week 2 -- Joyce

I was recommended that laparoscopic colorectal surgery (minimally invasive surgery) is worth watching for beginners to warm up, because it is not so bloody and the disease locations could be zoomed on the monitors. I went to see Dr. Sang Lee’s minimally invasive surgeries on this Thursday. The first case is colorectal cancer of typical MINT surgery in that the 50 years old female patient is immune suppressive due to leukemia complication and MINT surgery is better to avoid further big infection than traditional abdomen incision. I was surprised to such a tiny hole they made in patient’s abdomen with a size just fitting the special fiber optic camera called laparoscopy. I did mouse experiments before and know how hard to localize intestinal tumors in so long GI track, even under dissecting microscopy. While laparoscopic surgery is hundreds times harder than mouse surgery, because the intestines in abdomen are rolled disorderly and all pink tissues / organs look so similar. Dr. Sang Lee and his assistants are very experienced and skillful and it took only ten minutes to spot the tumor sites. The probing speeds of camera Lens are so first that I felt dazzled with the changing internal images in the monitor.
The research goes slowly but progressively. Colon cancer primary culture is difficult in that enough driver colon cancer stem cells need to be harvested from human samples and immortalized in in vitro dish culture medium which takes a long time. The medium conditions and growth factors need to adjust to generate suitable in vitro growth environment. The original goal of my project is to culture colon cancer stem cells which are believed to be the cancer initiating cells retaining all the “driver” mutations and we use the serum free stem cell medium to purify the stem cell population since stem cell medium will keep stem cells in undifferentiated stage while the differentiated progenitor cells die up. It is much harder for primary colon cancer cells to survive in FBS free stem cell medium and the immortalization process usually takes longer. To guarantee we won’t lose the precious human cancer samples, I also implant the rest tumor tissues from primary culture in SCID mice for backup which serve as a good vector to sterilize the tumor tissues, retain human cell viability, purify and amplify the cancer cells.
One of the most interesting phenomena is that actually the human colon cancer tissues are heterogenous different from the single cell cloning conventional cell lines. After enzyme digestion, the deformed crypt structures were released out of the tumor tissues and they are formed by differentiated cancer cells. I think this is a proof of cancer stem cell concept, at least in intestinal tissues which are thought to be one of several organs retaining active adult stem cells in human body.
So far I succeed culture two primary colon cancer cell lines in stem cell medium and two primary cancer tissues grow out in mice which I will use for dish culture later.