Isolating highly enriched
populations of circulating
epithelial cells and other rare
cells from blood using a magnetic
sweeper device
AmirAli H. Talasaz, Ashley A. Powell, David E. Huber,
James G. Berbee, Kyung-Ho Roh, Wong Yu, Wenzhong
Xiao, Mark M. Davis, R. Fabian Pease, Michael N.
Mindrinos, Stefanie S. Jeffrey, and Ronald W. Davis
Presented by: Casey Hua, Danyi Wu
Motivation
• Molecular Profiling Applications
• Improvement of:
• Cancer prognosis/treatment  rare circulating
epithelial cells (CEpCs)
• Immune monitoring  antigen-specific
lymphocytes
• Prenatal diagnosis  fetal cells
Motivation
Problem: Current CEpC isolation platforms lack
purification efficiency
Solution: MagSweeper
–High capture rate
–High purity
–Enriches target cells (108x)
MagSweeper Process
1. Pre-label diluted blood samples with magnetic particles
2.
3.
4.
5. Repeat to eliminate background cells
 improves purity at some cost to capture efficiency
MagSweeper Simulation
Magnetic flux
density
Magnetic forcedriven cell velocity
field
Cell capture
boundary
MagSweeper Simulation cont’d
Fluid
velocity/motion
Cell trapping profiles
Gap of uncaptured particles due
to fluid motion pushing
particles ahead of magnet
MagSweeper Performance
•
Enrichment Studies
1.
Rare Immunological Model Cells from a Mixed Sample (HLAA2)
•
•
2.
MCF7 Cancer Cells Spiked in Blood Samples
•
3.
Performance: isolating Circulating Epithelial Cells (CEpCs)
CEpCs from Breast Cancer Patients
•
•
Capture Efficiency
Purity
Application: CEpC isolation from Epithelial Cancers patients
Perturbation of Cellular Gene Expression
(1) Rare HLA-A2+ cells in Mixed Samples
Enrichment by ~2.5x105
(2) MCF7 Cancer Cells Spiked in
Blood Samples
Combining MagSweeper enrichment with visual inspection and
extraction of cells based on size:
•increase cell purification of the MCF7 cells from 51% to 100% purity
•similar cell capture rates from 62%± 7% of 59%± 27%
MCF7 cells isolated by MagSweeper with brightfield and fluorescence imaging.
(3) CEpCs in Breast Cancer Patients
•Found CEpCs in 47 of 47 samples from
patients with metastatic disease
•12±23 CEpCs per 9mL blood sample
MagSweeper isolation protocol does
not perturb gene expression
minimal changes in cell profiles:
94% of probe sets have changes
<50%
Fig. S2. Fold changes in logarithmic scale between the gene expression levels of
cultured cells before and after MagSweeper protocol.
Advantages of MagSweeper
• High enrichment
• No prior processing of blood required
• Flexibility in starting sample volume & process
scalability
• Further Optimization:
– Extension of the sweep to capture remaining particles in
gap left by fluid motion
– Refine magnet shape to yield more uniform magnetic field
gradient
Significance
• Diagnose malignancy from blood
– Improved cancer prognosis: CEpC numbers correlate better with
cancer progression than imaging, lymph node biopsy, and serum
biomarker analysis
• Enrich CEpCs for molecular analysis
– Identify surrogate endpoints for evaluation in clinical trials
• Extract individual CEpCs
• characterization of single cells for subpopulation studies on
heterogenous CEpCs