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Current topics in stem cell research

Current topics in stem cell research. Dr. Houda Darwiche UF CPET 23 July 2013. Disclaimer: This presentation contains graphic visuals. Unlimited Potential?. ES Cells and Reproductive Cloning. Reproductive cloning is the process of making an identical genetic copy of an existing organism

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Current topics in stem cell research

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  1. Current topics in stem cell research Dr. HoudaDarwiche UF CPET 23 July 2013 Disclaimer: This presentation contains graphic visuals

  2. Unlimited Potential?

  3. ES Cells and Reproductive Cloning • Reproductive cloning is the process of making an identical genetic copy of an existing organism • Naturally occurring clones – Identical twins • Artificial Embryo splitting • Somatic cell nuclear transfer

  4. Somatic Cell Nuclear Transfer (SCNT)

  5. History of Cloning and Nuclear Transfer • 1901 – Hans Spemann split a fertilized 2 cell embryo = 2 tadpoles • Artificial embryo splitting Hans Spemann • 1977 – John Gurdon cloned Xenopuslaevis from differentiated cells from an albino tadpole • Injected tadpole intestinal cell nuclei into enucleated oocytes

  6. History of Cloning and Nuclear Transfer • 1978 – Baby Louise Brown born – first child created through in vitro fertilization by Robert Edwards • 1996 - Ian Wilmut cloned Dolly the sheep from adult cells – major breakthrough

  7. History of Nuclear Transfer and Cloning • August 1997 - President Clinton proposed legislation to ban the cloning of humans for at least 5 years • September 1997 - Thousands of biologists and physicians signed a voluntary five-year moratorium on human cloning in the U.S. • January 1998 - Nineteen European nations signed a ban on human cloning

  8. Rescue Genetics Old or deceased animals Endangered species Dr. Hwang Woo-Suk with first successfully cloned dog named Snuppy RNL Bio will be cloning pets - $150,000 each Little Nicky, a cat cloned for a woman in Texas by Genetic Savings & Clone – cost $50,000 Guar, wild ox from Southeast Asia

  9. Genetically Engineered Livestock Increase disease resistance Increase heat tolerance Xenotransplants Milk Production Increase levels of milk Produce milk with better characteristics (i.e. more calcium, more vitamin D) Improve digestibility of milk (i.e. for people with lactose intolerance) Protein production for Pharmaceutical needs Increase nutritional value of meat Modification of muscle mass Increase reproductive capacity

  10. Genetically Engineered Meat Belgian Blue bull – contain a natural mutation where they lack a protein called myostatin that normally interferes with muscle development - produce large amounts of meat with very little fat – “doubly muscled”

  11. Cloning Livestock • Jan 2008, Food and Drug Administration approved the sale of food from cloned animals • U.S. Department of Agriculture asked producers to keep the meat off the market because of consumer fears • FDA stated that they will not require producers to put packaging labels on cloned meat or milk products

  12. Pharmaceutical uses • Genetically engineered cows to produce human immunoglobulins (antibodies) • Used for treating a variety of diseases from anthrax to the virus that causes earaches • Important for creating antibodies that can’t be made in the lab and can only come from human donors • Obtain these humanized antibodies from the cows blood and milk • Large quantities that you wouldn’t be able to obtain from humans Pampa, one of 4 cloned Jersey calves in Argentina that can produce human antibodies

  13. Reality of Cloning • Because cloning is expensive and inefficient only 1-5% of all cattle will be products of cloning • Most clones will be prized bulls/exotic breeds/endangered breeds • Disease won’t wipe out entire herd – only small percentage of herd actually the result of cloning • Nature vs Nurture • Clones will not necessarily take on the same personality or physical characteristics of the original • Cc, “CopyCat”, doesn’t have calico markings that original cat “Rainbow” has

  14. Adult Stem Cells • Also referred to as “somatic cells” • Small population of undifferentiated cells that are found in most adult tissues or organs • Self-renew and differentiate to yield all or many of the specialized cells found in that tissue or organ • Important to maintain or repair the tissue in which they are found • Found in many important organs in the body (skin, liver, brain, pancreas and blood) • More adult cell populations being discovered all the time • “adult” stem cell population found in deciduous teeth!

