intro to regenerative biology Flashcards
What is regenerative biology?
-Regeneration is the ability of organisms to restore damaged or diseased structures in form and function
-Aquatic vertebrates have more regenerative capabilities than terrestrial vertebrates (limb, eye, spinal cord, heart)
-Simple organisms have a remarkable ability to regenerate (whole body regeneration)
whats Morpholaxis vs epimorphosis
-hydra use morphallaxis
-salamander limb uses epimorphosis
-hydra chopped in half, then it will regrow without any proliferation
-these cells now have new identities and are much smaller
-limb uses proliferation, so when it reforms its an appropriate size
what does wounding cause
-immediate wound response
what are early wound signals
-ATP is released by damaged cells.
-Intracellular calcium is elevated.
-Reactive oxygen (H2O2) is released.
-These molecules act as signals over the first few minutes to initiate the wound response
what occurs in the wound response
1)causes cytoskeletal changes to close the wound. The cells on the edge will form “purse strings” to close the wound if it is small enough
2) recruits immune cells are recruited to the site
3) initiates regeneration or scar formation depending upon the regenerative capabilities
How does wounding initiate regeneration?
-damage-> wound response -> regeneration or scarring
whats fibrosis
-permanent and caused when fibroblasts secrete high levels of extracellular matrix (collagens etc)
what occurs in salamander regeneration
1) amputation: early wound signals
2) wound closure : cytoskeletal rearrangements and epithelial movement, early wound signals released
3) wound epithelium: signalling from wound epithelium to induce dedifferentiation
4) blastema: proliferate and dedifferentiate (reform limb in proper order)
whats wound epithelium
-thicker than the surrounding skin and is known to secrete signals. The formation of the wound epithelium is the first sign that regeneration has begun
-similar to the AER and the blastema is similar to the progress zone. Regeneration recapitulates development
what are the 2 hypothesis for blastema dedifferentiation
1) multipotent blastema cells: muscle -> undifferentiated blastema cells -> cartilage, muscle and dermis
2) lineage-restricted blastema cells: cartilage, muscle and dermis -> proliferative cells (individual rather than all together) -> cartilage muscle and dermis
which type of cells can transdifferentiate
-dermis and cartilage
whats planar
-whole body regeneration
-The minimum size of fragment that can regenerate is 1/279th (0.3%)
-Neoblasts are the adult stem cell of planaria and are scattered through out the animal
-Some neoblasts are pluripotent, others are lineage restricted.
-Head regeneration involves epimorphosis
-Regeneration from small fragments results in small animals – morphallaxis
whats hydra
-Simple animal with two germ layers and adult stem cells called interstitial cells
-They are continually growing due to the interstitial cells and reproduce by budding
-Cell division and the interstitial cells are not required for regeneration -> morphallaxis
whats a Zebrafish heart
-If 20% of the ventricle of an adult zebrafish heart is removed it will regrow.
1) Wounding causes activation of the epicardium – a thin layer of cells that encapsulates the heart.
2) Activated epicardium secretes retinoic acid, IGF2 and Hedgehog signals
3) Cardiomyocytes (muscle cells) de-differentiate and proliferate at the wound site.
4) Vascularisation takes place and the regenerated cardiomyocytes become active.
what does BMP2 soaked in beads induce
-skeletal regeneration from digit and limb amputations
-BMP is a ligand that is important during skeletal development
