Toxicology, cellular techniques

Chapter 4. Meyer, S. A. Overview of cellular techniques in toxicology. 

We postulate that the double13C -labeling technique presented in this chapter could be used to study adducts on large pieces of DNA and even follow the chemical details cellular metabolic processes in real time. The double 13C-labeling technique is currently being developed to solve problems in metabolism and toxicology. 

In the last 30 years, the use of in vitro tools for toxicological studies and evaluation has become relevant and the number of scientific works and techniques has increased day by day. One of the most important advantages of in vitro systems is their ability to serve as model for the central events in the in vivo toxicological process, and a depth evaluation of the intrinsic cellular toxicity can provide useful information for toxicological safety evaluation. 

Since Harrison, in 1907, first microscopically observed neurite outgrowth from cultured frog neurons, many have experienced the powerful persuasion of direct visualization of cellular responses in culture. Standardization of media composition, introduction of antibiotics, and development of cryopreservation techniques and immortalized cell lines in the 1950s enabled routine application of cell culture in the biological research laboratory. Utilization of cell culture in toxicology soon followed with development of systems for monitoring chemically induced mammalian genotoxicity. 

In this chapter we introduce various techniques for fabricating miniature cell culture devices and cell-based biosensors, provide examples of human and animal cells immobilized on the chip devices, and explain different approaches to pattern multiple types of cells on one device. The application of nano and micro techniques in precise control over the cellular microenvironment is discussed. Selective cell-based biosensors are described later in the chapter. Finally, we conclude that these novel cell culture systems, coupled with predictions from in silico mathematical modeling, can potentially improve predictions of human clinical responses and enable better understanding of toxicological mechanisms. 

The application of electrochemical techniques for providing insight into biological processes has become common practice over the last several decades. The study of cellular metabolism, largely ignored by the fields of molecular biology and toxicology until now [1, 2], is a vast field... 

Although bacterial clearance studies and models of infection are useful for showing how particle inhalation can alter host resistance to infection, analysis of cell type and function after in vivo or in vitro particle exposure can produce more detailed information about the molecular and cellular processes affected by the toxicant. Overall interpretation of these experiments is difficult because some studies show suppression of phagocytosis and downregulation of immune cytokines, whereas others indieate an increase in these functions, suggesting a state of activation. These eontradictory results can often be explained by differences in experimental protoeols and culture techniques, the endpoints under study, species from which the eells are derived, and the type of particle used. It is well to keep the old toxicology adage in mind, however, that the dose makes the poison, and that subtoxic concentrations of substances can often be beneficial or at least stimulatory. 

---