skin lesion and low donor cell frequency in bone marrow transfer - (Feb/02/2015 )

8-week-old C57BL/6 mice were irradiated from 700 to 1000Gy with a new X-ray irradiator in an attempt to decide optimal X-ray dose for bone marrow chimera experiment.

The goal was to find the dose of X-ray that completely eradicate recipient BM cells and achieve >99% donor cells.

It has been 4 weeks since mice were irradiated and BM cells from CD45.1 B6 were transferred.

Now irradiated mice show lesions on their dorsal skin and it seems mice with higher dose are severer.

700 and 800Gy mice show just hair loss on small area but 1000Gy mice have scabs all around their back.

I collected and analyzed blood from mice with concern that I might have over-dosed it, but CD45.1+ donor cells were only found less than 20%.

It does not make sense because I heard that BM-derived cells are the least resistant to irradiation, and I think if X-ray dose was strong enough that there is skin damage, then recipient BM cells should be long gone.

900-1000Gy is also routine dose in other publications.

What do you think went wrong? I would appreciate inputs from experienced colleagues.

Thanks.

Hmmmm I thought that death was likely if exposed to over 30gy. Are you sure the publications didn't use rad as the unit?

My mistake, all numbers are Rads, not Gy.

So I irradiated 7, 8, 9, and 10Gy and transferred donor bone marrow.

Have a look here: http://www.bu.edu/orccommittees/iacuc/policies-and-guidelines/irradiation-of-rodents/. It looks like the strain of the mice is important. It also seems that 700-1300 centiGy (i.e. 0.7-1.3 Gy) is enough to be myeloablative, whereas you are using 7-10 times that!

I think you did the calculation wrong, its centiGy not miliGy. 700-1300cGy is 7-13Gy.

Funny thing is that even though the mice got high dose of X-ray that they got radiation burn, it was not myeloablative at all. I see only less than 20% of donor cells.

True - wasn't thinking too straight then obviously. Are you sure you got the dosage of the mice right, it really sounds like they are getting too much.

I got the answer from the other site. In summary I did not filter soft x-ray and most of energy hit just skin of animals rather than whole body. That was why the animals got radiation burn while their bone marrow cells survived.

That would do it. Time to try again...