Most lyophilized collagenase containing tissue dissociation enzymes (TDEs) used today have a wide spectrum of color – tan to black – depending on the product. This color serves as a litmus test indicating that these enzymes are not pure and are likely have high variability in enzyme activity between lots. The information below presents more details of the biochemical characteristics of crude or enriched collagenase products and shows the benefits of using purified enzymes in place of these products.
Crude or partially purified collagenases are the most common tissue dissociating enzyme (TDE) products used for isolating rodent islets. A small number of reports used purified TDEs for this procedure1,2 but the practice is not widespread despite the major advantages of using purified TDE products that are routinely used for human islet isolation3,4. This post summarizes results from an ongoing collaboration with Dr. Raghu Mirmira’s lab at the Wells Center for Pediatric Research at the Indiana University School of Medicine to define an optimal collagenase and neutral protease composition for use in mouse islet isolation procedures.
Most reports show that at best, about 48% of the human islet isolations yield a sufficient number of islets for subsequent transplantation. Recently, Balamurugan and colleagues at the University of Minnesota’s Schulze Diabetes Institute showed that this percentage could be increased to > 75% by selecting the appropriate mixture of enzymes. The key to the UMN success was using a “new enzyme mixture” containing VitaCyte’s CIzyme Collagenase HA and Serva’s NB neutral protease.