Session 8 on Stem Cells
Stem Cell Basics
Stem Cells = undifferentiated cells of an organism that have the potential to differentiate into many “mature” cell types and can self-renew
Many factors that lead to differentiation, including:
Soluble factors (growth factors, cytokines)
Cell-cell contact/forced shapes
Epigenetic factors
Have the ability to self-renew
Constantly renew supply of stem cells without differentiation/getting old
Stem Cells vs Body Cells
Stem Cells
Undifferentiated
No specialized functions
Self-renewal capabilities
Body Cells
Differentiated
Specialized functions
May divide, cannot self-renew into stem cells
Potency Levels
Totipotent: cells can differentiate into any of the 3 embryonic germ layers AND extraembryonic structures (e.g. placenta)
Most common in morula form of embryo (16-32 cells)
Pluripotent: cells can differentiate into any of the 3 embryonic germ layers ONLY
Humans: blastocyst inner mass cells are pluripotent
Human Stem Cell Examples
Human Embryonic Stem Cells (hESCs): pluripotent
Extracted from human blastula inner cell mass
Mesenchymal Stem Cells (MSCs): multipotent
Extracted from many sources, including bone marrow and umbilical cord
Neural Stem Cells (NSCs): multipotent
Extracted from embryonic/adult brains
Ethics issue + iPSCs
Pluripotent cells = very good
Can only extract from embryos = very bad
Embryos die in the process
Solution: induced pluripotent stem cells (iPSCs)
iPSCs are pluripotent
Revert body cells to pluripotent SCs w/ embryonic transcription factors
Application--ALS
Amyotrophic Lateral Sclerosis: neurodegenerative disease
Stem cells used to regenerate neural/glial cells
Other effects: anti-inflammatory, temporarily recover motor function, delay disease onset and progression
Commonly used cell lines
BM-MSCs
NSCs
Approved SC treatment: NeuroNata-R
Application: Diabetes
Diabetes: body doesn’t make enough insulin/use it appropriately
Type 1 Diabetes: insulin-making beta cells are killed by immune system
Stem cell-derived islet cell therapy to produce insulin 👉
Stem cells/pancreatic progenitors can also differentiate into beta cells
Application: SCI
Spinal Cord Injury: damage to any part of the spinal cord
Extreme back pain, weakness, numbness, inability to move
Stem cells can differentiate into neuronal or glial cells
mESCs/hESCs differentiate into neural progenitors, helped recover motor function
NSCs differentiate most directly
SC-derived neural progenitors had neuroprotective effects and regenerated axons
Application Burns
Stem cells aided in neo-angiogenesis
Formation of new blood vessels
Treated mice regained body weight faster and experienced faster re-epidermal growth and a thicker epidermis than control mice
Inflicted with partial thickness burns (2nd degree burns)
