Purified high molecular weight synthetic Aß(1-42) and biological Aß oligomers are equipotent in rapidly inducing MTT formazan exocytosis.

Synthetic soluble Aß oligomers are often used as a surrogate for biologic material in a number of model systems. We compared the activity of Aß oligomers (synthetic and cell culture media derived) on the human SH-SY5Y neuroblastoma and C2C12 mouse myoblast cell lines in a novel, modified MTT assay. Separating oligomers from monomeric peptide by size exclusion chromatography produced effects at peptide concentrations approaching physiologic levels (10-100 nM). Purified oligomers, but not monomers or fibrils, elicited an increase of a detergent-insoluble form of MTT formazan within 2h as opposed to a control toxin (H(2)O(2)). This effect was comparable for biological and synthetic peptide in both cell types. Monomeric Aß attenuated the effect of soluble oligomers. This study suggests that the activities of biological and synthetic oligomers are indistinguishable during early stages of Aß oligomer-cell interaction.