Percolls-cell clumping

[Colin Farquharson]

I am trying to separate chondrocytes into their different sizes using 
Percoll (Pharmacia) discontinuous gradients (1.04 - 1.08).  2mls of 
ech are gently layered on top of each other and the cells suspended 
(20-40 million) in 1 ml of medium on top.  Spun in a swing out motor 
at 400g for 30 min at RT.  Things often works but often there is 
extensive clumping at the 1.06 band and this results in poor 
separation.  Cells appear to be 'dragged down' from their band above 
and cells that should move further down are inhibited from doing so.

Has anyone else had trouble with cells clumping together and anyone 
know how to resolve it ?

Colin Farquharson
Roslin Institute
Edinburgh
Scotland