Blood is a routinely tested biological fluid for diagnosis and monitoring of diseases as many diseases would trigger a change in white blood cell count. Thus, several methods have been established to isolate or enrich white blood cells from patient blood samples for such analyses. One method of preparing an enriched white blood cell sample is through the selective lysis of red blood cells by hypotonic shock and restoration of osmolarity to maintain viability of target white blood cells. An inherent problem with this approach is the loss of target cells during sample handling. We report a two-stage separation system that can perform lysis and restoration of osmolarity of blood on-chip and direct the resultant sample to the second step of the analysis. Hence, there is no loss of sample. The post-lysis makeup features a protein-rich buffer to help stabilize cells. As proof of concept, we spiked HL-60 cells into a whole blood and a pre-lysed blood sample and compared capture metrics of each method using a downstream affinity separation. The capture efficiency of the whole blood sample ranged between 40 and 80% using <7 μL of sample compared to 10–52% from 60 μL of pre-lysed blood required for similar analysis. In addition, both pre-lysed and whole blood samples showed no significant difference in purity and viability. This two-stage separation system has demonstrated the capacity to replace centrifugation and wash steps required for the preparation of lysed blood, for white blood cell analyses.
- Blood processing
- Cell separation