Methods for studying renal toxicity

Mechanisms of renal cell repair and regeneration after acute renal failure

In many cases, acute renal failure (ARF) is the result of proximal tubular cell injury and death and can arise in a variety of clinical situations, especially following renal ischemia and drug or toxicant exposure. Although much research has focused on the cellular events leading to ARF, less emphasis has been placed on the mechanisms of renal cell repair and regeneration, although ARF is reversed in over half of those who acquire it. Studies using in vivo and in vitro models have demonstrated the importance of proliferation, migration, and repair of physiological functions of injured renal proximal tubular cells (RPTC) in the reversal of ARF. Growth factors have been shown to produce migration and proliferation of injured RPTC, although the specific mechanisms through which growth factors promote renal regeneration in vivo are unclear. Recently, interactions between integrins and extracellular matrix proteins such as collagen IV were shown to promote the repair of physiological functions in injured RPTC. Specifically, collagen IV synthesis and deposition following cellular injury restored integrin polarity and promoted repair of mitochondrial function and active Na(+) transport. Furthermore, exogenous collagen IV, but not collagen I, fibronectin, or laminin, promoted the repair of physiological functions without stimulating proliferation. These findings suggest the importance of establishing and/or maintaining collagen IV-integrin interactions in the stimulation of repair of physiological functions following sublethal cellular injury. Furthermore, the pathway that stimulates repair is distinct from that of proliferation and migration and may be a viable target for pharmacological intervention.

Use of video microscopy to study the mechanisms of cytotoxicity in vitro in individual living cells

Recent technological innovations have made it possible to determine simultaneously multiple biochemical parameters in individual living cells. This new technique, commonly designated as video microscopy, makes use of fluorescent probes, specific for a certain cellular parameter. Cells are loaded with the probes and placed under a fluorescence microscope. After excitation at a specific wavelength the probes emit light of a longer wavelength. The intensity of the emitted light is proportional to the magnitude of the specific parameter. Emission is recorded with a video camera and the signal transferred to an image processor for extraction of quantitative data from the image, or to improve image quality. An overview of the technique itself and the necessary hardware, the major types of calculations and how to handle cells and probes is presented in this paper.