a brief overview of stem cell research

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By: drtush (102 month(s) ago)

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STEM CELL RESEARCH:

STEM CELL RESEARCH Swati jaiswal M.pharm, II Sem (Pharmaceutics) Department Of Pharmaceutics, IT-BHU

Contents:

Contents Introduction Unique properties of stem cell Types of stem cell Embryonic stem cell Adult stem cell Embryonic verses Adult stem cell Applications of stem cell Current scenario of Stem cell research Future prospects Conclusion

Introduction :

Introduction 5/18/2011 Department Of Pharmaceutics,IT BHU Stem cells are biological cells found in all multi cellular organisms, that can divide through mitosis and differentiate into diverse specialized cell types and can self renew to produce more stem cells. Research on stem cells is advancing knowledge about how an organism develops from a single cell and how healthy cells replace damaged cells in adult organisms

Unique properties :

Unique properties Stem cells have three important characteristics that distinguish the from other types of cells

Slide 5:

The self renewing property of stem cell can take two form : Symmetrical division, which can give rise exclusively to only stem cell or instead all progenitor cell.[progenitor cells(non-self-renewing) are considered more ‘committed’ in differentiating towards specific cells, such as myocytes or alveolar type II cells, than are pure stem cells] Asymmetrical division, which can give rise to both stem cell and progenitor cells.

Types:

Types

TYPES ON BASIS OF POTENCY:

TYPES ON BASIS OF POTENCY Type of Cell Definition Traditional Examples TOTIPOTENT stem cells that can become an entire human being. Stem cells from a fertilized human egg. PLURIPOTENT Stem cells that can develop into any body cell type but can’t become an entire human being. Stem cells from a seven-day-old embryo, or blastocyst MULTIPOTENT Stem cells that can only differentiate into the same tissue type A bone marrow stem cell can differentiate into another type of bone marrow cell, but not into kidney, heart muscle or brain.

Embryonic Stem Cells:

Embryonic Stem Cells Embryonic stem cells, as their name suggests, are derived from embryos. Specifically from embryos that develop from eggs that have been fertilized in vitro and then donated for research purposes with informed consent of the donors. They are not derived from eggs fertilized in a woman's body. The embryos from which human embryonic stem cells are derived are typically four or five days old and are a hollow microscopic ball of cells called the blastocysts. The blastocysts includes three structures: the trophoblast , which is the layer of cells that surrounds the blastocyst ; the blastocoel , which is the hollow cavity inside the blastocyst; and the inner cell mass , which is a group of approximately 30 cells at one end of the blastocoel.

Source of Embryonic Stem Cell:

Source of Embryonic Stem Cell Embryos created by In vitro fertilization (IVF) for infertility treatments that were not implanted because they were no longer needed. Embryos created by IVF expressly for research purposes, Embryos resulting from somatic cell nuclear transfer (SCNT) or other cloning techniques. SCNT technology has, in fact, opened the door to a possible alternative approach to creating ES cells.

Culture of Embryonic Steam Cell:

Culture of Embryonic Steam Cell Embryonic steam cell lines

Identification of embryonic stem cells:

Identification of embryonic stem cells Growing and subculturing the stem cells for many months. This ensures that the cells are capable of long-term self-renewal. Meanwhile microscopic examination is done, to see that the cells look healthy and remain undifferentiated. Using specific techniques to determine the presence of surface markers that are found only on undifferentiated cells. ( FACS – fluorescent activated cell sorting, using GFP- green fluorescent proteins or reporter gene) Another important test is for the presence of a protein called Oct-4, which undifferentiated cells typically make.

Cont..:

Testing whether the human embryonic stem cells are pluripotent by: allowing the cells to differentiate spontaneously in cell culture. manipulating the cells so they will differentiate to form specific cell types. injecting the cells into an immuno suppressed mouse to test for the formation of a benign tumor called a teratoma . When examined under a microscope, it was noted that these tumors contain cell types derived from all three primary germ layers of the embryo—endoderm, mesoderm, and ectoderm . Cont..

Embryonic stem cells stimulated to differentiate:

Embryonic stem cells stimulated to differentiate As long as the embryonic stem cells in culture are grown under certain conditions, they can remain undifferentiated (unspecialized). But if cells are allowed to clump together to form embryoid bodies, they begin to differentiate spontaneously. Although spontaneous differentiation is a good indication that a culture of embryonic stem cell is healthy, it is not an efficient way to produce cultures of specific cell types. So scientists try to control the differentiation of embryonic stem cells. They change the chemical composition of the culture medium, alter the surface of the culture dish, or modify the cells by inserting specific genes.

