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 input additive channel, wherein said input additive channel is in fluidic communication with said input portion of said test channel;
ii) an anti-coagulated biological sample comprising cells, and
iii) an agent that restores the coagulation abilities of said biological sample;
b) flowing said anti-coagulated biological sample into said input channel and into said input portion of said test channel; and
c) flowing said agent into said input additive channel under conditions such that agent contacts at least a portion of said anti-coagulated biological sample, wherein steps b) and c) can be performed in any order or simultaneously.
2 . The method of claim 1 , wherein said flowing of step b) is done at first flow rate, and wherein said flowing of step c) is done at a second flow rate, wherein the first and second flow rates are proportional to each other.
3 . The method of claim 1 , wherein said contacting in step c) allows for a thrombotic process.
4 . The method of claim 2 , further comprising d) optically observing said thrombotic process.
5 . The method of claim 1 , wherein said biological sample comprises blood.
6 . The method of claim 1 , wherein said biological sample comprises at least one blood component.
7 . The method of claim 1 , wherein said agent that restores the coagulation abilities comprises calcium.
8 . The method of claim 4 , wherein said optically observing comprises live-cell imaging.
9 . The method of claim 8 , wherein said optically observing comprises live-cell imaging during said flowing of said biological sample.
10 . The method of claim 1 , further comprising a step of fixing said cells after step c).
11 . The method of claim 4 , further comprising a step of fixing said cells before step d).
12 . The method of claim 1 , wherein at least a portion of said anti-coagulated biological sample flows out said output channel.
13 . The method of claim 12 , further comprising the step of collecting at least a portion of said sample from the output channel.
14 . The method of claim 13 , further comprising the step of analyzing said sample collected from said output channel.
15 . The method of claim 14 , wherein said analyzing comprises testing for the existence of, or the amount of, components in said sample collected from said output channel.
16 . The method of claim 15 , wherein said components are selected from the group consisting of cytokines, antibodies, blood cells, cell surface markers, proteins, RNA, DNA, biomarkers and clotting factors.
17 . The method of claim 1 , wherein said device further comprises at least one output additive channel in fluidic communication with said output portion of said test channel.
18 . The method of claim 1 , further comprising adding a test a compound to the agent before step c).
19 . The method of claim 1 , further comprising adding a test a compound to the biological sample before or during step b).
20 . 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.
21 . The method of claim 20 , wherein at least one non-endothelial cell type is disposed within at least one portion of said back channel.
22 . The method of claim 21 , further comprising analyzing at least some of said cells of at least one non-endothelial cell type after step c)
23 . The method of claim 20 , further comprising d) flowing a third fluid into said back channel.
24 . The method of claim 23 , further comprising analyzing the outflow of said back channel.