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Bead Beating: A Primer (continued)

ANIMAL

Elastic Animal Tissue Homogenization: Skin/Sclera/Cartilage

Animal tissues that contain a significant amount of collagen such as skin, sclera, and cartilage are very difficult to homogenize by any method. The pliable and resilient nature of these tissues is by design. In order to effectively homogenize these elastic tissues, the mass of the sample needs to be very small relative to the grinding media and vessel. Samples less than 20 mg are best processed in a 4 ml polycarbonate vial with one 3/8” stainless steel ball. Larger samples are best processed in a 15 ml polycarbonate vial with two 7/16” stainless steel grinding balls. It is often necessary to homogenize elastic tissues cryogenically. In such cases, a GenoGrinder® or Mini G™ models equipped with Cryoblocks are needed.

Procedures

1. The grinding formats available for elastic tissues are limited. Sample size is also limited. Samples need to be dissected into small pieces (3 x 3 mm) prior to homogenization. Avoid thick, large pieces of tissue since these will not effectively homogenize. Samples are best processed cryogenically using liquid nitrogen to chill the sample, tube, ball and Cryoblock. Caps are usually made of polypropylene and, if too cold, will crack.
2. Prepare samples according to the following table:
4 ml Vials 15 ml Vials
Sample Mass 20 mg Up to 250 mg
Grinding Balls 1 x 3/8" 2 x 7/16”
Processing Time 5 minutes 5-10 minutes
Bead Beater Speed High High
3. Process the samples as stated in the table. Heat is generated during processing, so it is possible that samples may warm and thaw by the end of processing.
4. Sample homogenization can be monitored visually.  Ideally the tissue will be converted into a fine powder.  Samples with large amounts of collagen may not homogenize well.
5. Homogenized tissue can be stored frozen or thawed and used.

Suggested Products

Balls: 3/8’’ Stainless Steel (GBSS 375-1000-02), 7/16’’ Stainless Steel (GBSS 437-1000-03)
Vial Sets: 24 Well PC Vial Set (PCVS 04-240-03), 15 ml Polycarbonate Vial Sets (PCVS 15-050-22)
Homogenization Vessel: See Appendix A
Homogenizers: Cryogenic grinding requires a GenoGrinder® or Mini G™ (Appendix A)
Cryogenic Option: Cryoblocks (4 ml and 15 ml)