In some circumstances, homogenizers can be used to dissociate intact, viable cells from the tissues they constitute. If a high percentage viability is required or if the cells are large, it can be difficult. If, however, the cells you are looking to isolate are small and / or you only need a small percentage of viable cells, then homogenizers are a more attractive option compared to a relatively expensive and single-purpose tissue dissociator.
No matter what kind of homogenizer you are using (with perhaps the exception of paddle blenders), you want to ensure that you use the lowest speed or power setting possible to pull apart the tissue. There is generally a very narrow window where the structure of the tissue is dissociated but the cells remain intact, and it may take a fair amount of testing to optimize for cell yield and viability. It helps to have some spare tissue (for example, from animals sacrificed for other experiments) such that you do can optimize your protocol prior to using valuable experimental samples.
When testing protocols, start with a low speed setting then gradually increase the speed if the settings fail to dissociate the tissue. Remember that you will almost always achieve better cell viability if you use a longer run at a lower speed than a short run at a higher speed.
Be sure to process the tissue in a medium that is appropriate for the recovery of viable cells (cell culture media or another temporary cell-friendly media). Do not use detergents or other chemicals. Enzymes can be used to help dissociate the tissue, and a good guide to which enzymes and what concentrations to use can be found from Worthington Biochemical.
We find bead mills to be appropriate homogenizers for tissue dissociation. Be sure to choose a bead mill with a low minimum speed setting and use large beads, as these will effectively dissociate tissue but be less effective at lysing cells.
Paddle blenders can be used to isolate viable cells from some tissues. However, the pressing action of paddle blenders may not sufficiently disrupt the structure of tough and / or fibrous tissues.
Rotor-stators may also be able to dissociate tissue. A saw-toothed probe may help tear apart the tissue at lower speeds, and therefore subject the cells to less shear.
Mortar and pestles may also be appropriate, depending on the type of tissue. Fibrous or tough tissues may be difficult to dissociate using manual means. Do not use a dounce or other tightly fitted mortar and pestle as these are generally too efficient as lysing cells and therefore provide low viability.
Never use an ultrasonic or high-pressure homogenizer for cell isolation.