Adult Stem Cells:

Adult Stem Cells An adult stem cell is an undifferentiated cell found among differentiated cells in a tissue or organ, can renew itself, and can differentiate to yield the major specialized cell types of the tissue or organ. The primary roles of adult stem cells in a living organism are to maintain and repair the tissue in which they are found. Some scientists now use the term ‘ somatic stem’ cell instead of adult stem cell.

Tissues containing adult stem cells:

Tissues containing adult stem cells Bone marrow Skeletal muscle Epithelia of skin and digestive system Cornea, retina Peripheral blood Spinal cord Blood vessels Testes Liver Pancreas Kidney Heart, etc

Slide 20:

Types of adult stem cells

Differentiation Pathways of Adult stem cell:

Differentiation Pathways of Adult stem cell Adult stem cells occur in many tissues and they enter normal differentiation pathways to form the specialized cell types of the tissue in which they reside. Adult stem cells may also exhibit the ability to form specialized cell types of other tissues, which is known as Transdifferentiation or Plasticity / Adult stem cell pluripotency .

Slide 24:

5/18/2011 Department Of Pharmaceutics,IT BHU Normal Differentiation Pathway

Slide 25:

Plasticity of adult steam cells / Transdifferentiation

Stem Cell Applications:

Stem Cell Applications 5/18/2011 Department Of Pharmaceutics,IT BHU Preclinical tools for screening pharmaceutical drugs. Only therapy with broad spectrum applications Cost and limitations of organ transplantation Only stem cells have the potential to repair, regenerate and cure diseased tissues . Heart disease. Juvenile Diabetes Pulmonary diseases Blood disorders Rheumatologic disorders Neurological disorders Countermeasures for chemical, biological and nuclear threats. Pandemic infectious diseases

Advantage Of Embryonic Stem Cell:

Advantage Of Embryonic Stem Cell They can multiply almost indefinitely in vitro, so you can get very large numbers of them and undifferentiated cell can easily be differentiated in to specific cell They offer one cell source for multiple indications. They provide the potential for a wider variety of applications than do adult stem cells. Another advantage of embryonic stem cells, is that they appear to be immortal in vitro, while adult and differentiated stem cells cannot be cultured indefinitely in the lab. Once differentiated, these stem cells seem to die off like typical tissue cells .

Limitation of Embryonic Stem cell:

Limitation of Embryonic Stem cell “Ethical dilemma” that embryonic stem cells do because harvesting them destroy the embryo. Immune rejection would be an another issue. It is also known that upon injection into mice with compromised immune systems, undifferentiated embryonic stem cells elicit the formation of a benign tumor called a teratoma . This tumor formation causes scientists to doubt the therapeutic applicability of embryonic stem cells.

Advantages of Adult Stem Cells :

Advantages of Adult Stem Cells Adult stem cells avoid the ethical issues . Therefore, many stem cell therapies are currently being tested using adult stem cells Additionally, adult stem cells offer the potential for autologous stem cell donation, which may help to avoid issues of immune rejection in certain situations Unlike embryonic stem cells with which risk of tumor formation after administering in body, it is not yet known whether similar results are observed with adult stem cells

Limitation of Adult Stem Cell:

Limitation of Adult Stem Cell "Adult stem cells are often present only in minute quantities, are difficult to isolate and purify, and their numbers may decrease with age,". Further, adult stem cells have not yet been found in all tissues of the body. Those that do exist may not be useable if a patient has a genetic defect, since the defect would probably be present in the stem cells as well as other cells. Or the cells may contain DNA errors caused by replication or exposure to toxins.

Slide 33:

STEM CELL RESEARCH PRESENT SCENARIO

Slide 34:

Stem cells-activity and applications across the world

Organizations involved in stem cell research:

Organizations involved in stem cell research Public agencies: National Institute of Health (NIH) International Stem Cell Forum UK Medical Research Council sponsors the UK Stem Cell Bank, Several Educational institutes Non-Profits: International Society of Stem Cell Research(ISSCR) Genetics Policy Institute(GPI) NWABR(North West Association for Biomedical Research) Publishing: BIOZONES, Stem Cell Portal(the stem cell online journal community)

Slide 36:

