Kryokonservierung im Labor - Alle Produkte in der Übersicht

Cryopreservation has become an integral part in lab routines. It helps to avoid laborious maintaining of cell cultures, by thawing cells only when necessary in the course of experimental practices. Whether you use cryopreservation for cells or organs, molecular biology, ecology and plants, or medical applications such as IVF, you can follow some guidelines to help optimize the process for your desired application.

For the freezing of mammalian cells, mainly two cryopreservation processes are used.

Cryopreservation processes:

Slow freezing

With the slow freezing method, the cooling process is strictly controlled to guarantee gradual cooling of the sample and avoid intracellular ice formation. As the surrounding medium freezes, it becomes hypertonic to the cells, causing cytoplasmic water to exit the cell to balance the osmotic gradient. Cryoprotective agents (CPAs) increase the amount of solvent, reducing the electrolyte concentration and preventing cellular death. This method relies on the cell's ability to move water across the plasma membrane, making optimal cooling rates dependent on cell type permeability. Typically, a cooling rate of about -1 °C per minute is adopted in slow-freezing protocols, which can be achieved with a high-cost controlled-rate freezer. This approach is widely used because of its low risk of contamination and ease of use. On the other hand, slow freezing presents a high risk of freeze injury due to the formation of extracellular ice.

Vitrification

During vitrification, cells are first exposed to high concentrations of CPA, and then directly cooled to very low temperatures, that are achieved using liquid nitrogen. This process allows the cells to transition directly from an aqueous phase to a glass-like state, effectively preventing ice nucleation. Key factors influencing successful vitrification include the viscosity of the sample, the cooling and warming rates, and the sample volume. The primary advantages of vitrification include a low risk of freezing damage and a high survival. However, this technique demands precise handling skills and is more prone to contamination.
The major differences between these two techniques are the concentrations of CPA and the cooling rates used. This highlights the importance of finding the right freezing medium and temperature control equipment suited to your needs.

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