8. Cryobiology: Past, present and future

Abstract

Before 1949, the majority of mammalian cells could not be kept in storage at low temperatures and recovered with high functional viability. Artificial cryopreservation was observed and published in 1948 by Polge, Smith, and Parkes through the serendipitous discovery of the cryo-protective properties of glycerol for foul sperm and, subsequently, for red cells. Lovelock (1954) expanded the concept and use of cryoprotective agents (CPAs) by proposing that the protective action of glycerol was shared with a number of other neutral solutes of low molecular weight, including methanol, acetamide and glyceryl monoacetate. This led to the introduction of dimethyl sulfoxide (DMSO) and the first report of its protective action against freezing damage to human and bovine red blood cells and to bull spermatozoa. The ready permeability of DMSO to a wide array of cell types ultimately allowed for widespread use of cryopreservation of cells for research, conservation and clinical use. Scientists interested in the natural phenomena and biomedical applications associated with freezing biological systems have continued to investigate the fundamental processes governing the relationship and the biological, chemical and physical underpinnings. However, as this has been applied over the years with the increasing reliance on cryopreserved cells for agricultural production, biobanking for research/diagnostic reasons and cryopreservation of cells for clinical use, some misconceptions surrounding the science have become problematic. In some ways, the initial successes with cryopreservation of various cell models arguably caused some complacency among practitioners and led to a disconnect between fundamental cryobiology research and end users of the technology. This has become most apparent in the widespread use of sub-optimal “one size fits all” cryopreservation approaches and with respect to defining shelf life of cryopreserved cell products. Most scientific advances are built upon incremental refinements in methodology and are consequently iterative. As a result, for the most part, even with all of these advances cryopreservation protocols today look very similar to those first discussed over 50 years ago. The future of cryobiology will need to go beyond applying new technologies to the same biophysical problems. The explosion of various technologies to assess and manipulate cells and tissues at a phenotypic, cytologic, biochemical and molecular level will allow the next wave of disruptive cryopreservation technologies to take root.