http://wside.k12.il.us/TMS/Science/stemcellfolder http://www.sciencecases.org/stem_cells/stem_cells.asp STEM CELLS AND KIDNEY DISEASES http://www.scidev.net/news/index.cfm?fuseaction=readnews&itemid=1994&language=1
A major new healthcare sector Stem cell research with: • potential to transform disease, treatment, reduce costs to society, and enhance quality of life for millions of patients. • scope for significant business opportunities, with new directions for industry innovation and productdevelopment.
In an adult organisim, each tissue and organ is generally accepted to contain a small population of cells capable of self-maintainence, has indefinate proliferative potential and with ability to give rise to large family of descendants with defined spectra of specialization(multipotential stem cells)
STEM CELLS OR PROGENITOR CELLS- DEFINATIONS, STEM CELLS:- CELLS CAPABLE OF BOTH SELF RENEWAL AND MULTILINEAGE DIFFRENTIATION. PROGENITOR CELLS:- IMMATURE AND PROLIFERATIVE CELLS WHICH ARE LIMITED IN THEIR DIFFRENTIATION POTENTIAL TO ONLY ONE CELL TYPE.
STEM CELLS (ANCESTORS-PLURIPOTENT) PROGENITOR CELLS (UNIPOTENT)
CHARACTERISTICS OF THE STEM CELLS:- • MULTIPOTENCY:- - able to generate many or all the differentiated cell types in the organ, BONE MARROW STEM CELL BONE MARROW SPLEEN BLOOD
Stem Cell Potency • Differentiation potential • Totipotent • Can be any type of cell in the body • Pluripotent • Can become almost any kind of cell in the body (an example would be fetal cells) • Multipotent • Can differentiate into only a limited range of cell types (examples include umbilical cord and adult stem cells) “Stem Cell Research Foundation” http://www.stemcellresearchfoundation.org/WhatsNew/Multipotent.htm
Self-renew a stem cell can reproduce itself by cell division Differentiate a stem cell can specialize into a particular type of somatic cell 2) SELF GENERATION AND ASSYMETRIC DIVISION:- - have ability to regenerate, - product of cell division is asymmetric.
Stem cell division and differentiation LEGEND A - stem cell B - progenitor cell C - differentiated cell 1 - symmetric stem cell division 2 - asymmetric stem cell division 3 - progenitor division 4 - terminal differentiation
PATTERNS OF CELL DIVISION IN STEM LINEAGE:- a) All divisions are obligatory asymmetric and controlled by a cell intrinsic mechanisim, S P S P S P S
b) A population of stem cells, in which all divisions are ultimately asymmetric and self-renewing, S S S S P P S S S P P S
c) Individual stem cell division are asymmetric with respect to daughter cell fate, S S S S P
3) STEM CELL PLASTICITY OR TRANSDIFFRENTITION:- Tissue stem cells which are thought to be lineage committed multipotent cell, posses the capacity to differentiate into cell types outside their lineage restriction. Eg, stem cells can convert to neurons as well as germ cells.
4) SELECTION VS INSTRUCTION:- Mechanism by which a progenitor cell enter a path, leading to terminal differentiation is explained by, • Selection:- cell is seen as one whose fate is determined. The cells expresses certain types of proteins which guides them to develop in certain type of cells.
2) Instruction:- Factors induce expression of new genes that mediate a specific program to force the cells into a specific diffrentiative path, Eg, erythropoetin, thrombopoetin, G-CSF etc.
CONTROL OF SELF RENEWAL AND DIFFERENTATION:- STEM CELL ENVIROMENT, guide the distribution of messenger RNA and determine differentiation.
History of Human Stem Cell Research • In 1968, the first bone marrow transplant was successfully used in treatment of SCID • Since the 1970’s, bone marrow transplants have been used for treatment of immunodeficiencies and leukemias • 1998 - James Thomson (University of Wisconsin-Madison) isolated cells from the inner cell mass of the early embryo, and developed the first human embryonic stem cell lines. • 1998- John Gearhart (Johns Hopkins University) derived human embryonic germ cells from cells in fetal gonadal tissue (primordial germ cells).
