Stem Cells & Neurological Disorders
Said IsmailFaculty of Medicine University of Jordan
Outline:- Introduction
- Types & Potency of Stem Cells- Embryonic Stem Cells- Adult Stem Cells- iPSCs
- Tissue Engineering and Regenerative Medicine
- Stem Cells & Neurological Disorders:- Neural Stem Cells
- Examples of Therapeutic Applications
- Conclusion
Stem Cells and Neurological Disorders
Introduction
Stem Cells and Neurological Disorders
Benefits of stem cell research :
- Treatment of complex diseases:
Chronic Disorders: Diabetes
Neurological Disorders: Alzhimer’s
Parkinson’sSpinal Cord Injuries
Heart disorders: MI
- Regenerative medicine (Spare parts !)
Skin Cartilage Bone Cornea Heart Valves
Stem Cells and Neurological Disorders
Definition:
• stem cells:
(i) renew itself indefinitely
(ii) differentiate to multiple tissue types
A stem cell is not committed to a specific function until it receives a signal to differentiate into a specialized cell
Stem Cells and Neurological Disorders
Types & Potency
Stem Cells and Neurological Disorders
1. Embryonic:- Blastomere (4-5 day embryo) - Pluripotent
2. Adult:
- Adult tissue - multi or uni potent
Other :
- Fetal: - Aborted embryos- Pluripotent
- Umbilical: - Umbilical cord blood
- Multipotent
Stem Cells and Neurological Disorders
Potency:1.Totipotent (Fertilized egg) Generate: - all embryonic cells and tissues
- supporting tissue like placenta and umbilical cord
2. Pluripotent - Give rise to cells of all 3 germ layers (ecto-, meso-, and endoderm- Come from embryos and fetal tissue- Have active telomerase (maintain long telomers)
3. Multipotent - Give rise to multiple different cell types
4. Unipotent- Cell differentiating along only one lineage
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Embryonic Stem Cell
Stem Cells and Neurological Disorders
The Embryonic Stem Cell
Source:
1. IVF embryos
2. Aborted Fetus
3. Therapeutic cloning
Stem Cells and Neurological Disorders
IVF embryos
Thousands of frozen embryos are routinely
destroyed when couples finish their
treatment.
Somatic Cell Nuclear Transfer
The nucleus of a donated egg is removed and replaced with the nucleus of a mature, "somatic cell" (a skin cell, for example).
Embryonic Stem Cell First isolated and cultured in 1998
From inner cell mass of blastocyst (4-5 day embryo).
Pluripotent with long-term self-renewal
Capable of unlimited number of divisions without differentiation
Can essentially live forever without forming tumors
Maintain normal diploid complement of chromosomes (stable karyotype)
Telomerase activity
Clonogenic: give rise to genetically identical group of cells
Expresses transcription factor Oct-4 (+ or – genes needed for proliferative state)
Spend most of their time in S phase
- In-Vitro: 300 population doublings
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Human Blastocyst showing Inner Cell Mass
GROWING HESC IN VITRO:
Stem Cells and Neurological Disorders
Advantages:
- Immortal: supply endless amount of cells- Flexible: can make any body cell- Available: IVF clinics
Disadvantages:
- Hard to control their differentiation- Ethics- Immune rejection
Stem Cells and Neurological Disorders
Avoiding Immune rejection:
1. Genetically engineering stem cell to:a. Express MHC antigens of recipientb. produces stem cells with deleted MHC genes
2. Therapeutic Cloning: Clone somatic Cell nucleus of recipient into eggdevelop into blastocyst and isolate ES cellsSuch ES cells have recipient immunological profile
3. Co-transplantation with Hematopoitic Stem cells
Avoiding Immune rejection
Laboratory tests to identify ESC :
1. Immortality: Sub-culturing stem cells for many months (long-term self-renewal)
2. Morphology: Inspecting culture by microscope (for undifferentiation)
3. Surface markers & Stemnss genes: (e.g. Oct-4)
4. Karyotype stability: Examining the state of chromosomes
5. Telomerase Activity
6. Pluripotency: testing differentiation potential into diff. cells types
Stem Cells and Neurological Disorders
Here Here or Here
When is it OK….when is it NOTStem Cells and Neurological Disorders
Ethics and ESCs:
Group of cells or Human life
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Adult Stem Cells
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
The Adult Stem Cell Undifferentiated cell found in a specialized tissue in adult. Capable of self-renewal Become specialized to cell types of the tissue from which it
originated.
