technologies, and thus, has no official position on those issues. The agency basically considers cloning as another breeding technology, which can be used to introduce traits that benefit animal health, such as resistance to certain diseases, or human preferences, such as softer meat. These conclusions agree with those of the National Academy of Sciences, published in 2002. Since its own publication in 2008, the FDA has updated its findings. Also, it is not the responsibility of the FDA to address non-science-based concerns such as the religious, moral, and ethical topics related with animal cloning for agricultural purposes, the economic impact of its products in the market, or other social issues unrelated to its public health impact.
Animal Cloning and Related Ethical Issues
Many ethical issues exist in reference to both actual and potential usage of cloning technology with animals today, covering controversial issues such as the well-being of the animals and their progeny, the usage of cloning in preserving or reviving endangered and extinct species, and, as a commercial offshoot of these practices, actions such as the cloning of deceased favorite pet animals. Many are concerned about cloning pets, for example, because pet owners may expect their cloned pet to be a perfect copy of the progenitor or parent pet, which is not the case. In addition, cloned animals are known to suffer distinct health issues. Many of these issues overlap with the possibility of animal cloning crossing the frontier into cloning of humans.
Many argue that the benefits are greater than the unfavorable issues associated with the cloning procedure. Others oppose it because of the novelty, uncertainties, and the ethical risks involved. Those who oppose or remain wary of cloning warn of the possibility of unwitting transmission of trans-species pathologies. Still others are concerned that a scientist may attempt to proceed beyond animal cloning for currently accepted purposes and create a human being. The development of animal cloning then, has sparked a scientific controversy among those who hope to find a cure for diseases, better food quality, and a greater supply of food on one hand, and ethical and religious opposition—or those who prefer to err on the side of caution—on the other.
To date, however, no human being has yet been cloned successfully. Still, the possibility of this event is a cause for trepidation not only for policymakers and the public at large, but also for the majority of ethical scientists. Nevertheless, most scientists are firmly opposed to reproductive human cloning. Animal cloning advocates argue that with responsible policies, risk assessments, government and institutional oversight, and conscientious monitoring in place, cloning technologies can be performed ethically and appropriately in sustainable ways.
In order to be medically and commercially applicable, advances in biotechnology require not only an understanding of scientific knowledge, but also of policy-related and ethical implications. In this regard, legislative and funding imperatives—as well as conflicts of interest—need to be addressed. Considerations for the future should include a formal distinction between therapeutic and reproductive cloning and their risks in policy-making and legislative formulations. Cloning has opened many doors that lead to remarkable medical advancements but, as with all new technologies, it raises many ethical and social dilemmas.
Trudy M. Mercadal
Florida Atlantic University
See Also: Cloning, Ethics of; Embryonic Stem Cells, Methods to Produce; Gene Patents; Genome Sequencing.
Further Readings
Cibelli, Jose, Ian Wilmut, et al. (eds.). Principles of Cloning. Waltham, MA: Academic Press, 2013.
Levine, Aaron D. Cloning: A Beginner’s Guide. London: Oneworld Publications, 2007.
Woestendiek, John. Dog, Inc. How a Collection of Visionaries, Rebels, Eccentrics and Their Pets Launched the Commercial Dog Cloning Industry. New York: Avery Trade, 2012.
Anversa, Piero
Anversa, Piero
53
54
Anversa, Piero
Physician and scientist Dr. Piero Anversa was born in Parma, Italy, where he earned his doctorate in medicine. His interest in cardiovascular research began in his final years in medical school, and his commitment to science has remained intact in the last 50 years. Shortly after graduation, he obtained a NATO fellowship and moved to the United States in 1971. Although he lived most of his life in the United States and considers New York his real home, he maintains strong bonds with his country of origin. Myriad of fellows have been mentored by Dr. Anversa throughout his career.
The research conducted in Dr. Anversa’s laboratory has questioned the paradigm that the heart is a post-mitotic organ characterized by a predetermined number of parenchymal cells, which is defined at birth and is preserved throughout life. The work that Dr. Anversa conducted in the last 30 years has led to the recognition that the heart is an organ permissive for myocardial regeneration, which can be mediated by exogenous progenitor cells, endogenous progenitor cells, or both. Historically, the foundations for the notion that the heart is a static organ incapable of regeneration were established in the mid-1920s. The impact of this research was enormous, leading generations of pathologists and cardiovascular scientists to adhere to the concept that replicating myocytes are not to be found in the adult myocardium. Dr. Anversa’s critical analysis of the published data resulted in the development of a simpler and more convincing hypothesis of the cellular mechanisms regulating cardiac growth. If the assumption is made that cardiomyocytes lack the ability to reenter the cell cycle and replicate, differences in myocyte size would be expected to reflect comparable differences in the size of the organ. Dr. Anversa observed that changes in heart mass and cardiomyocyte volume rarely coincide, challenging the notion that the number of myocytes is an entity that remains largely constant throughout the organ lifespan, physiologically and pathologically. He demonstrated that hearts varying in weight can be composed of myocytes of similar volume, pointing to cell number as a crucial determinant controlling the size of the organ. Based on this work, numerous laboratories worldwide have demonstrated that the adaptive plasticity of the adult myocardium could not be equated to myocyte hypertrophy any longer.
Dr. Anversa introduced the concept of cardiomyocyte death as a cellular process strictly interrelated to myocyte formation in the control of cell number and heart homeostasis. Although the critical interaction of cell death and cell renewal is not unique to the myocardium, the concept that myocyte death is inevitably accompanied by the generation of new myocytes remains highly controversial. However, the fundamental observations obtained by Dr. Anversa and others impose a reexamination of cardiac biology in an attempt to provide novel information for a better understanding of the processes involved in the manifestations of severe ventricular dysfunction.
As stated by Angelini and Markwald, “almost single-handedly, Anversa and colleagues have raised new interest in the capacity of adult cardiac myocytes to replicate naturally. These investigators have proposed the innovative concept that, contrary to previous assumptions, the adult human heart is not terminally differentiated but has a significant population of stem cells capable of reproducing and differentiating into myocytes.”
To define whether cardiomyocyte renewal derives from endogenous and/or exogenous progenitors, Dr. Anversa studied initially sex-mismatched human cardiac transplants, a condition that offers the unique opportunity to determine whether host male cells develop within the female donor heart. This research provided the first evidence in support of the notion that the heart is a stem cell–regulated organ. Male cardiomyocytes and coronary vessels were detected and quantified in transplanted female hearts. Although discrepancies exist among groups in terms of the magnitude of cardiac chimerism, these results documented that male stem cells likely colonize the donor heart and differentiate into cardiovascular structures.
In numerous following publications, Dr. Anversa has shown that the heart belongs to the group of constantly renewing organs, where the capacity to replace cells depends on the persistence of a stem cell compartment. These findings have formed the basis of a new