A Flexible Micro Spring Array for Viable Enrichment of Circulating Tumor Cells

Open Access
Author:
Harouaka, Ramdane
Graduate Program:
Bioengineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
July 14, 2014
Committee Members:
  • Siyang Zheng, Dissertation Advisor
  • Siyang Zheng, Committee Chair
  • Justin Lee Brown, Committee Member
  • Andrea Marie Mastro, Committee Member
  • William O Hancock, Committee Member
Keywords:
  • Circulating Tumor Cell
  • CTC
  • Cell Enrichment
  • Microfiltration
  • BioMEMS
  • Cancer Metastasis
Abstract:
The dissemination of circulating tumor cells implicated in the metastatic spread of cancer accounts for the majority of cancer-related deaths. Circulating tumor cells have been established as a prognostic biomarker and are associated with worse outcomes. The true nature and mechanism of circulating tumor cells remain a mystery. Their comprehensive analysis has been hindered by the fact that they are extremely rare, occurring at a rate of one in a billion blood cells. This work describes the development of a Flexible Micro Spring Array system for label-free enrichment of circulating tumor cells from whole blood. It incorporates flexible spring structures microfabricated from parylene polymer to rapidly separate cells based on their size and deformability. Device performance was characterized with respect to capture efficiency, enrichment against leukocytes, and maintenance of cell viability and proliferability through reconstructed model systems using cancer cell lines. Circulating tumor cells and microclusters were successfully enriched from clinical samples obtained from breast, lung and colorectal cancer patients, and characterized through immunocytochemical analysis. The detection of circulating tumor cells was correlated to cancer patient survival in a structured trial in non-small cell lung cancer to demonstrate the clinical relevance of the flexible micro spring array device. The mechanism of physical cell separation at low pressure was investigated through analytical models accounting for cell size and deformability. It was ultimately determined that the critical factor for cell capture is the size of the cell nucleus, comprising a novel mechanism for circulating tumor cell enrichment.