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WHY stem cell research?

WHY stem cell research?. Potential medical applications. Stem cells produce new cells Adult: replace damaged/lost cells Embryonic: build the organism Can this power be harnessed to produce new cells artificially?. Potential medical applications.

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WHY stem cell research?

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  1. WHY stem cell research? Potential medical applications

  2. Stem cells produce new cells • Adult: replace damaged/lost cells • Embryonic: build the organism Can this power be harnessed to produce new cells artificially?

  3. Potential medical applications • Manipulate stem cells: replace lost/damaged cells • Injury • Burns, spinal cord damage (paralysis) • Degenerative diseases • Heart disease, juvenile diabetes, Parkinson’s • “Non-degenerative” diseases • Cancer?

  4. General Procedure • Isolate highly potent stem cells • Coax SC to differentiate into the needed specialized cell • Introduce differentiated cells to the site of damage • Cells formerly known as stem cells replace the lost cells

  5. Cells ‘home in’ on the site of injury Cultured stem cells in the lab DELIVER (inject/transplant) the cultured SC One way: ‘Niche’-directed differentiation DAMAGED TISSUE HEALTHY TISSUE Peer pressure: Neighbors cause SC to differentiate appropriately

  6. Leukemia treatment“Bone marrow transplants” • Cancer of the blood cell progenitors • Rapid production of blood cells • Acute: high # of immature blood cells crowd bone marrow • Chronic: high output of abnormal blood cells • Lack of normal blood cells: • Platelets…clotting disorders • White blood cells…propensity for infection • Red blood cells…anemia

  7. Production of blood cells occurs in the bone marrow

  8. (One form of…) Stem Cell Treatment • Kill patient’s bone marrow • Radiation/chemotherapy • Destroys cancerous (and healthy) stem cells • Patient needs RBC, platelets from donors • Highly susceptible to infection • Now it’s a ‘degenerative disease’ • Refurbish the bone marrow • ‘Healthy’ stem cells • Patient’s own bone marrow, treated to enrich for healthy cells • Healthy donor • Stem cells ‘move in’ to the bone marrow, start making new blood cells

  9. Problems… • Susceptibility to infection before new stem cells kick in • Stem cells may not ‘take’ • Graft-vs-Host disease • New immune system attacks the recipient • Skin, liver, intestinal tract

  10. Another way: Factor-directed differentiation DAMAGED TISSUE HEALTHY TISSUE Cells heal the damage Allow cells to differentiate appropriately Add a chemical factor to induce differentiation Culture stem cells in the lab DELIVER (inject/transplant) the differentiated cells

  11. Factor-directed differentiation • Retinoic acid + insulin: fat cells • Retinoic acid: nervous system • Retinoic acid + DMSO: muscle cells • Interleukin-3: neurons, white blood cells

  12. Niche-directed differentiation • Advantages • Don’t need to know a whole lot about the cells (Let the ‘niche’ do the dirty work) • Disadvantages • Will all the cells differentiate appropriately? (Remember the teratoma)

  13. Factor-directed differentiation • Advantages • More control over the identity of the delivered cells • Disadvantages • More research needed to determine the correct factors (may be impossible in some cases) • Too differentiated? Lose proliferation?

  14. Niche- vs. factor-directed differentiation • Ultimate answer: hybrid between the two?

  15. Paralysis (spinal cord injuries) • Juvenile diabetes • Parkinson’s

  16. Spinal cord injuries Hwang Mi-Soon: South Korea Paralyzed 19 years Multipotent adult stem cells injected into her spinal cord Currently: debilitating pain Published in 2005 (Cytotherapy) Success of stem cell therapy?

  17. Dr. Hans Keirstead • Use of human embryonic stem cells to ‘cure’ paralyzed rats • Partially differentiate in culture (factor-directed) • Inject into the spinal cord

  18. http://www.hopkinsmedicine.org/Press_releases/2006/images/video1.wmvhttp://www.hopkinsmedicine.org/Press_releases/2006/images/video1.wmv • http://www.hopkinsmedicine.org/Press_releases/2006/images/video2.wmv • http://www.uci.edu/experts/video.php?src=keirstead&format=mov&res=high

  19. Trials in humans ‘soon’…one to two years? • Need to convince FDA that it’s safe enough…and ethically responsible

  20. Juvenile (Type I) Diabetes • Insulin: hormone that regulates the amount of sugar in the blood • Lots of sugar: insulin released by the pancreas (islet cells) • Tells cells (mainly muscle & fat cells) to take up sugar from the blood stream

  21. Diabetes mellitus • “Sweet urine” • High blood sugar • Cells don’t take up sugar appropriately • Type I: pancreas doesn’t make insulin • Inject insulin • Type II: cells don’t respond to insulin • “Non-insulin dependent”

  22. Type I Diabetes • “Auto-immune disorder” • Your immune system attacks your own body • Pancreatic islet cells damaged • Body can’t make insulin • Blood sugar remains high • Damage to blood vessels, other tissues • Stem cells to the rescue? • Replace insulin-producing cells

  23. Treatments • Insulin injection • pain, inconvenience, expense • Lack of ‘natural’ regulation of insulin levels • Islet cell transplantation • From cadavers’ pancreases • Works well (~300 trials) • Shortage of pancreases

  24. Embryonic stem cells? • ES cells: good at proliferation • Overcome the shortage problem • But can they be induced to specialize properly?

  25. Dr. Ron McKay, NIH • Induced mouse ES cells to form islet cells • At least cells that look like islet cells • Seem to behave like islet cells when injected into mice

  26. What about humans? • Can human ES cells be differentiated appropriately? • Right ‘cocktail’ of factors • Lab at University of Florida (Bryon Petersen) • Made insulin-producing cells • Cured diabetic mice for ~ three weeks • Teratoma formation

  27. Parkinson’s disease • Motor disorder • Tremor • Slow movement, Rigidity • Poor balance

  28. Cells in the substantia nigra Loss of the chemical dopamine No clear reason why Degeneration of brain cells

  29. Treatments • Several drugs • Mimic dopamine OR enhance the effect of what little dopamine is left • L-dopa • Transplantation • No positive results yet

  30. Stem cells to the rescue? • Harvard study: • Rats with “Parkinson’s disease” • Injected healthy ES cells • Cells began producing dopamine • Motor function improvement • 20% formed brain teratomas

  31. Stem Cell Targets • Degenerative diseases (or pseudo-degenerative: see leukemia) • Chronic diseases • Discrete/defined tissues AIDS?

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