DAVID GRANOVSKY

Posts Tagged ‘Doctor of Philosophy’

STEM CELLS USED TO RESTORE WOMEN’S FERTILITY

In SCIENCE & STEM CELLS, STEM CELLS IN THE NEWS on March 14, 2013 at 9:00 am

fertility-self

Egg-producing stem cells found in human ovaries

Scientists say they have found a way to use ovarian stem cells to perhaps one day help infertile women get pregnant — or add years to a woman’s reproductive cycle.

In a study published in Nature Medicine, researchers report finding egg-producing stem cells in human ovaries. They also report being able to make some of those ovarian stem cells grow into immature eggs that may someday be useful for reproduction.  At this point, such “seed” eggs can’t be fertilized by sperm. But if scientists are able to entice them to mature and can prove they can be fertilized and grow into embryos — a feat that has been reported in mice — it would overturn a long-held scientific belief that women can’t make new eggs as they get older.

“What it does is really open a door into human reproduction that 10 years ago didn’t even exist,” says researcher Jonathan L. Tilly, PhD, director of the Vincent Center for Reproductive Biology at Massachusetts General Hospital, in Boston.

Outside experts agree. They say the findings could have profound importance for reproductive medicine and aging, allowing doctors not only to restore a woman’s fertility but also to potentially delay menopause.  “I think the significance of this work is like reporting that we found microorganisms on Mars,” says Kutluk Oktay, MD, who directs the Division of Reproductive Medicine and the Institute for Fertility Preservation at New York Medical College in Valhalla, N.Y.

“It’s a proof of principle that they could do it,” says David F. Albertini, PhD, director of the Center for Reproductive Sciences at the University of Kansas Medical Center in Kansas City, Kan.

The egg-generating stem cells the researchers were able to extract from ovaries were very rare. The researchers only came across one for every 10,000 or so ovarian cells that they counted.  But when they took those cells and implanted them back into human ovarian tissue, they divided and essentially made young eggs.

Tilly says his team stopped short of trying to make one of the eggs functional because “for a lot of reasons, as it should be,” it is illegal in the U.S. to experimentally fertilize human eggs.

“We think the evidence provided clearly indicates that this very unique, newly discovered pool of cells does exist in women,” he says.

“It’s a really exciting result,” says Evelyn Telfer, PhD, a cell biology expert at the University of Edinburgh in Scotland.  “What we’ve previously believed is that you don’t get new eggs formed during your adult life. This discovery shows that there’s the potential for them to be formed, no question about that,” Telfer says, “but it doesn’t actually show that they’re being formed under normal conditions.”

Indeed, she notes, experience would suggest otherwise. Women, after all, do lose their fertility as they age.  “There are cells there that under certain conditions have the potential to form [eggs]. That’s the really exciting part of this work. And of course they can be used. There’s a practical application,” she says.

Telfer has pioneered a technique that allows her to take immature human eggs and turn them into mature, fertilizable eggs outside the body. She has already partnered with Tilly to try to take his “seed” eggs to the next stage of development. With special government permission, she says, they may even be able to try to experimentally fertilize the eggs.

“It’s actually opening up a whole new field of research, to define these cells, to characterize these cells, and to use them in a practical way,” she says.

Tilly says that by using egg-generating stem cells to make large numbers of viable eggs, doctors might one day be able to cut the expense of in vitro fertilization (IVF), since women would no longer have to go through multiple cycles of treatment to harvest enough eggs to generate a pregnancy.

WebMD Health News

ORIGINS OF SCHIZOPHRENIA IDENTIFIED THROUGH STEM CELL RESEARCH

In ALL ARTICLES, SCIENCE & STEM CELLS, STEM CELLS IN THE NEWS on January 24, 2013 at 9:00 am

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Stem Cell Research Helps to Identify Origins of Schizophrenia

Jan. 22, 2013 — New University at Buffalo research demonstrates how defects in an important neurological pathway in early development may be responsible for the onset of schizophrenia later in life.  The UB findings, published in Schizophrenia Research, test the hypothesis in a new mouse model of schizophrenia that demonstrates how gestational brain changes cause behavioral problems later in life — just like the human disease.

