Stem Cell (1-4)

Education & Work Experience of Dr. Shamsul Azlin Bin Ahmad Shamsuddin

• 1987-1989: A.S.A.S.I. sains
• 1989-1993: BSc Zoology
• 1993-1997: MPhil, UM
• 1997-2000: Embryologist, Pantai Bangsar Medical Centre
• 2000-2003: Embryologist, Gleaneagles, Ampang Medical Centre
• 2003-2006: Embryologist, Damansara Specialist Hospital
• Oct 2006- June 2011: PhD, Sheffield University, UK
• 1997: Embryologist training, Melbourne, Australia (2 months)
• 2000: Embryologist training, Cairns, Queensland, Australia (2 weeks)
• 2003: Embryologist training, NUS, Singapore (3 days)

Embryologist Locums

• Sime Darby Medical Centre, Subang Jaya
• Metro Hospital, Kelang
• Gleaneagles, Penang
• Darul Ehsan Medical Centre, Shah Alam
• Mahkota Medical Centre, Melaka
• LPPKN, KL
• Columbia Asia Hospital, Setapak, KL
• Prince Court Hospital, KL

Regeneration in Nature

• Planarian
• Crayfish
• Embryos

Inverse Relationship

• Increase complexity
• Decrease regenerative ability

Regeneration in Humans

• High: Skin, Liver, Muscles, Gut Lining
• Moderate: Bone
• Low: Heart, Brain, Joints (Knee)

Clinical Needs for Stem Cells in Humans

• Cardiovascular: Myocardial infarction, Stroke
• Bone: Non-union fractures, Tumor resections
• Nervous: Spinal Cord Injury, Degenerative diseases

Definitions of Stem Cells and Differentiation

• Stem cells: Undifferentiated cells that divide indefinitely in culture (self-renew) to become specialized cells
• Differentiation: The process where cells become specialized
• Stem cells with decreasing potential (Adult stem cell): No longer capable of cell division
  • Cardiac muscle cells, Neurons produced during embryonic development, differentiate, and retained through life

Cell Differentiation Diagram

• Pluripotent stem cell (Embryonic stem cell)
• Multipotent stem cells (Adult stem cell)
• Differentiated cells (muscle, nerve, skin, fibroblast, etc.)

Types of Stem Cells

• Embryonic Stem (ES) Cells
• Embryonic Germ Cells
• Adult Stem Cells
• Umbilical Cord-Blood Stem Cells
• Somatic Cell Nuclear Transfer (SCNT)
• Induced-Pluripotent Stem (iPS) Cells

Embryonic Stem Cells Details

• Embryos are from in vitro fertilization (IVF)
• Cells are taken from the Inner Cell Mass (ICM) of a blastocyst.
• ICM cells are nourished in a petri dish in an incubator.
• Cells are given different types of factors/chemicals to differentiate.
• These cells can give rise to most types of cells.
• Human embryonic stem cell lines were first derived in 1998 by Dr. James Thompson.

Stem Cell Capacity

• Embryo
• Inner cell mass
• Broad capacity

Somatic Cell Nuclear Transfer (SCNT)

• Creates clones for reproductive and therapeutic reasons.
• The diagram shows the removal of the donor nucleus from a somatic cell for the schematic purposes (In general, the whole donor cell is usually transferred).

Induced Pluripotent Stem Cells (iPSCs)

• Mature somatic cells were genetically engineered by viruses to achieve pluripotency (ES-like state) in 2007
• Forced expression of genes helped reprogram adult mouse/human cells into pluripotency
• Strategies were developed to deliver genes (e.g., non-integrating viruses, chemicals, small molecules) to prevent harmful changes
• This method allows for patient-specific cell therapies avoiding immune rejection after transplantation

Stem Cells Research in Malaysia

• Haematopoietic stem cells (UKM)
• Mesenchymal stem cells (IMR & UMMC)
• Tooth pulp stem cells (Dental, UMMC)
• Bone marrow stromal stem cells (also known as mesenchymal stem cells or skeletal stem cells)

Cord Blood versus Bone Marrow

• Cord Blood: Collection non-invasive, painless, no donor risk. Greater HLA compatibility due to decrease fetal lymphocyte functionality. Graft versus Host Disease (GVHD) reduced to 10% due to the absence of antibodies in the stem cells. Units are processed and ready for transplant. Significantly less expensive.
• Bone Marrow: Collection is invasive, painful. Must be performed in a hospital surgical setting. Stem cell maturity requires a greater HLA match to perform a transplant. Serious GVHD occurs in 60% of all unrelated Bone Marrow transplants. Bone Marrow is donor-dependent.

