem Cells

Mechanical

Immunosurgery

Adult Stem Cells

The types of Stem Cells based on potential

Totipotent stem cellsPluripotent stem cells

EGEC

Multipotent stem cells

http://commons.wikimedia.org/wiki/Image:Stem_cells_diagram.png

Pluripotent stem cells

Advantages and Disadvantages to Embryonic and Adult Stem Cells.

Embryonic S.C. Adult S.C.“Pluripotent”

(can become any cell)

“Multipotent”

“(can become many but not any)”

Stable. Can undergo many cell divisions.

Less Stable. Capacity for self-renewal is limited.

Easy to obtain but blastocyst is destroyed.

Difficult to isolate in adult tissue.

Possibility of rejection ?? Host rejection minimized

Reprinted with permission of Do No Harm. Click on image for link to website.

Reprinted with permission of Do No Harm. Click on image for link to website.

Why is Stem Cell Research So Important to All of Us?

Stem cells allow us to study how organisms grow and develop over time.

Stem cells can replace diseased or damaged cells that can not heal or renew themselves.

We can test different substances (drugs and chemicals) on stem cells.

We can get a better understanding of our “genetic machinery.”

Why the Controversy Over Stem cells?

Embryonic Stem cells are derived from extra blastocysts that would otherwise be discarded following IVF.

Extracting stem cells destroys the developing blastocyst (embryo).

-Questions for Consideration-Is an embryo a person?Is it morally acceptable to use embryos

for research?When do we become “human beings?”

Therapeutic Possibilitiesof Stem Cell Research

Reprinted with permission from the Univ. of Kansas Medical Center. Click on image

for link to originating website.

What Human Diseases are Currently Being Treated with Stem Cells?

Parkinson’s Disease Leukemia (Bone Marrow Transplants) Skin Grafts resulting from severe burns

Stem Cell Therapy has the Potential to: Regenerate tissues/organs Cure diseases like diabetes, multiple sclerosis,

etc.

Olfactory Bulb Stem Cells Primitive stem cells that normally feed the constant,

life-long regeneration of odor-detecting nerves Like embryonic stem cells, they develop into many

different types of cells in the right chemical or cellular environment

Fairly accessible, readily obtained in all individuals and easy to grow and multiply

Potential non-embryonic source for cells that could prove useful in replacing nerve cells lost due to injury or diseases like ALS and Parkinson's

Transplant not subject to immune rejection

Lou Gehrig’s Disease (ALS)

Mouse experiments Neuronal stem cells

transplanted into spinal cord

Significantly prolonged lives by becoming neurons and interacting with existing neurons

Symptoms developed at 137 days verses 90 days

Treated mice lived 2 months longer

A neuromuscular disease that attacks the nerve cells and pathways in the brain and spinalcord

Bone Repair

NJ Institute of Technology – use of stem cells to induce bone repair

Adult Stem Cells mixed with biomaterials known as scaffolds to regenerate bone growth

Stem Cells from one person can successfully implant in another

Diabetes, osteoporosis, cancer surgeries Also testing biomaterials that may repair

cartilage, tendons and neuronal tissue

Spinal Cord Injury

Rat Experiments

Sensory and motor deficiencies; paralysis Treatment derived fromhuman embryonic stem cells and must occur in theacute phase of spinalStabilization

Cells differentiate into earlystage oligodendrocytes, the building blocks of myelin Transplanted cells migratedto appropriate neuronalsites in the spinal cord 7 days post injury vs. 10 months post injury

Retinal Degeneration

Mice predisposed for Retinitis Pigmentosa: a degenerative disease that destroys retinas

Injected bone marrow derived stem cells into the back of mouse eyes during development

Dramatically curtailed retinal degeneration

Completely normal vasculature, improved retinal tissue and light response

Disorders of the retina that have vascular and neuronal degeneration: genetic disorders known collectively as retinitis pigmentosa

Biological Pacemaker

Human Embryonic Stem Cells genetically engineered and coaxed to become heart cells

Clusters of cells beat on their own triggered the unified beating of rat heart muscle cells

Triggered regular beating when implanted in guinea pigs

Cells responded to drugs used to slow or speed up heart rate

Use genetic engineering to customize the pacing rate of the cells

Cystic Fibrosis: Stem Cell-GeneTherapy Approach

Cosmetic and Reconstructive Surgery

Conventional soft tissue implants lose 40 to 60% of volume

Stem cell generated natural tissues instead of synthetic implants

Avoid problems of saline and silicon Won’t shrink or lose shape Mouse experiments: bone marrow stem cells placed

under the skin for four weeks; stem cells differentiated into fat generating cells and implants retained original size and shape

Breast cancer surgery, post-cancer facial soft tissue reconstruction, trauma surgeries

Cloning

Cloning Defined

• What is cloning?• Asexual reproduction

• Examples?• Bacteria, fungus• Plants – cutting – potato• Farm animals

Asexual Reproduction

The Association of Reproductive Health Professionals

Cloning Dolly

1997 - 2003

(Roslin Institute http://www.roslin.ac.uk/library/)

Cloning A Sheep

Human Stem Cell Production

Removing Nucleus

Removing the maternal nucleus before nuclear transfer

(Roslin Institute http://www.roslin.ac.uk/library/)

Nuclear transfer

Nuclear transfer embryo about to be activated

(Roslin Institute http://www.roslin.ac.uk/library/)

Coning for use in Stem Cells

Cloning techniques for creating stem cells

Therapeutic cloning

Reproductive cloning

IVF – In Vitro Fertilization Available since 1986 About 100,000 IVF kids in U.S. Often creates extra embryos U.S. - About 400,000 frozen

embryos )unregulated( England – 52,000 )regulated by

government(

Intracytoplasmic Sperm Injection)ICSI(

How many are needed for fertilization?

Natural conception20,000,000

Intra-uterine insemination1,000,000

In-vitro fertilization )IVF(10,000

Intra-cytoplasmic sperm injection )ICSI(1

The Science of Transgenics

Biotechnology - General Definition

The application of technology to improve a biological organism

Biotechnology - Detailed Definition

The application of the technology to improve the biological function of an organism by adding genes from another organisms

ATTCGA

ATTGGA

SusceptibleNormalGene

ResistantMutantGene

MutagenesisTreatment

Mutagenesis Changes the DNA Sequence

Thank you