Methods of isolating cellular products, such as pancreatic islets, may be used in diabetes research and therapeutic transplantation. The methods may involve providing a tissue having desired cells that are less prone to destructive freezing and undesired cells that are more prone to destructive freezing, or pre-treating a tissue to have such characteristics. The methods may involve freezing the tissue, disrupting the tissue, warming the tissue, and separating the desired cells from undesired cellular material to obtain the cellular product. The methods may thereby provide an enzyme-free or reduced-enzyme method of isolating a cellular product that is more consistent, reliable and less toxic than conventional methods. The methods may also yield an optimum quantity of cellular product that retain sufficient functional integrity to be useful as a transplantation resource.