Era of Hope 2011 Investigator Vignette

Title: A Breast Cancer Tissue Bioreactor

Investigator: Lisa Joy McCawley, PhD; Vanderbilt University Medical Center

The purpose of this research is to build a breast cancer tumor bioreactor that has controls over the tumor microenvironment such as pH and oxygen concentrations. And what we're going to use this reactor system for is to challenge a biopsy sample with an anticancer drug to determine its therapeutic value in that particular patient.

One of the interesting things about the microenvironment that a tumor lives within is-it is-it's different from the normal system. And the cells that grow in it become altered in their behavior. And one of the changes to their behavior is even their response to anticancer drugs. So the idea behind this is that we might be able to take a patient biopsy sample, put it in both a variety of different microenvironments and see if a treatment would actually work in that patient before giving that therapy. That's the bigger idea behind this grant.

So this work is around building a breast cancer tumor bioreactor. This is a mock-up, a base module, and here filled in red is one of these little cell chambers. And on blue in top is a feeding system nourishing these cell chambers, and the channels in here are as wide as a human hair, so envision this is really a small scale reactor system.

One of the standard cell culture techniques that we use are using mammary epithelial cell lines that go from normal to tumorigenic. And the normal ones you can place them in a thick matrix and they'll develop into forming glands. They'll form these hollow what are called mammospheres that makes this hollow sphere but it really is like a little gland.

We've shown that we can get these hollow spheroids to form in our system along with tumorigenic counterparts. So one of the things we needed to know was could we deliver a drug to this system and actually get some sort of cellular response.

We started with was just even modeling. Here we're taking a cell chamber with no drug and you see colors representing over time drug diffusing into this reactor system. We were able to take this information and use a drug that inhibits a variety of proteases-that's something that knows to influence this mammosphere development. And if we add a-a protease inhibitor cocktail into the system we can see that we go from making nice mammospheres to really tiny mammospheres that really blocks their formation.

The other thing we're able to do is to take an activity measure. This green here is taking mammospheres and looking at the level of protease activity along their edges and in the presence of the inhibitor of course that activity has disappeared. So, we are ready now to add in some of these other environmental aspects such as oxygen and pH levels.

We've picked very specific targets for what we'd like for the oxygen levels to be under these tumor conditions as well as pH, and we're going to be monitoring that we've reached these target levels over the time period of the experiment by using a detector system that's been put in thin films. You can take chemical reagents and lay them in a thin film that are going to lay on the glass that's right at the bottom of the cell chamber. And it'll give you a 2D map then of what the-of both the oxygen and the pH level, the actual level is in the system. And what's shown here is delivering across a gradient of oxygen, and you can see the color slowly decreasing in intensity as it is interacting with higher concentrations of oxygen.

The other thing that we've been working on along with the oxygen films are also a film to-to test acidity in the environment, and this is just illustrating again if we take something at a higher pH and a lower pH and run it along the channel you see this change in color depending upon whether the chemical is at a more acidic or more neutral pH. So we're at the point now where we have a reactor system. It maintains a long-term cell culture model. We can monitor our target oxygen and pH levels now. And we're at the point now of joining all this together and beginning our next set of experiments where we're going to start challenging a tumor biopsy within the system under these varying different conditions and test its response to an antitherapeutic-anticancer therapeutic drug.