Humans have about 200 types of cells.
Examples? (Record a few…)
• Neurons (nervous system); adipocyte (fat cells), heart muscle cells; erythrocyte (red blood cells); helper T cells
(immune system); rod and cone cells (eyes)
MOST of these cells either:
• Only reproduce to form same type of cells (e.g. skin cells)
• Don’t reproduce to make new cells
• Ex) damaged neurons, damaged heart muscle
• Can’t easily be replaced (think spinal injuries)
Totipotent stem cells – first few cells in an embryo
• Can reproduce to become any cell type
• Can hypothetically form an entire new organism
• Human embryos only totipotent for first 3-4 days.
Pluripotent or “embryonic” stem cells
• Present in embryos after the first 3-4 days/week
• Can form any type of cell in the developing baby
• But not a complete organism
• Obtain most embryonic pluripotent stem cells from discarded embryos (e.g. fertility clinics)
• Controversy ?
Induced pluripotent stem cells
• Obtained from adults – “tricked” from specific cell type
(e.g. skin) back into pluripotent in the lab
• No controversy (video will explain more)
Multipotent or “adult” stem cells
• Can divide to become only a FEW cell types
• Present in children, adults
• NOT embryos
• Multipotent stems cells are found in most organ/tissue systems
• Ex) blood stem cells
• Can create RBCs, WBCs, platelets…
Research with stem cells – why could it be good?
• If we can force stem cells to create cells that can’t “naturally” be replaced (e.g. neurons), maybe we can cure/fix damage/problems.
• We could research how to create properly working cells to cure diseases (like diabetes) in which cells are not working properly.
• Stem cells could be used to regenerate tissue damaged, for example in cancer treatment.
• Stem cells let us learn how all types of cells develop and work
– and this provides information on how to potentially cure all sorts of problems.
• Most stem cell research uses pluripotent or induced pluripotent stem cells
• Record 3 substantive facts/ideas you learn about induced pluripotent stem cells