Abstract
Lyophilization is a cost-effective method for biological specimen preservation but detailed tissue-specific reference protocols are still lacking. Moreover, data are limited on the long-term stability of proteins and nucleic acids in lyophilized samples.Here, we offer lyophilization protocols for various rat and mouse tissues (kidney, heart, liver, lung, aorta, and skin) coupled with technical hints for optimal sample preparation. We demonstrate that lyophilized samples stored at 4 °C for 20 months can yield protein and RNA of similar quantity and quality to −80 °C storage, while phosphorylated proteins are preserved as well. Freeze-dried and subsequently pulverized samples can provide more consistent, more reliable data especially when investigating focal injuries, such as fibrosis. We developed a protocol for the concentration of biological solutions and achieved 20-times concentration in human peritoneal dialysis effluent solution which enables the previously unattainable detection of proteins in these samples. We established a method for water removal as well as accurate water content measurement of fecal samples, which can be valuable for gut metabolome analysis.Taken together, lyophilization is a valuable tool for the preservation of biological samples with many advantages. We aim to draw attention to the wide range of possibilities offered by freeze drying in pre-clinical or basic research.
Highlights
Water removal by vacuum freeze-drying of biological materials is a first-rate method of preservation that yields final products of the highest quality
This paper offers detailed protocols for rat and mouse kidney, heart, liver, lung, and skin tissue lyophilization, human peritoneal dialysis (PD) fluid concentration, as well as water and solvent removal from human fecal samples
Realizing the numerous possibilities offered by freeze-drying biological samples and considering the lack of definitive process parameters in the literature, appropriate protocols for various rat and mouse tissues were established
Summary
Water removal by vacuum freeze-drying of biological materials is a first-rate method of preservation that yields final products of the highest quality. The technique offers an appealing, yet untapped potential for long-term storage, but the use of lyophilized tissue samples may improve validity and reproducibility and may reduce scatter in molecular biology research. In today’s highly collaborative scientific community there is a growing need to transport biological samples. Liquid nitrogen or dry ice is not required for the storage of freeze-dried samples, which significantly reduces shipping and storage costs (Lewis et al 2016). Data are limited on whether RNAs and proteins, as well as post-translational modifications such as phosphorylation are preserved in freeze-dried samples stored for long periods of time (20 months or more)
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