The genomic pathway, called the Integrative Nuclear FGFR 1 Signaling (INFS), is a central intersection point for multiple pathways of as many as 160 different genes believed to be involved in the disorder. “We believe this is the first model that explains schizophrenia from genes to development to brain structure and finally to behavior,” says lead author Michal Stachowiak, PhD, professor in the Department of Pathology and Anatomical Sciences in the UB School of Medicine and Biomedical Sciences. He also is director of the Stem Cell Engraftment & In Vivo Analysis Facility at the Western New York Stem Cell Culture and Analysis Center at UB.

“A key challenge with the disease is that patients with schizophrenia exhibit mutations in different genes, he says.   How is it possible to have 100 patients with schizophrenia and each one has a different genetic mutation that causes the disorder?” asks Stachowiak. “It’s possible because INFS integrates diverse neurological signals that control the development of embryonic stem cell and neural progenitor cells, and links pathways involving schizophrenia-linked genes.  INFS functions like the conductor of an orchestra,” explains Stachowiak. “It doesn’t matter which musician is playing the wrong note, it brings down the conductor and the whole orchestra. With INFS, we propose that when there is an alteration or mutation in a single schizophrenia-linked gene, the INFS system that controls development of the whole brain becomes un-tuned. That’s how schizophrenia develops.”

“Using embryonic stem cells, Stachowiak and colleagues at UB and other institutions found that some of the genes implicated in schizophrenia bind the FGFR1 (fibroblast growth factor receptor) protein, which in turn, has a cascading effect on the entire INFS.  “We believe that FGFR1 is the conductor that physically interacts with all genes that affect schizophrenia.  We think that schizophrenia occurs when there is a malfunction in the transition from stem cell to neuron, particularly with dopamine neurons”, said Stachowiak. The researchers tested their hypothesis by creating an FGFR1 mutation in mice, which produced the hallmarks of the human disease: altered brain anatomy, behavioral impacts and overloaded sensory processes.

“By attacking the INFS pathway, we were able to produce schizophrenia in mice.”  He adds that if such a generalized genomic pathway is causing the disease, then it should be possible to treat the disease with a more generalized approach. “We may even be able to devise ways to arrest development of the disease before it presents fully in adolescence or adulthood.”

http://www.buffalo.edu/news/releases/2013/01.html

For More articles on Schizophrenia, Click HERE

WHAT IS SCHIZOPHRENIA????

“Psychological disorder is a mental disorder that impacts on life and creates fake experiences. There are many kinds of psychological disorder such as anxiety, childhood, eating, and gender identity disorder. Schizophrenia is one of childhood disorder that is occurred where people have difficulty to distinguish their reality from unreal and fake experiences.” – http://dasolkimuou.wordpress.com/2012/11/21/what-is-schizophrenia/

DISCOVERY OF PRIMARY CILIA IN STEM CELLS

In ALL ARTICLES, SCIENCE & STEM CELLS on January 7, 2013 at 10:40 am
“…since stem cells are now being more routinely used for regenerative medicine such as repair of severed spinal cord (Lu et al. 2012), it behooves us to better learn the molecular mechanisms that keeps these invaluable cells in an undifferentiated state so that we can harness their full therapeutic potential.”
Discovery of Primary Cilia in Stem Cells

Author: Aashir Awan, PhD

The primary cilium is organelle that has garnered much attention in the field of cell biology during the last 15 years. It is a slender, solitary hair-like organelle that extends 5-10 uM from each mammalian cell (in the G0 cell cycle state) that is microtubule-based (9 outer doublets arranged in a circular fashion) and dependent on a process called Intraflagellar Transport (IFT). IFT is the bidirectional movement of motors (kinesin-2 in the anterograde and dynein-2 in the retrograde direction) responsible for the assembly and maintenance of the cilium (Pedersen et al., 2006).

