TOPICS IN (NANO) BIOTECHNOLOGY Stem Cell Therapy Lecture 10 20th November, 2006 PhD Course

Stem Cells Introduction Sources and types of Stem Cells Main Applications Companies in the Field Stem Cells for Gene Therapy Legal and Ethical Issues

What is a stem cell?

What is a Stem Cell? Stem cells are undifferentiated cells capable of producing a wide variety of different cell types Stem cells are characterized by three hallmark properties: –Pluripotent: capable of differentiating into most cells, but incapable of forming placental tissue so cannot form a fetus –High Proliferative Potential: theoretically, one cell can give rise to an entire organ system –Self-Renew: can regenerate themselves so are “immortal”

Where Do Stem Cells Come From? Stem cells exist in different forms in both the embryo and the adult Embryonic stem (ES) cells are taken from blastocyst stage embryos (just a few days old and composed of few cells), of which there are about 200,000 in cryopreservation in IVF clinics ES cells are pluripotent and adult stem cells - plasticity

ES cells: - spare embryos - special purpose embryos - cloned embryos Adult stem cells: - adult tissue - cadavers Other sources: - aborted fetuses - umbilical cords Sources of stem cells

20 years ago - mouse ES cells James Thompson - human ES cells Stem cell proliferation

Multiple embryos are produced in vitro for clinical purposes. Donated surplus embryos are used as a source of ES cells. These surplus embryos would otherwise be discarded or remain unused How are ES Cells Generated?

Fertilized Embryos Are Allowed to Divide Several Times in Culture

Harvesting ES Cells The blastocyst is the stage of development (~1,000 cells) at which the embryos inner cell mass (ICM) forms. It is the ICM that harbors ES cells. Stem cells exist only fleetingly at this stage of development

Generating an ES Cell Line The trophoblast is removed from the embryo, the inner cell mass is isolated and, using a micropipette, ES cells are extracted and placed in tissue culture. These cells are passaged for many generations until some spontaneously form “immortal” lines

Generating an ES Cell Line In vitro growing Growth medium Feeder layers Spontaneous differentiation

Differentiation

Stem Cell Therapy Using replacement cells to cure disease may prove to be one of the most significant advances in medicine Unlike current treatments that rely on surgery or drugs to modulate activities, stem cells provide a replacement for dysfunctional or degenerating tissue In the future, stem cells could enable the means to create entire organs that fail due to aging or disease

Sources Plasticity - Adult Central Nervous System (CNS) - Bone marrow and blood stem cells - Other tissues Adult Stem Cells

Stem Cell Therapy for Tissue Replacement Stem cells are the parent cells of every cell in the body. Under the right conditions, ES cells can be transformed into a variety of cells that make up the bone marrow, brain, muscle, skin, pancreas, and liver

Clinical Applications When transplanted into an injured tissue (eg. damaged cardiac muscle following heart attack) heart cells derived from ES cells in culture can contribute to tissue regeneration in vivo

Other Sources of Stem Cells Spare Embryos: leftover from IVF clinics Special Purpose Embryos: created by IVF for the sole purpose of extracting stem cells Cloned Embryos: embryos can be cloned in the lab by somatic nuclear transfer in order to harvest their stem cells Aborted Fetuses: can be used as a source of stem cells early in development (5-11 weeks of gestation) Umbilical Cords: this normally discarded tissue holds great promise as a source of blood-forming (hematopoietic) stem cells Adult Tissues or Organs: stem cells can be isolated from tissues of living adults during surgery (eg. hematopoietic stem cells from bone marrow) Cadavers: neural progenitor cells have been isolated from human brain tissue up to 20 hours after death

Comparing Embryonic and Adult Stem Cells Advantages Flexible: have the potential to make any cell Immortal: one ES cell line can potentially supply endless cells with defined characteristics Easily Available: embryos from IVF clinics Disadvantages Difficult to Culture: the conditions for inducing tissue- specific differentiation are poorly understood Immunoreactivity: ES cells from another donor may be rejected after transplantation into an incompatible recipient Ethically controversial: embryonic sources of stem cells are opposed by people who believe that life begins at conception even if donors give consent

