A cell loading technique that can efficiently capture ultra-small samples (down to 10 cells) in several microliters of solution has been developed at the University of Michigan. The capability to collect and utilize small samples is a key challenge in cancer studies and personalized medicine. Conventional (dish based) approaches often require hundreds of thousands cells for an assay, and biopsies often do not yield enough cells in addition to being painful for patients. Circulating tumor cells (CTC) obtained from patient blood, while promising, are very rare, and typically only yield tens of cells from milliliters of blood.
The method of microfluidics overcomes the challenges above by working with small volumes of liquid and by allowing for the manipulation of extremely small samples. The microfluidics method is applicable in the range of thousands of cells, and can capture, identify, and culture even single cells in tiny (approximately nanoliter) chambers. However, even though microfluidic techniques demonstrate single cell capture rates (number of captured cells/number of chambers) of 80-90%, cell capture efficiency (number of captured cells/number of cells used) is typically low (<10%). Methods to capture single cells such as hydrodynamic, DEP or other techniques entail major losses in the sample preparation and cell capturing processes making them impractical for tens of cell samples. The cell loading technique developed at the University of Michigan aims to minimize dead volume (solution that does not flow into the microfluidic chambers), and can efficiently capture ultra-small samples down to 10 cells in several microliters of solution. The polydimethylsiloxane (PDMS) -based design utilizes chambers distributed along a main fluid channel and a vacuum channel. Given PDMS’s gas permeability, air diffuses into the vacuum channel to drive fluid into the chambers. Experimental results on the design show cell capture efficiencies of 70%.
- Collection and utilization of ultra-small cell samples
- Cancer diagnostics and treatment
- Genomics applications
- High capture efficiency (70%)
- Easy and reliable cell and chamber isolation
- Support for cell-cell interaction studies using small samples
- Support for monitoring secretion profiles and metabolism of single cells from small samples