  15. Characteristics of HSCs Large capacity for self-renewal Multipotent – able to give rise to many different cells types Used to treat a variety of diseases Hematopoietic Stem Cells

  16. Early HSC Experiments • “Discovered” in the mid 1940’s when first bone marrow (BM) transplants were performed • Complete hematopoietic recovery in irradiated patients

  17. What diseases can HSCs be used to treat? (without alteration) • Leukemia and Lymphoma – cancers of the blood characterized by uncontrolled growth of the white blood cells • Patient’s own cancerous hematopoietic cells have to be destroyed (chemotherapy or radiation) and replaced with donor cells (bone marrow transplant) • Inherited blood disorders • Anemia – failure to produce normal red blood cells resulting in low blood iron levels (i.e. aplastic anemia, sickle-cell anemia) • Metabolic disorders - genetic defects in key enzymes needed to perform basic biological functions and breakdown chemical byproducts (i.e. Hunter’s syndrome, Hurler’s syndrome)

  18. Mesenchymal Stem Cells • Also referred to as “stromal stem cells” • MSCs, like HSCs, are also found in the bone marrow • MSCs can also be isolated from umbilical cord blood and adipose tissue • Responsible for bone and cartilage formation in the developing embryo and bone and tissue repair in the adult

  19. Clinical Applications for MSCs • MSCs give rise to a variety of cell types • bone cells (osteocytes) • cartilage cells (chondrocytes) • fat cells (adipocytes) and • other kinds of connective tissue cells such as those in tendons • Use of mesenchymal stem cells to expedite wound repair • Repair burn wounds • Chronic non-healing wounds • Elderly patients with diabetes • Skin cancer wounds

  20. MSCs and Wound Repair D B Application of bone marrow–derived cultured cells to human chronic wounds A) Non-healing wound (for more than a year) on ankle of patient B) Third application of MSC-fibrin spray to the now healing wound C) Wound at 3 months, the wound is almost healed D) Wound closure at 6 months

  21. Other Clinical Implications of MSCs • Bone regeneration • OsteoCel – “off-the-shelf” cellular product created by Osiris therapeutics • bone graft using MSCs seeded onto a biomatrix speed bone healing from injury, disease or degeneration • Cartilage and joint repair • Chondrogen – another Osiris product • Aimed at regenerating the meniscus of the knee • Slow the progression of osteoarthritis in the knee Chondrogen untreated Chondrogen treated

  22. Stem Cells and Cancer • Cancer – cell or group of cells that display uncontrolled growth and display protection against programmed cell death (apoptosis) • Benign – self-limited, do not spread • Malignant – spread to other sites in the body via lymph or blood • Sites of tumors different from original tumor site often referred to as “metastases” • Difficult to treat, poor prognosis • Patients often unable to tolerate amount of chemotherapy needed to destroy all tumor sites in the body • Especially true for children • Also, people with reoccurring cancer

  23. Stem Cell Therapeutics • St. Jude Children’s hospital • Researchers created a human neural stem cell line that expresses a specific enzyme needed to activate an anti-cancer drug • When injected into the body - neural stem cells migrate to the various sites where the tumor has spread to • Phenomenon called “tumor-tropism” • Stem cells migrate toward a site of tumor development • Shown in neural stem cells and in mesenchymal stem cells

  24. Stem Cell Therapeutics • Neural stem cells target specific tumor sites throughout the body • Engineered neural stem cells express an enzyme that cleaves a pro-form of an anti-cancer drug • Conventional chemotherapy is systemic • Causes damage to healthy tissue as well as the cancerous tissue • This method allows drug to only work at specific sites where these neural stem cells are found • If stem cells migrate to tumor site  targeted delivery

  25. Cells formed multiple tumors to simulate metastases throughout the body • Injected mice with human neuroblastoma cells • Neural stem cells migrate towards metastatic tumor sites • Injected mice with neural stem cells containing the specific enzyme required for the anti-cancer drug to work

  26. Stem Cell Cancer Therapy Aboody et al., 2006 Green = Tumor cells Red = neural stem cells that express enzyme

  27. Stem Cell Cancer Therapy • Animals that received neural stem cells + anti-cancer drug had a higher rate of survival compared to animals that received neural stem cells alone or drug alone Neural stem cell line with enzyme + anti-cancer drug Anti-cancer drug Neural stem cell line with enzyme alone

  28. Case Study #1 • Spinal cord injury • At 24, Susan suffered an injury to her spine in August, 2001 that left her paralyzed • 1 of 7 patients (ranging from 18-32 yrs of age) treated in Portugal in a study by Dr. Carlos Lima • Used her own adult stem cells derived from olfactory mucosa • Olfactory mucosa is located in the upper nasal cavity • Neurons that detect smell are found here • Stems here are being used to produce neurons to replace damaged neurons in spinal cord

  29. “Only part of my dreams has been attained. But I have come farther than my American doctors ever thought. My most recent MRI took place 5 days ago. The doctors were in disbelief at the improvement they saw where my spinal cord had been injured. I have recovered some functional improvement through Dr. Lima's procedure, such as the ability to hold my bladder and at times even void on my own. Sensation has been restored, though it is not completely normal. When concentrating I am now able to contract my thighs slightly; once again, this was also impossible before my surgery in Portugal. But most important on my way to recovery is that I can now walk with the aid of braces. I am now preparing to shed the shell of this wheelchair, which has confined me for over two years, to more and more use my braces and walker for mobility. This is something my doctors here in America told me would never be possible with my level of injury and to accept my fate. With Dr. Lima's adult stem cell based therapy, I have accomplished much more than my U.S. doctors said was possible. But this is only the first step to a complete cure.”

