Stem cells and their directed differentiation

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Stem Cells and their characteristics

Cells which are capable of differantiatinginto different kind of cells are called STEMCELLS. Stem cells have followingcharacteristics:

Stem cells are unspecialized Unlimited self renewal through cell division. They can specialize under certain physiologic or experimental

conditions

Stem cells then become cells with specialfunctions such as:beating cells of the heart muscle

insulin-producing cells of the pancreas


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Types of Stem cells

On the basis of origin1) Embryonic stem cells2) Adult stem cells

3)Fetal stem cells4)Umbilical cord stem cells

On the basis of potency1)Totipotentstem cells2)Pleuripotent stem cells3) Multipotent stem cells4) Unipotent stem cells


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Pleuripotent Stem cells


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Potential uses of human stem There are many technical hurdles between the promise of stem cells andthe realization of these uses. This will only be overcome by continuedintensive stem cell research.Basic research: elucidation of complex events that occur during humandevelopment & understanding molecular basis of cancerMolecular mechanisms for gene expression controlRole of signals in gene expression & differentiation of the stem cell.Stem cell theory of cancer

Biotechnology (drug discovery & development): stem cells can providespecific cell types to test new drugsSafety testing of new drugs on differentiated cell linesScreening of potential drugsScreening of potential anti-tumor drugs in cancer cell linespluripotent stem cells used for testing drugs in a wider range of celltypes & to reduce animal testing

Cell-based therapies:Regenerative therapy to treat Parkinson's, Alzheimers, spinal cordinjury, stroke, burns, heart disease, diabetes, osteoarthritis, andrheumatoid arthritis.Stem cells in gene therapystem cells as vehicles after their genetic manipulationStem cells in therapeutic cloning


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Generation of embryonic


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Blastocyst (5 days)

Unfertilized Egg/ Oocyte

Fertilized Egg/ ZygoteSperm

Morula(3-4 days)

Early Embryonic Development

~200 cells


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Blastocyst (5 days)

Unfertilized Egg/ Oocyte

Fertilized Egg/ ZygoteSperm

Morula(3-4 days)

Early Embryonic Development

~200 cells


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The Future? Stem Cells Cloning Creation of embryos for

research Patenting of human life

forms Germline Genetic

Engineering Chimerism

Cybernetics andNanotechnology


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Regenerative Medicine with


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Promises, Premises, and Published DataClaims for embryonic stem cells

unsubstantiated

Current and potential embryonic stem cell problems:No current clinical treatmentsFew successes in animal modelsDifficulty in obtaining pure cultures in the dishDifficult to establish and maintainProblem of immune rejectionPotential for tumor formation

Genomic instability


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D i ti f E b i St C ll


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Derivation of Embryonic Stem Cells

Purported Advantages:1) Proliferate indefinitely2) Form any tissue

Method patentedU.S. patent held by Univ.


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Major Goals in DevelopingTransplantation Therapies from

Establish pure cultures of specific cell types

Human ES cells

Test physiologic function

Demonstrate efficacy Demonstrate safety Test methods toprevent rejection

Human Trials


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EmbryonicEmbryo

Embryonic Stem Cells growing on irradiated

Mouse Embryo FibroblastsDifferentiation directedby growth anddifferentiation factors(now unknown )

Bone, Skin, Muscle, Nerves,

Documents

Stem cells and their directed differentiation