Dendritic cells and mouse cycle

[iansmith]

Lately in our lab, the DC have been growing more rapidly than usual (4 days vs 6 days). Our lab is new to cell culture but according another lab in our department has the same problem. It appears that the problem is seasonal and it start in early in the fall and ends around christmas.

Does anybody know a reason? Could it be related mouse seasonal cycles?

 

[Moonbear]

Lab mice shouldn't be seasonal. If you're using some species of field mice, it might be different (Peromyscus (sp?) species are seasonal).

Do you have any room temperature steps? It could have to do with the room temperature changing with heating vs. air conditioning. Just a thought of something that might change seasonally in a lab. There are a lot of "rhythms" in buildings that most people don't notice (fluctuations in temperatures between day and night, either due to thermostats being set lower at night, or because of the added body heat of people in the building during the day), vibrations from traffic on nearby roads (not likely to affect your cell culture, but is a problem in animal studies of circadian rhythms), fluctuations in the amount of sunlight exposure to everything in the lab if you have windows, etc.

 

[DocToxyn]

Lab mice shouldn't be seasonal.

Technically, I agree that they shouldn't be, but sometimes they are. Our transgenic breeding efforts will go through variations throughout the year, sometimes being more productive, other times not and it generally occurs in the entire colony on a cyclic basis. One of our recent graduates was doing some circadian rythmn work on some of our KO animals and he also observed seasonal (circannual) variations in his responses. Some of his replicates had to wait an entire year to be performed! I think it is almost impossible under normal animal husbandry situations to avoid introducing cues from the environment, especially olfactory stimuli which, as you know, mice are very sensitive too.

However it is hard for me to believe that you are seeing such seasonal variation in a cell culture system. Too much of the circadian system of genes/proteins/brain/body systems are disrupted or missing. It must be something environmental - heating systems, humidity, etc.

 

[iansmith]

We are isolating cells from the bone marrow from freshly killed lab mice when we required the cells.

The only difference i can see is the change in AC vs heat. August is a warm period and in october the temperature drops below 0 C,

The things is that the other lab are keeping the mice in a different facility. We are keeping our mice in the children hospital but the other lab are keeping their in the faculty of medicine. The facilities are managed by two different groups. Yet we are seeing the same kind of seasonal variation.

The problem does not seem to be that big of deal if we harvest the cell earlier. However, it would be interesting and important to know why the cells harvested from mice in may behaved differently than cells harvested from the november mice.

 

[Moonbear]

Your mice sound like my sheep. They apparently haven't read the literature to know what they're supposed to do.

That would be interesting if you can eliminate environmental changes and it points back to mouse seasonality.

 

[iansmith]

Your mice sound like my sheep. They apparently haven't read the literature to know what they're supposed to do.

I think I'll to put an article or two in their cage. They might change their behaviour after they read the articles.

That would be interesting if you can eliminate environmental changes and it points back to mouse seasonality.

Too bad we don't have the resources and the qualification to study it.

 

[Q_Goest]

Interesting phenomenon, is it very common? Are you concluding the cells have their own internal clock of some sort?

Could you eliminate all variables by having only artificial light, controlled and HEPA filtered air (including humidity control), controlled temperature, etc.?

 

[iansmith]

Interesting phenomenon, is it very common?

As far as I know it's only our lab and the lab that cooperate with us. We did not ask anybody else if they encounter the same issue.

Are you concluding the cells have their own internal clock of some sort?

No. It seem that it the mice have the internal clock. In halifax, from ocotober to december the exterior temperature fluctuates a lot and the temperature will drop below 0C often. The fluctuations probably make it hard to control the indoor temperature, based on the temperature fluctuation in our lab.

It is also the season that disease are more easily transmitted. Maybe he mice are priming their immune system when temperature starts to significantly change or fluctuate.

Could you eliminate all variables by having only artificial light, controlled and HEPA filtered air (including humidity control), controlled temperature, etc.?

