The delivery of biomolecules into the basic unit of life, the cell, certainly isn’t like a typical pizza delivery. Biomolecules, large and small, have to be delivered into the cell without damaging/killing the cell, or at the very least, cause minimum amount of damage to the cell and later the cell can recover from this damage.
Transferring biomolecules, foreign genetic material, and other cargo into cells without damaging them has attracted a lot of attention as it can be used for treating diseases, tagging, and tracking cells, and reprogramming cellular functions.
The usual methods to deliver material into cells, such as chemical and viral methods, are not preferred as they are highly toxic and usually have a lack of immune response. Thus physical methods such as microinjection, magnetoporation, sonoporation, and electroporation are considered. However, these methods too have drawbacks.
Thus, laser-based photoporation, or, optoporation has several advantages over the other methods. In optoporation, light-matter interactions are used to disrupt the plasma membrane of cells to allow biomolecules to enter the cell, without cell damage or causing death of the cell. It is a contactless, high-throughput (large amount of material uniformly passing through large number of cells) delivery method, and is less toxic and causes low cell damage.
Usually, a bulk population of cells is used to study delivery of material into the cell. However, cell behviour varies across populations of different cell types, or from other tissues as well as within a population of cells. Therefore, it is crucial to examine individual cells to comprehend the intricate biology of the heterogeneous cell population.
In order to study, control, and manipulate single-cells, or clusters of cells, cellular patterning has been gaining prominence. Cellular patterning is a technique for controlling the geometric organization of cells on the substrate surface.
Single-cell patterning is more difficult than bulk cell culture because of factors such as cell activity, cell size and their response, concentration, and cellular components. The individual cells need to be isolated and attached to specific areas.
Micro-pillar polydimethyl siloxane (PDMS) stamp was fabricated to generate a variety of protein islands on a substrate, and single-cell to small clusters of cells were patterned. For intracellular delivery of biomolecules into the patterned cells, a titanium micro-dish (TMD) device was aligned on top of the cells and exposed by infrared light pulses. It is an inexpensive, straightforward and very accurate method.
In this study conducted by Ms. Gayathri R, and Dr. Pallab Sinha Mahapatra from the Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, India (Ms. Gayathri R is also affiliated with the Department of Engineering Design, Indian Institute of Technology Madras, Chennai, India), Dr. Srabani Kar and Dr. Tuhin Subhra Santra from the Department of Engineering Design, Indian Institute of Technology Madras, Chennai, India (Dr. Srabani Kar is also affiliated with the Department of Physics, Indian Institute of Science Education and Research, Tirupati, India), and Dr. Moeto Nagai from the Department of Mechanical Engineering, Toyohashi University of Technology, Japan, a massively parallel high throughput single-cell and cluster of cells patterning and intracellular small to large biomolecular delivery was done.
None of the research work so far has carried out microcontact single-cell patterning for exploration of massively parallel small to large biomolecular delivery into diverse cell types and their analysis.
In this study, small to very large biomolecular delivery of PI dyes, dextran, siRNA, and enzymes were delivered into the cell lines SiHa, L929, and MG63.
The patterning efficiency for SiHa, L929, and MG63 cells was approximately 97 to 99 percent. The platform was found to be compact, robust, easy for printing, and potentially applicable for single-cell therapy and diagnostics.
Prof. Hwan-You Chang, from the Department of Medical Science, National Tsing Hua University, Taiwan, acknowledged the significance of the work done by the authors with the following comments: “The study presents an innovative device utilizing a micropillar stamp and microprinting technology to create single-cell patterns. This is followed by photoporation, wherein an aligned titanium micro-dish is placed atop the cells and exposed to infrared light pulses. Notably, this compact and robust device allows for the simultaneous patterning of a substantial number of single cells and facilitates highly efficient cargo delivery. Such a versatile platform holds significant promise for a wide range of applications in basic cell research and drug development.”
Article by Akshay Anantharaman
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