Stem Cell Capacity Chart

• Embryo (Broad)
• Fetus
• Adult Organism (Limited)

Epigenetics Summary

• Epigenetics literally means "above" or "on top of" genetics.
• It refers to external modifications to DNA that turn genes "on" or "off".
• These modifications do not change the DNA sequence.
• They affect how the cells "read" the genes.
• Heritable changes in gene expression (active versus inactive genes) that do not involve changes to the underlying DNA sequence: a change in phenotype without a change in genotype. -Epigenetic change is a regular and natural occurrence but can also be influenced by factors like age, environment/lifestyle,and disease state.
• Epigenetic modifications can manifest in many ways, such as terminal differentiation of cells into skin, liver, and brain cells.

Mechanisms of Epigenetics

• DNA Methylation
• Histone Modification
• Non-coding RNA (ncRNA) associated genes

Terminology of Potential (Plasticity)

• Totipotent
• Pluripotent
• Multipotent
• Unipotent

What makes stem cells pluripotent?

• Receptors on their surface that make them responsive to signals from their environment (the niche)
• Low levels of gene expression for cell types, (e.g., bone, fat, muscle, cartilage).
• Genes packaged into active and inactive segments
  • Active genes: open configuration (accessible)
  • Inactive genes: closed configurations (inaccessible)
• Inactive genes with the potential for activation (open configuration but with a brake on)

Early Development

• Signals come from within cells and neighboring cells.
• Maternal nutrition is important for fetal development.
• Maternal stress hormones can affect the fetus.

After Birth and Continuing Life

• Variety of environmental factors shape the epigenome.
• Social interactions, activity, and diet generate signals that travel throughout the body.
• Signals within the body are important for many processes including growth and learning.
• Hormonal signals trigger puberty-related changes.

Even Into Old Age

• Cells continually respond to environmental signals.
• Environmental signals trigger changes in the epigenome.
• Cellular signals direct body maintenance processes.
• Re-establishment of cellular maintenance processes is similar to embryonic development.

The Epigenome Program

• Programmed alterations of histone patterns.
• Starts in egg cells, affecting differentiated skin/liver cells.

Comparison of Embryonic and Adult Stem Cells

• Adult Stem Cells: From mature tissues; umbilical cord and placenta
• Embryonic Stem Cells: From inner cell mass of a blastocyst
• Multipotent vs Pluripotent and Isolation times
• Further analysis of human tissue responses

iPSCs—The Wave of Future

• iPSCs are regarded as innovative stem cell research.
• Research on disease models, drug screening, and toxicology testing
• Generating patient-specific cells, allowing unprecedented access to human biology.
• Studying development and function of human tissues, and regenerative medicine.

iPSC Applications

• Treating Parkinson's Disease via cell replacement therapy.
• Creating electrically active neurons, for studying and treating neurological disorders.
• Regenerating beta cells (for diabetes)
• Creating mouse kidneys, (Hiromitsu Nakuchi)

iPSC Limitations

• DNA methylation errors compared to ESC lines.
• Unable to create viable chimeras.
• Some factors such as c-Myc are oncogenic.

iPSC Complications

• Potential tumor formation due to viral transfection systems.
• Successful use of adenovirus (Konrad Hochedlinger) for gene delivery to eliminate tumor formation risk.

Cloning Types

• Reproductive Cloning: Creating identical individuals
• Therapeutic Cloning: Cloning embryos for research; never implanted
• This is used for drug designing, disease modeling and in regenerative medicine.

Animal Models of Regeneration

• Hydra: Regenerates every part of the body.
• Planaria: Contains neoblast cells.
• Annelids: Formation of blastema (cells under the wound or severed area).

Regeneration of Vertebrates and Types of Regeneration

• Fish, amphibians, reptiles can regenerate.
• Regeneration power is well-marked in urodel amphibians (salamanders, and newts).
• Lizards exhibit autotomy (detaching the tail for defense).
• Mammals display regeneration in the liver (compensatory hypertrophy) but external parts are not regenerated. Types include:
• Epimorphosis, Morphallaxis, Heteromorphosis, and Super-regeneration

Steps of Regeneration of a Limb in a Newt

• Wound healing: Migration of epidermal cells from wound edges.
• Blastema formation: Undifferentiated cells creating a bulge.
• Redifferentiation and morphogenesis: Developing rudiments (e.g. digits)
• Growth: Regenerating limb increasing to normal size.

Growth Factors

• Epidermal growth factor (EGF), Fibroblast growth factors (FGF), Platelets (Derived growth factors).
• These act locally to initiate cell mitosis, contributing to wound healing and limb regeneration

Polarity in Regeneration

• In organisms such as Hydra and planarians, bodies exhibit distinct polarity.
• Anterior end regenerates into head, while posterior end regenerates into the tail.