Growth, post-embryonic development and regeneration Flashcards
Approaches for cell-replacement therapies
- ESCs
- ASCs
- iPSCs
- Transdifferentiation
(All make differentiated cells)
Type 1 diabetes
1. pancreas –β-cells destroyed –no stem cells 2. No insulin 3. Cells from cadavers scarce, rejection, disease
A cure for type 1 diabetes?
A treatment using stem cells that produce insulin has surprised experts and given them hope for 1.5 million Americans living with the disease
Embryonic development
Basic form & pattern
Post-embryonic development
Growth increases with size
Metamorphosis
Larva turns into an adult where old organs disappear & new organs appear
Regeneration
Juvenile or adult replace tissue/organ
Growth
Increases in size or mass, where post-embryonic stage determines organ size & body size
Proliferation
- Mitosis
2. Net growth - Mitosis vs apoptosis
Enlargement
- Hypertrophy
2. Mammals (heart, kidney, nerves )
Accretion
Increase extracellular space secrete ECM bone, cartilage
Proliferation control
Cyclins check point proteins
Proliferation & cancer
- Mutation in cell division genes
- 85% cancer in epithelia (gut, skin, etc., have stem cells)
- stem cell division (tight regulation, mutations → uncontrolled division)
- tumor progression (accumulate many mutations, pancreatic cancer
has 63 mutations in proliferation genes
Tadpole turning a frog
Tadpole has a tail but losses tail to turn into a frog (apoptosis), tadpole also has no limbs but gains limbs when turn into a frog (metamorphosis)
Amphibian metamorphosis
- Environmental cues then act on hypothalamus, pituitary gland then thyroid then metamorphosis
- Thyroid hormone different effects where limb increase cell growth & tail decrease cell growth
Regeneration with amphibians
Adults maintenance where if they get injured, they just repair & replace.
Regeneration occurs at a faster rate when younger than it goes when older why?
Because have more stem cells to replace injury when younger than when your older
Regeneration with invertebrates
Some invertebrates have asexual reproduction where they can regenerate themselves (have mitosis but no meiosis), they can go from a fragment into a whole animal
Morphallaxis regeneration
- No new cells initially
2. Existing cells reorganize then divide after
Epimorphosis regeneration
New cells immediately from mitosis
Describe the process of limb regeneration for frogs
- Amputations
- Healing- epithelium covers wound
- Dedifferentiation - mature become immature cells
- Proliferation- Cone stage
- Redifferentiation- immature cells become mature cells
Blastema
Stem cells that can be multipotent or lineage restricted, it is also mostly lineage specific
Amphibian limb: epimorphosis
- Macrophages necessary
(dedifferentiation) - No macrophages (no regeneration)
Heart regeneration
Was tested in adult zebra fish, where after 20% injury some grow back, the origin of the new tissue used to come from stem cells but now it comes from differential cells
