Which of the two methods of purification of pancreatic islets is the best for their viability: Modified Continous Gradients (with the use of Heavy and Light Density Gradients (Ficoll) and UW), or Optiprep Continuous Density Gradients (Purification solution, Gradient Stock Solution and Optiprep)? Could anyone tell me, please,  how the use of Optiprep influences pancreatic islets in comparison to other methods? I cannot find any information about the influence of various purifying methods on the quality of the pancreatic islets.