Additive channels
Compositions, devices and methods are described for preventing, reducing, controlling or delaying adhesion, adsorption, surface-mediated clot formation, or coagulation in a microfluidic device or chip. In one embodiment, blood (or other fluid with blood components) that contains anticoagulant is introduced into a microfluidic device comprising one or more additive channels containing one or more reagents that will re-activate the native coagulation cascade in the blood that makes contact with it “on-chip” before moving into the experimental region of the chip.
1. A method of using a microfluidic device, comprising:
a) providing,
i) a microfluidic device, comprising:
an input channel,
an output channel,
a test channel, wherein said test channel comprises an input portion in fluidic communication with said input channel and an output portion in fluidic communication with said output channel,
endothelial cells disposed within at least one portion of said test channel; and
an output additive channel, wherein said output additive channel is in fluidic communication with said output portion of said test channel;
ii) a biological sample,
iii) an anti-coagulation agent, and
b) flowing said biological sample at a first flow rate into said input channel to produce a first flow stream that flows in a direction from said input portion of said test channel into said output portion of said test channel and then into said outlet channel ; and
c) flowing said agent at a second flow rate into said output additive channel to produce a second flow stream that merges with said first flow stream and that flows in said output channel in a direction away from said output portion of said test channel and away from said test channel, such that said agent contacts at least a portion of said biological sample,
wherein steps b) and c) can be performed in any order or simultaneously, and said second flow rate is a fraction of said first flow rate.
2. The method of claim 1 , wherein said flowing in step b) allows for a thrombotic process.
3. The method of claim 2 , further comprising d) optically observing said thrombotic process.
4. The method of claim 1 , wherein said biological sample comprises blood.
5. The method of claim 1 , wherein said biological sample comprises at least one blood component.
6. The method of claim 1 , wherein said agent is selected from the group consisting of EDTA, citrate, ACD, heparin and coumarin.
7. The method of claim 3 , wherein said optically observing comprises live-cell imaging.
8. The method of claim 7 , wherein said optically observing comprises live-cell imaging during said flowing of said biological sample.
9. The method of claim 1 , further comprising a step of fixing said cells after step c).
10. The method of claim 1 , further comprising a step of fixing said cells before step d).
11. The method of claim 1 , wherein at least a portion of said biological sample flows out said output channel.
12. The method of claim 11 , further comprising the step of collecting at least a portion of said sample from the output channel.
13. The method of claim 12 , further comprising the step of analyzing said sample collected from said output channel.
14. The method of claim 13 , wherein said analyzing comprises testing for the existence of, or the amount of, components in said sample collected from said output channel.
15. The method of claim 14 , wherein said components are selected from the group consisting of cytokines, antibodies, blood cells, cell surface markers, proteins, RNA, DNA, biomarkers and clotting factors.
16. The method of claim 1 , wherein said device further comprises at least one input additive channel.
17. The method of claim 1 , further comprising adding a test compound to the agent before step c).
18. The method of claim 1 , further comprising adding a test compound to the biological sample before or during step b).
19. The method of claim 1 , wherein said microfluidic device further comprises a porous membrane and a back channel, wherein said membrane is situated between at least one portion of said test channel and at least one portion of said back channel.
20. The method of claim 19 , wherein at least one non-endothelial cell type is disposed within at least one portion of said back channel.
21. The method of claim 20 , further comprising analyzing at least some of said cells of at least one non-endothelial cell type after step c).
22. The method of claim 19 , further comprising d) flowing a third fluid into said back channel so as to create an outflow of said back channel.
23. The method of claim 22 , further comprising analyzing the outflow of said back channel.
24. The method of claim 1 , wherein said output additive channel lacks cells.