Lecture on Understanding Embryonic Stem Cells

Embryonic stem cells (ES cells) are stem cells derived from the inner cell mass of an early stage embryo known as a blastocyst. Human embryos reach the blastocyst stage 4-5 days post fertilization, at which time they consist of 50-150 cells.



ES cells are pluripotent. This means they are able to differentiate into all derivatives of the three primary germ layers: ectoderm, endoderm, and mesoderm. These include each of the more than 220 cell types in the adult body. Pluripotency distinguishes ES cells from multipotent progenitor cells found in the adult; these only form a limited number of cell types. When given no stimuli for differentiation, (i.e. when grown in vitro), ES cells maintain pluripotency through multiple cell divisions

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How Does an Egg Make an Organism

Lecture is presented by Sir John Bertrand Gurdon ,In 1962, Gurdon, then at Oxford University, announced that he had used the nucleus of fully differentiated adult intestinal cells to clone South African clawed frogs (Xenopus laevis).This was the first demonstration in animals that the nucleus of a differentiated somatic cell retains the potential to develop into all cell types (ie, is totipotent) and paved the way for future somatic cell nuclear transfer experiments, including the 1996 cloning of the sheep, Dolly.

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Gurdon began cloning experiments using nonembryonic cells—specifically, cells from the intestinal lining of tadpoles. Gurdon believed that the tadpoles were old enough so that cells taken from them would be differentiated. Gurdon exposed a frog egg to ultraviolet light, which destroyed its nucleus. He then removed the nucleus from the tadpole intestinal cell and implanted it in the enucleated egg. The egg grew into a tadpole that was genetically identical to the DNA-donating tadpole. But the tadpoles cloned in Gurdon’s early experiments never survived to adulthood and scientists now believe that many of the cells used in these experiments may not have been differentiated cells after all. In later work, however, Gurdon successfully produced sexually mature adult frogs from eggs into which genetically marked nuclei had been transplanted from differentiated tadpole cells.

Gurdon’s experiments captured the attention of the scientific community and the tools and techniques he developed for nuclear transfer are still used today. The term clone (from the Greek word klōn, meaning “twig”) had already been in use since the beginning of the 20th century in reference to plants. In 1963 the British biologist J. B. S. Haldane, in describing Gurdon’s results, became one of the first to use the word clone in reference to animals.

In this Hitchcock lecture he explores the process of going from egg to organism.

Stem Cells: Programming and Personalized Medicine

Rudolf Jaenisch is one of the founders of transgenic science (gene transfer to create mouse models of human disease). His lab has produced mouse models leading to new understanding of cancers and various neurological diseases.

He received his doctorate in medicine from the University of Munich in 1967. He came to the Whitehead from the University of Hamburg in Germany, where he was head of the Department of Tumor Virology at the Heinrich Pette Institute.

Jaenisch received the 2002 Robert Koch Prize for Excellence in Scientific Achievement. In 2003, he was awarded the Charles Rodolphe Brupbacher Prize for basic research in oncology and was elected a member of the National Academy of Sciences.

Jaenisch is a fellow of the American Academy of Arts and Sciences and the American Academy of Microbiology, and a member of the American Association for the Advancement of Science

Stem Cells & Cloning Lecture

About Speaker
Robert A. Weinberg '64, PhD '69
Founding Member, MIT Center for Cancer Research

Member, Whitehead Institute Daniel K. Ludwig and American Cancer Society Professor for Cancer Research Department of Biology

Robert A. Weinberg has earned some of the top honors in his field. Most recently, he won the 2006 Landon-AACR Prize for Basic and Translational Cancer Research. He is also a 1997 National Medal of Science awardee.

Weinberg's laboratory discovered the first human oncogene and the first tumor suppressor gene. Today, much of his research focuses on new models of breast cancer development including the stages of tumor invasiveness and metastasis.

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He earned his Ph.D. in biology from MIT in 1969, and was one of the Founding Members of the MIT Center for Cancer Research in 1973. He was appointed a professor at MIT in 1982, the same year he joined the Whitehead Institute. Weinberg was named American Cancer Society Research Professor in 1985 and received the Daniel K. Ludwig Professorship for Cancer Research in 1997. He is a member of the National Academy of Sciences and the Institute of Medicine.

Genetics and the Effect of Aging on Stem Cell Regulation

Genetics research is key to understanding the effects of aging and age-related diseases. How do stem cells change as we grow older, and can they be regulated to decrease cancer risk?

The Promise of Human Embryonic Stem Cell Research

Dr. Benjamin Reubinoff explores the research his team at Hadassah University Hospital in Jerusalem has conducted with stem cells including the use of stem cells to treat rats with Parkinson's disease.
Stem cells are immature unspecialized cells that renew themselves for long periods through cell division. Under certain conditions, they can be induced to become mature cells with special functions such as the beating cells of the heart muscle or the insulin-producing cells of the pancreas.

Human embryonic stem cells (hESCs) are derived from early surplus human embryos (5-6 days after fertilization). The embryos used to derive these stem cells were created for infertility treatment purposes through in vitro fertilization (IVF) procedures and were donated to research when they were no longer needed for that purpose.

Human ES cells are unique in the universe since they can self-renew infinitely in culture yet still retain a normal genetic pattern, and also since they have a remarkable potential to develop into all cells and tissues of the human body.

The Potential of hESCs for Transplantation Therapy

Given their unique properties, hESCs are expected to have far- reaching applications in the study of early human development, the development of new drugs, and regenerative medicine. Human ES cell lines can serve as a renewable unlimited donor source of specialized human cells for transplantation therapy.

Human ES cell-derived mature cells could potentially be transplanted to restore tissue function in a wide range of human diseases that are associated with loss of cell function.

These conditions may include neurodegenerative disorders such as Parkinson’s and Alzheimer’s diseases, Multiple Sclerosis, cerebrovascular accidents, spinal cord injuries, as well as heart failure, diabetes mellitus, and others. The number of patients that potentially could benefit from transplantation of hESCs is overwhelming. For example there are over 16 million patients worldwide with neurodegenerative disorders, and over 120 million diabetic patients. Moreover, transplantation of genetically modified hESCs may allow the transfer and expression of foreign genes in target organs in the course of gene therapy.

While the promise of hESCs for cell and gene therapy is remarkable, further extensive research and development are required to exploit their potential for regenerative medicine.