Microfluidic platform enables live imaging and retrieval of single cells

Microfluidic single-cell analysis platforms often take advantage of droplet microfluidic for encapsulating the cells within nL-pL droplets at high throughputs. Depending on the target outcome (genomics, epigenomics, transcriptomics, etc.), specific protocols are available for the tests.

Cells in a culture can be highly heterogeneous and impose challenges in the analysis of dynamic processes. Even cells from the same tissue can show a high degree of heterogeneity and express different phenotypic features. In droplet microfluidic single-cell analysis, this problem is often resolved by encapsulating barcoded beads with the cells to attach to the cell lysate. Retrieving the single-cells, however, can be challenging.

A microfluidic chip has been developed by researchers at the University of Cambridge for 3D cell culture of embryonic stem cells inside droplets, on-chip screening, and cell retrieval. Using this method, the cells could be retrieved for further assays without disturbing other cells.

“To achieve this, we combine a hydrogel 3D encapsulation system with a microfluidic platform that is compatible with live imaging and single clone retrieval. The platform offers the potential to link the cell’s history with cell state, characterised at the molecular or functional level.”

Droplet microfluidic techniques empower us by providing us with details of the cells but the history of the cell is often not accessible. To overcome this issue, the team took a microfluidic approach to combine live imaging with cell retrieval.

For this, they combined a flow-focusing droplet generator with a microfluidic device for culture and extraction. The droplet generator was employed for encapsulating single cells inside agarose-based hydrogel beads. The proposed platform for imaging and extraction has two layers. The bottom layer consists of microchannels and microchambers for trapping the cells for live imaging and side channels for introducing the immunofluorescence reagents (fixing, washing, staining). The top layer housed several valves that were used for controlling the flow by actuating a thin PDMS membrane between the top and bottom layers (Quake valve). A graphic user interface (GUI) developed in MATLAB was used to control the valves. The CAD file of the devices along with the details of the fabrication and computer codes are provided by the authors which can be used for replication or further development.

The reported microfluidic device was tested with embryonic stem cells as a proof of concept and was envisioned to capture rare events in dynamic cellular processes. The imaging and extraction device allows different cells to be extracted at different times without disturbing other cells to be interrogated to identify the transient events.

Read the original article: Microfluidic platform for 3D cell culture with live imaging and clone retrieval