Download Stem Cells - Biology-Anatomy

Stem Cells
CH 8.4
S T E M CE LL B A S ICS - T E D T A LK 4 MI N S
Ch 8.4 Objectives
• State the developmental stages from zygote to fetus.
• Explain how gastrulation forms the three germ layers with
examples of each.
• State the two main types of stem cells and their characteristics.
• Explain the potency of particular stem cells and how this
defines the types of tissues that they can form.
• Relate the source of the stem cells to the therapies the are
applied to and link this to the range of controls and concerns
regarding their use.
Embryo development
Video of fetal development
Fertilization – by gametes [sperm and ovum] to form one cell
diploid cell.
• Zygote – fertilized egg [one cell]
• Morula – cell division to 16 [cleavage but no size growth]
• Blastocyst – inner [organism] and outer [placenta] layers present
and implants into the uterus around day 6-7
• Granula – 3 germ layers present [ecto, meso and ecoderms
• Embryo – up to the 8th wk [all major organs present]
• Fetus – 8 wk +
Do not copy
Do not copy
Do not copy
Embryo - Layers of the Gastrula
Do not copy
Germ layers and cell differentiation
Germ layers and cell differentiation
This is highly simplified
• Ectoderm [outside]
• Skin
• Nerves
• Endoderm [inside]
• Pancreatic
• Respiratory
• Digestive
• Mesoderm [middle]
• Muscle
• Bone
• Blood cells
Do not copy
Germ layers and cell differentiation
Do not copy
Stem Cells
• Stem cells are an undifferentiated cell of a multicellular organism that is capable of
giving rise indefinitely to more cells, and to all kinds of cells by differentiation. Cell
differentiation is normally permanent/non-reversible.
• Embryonic stem cells – [ESC’s] obtained from 3-5 day old embryos
• Adult stem cells – [ASC’s] found in very small numbers in some adult tissues for tissue
repair and replacement.
• Induced pluripotent – [IPSC’s] differentiated adult cells that have been synthetically
re-programmed to act as stem cells.
Stem Cells
Potency – the potential of a stem cell to differentiate into cell types
• Totipotent - fully potent [zygote up to morula 16 cells] – eg twins
• Pluripotent - [ESC’s] stem cells that can differentiate into any of the 3 germ layers +
gametes or [PGC’s – primordial germ cells]
• Multipotent - arise from within one specific germ layer [ecto, meso or endoderm]
• Unipotent - replacement of one specific cell type [eg skin]
Multipotency – within a germ layer
Stem Cell Therapies
Axolotls – organ and tissue regeneration – intro then skip in about 1:50 mins
Current Therapies 1/2
• Bone marrow and blood stem cells – bone marrow contains haematopoietic stem
cells [create all blood related cells] – used to treat patients that have undergone
chemotherapy or to treat leukaemia [cancer of the white blood cells].
• Cord Blood - stem cells can be taken from blood in an umbilical cord enhance blood and
immune systems. Also used for treating diabetes
• Mesenchymal stromal cells also in cord blood, can be grown into bone, cartilage
• Intestinal stem cells – epithelial cells lining the gut have a remarkable ability to
renew and repair
Current Therapies 2/2
• Epidermal stem cells – the skin helps regulate body temperature and exclude
infections, so treatments for skin problems such as burns and genetic disorders are
of high importance using these cells.
• Embryonic stem cells – harvested from 3-5 day old surplus embryos from IVF clinics.
They can be used to treat all types of tissue damage, but there use is not effective
yet.
• Induced pluripotent stem cells – harvested from the patient, are pluripotent, but
much research is required to understand their full potential and problem.
Ethical considerations
Pros and Cons of stem cell research
If you, or a loved one required Human Stem Cell Therapy [HSCT], which
of the current therapies would you consent to and why?
Resources
Stem Cells wiki
• Embryo development - Khan Academy - 12 mins
University of Utah
• Overview Stem cells - Uni of Utah - interactive site
• The nature of stem cells - video Utah 3:30 mins
• Unlocking stem cell potential - video Utah 4 mins
Videos
• SciShow - Stem cells 4 mins
• Stem Cell Basics - Ted Talk 4 mins
• BBC Stem Cells - mini doco 4 mins
• How cells specialise - the amoeba sisters 7:50 mins
The End