Until this time, it had been labeled a ‘vestigial’ organelle not worthy of research. Yet, a breakthrough into the sensory role of the primary cilium came in 2000 based on Dr. Rosenbaum’s research on Chlamydomonas and the motile cilium or flagella. Along with Dr. George Whitman’s group, they were able to show the importance of Tg737 (IFT88) protein to the pathology of polycystic kidney disease in mouse (Pazour et al., 2000). Since then, research into the primary cilium has exploded and has been linked to diverse pathologies (collectively known as ciliopathies) such as

  • retinitis pigmentosa,
  • hydrocephaly,
  • situs inversus,
  • ovarian and pancreatic cancers among others (Nielsen et al., 2008; Edberg et al., 2012). Also, various
  • signal transduction pathways have been found to be coordinated by the primary cilia such as hedgehog, wnt, PDGF among others (Veland et al., 2008).

Thus, in 2006, the Christensen lab at the University of Copenhagen (Denmark) with the collaboration of Dr. Peter Satir’s group at Albert Einstein College of Medicine (Bronx, NY) began to investigate whether the human embryonic stem cells (hESCs) possess primary cilium and then to begin preliminary molecular dissections of the role that this organelle could play in the proliferation and differentiation profiles of these pluripotent cells. The Albert Einstein group, due to NIH restrictions, had to work with two federally-sanctioned cell lines. Working with the Laboratory of Reproductive Biology at RigsHospital, the Danish side had access to in-house derived stem cell lines from discarded blastocysts. The advantage for the Danish side was obvious since these newer cell lines hadn’t undergone as many passages as the NIH cell lines and were thus more robust. To begin preliminary characterizations of these lines, some basic hallmarks of hESCs (Bernhardt et al., 2012) had to be localized to the nucleus such as the transcription factor (TF) Oct4 (Fig. 1).

In addition, a single primary cilium can be seen denoted by the acetylated tubulin staining emanating from each cell in the micrographs. Also, the base of the cilium is marked by the presence of pericentrin and centrin which demarcate the centriole.

Fig1 Fig. 1 Primary cilia stained with anti-acetylated tubulin (tb, red) are indicated by arrows and undifferentiated stem cells are identified by nuclear colocalization of OCT-4 (green) and DAPI (dark blue) in the merged image (light blue). A primary cilium (tb, red, arrow) in undifferentiated hESCs emerges from one of the centrioles (asterisks) marked with anti-centrin (centrin, green). Inset shows anti-pericentrin localization to base of cilia (Pctn, green).

Together, the three labs were the first to discover primary cilia in stem cells while other groups have since then confirmed these findings (Kiprilov et  al. 2008; Han et al. 2008). Attention was then to characterize different signal transduction pathways in the stem cell cilium. Since the hedgehog pathway has been shown to be important for differentiation and proliferation (Cerdan and Bhatia, 2012), the groups characterized this signal pathway in these cells using immunofluorescence, electron microscopy and qPCR techniques. One particularly interesting experiment to show that the hedgehog pathway was functional in these cells was to add the hedgehog agonist, SAG (Smoothened agonist), and then to isolate the cells for immunofluorescence at different times.

Gradually, one can see the appearance of the smoothened protein into the cilium as indicated by increasing intensity of the immunofluorescence staining. Conversely, patched levels in the cilium, decreased. This is a hallmark of hedgehog activation (Fig. 2).
Fig. 2 copiaFig. 2 Immunofluorescence micrographs of hESC showing smoothened (green), acetylated tubulin (red) and DAPI (blue). The micrographs from left to right represents SAG treatments at t = 0, 1 and 4 hours.

However, an additional interesting observation was made concerning these stem cells. An important characteristic for stem cells is the presence of certain transcription factors which render these cells in the pluripotent or undifferentiated state. These include Oct4, Sox2, and Nanog whose localization had been observed in the nucleus as expected for other TFs.

