Isolation and characterization of tumor cells using shear stress measurements
Methods for isolating viable cancer cells from a sample that comprises a mixture of cancerous cells and normal (non-cancerous) cells are provided. In the methods, a fluid preparation comprising a mixture of cancerous and normal cells is repeatedly exposed to fluid shear stresses, whereby the repeated exposure to the fluid shear stresses preferentially imparts fluid shear stress-resistance to the cancerous cells.
1. A method for purifying a fluid sample comprising extracellular calcium and cells of a mammalian subject, the cells comprising viable normal cells, the method comprising:
applying an initial pulse of fluid shear stress to the sample in vitro, wherein the initial pulse of fluid shear stress is sufficient to induce a fluid shear stress resistance in viable cancerous cells present in the sample such that the magnitude of shear stress required to kill the viable cancerous cells is greater than the magnitude of shear stress required to kill the viable normal cells; and
subsequently applying one or more additional pulses of fluid shear stress to the sample in vitro, said fluid shear stress sufficient to selectively kill the viable normal cells relative to the viable cancerous cells such that the ratio of the viable cancerous cells to the viable normal cells is increased.
2. The method of claim 1 , wherein the cells of the mammalian subject comprise lung cells.
3. The method of claim 2 , wherein the mammalian subject is a human.
4. The method of claim 1 , wherein the fluid sample is an in vitro fluid preparation.
5. The method of claim 4 , wherein the in vitro fluid preparation is prepared from a solid tissue biopsy.
6. The method of claim 1 , wherein the cells of the mammalian subject comprise the viable cancerous cells in addition to the viable normal cells.
7. The method of claim 1 , wherein the viable cancerous cells are viable cancerous epithelial cells.
8. The method of claim 1 , wherein the ratio of the viable cancerous cells to the viable normal cells in the sample is at least doubled.
9. The method of claim 1 , wherein the percent viability for the viable cancerous cells is at least 40% and the percent viability for the viable normal cells is no greater than 20% substantially immediately following the application of the initial and additional pulses of fluid shear stress, wherein percent viability is determined as the percent viability relative to a control maintained without the application of shear stresses for the duration of the pulse applications.
10. The method of claim 1 , wherein the initial and additional pulses of fluid shear stress apply a fluid shear stress in the range from about 500 dyn/cm 2 to about 6500dyn/cm 2 .
11. The method of claim 1 , wherein the additional pulses apply a supra-physiologic level of fluid shear stress.
12. The method of claim 1 , wherein the steps of applying the initial pulse of fluid shear stress to the sample and applying one or more additional pulses of fluid shear stress to the sample comprise passing the sample through a conduit at a substantially constant flow rate.
13. The method of claim 1 , wherein the initial pulse and the one or more additional pulses each have a duration of no greater than about 20 msec.
14. The method of claim 1 , wherein at least two additional pulses of fluid shear stress are applied to the sample.
15. The method of claim 1 , further comprising subsequently measuring the concentration of the viable cancerous cells in the sample.
16. The method of claim 1 , further comprising subsequently conducting an assay on the sample, the assay providing a cancer diagnosis or a cancer prognosis for the mammalian subject.