Recommendations for Science-Based Safety Assessment of Genetically Modified (GM) Plants for Food and Feed Uses

Since the commercial introduction of genetically modified (GM) plants in agriculture over two decades ago, technology developers and regulatory authorities have gained significant experience in assessing their safety based on assessing potential impact to humans, animals and the environment.  Over 3500 independent regulatory agency reviews have positively concluded on the safety of GM plants for food and feed. Yet, divergent and increased regulatory requirements have led to delayed and asynchronous approvals, and have restricted access to innovative products for farmers and consumers. With accumulated knowledge from safety assessments conducted so far, an enhanced understanding of plant genomes, and a history of safe use, it is time to re-evaluate the current approaches to the regulation of GM plants used for food and feed.  A stepwise approach using weight-of-evidence should be sufficient for the safety assessment of newly expressed proteins in GM plants.  A set of core studies including molecular characterization, expression and characterization of the newly expressed proteins (or other expression product), and safety assessment of the introduced protein are appropriate to characterize the product and assess safety.  Using data from core studies, and employing a “problem formulation” approach, the need for supplementary hypothesis-driven or case-by-case studies can be determined.  Employing this approach for the evaluation of GM plants will remove regulatory data requirements that do not provide value to the safety assessment and provide a consistent framework for global regulation. doi: 10.21423/jrs-v09i1water

Neurotrophin and Neurotrophin Receptors in Vascular Smooth Muscle Cells: Regulation of Expression in Response to Injury

The neurotrophins, a family of related polypeptide growth factors including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin (NT)-3 and NT-4/5 promote the survival and differentiation of distinctive sets of embryonic neurons. Here we define a new functional role for neurotrophins, as autocrine or local paracrine mediators of vascular smooth muscle cell migration. We have identified neurotrophins, and their cognate receptors, the trk tyrosine kinases, in human and rat vascular smooth muscle cells in vivo. In vitro, cultured human smooth muscle cells express BDNF; NT-3; and trk A, B, and C Similarly, rat smooth muscle cells expressed all three trk receptors as well as all four neurotrophins. Moreover, NGF induces cultured human smooth muscle cell migration at subnanomolar concentrations. In the rat aortic balloon deendothelialization model of vascular injury, the expression of NGF, BDNF, and their receptors trk A and trk B increased dramatically in the area of injury within 3 days and persisted during the formation of the neointima. In human coronary atherosclerotic lesions, BDNF, NT-3, and NT-4/5, and the trk B and trk C receptors could be demonstrated in smooth muscle cells. These findings suggest that neurotrophins play an important role in regulating the response of vascular smooth muscle cells to injury

Core and Supplementary Studies to Assess the Safety of Genetically Modified (GM) Plants Used for Food and Feed

Genetically modified (GM) plants used for food and feed have an established history of safe use over more than 25 years of their commercialization. Developers and regulatory authorities have accumulated extensive experience in evaluating their safety over time. The studies required for the safety assessment of GM plants used for food and feed should now be re-defined to leverage this experience and increased scientific knowledge. This paper, a companion paper for Waters et al. also published in this issue, presents a systematic approach for the safety assessment of newly expressed proteins (NEPs) in GM plants by evaluating the two components of risk: hazard and exposure. Although the paper focuses on NEPs, the principles presented could also apply to other expression products that do not result in a NEP. A set of core studies is recommended, along with supplementary studies, if needed, to evaluate whether the GM plant poses risk. Core studies include molecular and protein characterization and hazard identification encompassing toxicity and allergenicity. In the absence of hazard, core studies are sufficient to conclude that GM plants are as safe as their conventional counterparts. Depending on the GM trait and intended use, supplementary studies should be performed to characterize hazard and exposure when a hazard is identified. Problem formulation should be used to identify hypothesis-driven supplementary studies. Acute toxicity studies, compositional assessment, and dietary exposure assessment are recommended to be hypothesis-driven supplementary studies. Further discussion on the current food and feed safety assessment landscape for GM plants and the use of problem formulation as a tool for identifying supplementary studies can be found in the companion paper [62]. doi: 10.21423/jrs-v09i1brun