Stem cell biology
Christine Hauskeller, Arne Manzeschke, Anja Pichl in The Matrix of Stem Cell Research, 2019
Much ethical debate over stem cells concerns the permissibility of using human embryos for research. In the background of these debates are views about biological development: what a developing entity is, the meaning of its ‘potential’, and what controls the transformation from fertilized egg to whole organism. Stem cell biology aims to clarify all these ideas. So understanding stem cell research is crucial for making sense of the ethical debates. The field’s central concept, that of a stem cell, is peculiar in that it unites two very different ideas. A cell is a well-characterized biological entity, observable via relatively simple technology and clearly distinguished from its environment and other cells by a bounding membrane. A stem is the beginning of a process, the point of origin for something that is to be. A stem cell, then, is both entity and process; a cell defined by what it gives rise to rather than its observable traits. More precisely, a stem cell is generally defined today as a cell that has ‘the capacity to both self-renew and give rise to differentiated cells’ (Ramelho-Santos and Willenbring, 2007, 35).1 Cell differentiation is one key aspect of organismal development. So the very idea of a stem cell involves assumptions about the process of development, which often remain tacit and unquestioned. One goal of this chapter is to make these assumptions explicit. To do so I present a minimal definition of ‘stem cell’, which further explicates the prevailing scientific definition citing self-renewal and differentiation.
Cancer
Shamim I. Ahmad in Aging: Exploring a Complex Phenomenon, 2017
Developmental biology traditionally presents the human ontogeny with emphasis on the birth of a child or on body growth. However, aging is another integral component of human ontogeny. This process seems to be influenced by many endogenous as well as exogenous factors. It was described in monozygotic twins that the age of onset, as well as disease occurrence and course, can be quite discordant [67,68]. However, our life span seems to be genetically determined including reduced activity of gene repair that can reflect the high incidence of malignant tumors in the elderly. The activity of genes such as transcription factors of the FOXO family can affect the extreme longevity of centenarians in a pleiotropic manner, influencing several cell-regulated activities such as stress resistance, metabolism, cell cycle arrest, and apoptosis, and probably minimize cancer incidence in the elderly [69].
A lifecourse perspective on bone health and disease: Scientific and social implications
Nicholas C. Harvey, Cyrus Cooper in Osteoporosis: a lifecourse epidemiology approach to skeletal health, 2018
The concept that aspects of the maternal phenotype, and her environmental exposures and experiences, can have important influences on the development of her offspring and may confer a Darwinian fitness advantage, is well established in evolutionary developmental biology (16,31). In humans, the effects of maternal diet during pregnancy, such as vitamin D levels, and other behaviours such as smoking, on the bone development of the fetus are well documented (see elsewhere in this volume). For human development, however, the concept of ‘maternal constraint’ of fetal growth – a process in which maternal factors limit the growth of the fetus during development (32,33) − has particular implications that are less widely known. Maternal constraint is greater in low-stature women, in first pregnancies and with a male fetus, which are risk factors for obstruction and complications such as obstetric fistula in low-resource settings (34). Greater constraint of fetal growth followed by more abundant nutrition in subsequent life might produce a greater degree of ‘mismatch’ between developmental experiences and the later life environment (15). This might increase the risk of noncommunicable disease in adults in these settings when economic development leads to adoption of Western diets and lifestyle.
One of these things is not like the other: time to differentiate between relative age and biological maturity selection biases in soccer?
Published in Science and Medicine in Football, 2022
Chris Towlson, Calum MacMaster, James Parr, Sean Cumming
A recent study by Parr et al. (2020) has shown that the effect of both maturation and relative age upon physical performance measures in youth soccer players is discrete, highlighting that these measures should not be considered mutually influential. This implies that the underpinning mechanisms for these selection phenomena in this scenario are separate entities. However, relative age did have a weak (R= 0.19 to 0.23) correlation with physical performance measures; that said, it was biological maturation which likely acted as the underpinning mechanism for change within these phenotypes evidenced by strong (R= 0.75 to 0.71) and significant (P< 0.01) correlation values of the examined physical fitness characteristics, with only maximal vertical jump height being significantly (P< 0.05; R2 = 0.23) influenced by relative age. It is, therefore, likely, that individual biological development is responsible for regulating these physical characteristics. Despite limitations associated with the participant group, specifically the small sample size representing Q4 and all players being from the same academy setup, the results agree with previous research by Johnson et al. (2017).
Developing a Reflexive, Anticipatory, and Deliberative Approach to Unanticipated Discoveries: Ethical Lessons from iBlastoids
Published in The American Journal of Bioethics, 2022
Rachel A. Ankeny, Megan J. Munsie, Joan Leach
Study of early human development is essential for continued understanding of pregnancy including effects of environmental toxins and gene mutations on development, and for studying fertility problems and refining assisted reproductive technologies. Although difficult to measure and hotly debated, recent estimates indicate that for women of reproductive age, losses between embryo implantation and clinical recognition of pregnancy are approximately 10–25%; although considerably lower than older estimates which ranged from 30–70%, this rate is still non-trivial (Jarvis 2016). But research on these developmental stages has been accompanied by considerable challenges in many locales related to ethical, social, and legal constraints on the availability of human embryos for research purposes. Hence developing in vitro models of human development (particularly three-dimensional [3-D] models that are scalable and versatile) has been a priority amongst developmental biology researchers.
Using longitudinal data to understand nutrition and health interactions in rural Gambia
Published in Annals of Human Biology, 2020
The accumulated demographic and health data have also been used to address two questions in relation to evolutionary and developmental biology. In the first paper, by Rickard et al. (2012), data from Keneba was used to test the hypothesis that maternal twinning status predicts offspring birthweight. This was on a backdrop of evidence to suggest that variations in the dynamics of the insulin-like growth factor (IGF) system – a key regulator of foetal growth – may also influence twinning propensity. Using a cohort of 1889 singleton infants born between 1978 and 2009, for those who were born between January and June and thus were hypothesised to experience a favourable in utero environment, births before and after twins were associated with an increase in birth weight (134 and 226 g increase for those born before and after twins, respectively) compared to those born to non-twinning mothers. Of note, these findings were not mediated by maternal body size. An intriguing finding, but highlighted here to demonstrate the wide utility across research domains of the collated longitudinal data contained in the Keneba cohorts.
Related Knowledge Centers
- Animal
- Metamorphosis
- Morphogenesis
- Regeneration
- Embryo
- Cellular Differentiation
- Stem Cell
- Regional Differentiation
- Tissue Growth
- Cytoplasmic Determinant