L14 Regeneration (Imported from Quizlet)

What is regeneration?

The ability of organisms to restore their structures in form and function

________ vertebrats have more regenerative capabilities than __________ vertebrates (limb, eye, spinal cord, heart)

Aquatic, terrestrial

Simple organisms have a remarkable ability to ___________ (whole body)

Regenerate

Regenerative biology plays a role in ...?

Homeostasis, development, wound healing, regenerative medicines senescence (process of ageing), inflammation (inflammatory cells guided to damaged tissue), stem cells

Hydra uses ___________ (more posterior, head)

Morphallaxis

Salamander uses __________ (more anterior, tail)

Epimorphosis

When you cut an organism to remove part of it, what do you have to restore?

Missing tissue

What does morphallaxis do?

Takes existing tissue and re-patterns, creates a smaller organism

What does epimorphosis do?

Posterior cells will proliferate, lay out and regain the missing tissue, same size as the original before you cut it

Wounding causes an ...?

Immediate wound response

What are the early wound signals?

ATP is released by damaged cells, intracellular calcium is elevated, relative oxygen (H2O2) is released

These molecules act as _______ over the first few minutes to initiate the ______ response

Signals, wound

How does wounding initiate regeneration?

Fibrosis (scarring) is permanent and caused when fibroblasts secrete high levels of extracellular matrix (collagen, etc)

What is the wound response?

Causes cytoskeletal changes to close the wound, the cells on the edge will form pure strings to close the wound if it is small enough

Immune cells are recruited to the site

Initiates regeneration or scar formation

Salamander regrowth begins once __________ has formed, _____________ occurs and pushes ______ out to regenerate the limb entirely

Blastema, proliferation, distal

_________ __________ is thicker than the surrounding skin and is known to secrete _________

Wound epithelium, signals

What is the first sign that regeneration has begun?

Formation of the wound epithelium

The blastema is formed by cells that ...?

Dedifferentiate (partially)

Dedifferentiation to the point where cells still have their ________, they are not turning into ___________ cells

Identity, multipotent

What is the minimum size of fragment that can regenerate?

1/279th (0.3%)

What are neoblasts?

Adult stem cells of planaria

Where are neoblasts located?

Scattered throughout the animal

Head regeneration in planaria involves what?

Epimorphosis

Regeneration from small fragments results in small animals, what kind of regeneration is this?

Morphallaxis

Some neoblasts are ___________ (differentiate into many different cell types), others are ________ ___________ (only same cell type)

Pluripotent, lineage restricted

What is a hydra?

Simple animal with two germ layers and adult stem cells called interstitial cells

Hydra's are continually _________ due to the __________ ______ and reproduce by ___________

Growing, interstitial cells, budding

Cell division and interstitial cells are not required for regeneration -> ?

Morphallaxis

Wnt signals from the hypostome are able to induce what?

Bud formation

Stem cells in hydra don't contribute to regeneration, interstitial cells aren't __________ they don't ____________ to repair the tissue

Activated, proliferate

If 20% of the ventricle of an adult zebrafish heart is removed, what happens?

It will regrow

Wounding in a zebrafish causes activation of _________ -> a thin layer of cells that encapsulates the skin of the heart

Epicardium

What does activated epicardium secrete?

Retinoic acid (a signal), IGF2 (induce mitosis) and hedgehog signals

What are these signals secreted by activated epicardium required for?

Regeneration

_______________ (muscle cells) dedifferentiate and proliferate at the wound site

Cardiomyocytes

Vascularisation take place and the regenerated cardiomyocytes become active which results in ...?

A heart with a scar

What do humans regenerate?

Bone, skin, muscle and liver

Could we harness the power of endogenous regenerative mechanisms?

BMP2 soaked beads induce skeletal regeneration from digit and limb amputations

BSA is not a signal but BMP2 is

This is more dramatic with hind limbs