1Stem Cells and Regenerative MedicineNao Terada, MD, PhDD f Phl Cll f MdiiDepartment of Pathology, College of Medicine (352) 392‐[email protected]://www.pathology.ufl.edu/~nterada/Program in Stem Cell and Regenerative Medicinehttp://stemcell.ufl.edu/ Stem Cells in Biomedical ResearchPluripotent Stem CellsTissue/OrganStem CellsEmbryonic Stem (ES) Cells Induced Pluripotent Stem (iPS) CellsHematopoietic Stem CellsMesenchymal Stem CellsNeural Stem CellsLiver Stem CellsGermlineStemCellsTissue EngineeringCell TransplantationRegenerationGermlineStem CellsetcDonovan & Gearhart, Nature 414, 92 (2001)Cancer Research, Aging Research etcES Cell‐Derived CardiomyocytesES cells can differentiate in vitro into functional cardiac myocytesMouse ES cells CardiomyocytesThe Mouse With A Human Ear On Its BackBy implantation of ear‐like scaffolding of porous, biodegradable polyester fabric + human cartilage cellsC. Vacanti and R. Langer (1995)Heart EngineeringOtt et al (2008) Nat Med 14, 213Decell‐Kidney (PAS)Kidney EngineeringRoss et al (2009) J Am Soc Nephrol 20, 2338Decell‐KidneyDecell‐Kidney (SEM) Recell‐Kidney (HE)2Lecture Agenda11/17/2009 (Tue) 1. Stem Cells in Homeostasis2. Regeneration Research in Other Organisms3. Embryonic Stem Cells and induced Pluripotent Stem Cells 1. Stem Cells in Homeostasis•Why do we need stem cells?•How do we define stem cells?•Where do stem cells reside? •How do stem cells differentiate?• Turnover of blood cells–Half‐life of RBCs, ~120 daysYou are not exactly the same as you were yesterday!–Losing RBCs at a rate of 2 millions per second–Half‐life of Neutrophils, 4~7 hrs–Losing WBCs at a rate of 1 million per second• Turnover of whole body–Losing ~1 trillion cells per day (?)Hematopoietic Stem Cells3~4 cells/105BM cells"gemeinsame Stammzelle”(common stem cell)The concept of a common undifferentiated mesenchymal precursor cell for all blood lineages and endothelium, the Postulated the existence of an undifferentiated stem cell giving rise to the plethora of blood cells solely based on morphological observations.Artur Pappenheim (1870‐1916)"Retikuloendothelzelle" From Folia Haematologica 21, p. 91 (1917).• Colony Forming Unit (Till & McCulloch, 1961)–Traced hematopoietic repopulation capacity to clonogenic cells.•Bone Marrow Transplantation (1951~1956)– Corroborated the existence of the hematopoietic stem cells in the BM by showing hematopoietic recovery from transplanted BM after irradiation damage.3How do we define a Stem Cell?•A cell that is capable prolonged self‐renewal•A cell that is able to differentiate into one or more lineages• Totipotent‐ ability to give rise to all embryonic and extra‐embryonic tissues• Pluripotent‐ ability to give rise to embryonic tissues (3 germ layersDifferentiation Potential of Stem Cellsembryonic tissues (3 germ layers‐ectoderm, endoderm, mesoderm• Multipotent‐ can produce cells of closely related family of cells • Unipotent‐ can produce only one cell type, have property of self‐renewalEckfeldt (2005) Nature Reviews: MCB 6:728Where Do Stem Cells Reside?Sprading et al., Nature 414, 98 (2001)Transit AmplifyingcellStem Cell NicheMammalian Epi dermal Stem Cells(Hair Follicle)Mammalian Gut CryptSprading et al., Nature 414, 98 (2001)Control of Stem Cell Self‐Renewal in DrosophilaSpermatogenesis by JAK‐STA T SignalingStem Cell Self‐Renewal in NicheKiger et al:Science 294, 2542 (2001) Tulina & Matunis:Science 294, 2546 (2001)UpD JAK/STATOsteoblast cells are the top candidate for the “Niche cells” in the bone marrow.Niche for HSCThese cells likely provide some of the signals responsible for HSC self‐renewal and proliferation4Asymmetric Stem Cell DivisionTo Make Sister Cells DifferentDrosophila NeuroblastsNeuroblast (NB) ‐ neural stem cell that gives rise to GMCGanglion mother cell (GMC) ‐ yields neurons (and glia)Mitotic Spindle Axis Rotation in NBsPAR proteins, an atypical protein kinase C (aPKC), and a small G‐protein (Cdc42) play central roles in establishing and maintaining cell polarity and spindle orientation.Involved in spindle orientationCell Division AxesA. & B. Cake models. Apical in up and basal is down.C. Epithelial cells (red) divide symmetrically. Cell fate determinants (green) are localized at basolateral cortex and are partitioned equally.D. Neuroblast (blue) divisions are asymmetric: daughter cells differ in size, mitotic potential and cell fate. Asymmetrically localized cell fate determinants (green) are segregated asymmetrically.General ModelAsymmetric distribution of fate‐determining molecule (pr otein and/or RNA)Establishment of polarity axis that orients mitotic spindlePolarity axis induction ‐ internal mechanism or external cue51. Stem Cells in Homeostasis•Stem Cells Required for Homeostasis•Concept of Stem Cells•Stem Cell Niche•Asymmetric Stem Cell Division Further Readings• Drosophila neuroblast asymmetric cell division: Recent advances and implications for stem cell biology– Fengwei Yu et al.–Neuron, 51:13‐20 (2006)2. Regeneration Research in Other Organisms•Whycan’t we while others can?•Why can t we while others can?Medicine's Cutting Edge: Re‐Growing OrgansThe Future Is Here: Regenerative Powder, Ink Jet Heart Cells And Custom‐Made Body PartMarch 23, 2008 http://www.cbsnews.com/stories/2008/03/22/sunday/main3960219.shtmlFingertips amputated distal to the distal interphalangeal joint have been observed to regenerate in children under 12 years of age. (1972, 1974)6Regeneration is widely but non‐uniformly represented among all animal phylaAlvarado and Tsonis Nature Reviews Genetics 7, 873–884 (November 2006)Old (and Unanswered) Questions‐‐‐Alejandro Sanchez Alvaradohttp://www.ascb.org/ibioseminars/sanchez/sanchez1.cfm•Why does regeneration occur?•How does the body detect and restore the precise missing parts?parts?•How do new parts regulate growth to reach appropriate size and proportion?•How do new parts functionally integrate to pre‐existing parts?PlanarianA free living flatworm having:•Laterally symmetric•All three germ layers•Small genome size (~700Mb, 4 chr)“Immortal under the edge of knife”A fragment 1/279th the size of the original organism is competent to regenerate a whole animal.Harriet Randolph (1897)Asexual Reproduction by Spontaneous Fission7Planarian Regeneration After DecapitationNeoblasts (scattered throughout the