  30. Case Study #2 • Parkinson’s disease • Suffered extreme shaking of the right side of his body and was unable to use his right arm • Neurosurgeon Dr. Michele Levesque isolated neural stem cells from Mr. Turner’s brain • Cells were expanded, induced to differentiate into nerve cells and injected into the left side of Mr. Turner’s brain • Soon afterwards, the Parkinson’s symptoms began to improve in his right side. • trembling decreased • neurological evaluation indicated a marked improvement in his symptoms • Lasted about 5 years • Expressed willingness to undergo a repeat surgery to further slow the progression of his symptoms Dennis Turner

  31. “By early 1991 I suffered extreme shaking of the right side of my body, stiffness in my gait and movements. After some years of medication, I developed fluctuation and poor response to Sinemet. This made daily activities needing the coordinated use of both hands hard or impossible, such as putting in contact lenses. My disability prevented me from using my right arm. And since my only other realistic alternative was to continue growing worse until I eventually died, I decided to have the surgical procedures in 1999, one to remove the tissue and another to inject the cells. I was awake for both procedures, under local anesthesia. Soon after having the cells injected my Parkinson’s symptoms began to improve. My trembling grew less and less, until to all appearances it was gone, only slightly reappearing if I became upset. Dr. Levesque had me tested by a Neurologist, who said he wouldn’t have known I had Parkinson’s if he had met me on the street. I was once again able to use my right hand and arm normally, enjoying activities that I given up hope of ever doing. Because of my improvements through Dr. Levesque’s treatment I’ve been able to indulge in my passion for big game photography these past five years. While on safari in 2001 I scrambled up a tree to avoid being run over by a Rhino. I swam in the South Atlantic with Great White Sharks. Two weeks ago I returned from Africa after photographing Cheetahs and Leopards in the wild. The pictures I took represent memories and experiences I feel I have Dr. Levesque to thank for. I came here to offer him my sincere gratitude, and to offer others with Parkinson’s a concrete reason for hope.”

  32. Adult stem cell treatments • Phase I/II study in Brazil involving 15 newly diagnosed patients with Type I diabetes mellitus (ages 14-31 yrs) • Patients were given immunosuppressive drugs and their own stem cells via IV injection. • During a 7- to 36-month follow-up, 14 patients became insulin free • 1 for 35 months, 4 for at least 21 months, 7 for at least 6 months and 2 with late response were insulin-free for 1 and 5 months • All displayed increased b-cell function

  33. Need to regrow a finger? There’s an app for that!

  34. General Issues in stem cell research • Very-slow going • Although most stem cell populations were discovered over 40-50 years ago – still much we don’t understand about them • Signaling pathways? • What factors control differentiation/self-renewal? • In vitro vs in vivo conditions • What a cell does in culture may not reflect what the cell can do once in the body • How do we know what the cell will do in a new environment outside its “niche” • In vitro = controlled environment • In vivo = signals/factors that we can’t account for in vitro • Animal models vs. humans

  35. Wave of the Future? • Induced Pluripotent Stem Cells • Adult cells that have been genetically reprogrammed into immaturity via the induction of 4 genes • Oct3/4, Sox2, Klf4, c-Myc • Genes initially induced virally, but new methods have recently been developed • Mouse iPS cells first reported in 2006; human iPS cells in 2007 • Both mouse and human iPS cells… • express stem cell markers • are capable of generating cells characteristic of all three germ layers

  36. Wave of the Future?

  37. Clinical Applications of iPS Cells

  38. General Issues in stem cell research • Lots of hype, comparitively few results • We’re making progress, but can’t cure diseases overnight • Stigma in the media • When most people hear “stem cell research” they immediately think embryonic stem cells • Lack of education and familiarity with the use of adult stem cells • Recent controversies

  39. Stem Cell Controversies • Dr. Hwang Koo-Suk of Korea • Biomedical scientist and former Professor of Veterinary Medicine at Seoul National University- • Claimed to have created 11 human ES cell lines by SCNT • Discovered that some data had been fabricated • Accepted egg donations from two of his own junior researchers • Violation of scientific ethics • Two Science papers (2004, 2005) retracted

  40. A Long Road Ahead…

  41. http://www.youtube.com/watch?v=TRtlkcQ6brE&feature=related

  42. Stem Cell Resources • www.pubmed.gov • Research articles • http://stemcells.nih.gov/ - NIH Stem cell resource center • Stem cell background info • Current stem cell experiments • Current U.S. policies regarding research, funding etc • www.isscr.org/public/adultstemcells.htm • International Society for Stem Cell research

  43. Resources • Links to articles describing use of adult stem cells to treat diseases • http://www.stemcellresearch.org/facts/asc-refs.pdf • Cloning Information http://www.ornl.gov/sci/techresources/Human_Genome/elsi/cloning.shtml

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