In order to study the biochemical behavior of cells or tissue clusters in vivo, it is necessary to construct three-dimensional cell clusters in vitro rapidly and cheaply.
For example, in the research and treatment of cancer diseases, tumor cell mass screening tests conducted in vitro can provide key guidance for drug development and personalized drug treatment.
Body tissue masses have their three-dimensional structure, internal interconnection between cell adhesion, these cells are at the same time around the organization support packages, and by itself or the surrounding cells integrated environmental regulation and the extracellular matrix of the aggregation effect makes it show a corresponding unique behavior, functions, and biochemical properties (such as drug resistance).
Therefore, how to effectively form physical/biochemical connections between cells and simulate the extracellular THREE-DIMENSIONAL matrix environment is the key premise of downstream applications, and also the shortcoming of current traditional schemes.
Because traditional ideas often rely on long-term culture to connect the cells distributed in bulk into clusters, the lack of effective and non-destructive external forces of direct agglomeration of cells leads to low efficiency and difficulty in assembling cells with 3D structure.
Wuhan university professor Yang Yi team recently published in the journal Lab on a chip, entitled “on – chip hydrogelarrays individually encapsulating & formed multicellular aggregates forhigh throughput drug testing” of the research papers, this paper proposes a force based on acoustic rapid 3 d cells array assembly technique,
Miniature hydrogel arrays were fabricated to provide 3D support and extracellular matrix environments.
Under the combined effect of acoustic force and acoustic flow, the technology can aggregate cells near the wave nodes into an ideal 3D cell cluster structure, which is suspended in the environment, so that the cells are not affected by the substrate.
Thanks to GelMA hydrogel’s excellent micro-nano processing properties, these cell clusters are wrapped independently on the chip to maintain their THREE-DIMENSIONAL spherical structure, and finally thousands of 3D cell arrays can be generated on a chip at a time.
Due to acoustic forces, these in vitro models do not need to be cultured for long periods of time to form linkages, while biohydrogels provide structural support and an extracellular matrix enrichment environment.
Therefore, this technique can more realistically simulate in vivo conditions in multiple dimensions of structure and matrix environment with high efficiency, which is expected to facilitate related biological science research and rapid drug development and screening application.
The principle diagram of this technology is shown in Figure 1. Two pairs of fork finger electrodes are used to generate surface acoustic standing waves, and two vertical standing waves interfere with each other, which will generate a momentum trap with regular arrangement. The cells around the potential well will aggregate into 3D cells under the comprehensive action of acoustic radiation force and sound flow.
Cells were suspended in a solution of 8 W/V % GelMA (EFL team, GelMA-60), and an array of hydrogel columns was formed around each cell mass when the exposure area was exactly in line with the blub trap area.
Eventually, arrays of cells with three-dimensional structures were built on chips, and these models had tight internal connections without the need for extra long periods of culture.
Moreover, by controlling small cell concentration or sound wave wavelength, cell clusters from tens of microns to thousands of microns can be formed, which has great applicability.
Figure 2 shows the structure of the sound field (2a) and the cell force diagram in the sound field (2B).
Through three-dimensional confocal fluorescence, it can be seen that this technique can form the ideal hydrogel column microstructure (2C), which creates an ideal matrix environment and structural support for the cell mass.
The bright field and fluorescent confocal graph demonstrated the three-dimensional shape of the model constructed by this technology. This model unit has regular shape and compact THREE-DIMENSIONAL structure, which will well simulate the real shape and environment in vivo, and directly facilitate the downstream application.
(A-B) Simulation of sound field structure and force diagram of cells in sound field.
(c) GelMA hydrogel forms a microcolumn array.
(D-E) Bright field and fluorescence characterization of the three-dimensional cell mass in the hydrogel envelope.
(f) A three-dimensional confocal diagram of a cell mass constructed
As a demonstration, tumor mass model arrays were constructed and combined with a microfluidic chip using a tree-like structure to generate multiple drug gradients.
Different concentrations of drug solutions flowed through the array, with the vertical column of each array in the same concentration solution and the horizontal column in the gradient drug field, thus simultaneously monitoring the activity transformation of the tumor mass under the action of up to ten drug concentrations.
This technology can rapidly create in vitro models of cell clusters or tissues, simulate the real in vivo environment, and show its unique advantages in the field of rapid drug screening, so as to promote related research and application.
Dr. Hu Xuejia and Dr. Zhao Shukun of School of Physical Science and Technology, Wuhan University are the first author of this paper, and Professor Yang Yi is the corresponding author.