Cardiac system Flashcards
What happens to the heart in a heart attack?
- blockage of an artery
- cardiac tissue begins to die due to loss of oxygen
- myocytes become overactive to compensate for damaged tissue leading to monocyte enlargement, overexertion and heart failure
Define neovascularisation. How is this different to angiogenesis?
- the formation of microvascular networks with RBC perfusion i.e. the formation of new blood vessels
- angiogenesis is the branching of capillaries from existing blood vessels
What are some current treatments for heart attack?
- reducing risk factors in life
- drugs to reduce cholesterol, blood pressure etc
- stents to unblock arteries
- current treatments don’t recover cells that are lost - heart cells are terminally differentiated
What 4 types of cells are important for the function of the heart?
- myocytes - contractile cells
-vascular cells - form arteries and capillaries - stromal cells act as a scaffold
- inflammatory cells eliminate debris after damage and are increased in heart attack
What can vascular cells in the heart do in response to damage?
- can trigger growth factor-mediated angiogensis - migration of endothelial cells to form connections to provide blood to cut off cells or strengthen weakened blood vessels
What can inflammatory cells do in response to damage in the heart?
- resident macrophages in the tissue are recruited to dispose of debris and aid in cell survival
- both too much or too little inflammation can hinder recovery
What can mycocytes in the heart do in response to damage?
- undergo hypertrophy and increase in size
- however in excess this can lead to reduced heart function and overexertion of cells
What can stromal cells in the heart do in response to damage?
- scarring
- facilitated by fibroblasts
- collagen can substitute lost mycoctyes to at least prevent further damage
What is the aim of cell therapy in the heart?
to increase heart healing by supplying exogenous cells or stimulating the ones already residing in the heart
How can stem cells supply exogenous cells in the heart following damage?
cells from the bone marrow can be injected into the heart or you can stimulate endogenous SCs to be released from the bone marrow using chemokines and hope that they travel to the heart.
Why is the heart of a fish different to mammals?
has the ability for regeneration- lower on the evolutionary scale. but could we use mechanisms here to treat heart disease in humans?
What are some of the drawbacks in cell therapy of the heart?
- only a small number of cells can be used and they have a short survival time in the heart
- cells need external stimulation to cause engraftment that is hard to trigger
- direct reprogramming of endogenous heart cells would be better
How can the heart be stimulated to make new cells in mice?
- transgenic expression of IGF-1
- mice that overexpress IG-1 show increased heart growth and can recover from an induced heart attack
- IGF-1 stimulates the secretion of chemokines that may be involved in heart development
When can we use stem cells to repair heart tissue, how can we keep these cells alive?
- use endogenous cells to keep stem cells alive
- find an appropriate niche and ensure the cells receive blood, nutrients and the signals they need to survive and behave correctly
How are stem cells prepared for administration for the heart?
can take stromal or HSCs and differentiate them into specific heart cell types or can take skeletal muscle cells and dedifferentiate them into myoblasts
