Lecture 02 - Stem cells and hematopoiesis

Lecture 02 - Stem cells and hematopoiesis - Stem Cells and...

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Stem Cells and Hematopoiesis Hematopoiesis - The process of Blood development - Humans have robust regenerative capacity tissue repair depends on our blood - RBC carry oxygen - Platelet prevent us from bleeding to death - WBC fight off germs - The entire system can be regenerated by a single blood forming stem cell called a hematopoietic stem cell that normally resides in the marrow but can be mobilized in response to injury or stress Blood in bone marrow is DYNAMIC – not static! Erythrocyte (RBC) Gas Exchange - RBC gas exchange - CO2 picked up from tissue and then deposited in the lungs the RBC picks up more O2 and gets rid of the CO2 - This process changes at high altitude Platelet Plug Formation - First line to prevent us from bleeding to death - Platelet set up homeostasis and prevent the blood from going anywhere pass the site of injury Neutrophil Phagocytosis - Important for bacteria Innate Immunity: Macrophage Activation - Macrophages used to be very important for fighting only intracellular organisms (i.e. TB – which went inside the cell) - Now it is more important for cancer cells o We have low levels of malignant cells that circulate in our system o The first line of defense is the macrophages that keep them under control o The macrophages sense signals that are tagged for them not to eat the cells (CD4 are the signals for the macrophage to eat the cells) - HIV o Not enough T cell helpers to receive instructions from the macrophages and people develop opportunistic diseases T lymphocyte help - T cells help the B cells make the right immunoglobin to boost and help fight immune infections - i.e. case of patient with no spleen. . never vaccinated against pneumococcal developed infection o spleen is where we make most of our antibodies - How do we protect our cells made in bone marrow Bone Marrow: the Blood Factory - The bone marrow has a specialized microenvironment or niche (the close connection between stem cells and bone; niche – home of the stem cells) - The niche supports regeneration HSC and differentiation into progenitors - How do get the stem cells to stimulate?? - 80% of the stem cells are sleeping in the bone marrow a once they receive the cue from the micro system they mobilize when triggered by stress - GCSS – mobilize the stem cells into peripheral blood and into peri-vascular niche Normal Hematopoiesis - Weissman and colleagues identified HSC - HSC and progenitor populations change in number and function during aging. -
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Lecture 02 - Stem cells and hematopoiesis - Stem Cells and...

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