Properties:- Somatic- Long-term self-renewal- give rise to mature cell types
- Generate intermediate cell (progenitors) “committed”
- Can migrate whenever needed- Uni- or Multipotent
Stem Cells and Neurological Disorders
Sources of adult stem cells : Bone marrow Blood stream Umbilical cord blood Dental pulp of the tooth Cornea and retina Skeletal muscle Liver Skin (epithelia) Gastrointestinal tract Pancreas Brain & spinal cord
Stem Cells and Neurological Disorders
Bone marrow
umbilical cord blood
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Dental Pulp
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Adult stem cell plasticity
- Plasticity: stem cell from one adult tissue can generate the differentiated
cell types of another tissue:“unorthodox differentiation” or “transdifferentiation”
- EX. Hematopoietic stem cell Neurons
- Possible under specific conditions
Stem Cells and Neurological Disorders
Plasticity of adult stem cells
Stem Cells and Neurological Disorders
Advantages :
1. No immune rejection2. Available: eg HSC
3. Partly specialized: easier to control differentiation
4. Flexible: under the right conditions
Disadvantages :
5. Scarce (Rare): True for many Adult SCs
6. Unavailable: Some are difficult to isolate like Neural stem cells 7. Vanishing: Don’t live in culture as long as ES cells
8. Questionable quality: more prone to DNA abnormalities
Stem Cells and Neurological Disorders
Induced Pluripotent Stem Cells (iPSCs)
Stem Cells and Neurological Disorders
Induced Pluripotent Stem Cells (iPSCs):
= Retro-differentiation = Re-programming
Producing stem cells from differentiated cells !!!
Pluripotent embryonic like stem cells are produced
Reversal of normal process
Does Not require human embryos
No donor…..No rejection
Less expensive
No Ethical issues
Main Key Genes:
- iPSCs are derived from adult somatic cells by inducing expression
of certain Stemness genes: (usually by viral vectors: risk !!!)
- eg: Master transcriptional regulators:
Oct-4
Sox2
Nonog
- other genes: c-Myc (oncogene: cancer risk !!!!)
Stem Cells and Neurological Disorders
Pluripotency:
Believed to be identical to embryonic stem (ES) cells in many respects:
- expression of certain stemness genes
- chromatin methylation patterns
- doubling time
- embryoid body formation
- teratoma formation
- viable chimera formation
- potency and differentiability
Stem Cells and Neurological Disorders
(1) Isolate and culture donor cells.
(2) Transfect stemness genes into cells by viral vectors. Red cells express those genes
(3) Harvest and culture the cells according to ES cell culture, on feeder cells (light gray)
(4) A subset of the transfected cells become iPS cells and generate ES-like colonies
Generation of induced pluripotent stem (iPS) cells
Stem Cells and Neurological Disorders
Neurogenesis of iPS Pluripotent Neuronal Stem Cells derived from Adult Leukocytes
Stem Cells and Neurological Disorders
Potential target disorders for Stem Cell Therapy:
• Leukemia• Heart damage • Anemia • Cornea damage • Retinal damage• Parkinson’s • Alzhimer’s• Diabetes • Spinal Cord Injury • Kidney Failure • Skin grafts
leukemia
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Heart damage
Stem Cells and Neurological Disorders
Diabetes
Stem Cells and Neurological Disorders
Tissue Engineering &
Regenerative Medicine
Bone Repair
Stem Cells and Neurological Disorders
Skin graft grown from stem cells
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Cornea
Stem Cells and Neurological Disorders
trachea from stem cells
Stem Cells and Neurological Disorders
A grown ear seeded with cartilage cells
Stem Cells &
Neurological Disorders
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Which Stem Cell:
1. Neural stem cells
2. Other Adult SC (HSCs & MSCs)
3. Cord Blood SC
3. Embryonic SC
4. iPSCs
Delivery Strategy:1. Injection into brain2. Into Blood stream (Homing + immobilization by cytokines)
Graft type:3. Stem cells + Biomaterial 4. Stem Cells + Gene therapy
All have been shown to generate neural tissue
(Adult SCs are the mostlyused in clinical trials)
Stem Cells and Neurological Disorders
Comparison:
Stem Cell Embryonic Pluirpotent Ethics
Fetal Pluripotent Ethics
Cord Blood Potent RejectionAvailable
Adult Neural / Autologus Self low Numbers Same tissue Isolation
Adult (HSCs, MSCs,…) Easy isolation rejection (if allo.) Easy culture Plasticity ?!!