Dr. Jyotsna Dhawan, Dean of the Bangalore-based Institute of Stem Cell Biology and Regenerative Medicine, say successful treatments are a long way away and ethical questions, apart from health and scientific ones, have yet to be fully addressed. In 2007, India brought out a set of guidelines on conducting stem cell research, but the guidelines are not legally binding and have no power to curb clinical implementation of stem cell therapy. Only 15 clinical trials have been officially registered so far. The only stem cell therapy treatment tried and tested so far is bone marrow transplantation, allowed by the Indian Council of Medical Research (ICMR). Hundreds of patients are now streaming into stem cell therapy clinics all over India, despite the controversy surrounding stem cell research With a 2 percent share of the 56-billion dollar world market, India enjoys one of the highest growth rates in stem cell treatment and is widely perceived to be a centre of stem cell work. In India, 22 public and seven private research institutions are authorised to conduct stem cell research. Status in India

Slide 37:

Future Prospects

Slide 38:

The stem cell market is growing rapidly due to increasing regulatory approval and public acceptance bodies. The benefits of stem cell therapy are attracting an increasing number of patients. The market is divided into cellular therapeutics and therapeutic banking categories. Stem cells in therapeutic banking have the larger share of the market, worth $65.9 million in 2007 and expected to increase to $155.7 million in 2012, for a CAGR of 18.8%. Cellular therapeutics should be the faster growing segment. Cellular therapeutics generated $46.1 million in 2007 and is expected to generate $267.4 million in 2012, a CAGR of 42.1% The U.S. currently holds a 60% share of the global stem cell market.

Slide 40:

Some questions to be answered for commercialization

What you need to know to turn your cells into a therapy-are they “druggable”?:

What you need to know to turn your cells into a therapy-are they “ druggable ”? Cell quality Safety Controls Dosage Cell preparation Administration route

Is your cell therapy commercially viable?:

Is your cell therapy commercially viable? Cell source Where does it come from? Procedures What kind? How many? Process Cell manipulation Point of care Scalability and Manufacturing process Manual labour Additional product components What else Adoption Other existing oral therapeutics Surgical therapies

How to manufacture cell therapies-process and procedure:

How to manufacture cell therapies-process and procedure Cell therapy products must match the safety, purity, potency and identity criteria of conventional drugs, but: – Short shelf life – Unable to perform a final sterilisation step pre-implantation Manufacturing processes must be carried out aseptically: – In-process quality controls – Raw materials and manipulators – Segregation strategies Manufacturing procedures must be developed to compile with regulations – SOPs, batch documentation, testing

How to manufacture cell therapies-capacity and scale up:

How to manufacture cell therapies-capacity and scale up Currently in clinical trials small production volumes Production process: – Robust to be reproducible – Consistently validated to ensure quality – Scale up must be cost effective Automation must be implemented early in the process to improve safety -permit scale-up Standard and controlled scale up systems for cell therapy manufacturing include: – Cell selection or separation devices such as magnetic beads, density centrifugation, FACS etc. Cell culture technologies include: – cell factories, bags, bioreactors etc.. We are still a long way from optimised scale up conditions

Cell therapy treatment –it has a high price tag:

Cell therapy treatment –it has a high price tag Cell therapies have high production costs and so are expensive -currently up to $40,000 per treatment Multiple surgical procedures Aseptic conditions Extensive training Increased technical support and personnel Specialised facilities Production is highly labour intensive Sophisticated, fragile and in very small batches Adequate product targeting and marketing strategies are essential for financial success

Conclusion :

Conclusion The role of stem cells for use as medical therapy in humans is a major focus of research today. The promise of stem cell therapies is an exciting one, but significant technical hurdles remain that will only be overcome through years of intensive research. Scientists feel strongly we need embryonic stem cells. The answers are not just going to come from the adult stem cells and it would be extremely short-sighted to shift completely to just adult stem cells.

REFERENCES :

REFERENCES Stem Cell Information, “The official National Institutes of Health resource for stem cell research”. Caroline Ameeen et al; “Human embryonic stem cells: Current technologies and emerging industrial applications”; Critical Reviews In Oncology/Hematology; 65(2008)54–80. TeijaT. Peura et al; “Derivation of human embryonic stem cell lines”; Theriogenology; 67(2007)32–42. Gesine Paul et al; “Stem cells: hype or hope?” ; therapeutic focus Review; 7( 2002). Colin W.Pouton et al; “Pharmaceutical applications of embryonic stem cells”; Advanced Drug Delivery Reviews; 57(2005)1918–1934. Yoel Shufaro et al; “Therapeutic applications of embryonic stem cells”; Best Practice & Research Clinical Obstetrics and Gynaecology ;18(2004),6,909-927

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