It would be hard to control the artifical conditions because the mouse are housed in a common area shared with the other labs.

The problem could also be from the suppliers. We do not maitain the a colony and the mice have to ordered and shipped from a supplier.

 

[neurocomp2003]

"There are a lot of "rhythms" in buildings" COOL..

Rapid growth rate cool...maybe write down all your conditions, ask engineers and physicists about all the factors in a building and perhaps your location by the water(has halifax gotten snow yet?...i remmeber seeing pictures that covered the 3/4 of the first level door) and then repeat the experiment same time next year.
Perhaps more physics plays into brain growth then people ever imagined =]
or at least I ever imagined.

 

[iansmith]

has halifax gotten snow yet?...i remmeber seeing pictures that covered the 3/4 of the first level door

We started to have snow about 2 weeks ago but in december it is snowing one day but it rains the next. Temperature fluctates a lot in halifax. We can have a day 10C but the next is -10C.

 

[Moonbear]

It would be hard to control the artifical conditions because the mouse are housed in a common area shared with the other labs.

You can ask the folks who operate the facility about the housing conditions. Usually, if you don't request any special husbandry conditions, they'll house mice on a 12L:12D cycle for convenience. You could find out if the lighting has been changed by anyone else's request recently, if the diet has been changed, if they've had any problems with temperature or humidity regulation, etc. They have to keep records of all this information, so it should be easy to find out.

The problem could also be from the suppliers. We do not maitain the a colony and the mice have to ordered and shipped from a supplier.

This is actually more likely if you're not maintaining your own colonies and only house them short-term. Or, not even so much the suppliers, but the exposure to outside temperatures during transportation.

Do you always request mice of the same age/weight?

If you really think there's something seasonal, neurocomp's suggestion is actually a pretty good one. You don't have to go out of your way to study the seasonality, but keep records on the growth rate of your cells and ambient conditions in the building when you're housing mice there and collecting/growing cells. The lab can just keep general records on this and if in a few years it starts looking like there's a pattern, you can look to see if anything else correlates with it. If you can't find anything else, you have sufficient preliminary data to make it worthwhile pursuing a seasonal study.

 

[iansmith]

Do you always request mice of the same age/weight?

It depend on the vaccine study we are doing. We usually order extra mice for DC work and keep the mice until we need them.

 

[Moonbear]

It depend on the vaccine study we are doing. We usually order extra mice for DC work and keep the mice until we need them.

Could the different growth rates have anything to do with the age of the mouse when you harvest the cells?

 

[iansmith]

Could the different growth rates have anything to do with the age of the mouse when you harvest the cells?

We seen differences before. The difference between DC from a younger mice and an older mice is usually the shape of the cells and "vivacity" of the cells. However, it does not compare to what we are seeing now.

 

[DocToxyn]

OK, now it is much more clear. With acutely isolated cells from animals arriving from an independent source and going through all the trials of shipping, I'm not surprised you are seeing this phenomena. How long are you acclimating the mice prior to harvest? As suggested, it should be a fairly easy task to document when shipments arrive, when cells are harvested and how they react in culture. Even without the manpower/facilities/time to set up your own breeding colony as a comparison group, this should at least give you a handle on the parameters with which you are "forced" to work in and perhaps you can plan accordingly in the future.

 

[iansmith]

We never use the mice right away. They can be left in their cage for a week to a few months. I do not know if there is any differences between those that a picked the first week or those picked later.

 

[Moonbear]

We never use the mice right away. They can be left in their cage for a week to a few months. I do not know if there is any differences between those that a picked the first week or those picked later.

That's easy enough to track the arrival date and age when shipped so you can compare both the time to acclimate to your facilities and the age of the mice when you're harvesting the cells to see if there is a correlation. It could be that they are sitting longer at one time of the year than another due to the number of other experiments going on at the time (such as when you're scrambling to find projects for rotation students in the fall or when people are trying to finish up projects for abstract deadlines).