Tubing-Free Microfluidic Microtissue Culture System Featuring Gradual, in vivo-Like Substance Exposure Profiles

Abstract

In vitro screening methods for compound efficacy and toxicity to date mostly include cell or tissue exposure to preset constant compound concentrations over a defined testing period. Such concentration profiles, however, do not represent realistic in vivo situations after substance uptake. Absorption, distribution, metabolism and excretion of administered substances in an organism or human body entail gradually changing pharmacokinetic concentration profiles. As concentration profile dynamics can influence drug effects on the target tissues, it is important to be able to reproduce realistic concentration profiles in in vitro systems. We present a novel design that can be integrated in tubing-free, microfluidic culture chips. These chips are actuated by tilting so that gravity-driven flow and perfusion of culture chambers can be established between reservoirs at both ends of a microfluidic channel. The design enables the realization of in vivo -like substance exposure scenarios. Compound gradients are generated through an asymmetric Y-junction of channels with different hydrodynamic resistances. Six microtissues (MTs) can be cultured and exposed in compartments along the channel. Changes of the chip design or operation parameters enable to alter the dosing profile over a large range. Modulation of, e.g., the tilting angle, changes the slope of the dosing curves, so that concentration curves can be attained that resemble the pharmacokinetic characteristics of common substances in a human body. Human colorectal cancer (HCT 116) MTs were exposed to both, gradually decreasing and constant concentrations of Staurosporine. Measurements of apoptosis induction and viability after 5 h and 24 h showed different short- and long-term responses of the MTs to dynamic and linear dosing regimes

Controlled pharmacokinetic anti-cancer drug concentration profiles lead to growth inhibition of colorectal cancer cells in a microfluidic device

“…This is an emerging field in microfluidics. 14,15,[20][21][22][23] We contribute to this emerging field by offering an alternative technology to induce and validate dynamic dosing, test a drug used in the clinic, and translate clinical pharmacokinetics to technical requirements. We foresee use of this technology in the drug discovery process, for example in the lead optimization process where a handful of drugs are tested and optimized in in vitro and in vivo models.…”

“…14,15 While cancer drug testing has been performed extensively in microfluidic cell culture systems, [16][17][18][19] mimicking in vivo-like drug concentrations over time on-chip has up to recently been largely neglected in the oncology field, with recent notable exceptions. [20][21][22][23] Several current solutions rely on active perfusion of cell culture chambers with dynamic drug concentrations. 22,23 This perfusion results in shear stress, which increases with a higher concentration change rate.…”

“…For example, cells are cultured directly on a membrane, which hampers visual inspection, or specific geometries limit concentration rate change or concentration range. 14,15,20,21 Lohasz et al defined a hypothetical in vivo-like concentration profile for the non-clinical drug staurosporine and controlled its concentration on-chip through gravitydriven flow controlled by chip tilting and a specific chip geometry. 20 Chou et al administered a flat (investigative) drug dosage which stopped after two hours, and the diffused drug in the tissue channel acted as a reservoir to provide the drug for the declining concentration phase.…”

“…14,15,20,21 Lohasz et al defined a hypothetical in vivo-like concentration profile for the non-clinical drug staurosporine and controlled its concentration on-chip through gravitydriven flow controlled by chip tilting and a specific chip geometry. 20 Chou et al administered a flat (investigative) drug dosage which stopped after two hours, and the diffused drug in the tissue channel acted as a reservoir to provide the drug for the declining concentration phase. 21 Although these technical solutions are sophisticated, its strong reliance on microfluidic chip geometry might limit broad adoption and puts constraints on dosing schedules.…”

Femtosecond Laser-Based Integration of Nano-Membranes into Organ-on-a-Chip Systems

“…These devices are used to study the behavior of cells and develop an understanding of their interaction. Over the past decade, numerous cell growth forms inside the channel have been reported, including micro-3D tissues [1], spheroids [2], vessels [3], and wires [4]. One of the advantages of OoC devices is the possibility to combine 2D and 3D features into a single structure.…”