iPCs Pluripotent vector safetySelf
Ongoing clinical Trials in US and the world 2012
Sanberg et al.February 2012
Different strategies for stem cell delivery to repair degenerated tissue
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Neural stem cells:
- Generate new neural cells throughout the lifetime
- Can migrate and replace dying neurons
- Give rise to all types of neurons, astrocytes and oligodendrocytes, …
- Capable of only Minor repairs
- Their activity is up-regulated following injury
- Found in: - Sub-ventricular zone of lateral ventricles (Most neurogenic area)
- Dentate gyrus of Hippocampus (2nd)
fewer in:- Cerebellum - Spinal Cord
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Stem Cells and Neurological Disorders
Therapeutic Applications:
Main target disorders:
- Parkinson’s: localized degeneration (in substantia nigra) easier cell therapy
- Huntington’s: clear etiology, single gene disorders (Gene/Cell Therapy)
- Alzheimer : damage is less defined, widespread neuro-degeneration
- Spinal Cord injuries: very promising prospects
- Other: - Multiple Sclerosis (Siatskas and Bernard, 2009)- Ischemia / stroke- Epilepsy (Naegele et al., 2010) - Amyotrophic Lateral Sclerosis (ALS) (Wolfson et al., 2009).
Stem Cells and Neurological Disorders
Parkinson’s:
- Main Strategy:
- Replacing degenerated neurons with dopamine-producing cells
- Site:- Substantia nigra: area were most degeneration occurs in PD
- Source of SCs:
- Pieces of fetal midbrain tissue (Mendez et al., 2005)
- Autologous adult neural stem/progenitor cells (Michel et al., 2009)
- Embryonic SCs (Friling et al. 2009)
Stem Cells and Neurological Disorders
Huntington’s:
- Good Model: well characterized single gene disorder
- Main Strategy:
Blocking neuronal cell death & replacing lost neurons in striatum
- Source of SCs:
- SCs of fetal striatal primordium into striatum of HD patients (Bachoud-Lévi et al., 2006)
- Autologous adult neural stem/progenitor cells (Yu and Silva, 2008; Visnyei et al., 2006).
Stem Cells and Neurological Disorders
Alzheimer’s:
- Neuro-genesis in hippocampus deteriorates in AD patients
Example approaches: (Lunn et al., 2011)
1. Implanting Neural Stem Cells:
- Replace lost neurons
- Delay degeneration by producing Brain-Derived Neurotrophic Factor (BDNF)
2. Nerve growth factor (NGF) production:
- Genetically engineered patient fibroblasts that produce NGF …!!!
- Integration of NGF fibroblasts into a major cholinergic center of the basal forebrain provided some benefit to AD patients
Stem Cells and Neurological Disorders
Spinal cord injuries: (Salewski et al., 2010; Hu et al., 2010, Mathai et al 2008).
Stem cells can:
1. Replace neurons that died from injury
2. Generate supporting cells to re-form the myelin sheath & stimulate re- growth of damaged nerves
3. Protect cells at injury site from further damage, by releasing protective factors
Stem cells under trials:
- Embryonic SCs - Umbilical cord SCs - Adult neural SCs - Mesenchymal / bone marrow SCs - induced pluripotent Scs
Stem Cells and Neurological Disorders
Christopher Reeve
1952 - 2004
Stem Cells and Neurological Disorders
Paralyzed Patients Walking Again
http://www.youtube.com/watch?v=KGUAyKQKmmY
http://www.youtube.com/watch?v=-kygF2leZCE
http://www.youtube.com/watch?v=ZgI4tm8Tr5M
Stem Cells and Neurological Disorders
Conclusion:
- Very promising clinical trial results in the last few years
- More research needed to optimize diff. SC replacement protocols:- Cell type- Route- No. of cells- Single or multiple cell doses
- Choice between ESCs / ASCs / iPSCs: yet to be resolved
- Ethics (ESCs and Fetal tissue): Each Country has to decide
THANK YOU
Stem Cells and Neurological Disorders