Microfluidic Protein Imaging Platform: Study of Tau Protein Aggregation and Alzheimer's Drug Response.

Shubha Jain,Sarita Swain,Anand Kumar Kondapi,Lopamudra Das,Harikrishnan Narayanan Unni,Sarpras Swain,Lopamudra Giri

doi:10.3390/bioengineering7040162

Abstract

Tau protein aggregation is identified as one of the key phenomena associated with the onset and progression of Alzheimer’s disease. In the present study, we performed on-chip confocal imaging of tau protein aggregation and tau–drug interactions using a spiral-shaped passive micromixing platform. Numerical simulations and experiments were performed in order to validate the performance of the micromixer design. We performed molecular modeling of adenosine triphosphate (ATP)-induced tau aggregation in order to successfully validate the concept of helical tau filament formation. Tau aggregation and native tau restoration were realized using an immunofluorescence antibody assay. The dose–response behavior of an Alzheimer’s drug, methylthioninium chloride (MTC), was monitored on-chip for defining the optimum concentration of the drug. The proposed device was tested for reliability and repeatability of on-chip tau imaging. The amount of the tau protein sample used in our experiments was significantly less than the usage for conventional techniques, and the whole protein–drug assay was realized in less than two hours. We identified that intensity-based tau imaging could be used to study Alzheimer’s drug response. In addition, it was demonstrated that cell-free, microfluidic tau protein assays could be used as potential on-chip drug evaluation tools for Alzheimer’s disease.

Highlights

Alzheimer’s disease (AD) is one of the most common fatal neurological disorders affecting the lives of millions worldwide [1,2,3]
Tau aggregation is of paramount importance in understanding the dynamics of Alzheimer’s, the construction of cell-based models needs an expensive set up for performing in vitro experiments on neurodegeneration and drug response
We proposed a cost-effective microfluidic antibody assay to study adenosine triphosphate (ATP)-induced tau protein aggregation and methylthioninium chloride (MTC) drug response

Summary

Introduction

Alzheimer’s disease (AD) is one of the most common fatal neurological disorders affecting the lives of millions worldwide [1,2,3]. In the case of Alzheimer’s patients, tau protein is approximately three- to four-fold more hyperphosphorylated and aggregated into bundles of filaments than the native tau found in adult brains [8]. The N-terminal region of tau protein has a putative site for adenosine triphosphate (ATP) binding, and this passive phosphorylation of tau by ATP induces tau self-assembly into AD filaments [10]. In this regard, research focused on the identification of aggregated tau as a useful biomarker [11] has paved the way to novel therapeutic strategies for Alzheimer’s disease based on the inhibition of tau aggregation [12]

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