However, the Danish groups curiously found a subpopulation of stem cells where these TFs were additionally localized to the primary cilium (Fig. 3). This had never been observed or investigated before.  Additionally, proper negative controls were  carried out to exclude this phenomenon from being an artifact (e.g. bleed through).
Fig. 3 copia Fig. 3 Stem cell markers (Sox2, Nanog, and Oct4) localizing to the nucleus and the primary cilia (arrows) of hESC line LRB003. This and the previous figure show shifted overlay images whereby the green and red channels have been slightly shifted so that the red channel doesn’t swamp out the intensity of the green channels.

Thus, it raises an intriguing possibility that perhaps the primary cilia plays a previously uncharacterized role in the differentiation/proliferation state of the hESCs via possible modifications of these TFs perhaps analogous to the processing of the Gli transcription factors (Hui and Angers, 2011). Another curious observation is that the subpopulation of cells whose primary cilia are positive for these TFs always occur in clusters which might hint at its mechanistic explanation.  In conclusion, since stem cells are now being more routinely used for regenerative medicine such as repair of severed spinal cord (Lu et al. 2012), it behooves us to better learn the molecular mechanisms that keeps these invaluable cells in an undifferentiated state so that we can harness their full therapeutic potential.

REFERENCES

Awan A, Oliveri RS, Jensen PL, Christensen ST, Andersen CY. 2010 Immunoflourescence and mRNA analysis of human embryonic stem cells (hESCs) grown under feeder-free conditions. Methods Mol Biol. 584:195-210.

Bernhardt M, Galach M, Novak D, Utikal J. 2012 Mediators of induced pluripotency and their role in cancer cells – current scientific knowledge and future perspectives. Biotechnol J. 7:810-821.

Cerdan C, Bhatia M. 2010 Novel roles for Notch, Wnt and Hedgehog in hematopoesis derived from human pluripotent stem cells. Int J Dev Biol. 54:955-963.

Han YG, Spassky N, Romaguera-Ros M, Garcia-Verdugo JM, Aguilar A, Schneider-Maunoury S, Alvarez-Buylla A. 2008 Hedgehog signaling and primary cilia are required for the formation of adult neural stem cells.Nat Neurosci. 11:277-284.

Hui CC, Angers S. 2011 Gli proteins in development and disease. Annu Rev Cell Dev Biol. 27:513-537.

Kiprilov EN, Awan A, Desprat R, Velho M, Clement CA, Byskov AG, Andersen CY, Satir P, Bouhassira EE, Christensen ST, Hirsch RE 2008 Human embryonic stem cells in culture possess primary cilia with hedgehog signaling machinery. J Cell Biol. 2008 180:897-904.

Lu P, Wang Y, Graham L, McHale K, Gao M, Wu D, Brock J, Blesch A, Rosenzweig ES, Havton LA, Zheng B, Conner JM, Marsala M, Tuszynski MH. 2012 Long-distance growth and connectivity of neural stem cells after severe spinal cord injury. Cell 150:1264-73.

Nielsen SK, Møllgård K, Clement CA, Veland IR, Awan A, Yoder BK, Novak I, Christensen ST. 2008 Characterization of primary cilia and Hedgehog signaling during development of the human pancreas and in human pancreatic duct cancer cell lines. Dev Dyn. 237:2039-52.

Pazour GJ, Dickert BL, Vucica Y, Seeley ES, Rosenbaum JL, Witman GB, Cole DG. 2000 Chlamydomonas IFT88 and its mouse homologue, polycystic kidney disease gene tg737, are required for assembly of cilia and flagella. J Cell Biol 151: 709-18.

Pedersen LB, Veland IR, Schrøder JM, Christensen ST. 2008 Assembly of primary cilia. Dev Dyn. 237:1993-2006.

Veland IR, Awan A, Pedersen LB, Yoder BK, Christensen ST. 2009 Primary cilia and signaling pathways in mammalian development, health and disease. Nephron Physiol. 111: 39-53.

Discovery of Primary Cilia in Stem Cells.

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