IQP-43-DSA-4471 IQP-43-DSA-4317 STEM CELLS AND SOCIETY An Interactive Qualifying Project Report Submitted to the Faculty of WORCESTER POLYTECHNIC INSTITUTE In partial fulfillment of the requirements for the Degree of Bachelor of Science By: _________________________ _________________________ Brandon Alspach Nicholas Van Sciver August 24, 2012 APPROVED: _________________________ Prof. David S. Adams, Ph.D. WPI Project Advisor ABSTRACT The purpose of this project is to investigate the various forms of stem cells, how they are used, the ethics in doing this research, and current and past laws regulating this research. The first chapter will describe the types of stem cells and their potencies, while the second will discuss potential treatments for example diseases. The third chapter will investigate the ethics and religious views on stem cell research. Then the final chapter will go over the legalities of stem cell research in the US on both the federal and state level, as well as in other countries. 2 TABLE OF CONTENTS Signature Page …………………………………………..…………………………….. 1 Abstract ………………………………………..………………………………………. 2 Table of Contents ………………………………..…………………………………….. 3 Project Objective ………………………………..………...…………………………… 4 Chapter-1: Stem Cell Types ……………….…..…...………………………………… 5 Chapter-2: Stem Cell Applications ..…………..……………………………………… 18 Chapter-3: Stem Cell Ethics ………………………..………………………………….. 30 Chapter-4: Stem Cell Legalities …………………..…………………………………… 40 Project Conclusions ………………………………..……………….…………………... 56 3 PROJECT OBJECTIVES The objective of this IQP is to examine the controversial topic of stem cells, focusing on both the technology itself and its ethical controversies. Chapter-1 describes the various types of stem cells, showing their origins and potencies. Chapter-2 documents example uses of this technology for several chosen diseases, carefully distinguishing pre-clinical animal experiments from human clinical trials. Chapter-3 examines the ethics surrounding this controversial topic, while Chapter-4 examines the U.S. and international laws governing stem cell use. Finally, a conclusion is made by the authors regarding the use of stem cells, and which laws best represent the authors’ points of view. 4 Chapter-1: Stem Cell Types Brandon Alspach Throughout history, man has worked tirelessly on medical technology. Thousands of years ago, a medicine man would carve a hole in your skull to heal ailments; now we visit a drug store to treat the same ailment. But as much as we know about the human body and how to cure disease, there is still a great deal we do not know, and research seeks to find more cures. One such topic of strong current interest is stem cells. With this controversial topic, often people argue against their use before knowing all the facts. Perhaps before jumping to conclusions about stem cells and its research, we should ask more questions about them. Are all stem cells the same? Do they all come from the same place in the human body and perform the same tasks? The answer to both those questions is no. The purpose of this chapter is to describe the types of stem cells and their origins, focusing on which types destroy embryos. Stem Cell Potencies First discovered in 1908 by Russian histologist Alexander Maksimov, stem cell research did not expand much until the 1960’s, when it was discovered that self-renewing cells with blood forming characteristics existed in the bone marrow of mice (Till, 1961; Who Discovered…2012). The discovery of stem cells was monumental, as it was learned that they were very different from most cells in the body. Two very important characteristics set them apart from other cells. First, stem cells are unspecialized and, as stated above, are “capable of renewing themselves through cell division” (Kirschstein and Skirboll, 2001). Second, the cells have the ability to differentiate into specific tissue types, determined by the cell’s potency, which varies from 5 totipotent, to pluripotent, multipotent, and unipotent. The prefix “toti”, meaning “wholly”, refers to cells fertilized in the past 1-3 days that have the ability to create an entire organism and its surrounding tissues. Totipotent cells have the ability to become a viable embryo. Newly fertilized zygotes through the 8-cell stage are totipotent. A pluripotent stem cell, with the prefix “pluri” meaning “several,” has the ability to become any of the 200 different types of cells found in the human body. These cells are found in the inner cell mass of a 5-day old blastocyst. Embryonic stem (ES) cells are considered pluripotent, and their isolation from the blastocyst usually destroys the embryo; so ES cells are the most ethically controversial type of stem cell. Multipotent stem cells, multi- meaning many or more than one, have a limited number of cells they can become, but do retain the ability to turn into cell types of related cells. Examples of multipotent stem cells include hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs). HSCs taken from bone marrow and umbilical cord blood are among the best characterized of all the stem cell types, and have already shown successful therapeutic results. The final type of potency, unipotent stem cells, as their prefix suggests, are only capable of turning into a specific kind of cell, typically cells from the same tissue it resides (Types of Stem…2004). The issue of stem cell potency is still hotly debated today, especially with iPS cells, which will be discussed below, and whether they are truly pluripotent. Embryonic Stem Cells Most often when referring to stem cells, it is jumped to the conclusion that the cells come from a human embryo, and that all stem cells are controversial. While it is true that some types come from embryos, the vast majority come from elsewhere. Stem cells can be categorized by 6 their location. There are four main types of stem cells, embryonic stem cells, induced pluripotent stem cells, parthenogenetic embryonic stem cells, and adult stem cells, each of which will be discussed in detail. Embryonic stem (ES) cells are pluripotent stem cells taken from the inner cell mass of a blastocyst embryo (Figure-1). Human ES cells were first isolated and grown in 1998 by James Thompson at the University of Wisconsin-Madison (Thomson et al., 1998). Thomson showed that ES cells could be “sustained indefinitely in the lab” (Why Files…1998) by creating an ES cell line from which an endless supply of cells can be created. Egg and sperm are united in vitro, and the zygote is grown about 5 days to the 100 cell blastocyst stage from which the ES cells are obtained, destroying the embryo. No human implantation of the embryo is involved for blastocysts used for research. Currently in the U.S., human embryos cannot be created solely for research purposes, but must come from reproductive clinics from the surplus supply left over from IVF procedures. Figure-1: Diagram of a Blastocyst Embryo. The diagram shows the inner cell mass (green) from which embryonic stem cells are removed (Blastocyst English 2007). 