Automated Microinjection
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Microinjection involves delivering small quantities of liquid substances at the microscopic and borderline macroscopic level. Its usefulness is based on its ability to control both the location and duration of injection within a tissue sample. In addition, it can be used to introduce small molecule inhibitors or activators into cells, providing information about cellular physiology and function.
A typical microinjection experiment involves a user guiding an injection micropipette to a desired target, inserting it into the tissue and then withdrawing it within a short period of time. These procedures are highly dependent on the user’s skill and experience, leading to inconsistent results and low yield 5.
To address these limitations, we have developed a robotic system called the Autoinjector that automates microinjection by incorporating image guidance into a conventional microscope station. The system consists of a micropipette holder that holds the injection micropipette for use, and a pipette pressure inlet connected to an electronic micropipette pump. The pump is programmed to deliver a precise volume of material into the cell using programmatic three-axis position control (Fig 1A). The injection micropipette is guided by an imaging algorithm to precision locations in the microscope field of view, utilizing the camera’s output signal and a servo motor to control the micromanipulator’s movement.
We tested the Autoinjector on early zebrafish embryos to demonstrate its ability to perform precise, automated microinjection. By injecting sequences containing recognition sites for DNA modifying enzymes, we were able to efficiently incorporate foreign genes into the zebrafish genome and produce transgenic fish.
The Autoinjector is also capable of microinjection into single cells, enabling the study of cellular processes such as gap junction communication and lineage progression. Using the system, we were able to systematically investigate gap-junctional communication between neural progenitors in a cultured mouse embryonic telencephalon and establish that apical contact is sufficient for gap junction communication in these cells.
In conclusion, the Autoinjector is a versatile and cost-effective device for automated microinjection into living tissue. Its versatility, ease of use and high throughput will enable many users to study a wide variety of biological processes in vivo. We hope that our approach will encourage further research on this powerful technique and inspire other researchers to utilize the Autoinjector for their own applications. The system is available for purchase from Arbor Systems. micro injection