I was at the recent topic meeting on Aging, Stress, and Pathogenesis, in Madison, WI. During a forum on directions of future research that should be foci and areas lacking in the field, one of the points of discussion was on immortal C. elegans cell lines. Many felt that this would be of use for easing mechanistic studies by allowing experiments in a single cell type, similar to the power of S2 cells in Drosophila research. However, there seems to be no literature on what’s been tried and many commented on wasted time in repeating failed efforts. While some suggested that a WormBreeder’s gazette article may be a good platform to address this concern of repeating failed experiments and attempt to create a unified attempt by the field to generate a C. elegans immortal cell line, I thought the WormBase forum may be even more effective.
As an experiment in crowdsourcing, I put forth: i) who has tried to generate an immortal cell line; ii) were there any promising lines of experimentation; iii) why did you abandon the effort. I’d be really interested to hear what’s been done or even whether the community feels that this is possible or worthwhile.
My lab attempted this experiment some time ago, without success. We thought that some of the mutations that produce germline tumors might work. We tested glp-1, which produces tumors in both hermaphrodites and males; gld-1 (only hermaphrodite tumors); and puf-8 (only male tumors). We dissected germ cells and grew them in the embryonic cell culture medium. We observed clumps of dividing cells, but the cells became progressively smaller and ultimately stopped dividing. Our naive interpretation was that cell growth was defective while cell division proceeded. We did not pursue this line of investigation further, but perhaps some of the more recent work regarding the germ line stem cell niche might be incorporated in future attempts.
If anyone else has negative results to report, I’d be happy to work together on a report for WBG.
Vikas,
The Kuhn paper, as with earlier papers on the culture of embryonic cells, reports on efforts to replicate terminal differentiation in dissociated cells; there is some mitosis involved, but it is believed to be consistent with the elegans lineage and does not provide what Jordan Ward was asking about, i.e. continuously culturable immortalized cell lines.
The human and mouse parallels are interesting. They take primary cells and put in 1) telomerase, 2) knock out a couple of tumor suppressor genes (don’t hold me to this–p16? p27?) via small and/or large T antigen, and sometimes an activated protooncogene, often Ras. It’s not the same in all cell types.
I suspect that the problem is that they are not using terminally differentiated cells, but probably epithelial stem cells of some sort. Worm development is so hardwired that I don’t know to what degree one could find such cells. Maybe seam cells? Early embryonic blastomeres?
Here’s another problem: human cell culture of course has a long history, so when it came time to actually try to immortalize cells, they had the growth conditions pretty much ready, with all kind of diverse media at hand. We know how to keep worm primary cells alive in culture, but how do you keep them growing if you genetically immortalize them? In humans they generally use some form of supplemented calf serum, and different types of cells are exquisitely sensitive to types of serum. It’s not just nutritional, but there are lots of growth factors in there. Issues are apoptosis due to growth factor starvation, and anoikis due to loss of matrix substrate. But these are cancer protections in an organism with trillions of cells. Do elegans cells need such things? Dunno.
Flies I think you just fire in Ras or some other oncogene. My guess in worms is that you’d want conditional expression, since many activated oncogenes might be expected to cause lethality if spammed in any old cell type.
It’s an intriguing question, but I think that one would need to do a ton of ground work, and then a lot of bench work, realizing that it just may not work at all. That’s why nobody has nailed it (if indeed it can be nailed).