The preservation of biological samples is critical to the success of experimental studies and clinical treatments in the emergent field of immunotherapy. Cryopreservation – keeping cells at sub-zero temperatures – slows metabolic activity significantly, enabling storage and transportation, as well as a return to functionality upon thaw. Of course, it’s not as simple as placing them in a freezer and taking them out when needed. Carefully designed methods are needed to avoid morphological damages that can occur during the freezing process such as intra- and extra-cellular formation of ice crystals. DMSO has long been the gold standard for cryopreservation because of its ability to replace water within the cell, thereby protecting inner cellular components. However, there have been growing concerns about its toxicity. Scientists from the universities of Stanford, Purdue and Tufts, along with Akron Biotech, have recently developed and tested a bioinspired, non-toxic, serum-free cryoprotectant with the aim of improving and addressing these issues. This innovative cryopreservation solution has shown promise in immunotherapy, effectively cryopreserving immune cells.
The cryopreservation solution utilizes a cocktail of the biocompatible components, including carboxylated ε‐poly‐L‐lysine (CPLL) and dextran. Both are naturally occurring and have shown cryoprotective capabilities in various cell types. It is suggested that CPLL acts similarly to anti-freeze proteins by blocking the reformation of ice crystals as well as affecting the shape of ice crystals in a way that minimizes damage to the cell membrane. CPLL works synergistically with dextran by binding to and protecting the cellular membrane. Finally, these molecules have a high affinity to water, which helps to restrict movement of molecules in and out of the cell thus preventing any mechanical damage.
To study the effects of the cryoprotective agent, scientists used the slow freeze method to cryopreserve immune cells. This allowed for evaluation of viability during various points in the cryopreservation process. Results were comparable to those obtained with the control group. While immediate post thaw recovery was slower than the control, results on day 7 showed the CPLL/dextran group caught up to the control perhaps alluding to increased sustainability of a therapy after infusion. Functionality was assessed through a cytotoxicity assay against K562 cells. The assay revealed that CPLL/dextran cryopreserved immune cells had a significantly higher killing efficiency compared to DMSO.
The overall results of the study show great promise for improved cryopreservation solutions, and warrant further investigation into the mechanisms of the bioinspired components. Akron remains dedicated to the exploration and innovation of products focused on safe and effective methods for overcoming issues associated with the manufacture, storage, and transport of cell therapies. This new research conducted by university scientists, and scientists at Akron Biotech, brings us one step closer to realizing the transformative potential of immunotherapy.
This article titled “Bioinspired Preservation of Natural Killer Cells for Cancer Immunotherapy“ was published in Advance Science