The official method, the DIY solution and the science hack

Original title, let’s call it subtitle: Can we isolate human cell clone derived colonies with an inoculation loop?

The following post is dedicated for scientists who ever faced with a similar problem, that is running out of cloning disks and working late.

In experimental science, when people are facing with a problem need to be solved within a restricted time frame, they can choose out of 3 main scenarios: the official or the received method, the DIY solution and the shortcut hack. (There is also a ‘fourth’ solution: outsourcing, using networking capabilities). People in the lab are different by their affinity to these patterns: engineering, tinkering, hacking or ‘networking’. Here is a recent example.

Usually researchers are using sterile cloning paper disks when they want to isolate colonies growing from eukaryotic cell clones. The method is simple and effective, first the paper disk is saturated with trypsin EDTA, the targeted clones are marked at the bottom of the flask, then the medium is sucked off with an aspiration tube (nevertheless there is a thin liquid film layer left behind), the disk is placed over the clone, incubated there for 5 minutes, then picked up and placed into 24-well plates, disks are removed after 2 days, cells are grown for a week and depending on the downstream process (DNA, RNA, protein isolation, functional measurements, sorting, transplantation, whatever) are seeded into bigger flasks.

cloning disk vs. inoculation loopDue to a backorder I was unable to use paper disks (the usual and official way) last week, but growing cell cultures do not give a shit about backorders. So there were 3 options: i., loaning disks from other folks in the lab (the networking tool, sometimes the most efficient, also the least creative) ii., making those paper disks, then sterilize them (the DIY solution) and iii., using a tool or method developed for a similar but different purpose (the hack). I did what the lazy researcher does, asked around in my close proximity first with negative results, then went to eating free gumbo at a promotional event in the hall where salesmen of life science companies distributed their gifts and catalogues to hungry graduates and postdocs. One object out of the gifts was a tube of 10 disposable plastic inoculation loops, a thing I last met ages ago.

By contrast to the cloning disks, an inoculation loop is used by microbiologists to transfer microbes from agar to agar surfaces. It takes the liquid inoculum due to the surface tension forming within the 5 mm loop on the tip of the tool.

So this tool found me and my problem and I did the isolation with it last Friday as my cultures started to run out of space. I checked the flasks today and there definitely are some adhered cells (although not too many) but for control I finally did the isolation with loaned cloning disks from another clones/same flask.

Message: Sometimes the promise of a free gumbo can solve your burning lab problem.