The use of optical sensors to understand cellular interactions with renal cells.

Optical biosensor technology has revolutionized the assessment of receptor binding, enabling the characterization of low affinity interactions in real time. We report the application of the LAsys Optical Biosensor to the investigation of the affinity and specificity of the putative proximal tubular scavenging receptor for protein reabsorption and the specificity of AGE-modified protein interactions with primary human mesangial cells. Using the LLCPK cell line, the carboxy-methyl dextran cuvette surface and five different proteins (ranging in size and charge), we have shown that there is evidence to support the existence of a single scavenging receptor for all the proteins tested. The proteins competed with each other differing only in their relative binding affinity for the common receptor. We have also shown that human mesangial cells can bind to AGE-modified human serum albumin (AGE-HSA) immobilized onto the carboxylate surfaced planar cuvette and that binding can be inhibited using increasing concentrations of soluble AGE-HSA. However, increasing concentrations of soluble Non-AGE modified HSA can also inhibit binding to a similar extent which implies that there is relatively little AGE-receptor (RAGE) expression on cultured primary human mesangial cells. These results demonstrate the exciting potential of this technology as a tool to explore cellular interactions with renal cells.