The CellRaft™ Technology provides a cost-effective method to isolate and recover single cells for direct analysis or for the generation of clonal populations. The working principle of the CellRaft™ Technology is schematically shown in the Figure A.
Microfabricated from an elastomeric material, the CellRaft Array is a high density microwell array with thousands of individual wells. Each microwell contains a CellRaft that is held securely within the array. Within the array, the rafts serve as releasable culture sites for individual cells or colonies. The entire array is housed in a plastic cassette similar to a Petri dish, making it familiar to the biological research community.
Cells are plated on the CellRaft Array in the same manner as a standard tissue culture dish. The cells settle into the microwells and attach to the rafts within each microwell. Cells placed on the CellRaft Array are localized on the CellRaft surface and remain viable. The cells remain positioned on specific rafts while in culture so that single cells can be isolated or expand into clonal colonies.
A probe is mounted onto a 4× or 10× objective of a common inverted lab microscope to that is used to release individual CellRafts containing single cells of interest. To isolate target cells, the user engages the probe through the compliant polymer substrate of the CellRaft Array and dislodge an individual raft with its attached cell(s) (e.g. GFP+ cells in Fig. B).
The released CellRaft is then recovered using a magnetic wand (Fig. A) and transported to a 96-well plate or PCR tube. This procedure achieves cell isolation and recovery with excellent viability and purity. For example, single-cell cloning efficiencies of greater than 95% have been realized with 100% purity. The CellRaft™ Technology offers a high degree of flexibility as cells may be selected using a wide variety of criteria, including temporal and spatial characteristics, and requires only a very small sample size to conduct an experiment. The recovered cells can be used for direct analysis (e.g. PCR, MALDI, SDS-PAGE), or clonal expansion (Fig. B).
CellRaft Arrays in different formats are often matched to specific applications. For example, 100 x 100 micron CellRaft Arrays with a single reservoir are often used for isolating single nuclei for downstream molecular analysis. CellRaft Arrays with a “quad” reservoir are the best choice for isolation and recovery of single cells or clonal expansion under differing culture media using a single cassette. Cell Microsystems offers a custom fabrication service for these and other special purpose products.
QIAGEN offers the QIAscout Array, which is a 200 x 200 micron array based on the CellRaft Technology and with a single reservoir cassette. This array is suitable for single cell isolation and recovery for downstream molecular analysis or clonal expansion and colony selection.