Comparing Embryonic and Adult Stem Cells Advantages Already Somewhat Specialized: inducement may be simpler Not Immunogenic: recipients who receive the products of their own stem cells will not experience immune rejection Mixed Degree of Availability: some adult stem cells are easy to harvest (skin, muscle, marrow), while others may be dangerous to the donor (brain stem cells) Disadvantages Limited Quantity: difficult to obtain in large numbers Finite: don’t live as long as ES cells in culture Less Flexible: may be more difficult to reprogram to form other tissue types Genetically Unsuitable: may carry genetic mutations of disease or become defective during culture

Target Diseases for Stem Cell Therapy Blood Diseases Bone marrow transplants (BMT) are a well known clinical application of hematopoietic stem cell (HSC) therapy HSCs can regenerate all of the different cell types in blood BMT is used for the treatment of blood cancers like leukemia and lymphoma, as well as breast cancer and any other disease requiring immune system regeneration

Target Diseases for Stem Cell Therapy Heart Disease ES cells can be induced to form cardiac muscle cells that actually beat in culture When transplanted into damaged hearts, these cells can form gap junctions and contract in unison with surrounding cells HSCs can also be grafted into damaged heart muscle and, in this new environment, are reprogrammed to produce heart cells instead of blood cells

Target Diseases for Stem Cell Therapy Brain and Spinal Cord Injury Neural stem cells can be isolated from adult brains or generated from ES cells in culture HSCs can also be transplanted into the brain where they are reprogrammed to generate neurons and glial cells Potential applications include Parkinson’s disease, ALS, Huntington’s disease, stroke, Alzheimer’s disease, paralysis Animal and early human trials are underway

Target Diseases for Stem Cell Therapy Type 1 Diabetes Patients lack pancreatic beta cells and cannot produce insulin Insulin-producing structures similar to pancreatic islets have been generated from mouse ES cells in culture It may also be possible to isolate pancreatic stem cells from adult tissue Early stage of development

Target Diseases for Stem Cell Therapy Skin and Hair Replacement Skin (keratinocyte) stem cells reside in the hair follicle and can be removed when a hair is plucked These cells are bipotent, forming hair and epidermis in culture Provide tissue for autografting, without problems of immune rejection Clinical trials underway for venous ulcers, burn injury, and hair transplants

Stem cells for Gene Therapy

Commercial Opportunities in Stem Cell Research Devices: manufacture of equipment and materials needed to isolate stem cells from adult tissues (e.g. Antibodies, affinity beads and flasks, columns, cell sorters, etc.) Isolation: novel “processes” are patentable Composition: the make-up of the isolated stem cell product is patentable, irregardless of how it was obtained Manipulation: novel methods of culturing or reprogramming stem cells are patentable

Aastrom Advanced Cell Tech. BresaGen Cryo Cell Curis Diacrin Geron ReNeuron StemCells Incara Nexell NeuroNova Novartis Genzyme Others Biotechnology Companies in the Stem Cell Field

Nexell Isolex 300i Magnetic Cell Selection System. The only FDA approved device for clinical scale isolation of hematopoietic stem cells from blood Aastrom Manufacture a “bioreactor” that allows the growth of many hematopoietic stem cells from the small number that can typically be harvested from adult or umbilical cord blood

Biotechnology Companies in the Stem Cell Field StemCells Inc. Have parallel programs in pre-clinical development for the isolation and characterization of neural, liver and pancreatic stem cells. Primarily process and compositional patents Geron Own the intellectual property used to clone “Dolly” the sheep. Funded the University of Wisconsin research that generated the first human ES cells. Parallel programs in directing the development of ES cells into neural, liver and cardiac cells for transplantation

Biotechnology Companies in the Stem Cell Field Diacrin Developing xenotransplants using fetal pig cells in chronic stroke patients NeuroNova Strategy is to isolate adult brain stem cells, induce them to form dopaminergic neurons in culture, and then transplant these cells into the brain of patients with Parkinson’s disease

Biotechnology Companies in the Stem Cell Field ReNeuron Has developed neural stem cell lines from different regions of the human brain. Can be grown in large numbers for transplantation. Also examining the genes and proteins expressed in neural stem cells to identify novel targets for drug discovery Novartis Through its acquisition of SyStemix, Inc., now owns the composition patent on human hematopoietic stem cells