期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：52
页码：14915-14920
DOI：10.1073/pnas.1609569114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceStructural analysis of microscale three-dimensional tissues (3D microtissues) in high-throughput is becoming increasingly important in drug discovery, regenerative medicine, and other biomedical areas because they recapitulate many in vivo biological features not present in 2D models. This can be done by using microfluidic technology to control and apply external forces to on-chip 3D microtissues, and imaging these organ-on-chip systems with confocal microscopy. However, the high cellular density of 3D microtissues scatters light and fundamentally limits the ability to characterize the entire tissue construct. We developed an on-chip strategy to rapidly clarify, image, and analyze whole intact microtissues without compromising internal structures. Our technique removes the imaging depth limit, allowing accurate analysis and characterization of entire tissues in microfluidic chips. On-chip imaging of intact three-dimensional tissues within microfluidic devices is fundamentally hindered by intratissue optical scattering, which impedes their use as tissue models for high-throughput screening assays. Here, we engineered a microfluidic system that preserves and converts tissues into optically transparent structures in less than 1 d, which is 20x faster than current passive clearing approaches. Accelerated clearing was achieved because the microfluidic system enhanced the exchange of interstitial fluids by 567-fold, which increased the rate of removal of optically scattering lipid molecules from the cross-linked tissue. Our enhanced clearing process allowed us to fluorescently image and map the segregation and compartmentalization of different cells during the formation of tumor spheroids, and to track the degradation of vasculature over time within extracted murine pancreatic islets in static culture, which may have implications on the efficacy of beta-cell transplantation treatments for type 1 diabetes. We further developed an image analysis algorithm that automates the analysis of the vasculature connectivity, volume, and cellular spatial distribution of the intact tissue. Our technique allows whole tissue analysis in microfluidic systems, and has implications in the development of organ-on-a-chip systems, high-throughput drug screening devices, and in regenerative medicine.
