I recently had the chance to play around with the Scepter 2.0 Automatic Cell Counter from EMD-Millipore. The Scepter uses the Coulter Volume principle to count cells in a microfluidic chamber connected to a handheld device. I'm basically using it for things like confirming pre- and post-sort cell counts, as well as counting cells being passaged and primary cells such as PBMCs and splenocytes. The device itself is basically shaped like a pipetteman, and even has a plunger type action which simulates pipetting.
|EMD-Millipore Scepter 2.0|
|Scepter Software Pro Screenshot|
Now, about that snafu. What I kept finding was after the sample was loaded into the sensor, and then the sample started traveling through the sensor orifice into the counting micro-channel, I kept seeing bubbles creep in there. The effect of this was I'd start getting these really low volume events piling up near the end of the counting process. It was a small number of low volume events that I could probably gate out (see figure below), but it still messed things up for me. Since I was doing a 1:10 dilution (10ul sample, 90ul buffer), when I back calculate (or better yet, let Scepter Software Pro back-calculate for me) the concentrations, I was off as much as 1x10^6 cells (or a 12% swing in total cell counts). To solve this problem, I made one modification to the collection process. As soon as the sample was loaded into the sensor (it beeps at this point), I immediately flipped the entire Scepter apparatus upside-down as to force any air that begins to enter the sensor to remain near the tip and not enter the orifice and microfluidic channel. This got rid of all the air bubbles and my counts became extremely accurate. In one case, my MoFlo told me there should be 8.02x10^6 cells, and the Scepter counted 8.01x10^6 cells. This made me happy. To see this awesome flip move in action, check out the video below. I apologize for the sound, I was filming this in my sorter room, which has the gentle hum of a twin diesel engine for background noise. Also, you'll just have to trust me when I say "see the bubbles." UPDATE: After playing around with volumes a bit more, it's pretty evident that you definitely need 100+ microliters of volume in your tube. I could get bubbles every time if I only had the requisite 50ul of sample, but if I had 100-120ul, I almost never got bubbles. With this volume, there's no need to turn the scepter upside-down.
So, in all, I think this product was successful for what my purposes were. It's small. The counting process is fast. I can offload the data to my computer, and the counting was very accurate (as long as I remembered to hold it up-side-down to avoid the bubbles). Will I continue to use it? I guess it sort of depends on whether or not I can get over not 'knowing' the %live/dead. For what I'm doing, that's probably fine, but could another option be just as easy and accurate and cheap AND give me live/dead? To be determined. I will say that I've used early versions of the Countess and the Nexcelom, and neither impressed me so much as to make me want to buy one immediately. Hopefully I'll be able to check them out again and perhaps put together a head-to-head review.