In addition to observing the extravasation of single tumor cells, the group also looked at the behavior of cell clusters -- two or more cancer cells that accumulate in a blood vessel. From their observations, the researchers found that almost 70 percent of cell clusters broke through a blood barrier, compared with less than 10 percent of single cells.
But some cells that make it out of the circulatory system may still fail to metastasize. To see whether a cell's ability to extravasate correlates with its metastatic potential, the group compared the efficiency of extravasation of different cancer cell lines. The lines included breast cancer cells, cells from fibrosarcoma (a cancer of the connective tissue), and a line of nonmetastatic cancer cells.
Sure enough, the team observed that the most metastatic cells (fibrosarcoma cells) were also the most likely to extravasate, compared with breast cancer and nonmetastatic cells -- a finding suggesting that targeting drugs to prevent extravasation may slow cancer metastasis.
Going forward, the group is looking into how likely a given cancer cell is to proliferate and aggregate with others once it has exited into the surrounding tissue. The researchers are modeling various tissues within the microfluidic platform, including bone, to study how cancer cells form the beginnings of a secondary tumor.
"Although this platform isn't an in-vivo platform and obviously can't capture all the aspects that happen in vivo, we've come a lot closer to creating an in-vitro platform that's even more physiologically relevant, high-resolution and high-throughput than a lot of previous platforms," Chen says.
|Contact: Andrew Carleen|
Massachusetts Institute of Technology