Tissue Homogenization
Biological tissue is routinely homogenized in order to extract various analytes (proteins, DNA, RNA, small molecules, etc.). There are a number of considerations which should be taken into account when homogenizing tissue.
Tips for Homogenizing Tissue
The most important thing to consider is the toughness or fibrousness of the tissue. Not all homogenizers will be able to process tougher and / or more fibrous tissue, and even those that can will require a longer processing time than they would with softer samples.
While many tissue applications are deal with small (mg-scale) pieces of tissue, ensure that you select a homogenizer which is capable of processing the sample sizes which you intend to use. Also, remember that larger samples generally take more time to homogenize than smaller samples.
Pieces of tissue with a high-aspect ratio (long, thin strips for instance) will homogenize more quickly and efficiently than pieces of tissue which are round or square. Consider this when collecting your samples or preparing them for homogenization.
Choosing a Tissue Homogenizer
Bead mills are generally the most appropriate and most versatile homogenizers for tissue, with some high-powered bead mills even able to dry-grind bone. Note that bead mills are generally for lower-volume applications, with some bead mills only able to process volumes up to 0.5 ml, so ensure the bead mill you select is able to process the necessary sample size. If you are processing samples over 5 g, you will likely need to chop your sample into smaller pieces prior to processing.
Cardiac tissue before and after homogenization using a Bullet Blender bead mill type homogenizer.
Mortar and pestle homogenizers may be used for most small, soft, and / or cryogenically frozen samples. Larger, harder, and / or more fibrous samples will be difficult to effectively homogenize using a mortar and pestle.
Rotor-stator and ultrasonic homogenizers are effective for softer tissues. If using a rotor-stator, it is recommended that you use a generator probe with pointed teeth such that the tissue can be torn apart by the device. Also, remember that the sample needs to fit between the rotor and stator in order to be homogenized, so ensure that the pieces of tissue are no larger than ½ the diameter of the probe. If using an ultrasonic homogenizer, remember that it will generate a significant amount of heat so be sure to keep your sample on ice or cool it in another manner, in addition to using a pulsed setting, so heat buildup does not degrade your sample.
High-pressure homogenizers are not suitable for homogenizing tissue as it may clog the device.