7 The initial protocol for growing ES cells required a feeder layer of mouse fibroblast cells, which provided a scaffold and growth factors. But due to worries about mixing animal and human cells for therapy experiments, subsequent protocols use non-cellular extracellular matrix scaffolds (Klimanskaya et al., 2005). Not every dish yields a cell line. In some cases, the cells differentiate into other cells, or they begin to show genetic abnormalities. To create an embryonic stem cell line, over the course of months the cells must be re-plated in a cycle called subculture, with each cycle called a passage. At any point during this process, the cells can be frozen and kept for indefinite amounts of time, then thawed and re-plated. To ensure that the culture remains as embryonic stem cells, scientists periodically test the cells to ensure they remain undifferentiated, however the scientific community has not been able to agree on a standard method of determining whether the cells are undifferentiated. Most commonly, scientists examine the cells by microscopy to ensure they appear undifferentiated. By looking at the chromosomes of the cell under a microscope, it can also be determined if the cell has gone under any obvious genetic mutations. In other assays, the scientists analyze the genetic code of the cells to look for mutations, or analyze the types of transcription factors present. Transcription factors inside cells help regulate genes that turn on and off cell differentiation. Two important transcription factors that keep a cell in an undifferentiated state are NANOG and OCT4, both of which scientists look for when performing biochemical characterization. While embryonic stem cells show the most medical potential, they also have disadvantages to their use as well. Since the cells have not differentiated, they are simply a blank slate. They require complex chemical cues to change into the specific cell that is required for a 8 specific disease treatment. The cells also have a tendency to be rejected by the host immune system as invading cells. And ethically, their use produces strong debate on the ethical implications of life at conception. Induced Pluripotent Stem Cells Based on concerns with using ES cell research, scientists sought potential replacements for obtaining pluripotent stem cells without using a blastocyst. A breakthrough was made in 2006 when Takahashi and Yamanaka discovered a way to induce regular mouse skin cells called fibroblasts to become pluripotent (Takahashi and Yamanaka, 2006). And one year later, the same lab achieved the same success for human fibroblast cells (Takahashi et al., 2007). Originally done with the use of viruses encoding four transcription factors (OCT3/4 SOX2, KLF4, and c-MYC), scientists used the viruses to infect skin fibroblast cells, and the factors helped de-differentiate the fibroblasts to a pluripotent-like state, called an induced pluripotent stem (iPS) cell (Brind’Amour 2009). While this was one of the greatest breakthroughs in stem cell biology of the past decade, it raised some questions. One of the genes used in this procedure, c-MYC, had been linked to cancer growth. Indeed, when the iPS cells were added to early stage mouse embryos, the mice grew like normal mice, but were at a much more considerable risk of growing tumors. It was also a concern that a retrovirus was being used to introduce the genes into the fibroblast, as retroviruses integrate at random positions in the host genome. But, both of these concerns have been now been pushed to a backburner, as further research showed that using only the NANOG and LIN28 genes in place of the c-MYC and KLF4 genes reduced the risk of tumor growth in the recipient of the iPS cells (Kim et al., 2008), and scientists could avoid using viruses altogether 9 and simply deliver the transcription factors themselves or use non-integrating plasmids (Yu et al., 2009). One key remaining debate point with iPS cells is their potency. Some scientists claim iPS cells are as potent as ES cells, while others argue that iPS cells grow more slowly and have DNA mutations (Dolgin, 2010; Gore et al., 2011). More research will be required to resolve this issue before using them for therapy. Parthenogenetic ES Cells Another method under intensive study to produce viable stem cells is parthenogenesis. Parthenogenesis is a process by which an unfertilized egg retains two sets of chromosomes and beings to develop as if it were a normal fertilized egg. A few species of insects and reptiles that naturally undergo this form of replication, but it is not commonplace in mammals. Indeed, when parthenogenesis was attempted with mammals the embryos died within days of fertilization. Continuing with the research, it was found that the embryos of monkeys could be induced to live just long enough to become blastocysts and have their inner cell mass removed to derive ES cell lines (Mitalipov et al., 2001). Further research is being completed in the hopes that human eggs can be used to create parthenogenetic embryonic stem cells. Parthenogenetic embryonic stem cells would be genetically identical to the egg donor, so perhaps would be less likely to be rejected by that host. Some scientists even envision someday using non-sexual reproduction to create a genetically homogenous cell line that would be accepted by all human hosts (Westphal 2003). Ultimately, deriving parthenogenetic ES cells still requires the use of an embryo, even if 10