History of Human Stem Cell Research • 1999 - First Successful human transplant of insulin-making cells from cadavers • 2001 - President Bush restricts federal funding for embryonic stem-cell research • 2002 - Juvenile Diabetes Research Foundation International creates $20 million fund-raising effort to support stem-cell research • 2004 - Harvard researchers grow stem cells from embryos using private funding • 2004 - Ballot measure for $3 Billion bond for stem cells
History of Somatic Cell Nuclear Transfer (Cloning) • 1952 – Briggs and King cloned tadpoles • 1996 – The first mammal cloned from adult cells was Dolly, the sheep. • 1998 – Mice cloned • 1998 – Cows cloned • 2000 – Pigs cloned
“CC” Carbon Copy History of Cloning • 2001 – Cat cloned • 2002 – Rabbits cloned • 2003 – Mule cloned • 2004 – Bull serial-cloned • 2005 – Dog cloned
Types of Stem Cells • Embryonic stem cells • Derived from the blastocyst, which is a very young embryo shaped like a hollow sphere that contains 200-250 cells (pre-implantation embryos) • Adult stem cells • Misnomer, can be found in children and infants too • Derived from the umbilical cord and placenta, or from blood, bone marrow, skin, or other tissues “Stem Cell Research Foundation” http://www.stemcellresearchfoundation.org/WhatsNew/Pluripotent.htm
Day 2 2-cell embryo Day 3-4 Multi-cell embryo Day 1 Fertilized egg Day 5-6 Blastocyst Day 11-14 Tissue Differentiation Stages of Embryogenesis
What is a blast cyst? • Trophoblast - a hollow sphere of cells that develops into the extra-embryonic membranes such as the placenta, umbilical cord, and amnion. • Inner cell mass (ICM) - embryonic stem cells are the ICM
In vitro fertilization - current method of deriving an hESC line • Eggs and sperm donated and fused to create a fertilized egg in a Petri dish • Fertilized egg matures into a blast cyst • Embryonic stem cells extracted from blast cyst • Cells replanted on another Petri dish and grown in culture
EMBRYOLOGY OF THE KIDNEY AND ORIGIN OF STEM CELL IN THE KIDNEY Wolffian duct:- generates the urethra bud, the bladder and the urethra. The urethra bud generates all of the collecting system cortical, medullar, papillary) and the pelvic and urethra epithelia.
There must be at least 4 cell types in the embryonic kidney called as, a) Metamorphic mesenchymal epithelial cell precursor, (MM-EP) b) Angioplasty or endothelial cell precursors, (MM-Ang) c) Smooth muscle cell precursor, (MM-SM) d) Stoma cell precursor, (M-Str) Ten days later in postnatal kidney there are at least 26 differentiated cells with recognizable morphology, location, function.
WOLLFIN DUCT STEM CELLS Pleuripotent stem cell Intermediate stages, ?still pleuripotent. Precursor, ?multipotent Terminally differentiated cells MM-EP MM-Ang MM-SM MM-Str URETERIC BUD PCT Glomerular capillary Affrentarteriol Interstitial cell Principle cell
It is long been known that the urethra bud generate the epithelium of the collecting duct, but it is unclear wither the epithelium of the rest of the enthrone is derived from single progenitor cell. Her linger D et. al. (Development 114.1992), demonstrated presence of a single cell that can generate all the epithelial elements of the enthrone. Borensch et. al. demonstrated that the metamorphic mesenchyme contains cluster of cells destined to generate the epithelial cells of glomerulus's, and the tubules.
REGENERATION OF RENAL TISSUE:- The capacity of the kidney to regenerate and repair is limited and has been convincingly demonstrated in ischemic tubular necrosis, ORIGIN OF REGENERATING CELLS? DIVISION OF LOCAL DIFFRENTIATED CELLS, (Oliver J et. al. J. Clin. Invest.1951) BONE MARROW STEM CELLS (Ito et al. JASN 12, 2001)
Is there resident stem cells in the kidney? Oliver et al, demonstrated large number of slowly cycling cells in adult renal papilla, that persist thought the life and disappears during the recovery following episode of ischemia. (Oliver et. Al, Jclin, invest 14-2004) In his studies he demonstrated renal papillary cells grown in vitro were capable of incorporating into other parts renal parenchyma like renal tubules.
Marlies Elger et. Al (JASN 14, 2003), Demonstrated nephrogenic zone in adult kidney of shark and salmon, that has ability to grow new glomerulus's even after birth.
LOCATION OF STEM CELLS IN THE KIDNEY:- specific niche with ready access to blood supply and are protected from environmental damage, Presence of factors inhibiting local growth as well as factors guiding slow cycling and asymmetric division when needed.
Progenitor cell in the kidney:- • Endothelial cells:- Existence of endothelial progenitor cells and there contribution to repair of endothelium, comes from cardiovascular research on ischemia and angiogenesis EPC can stimulate vascular repair by, • Involved in new vessel formation by incorporating in the vessel wall, • Secreting proangiogenitic factors like VEGF, bFGF etc.
Pabst et. Al, reported in rats, the rate of total glomerular cell renewal of 1%per day, with endothelial cell fraction being the dominant one. Experimental rat models, with glomerular injury following anti-Thy1.1 glomerulonephritis is associated with proliferation and migration of endothelial cells and contribute to glomerular capillary repair.
2) Mesangium:- Glomerular mesengial play a central role in the pathogenesis of a number of human and experimental glomerular inflammatory diseases. Like glomerular endothelial cells, in normal rats mesangial cell turn over accounts for less than 1%(Pabst et al. KI.1983)
Hugo et al in his study demonstrated that during the recovery of anti-thy1.1 glomerulonephritis, proliferation of immature cells from JGA and hilar region of the glomerulus's. Immasawa et al. demonstrated involvement of bone marrow derived cells in the normal mesangial cell turnover. Takashashi T et al (KI 1998) demonstrated mesangial cell recruitment during embryonic glomerulogenisis and the involvement of the extraglomerular mesangial progenitor cells in the glomerular repair.