Overview of the development of cell cryopreservation solutions

The Problems of Cryopreservation and How to Solve Them

Cryopreservation is a critical technology in the fields of biomedicine, regenerative medicine, and biological research. It allows scientists to store cells, tissues, and even organs for extended periods at ultra-low temperatures, preserving their viability and functionality. The history of cryopreservation medium development is a fascinating journey marked by persistent challenges and innovative solutions.

The Challenge of Cryopreservation

The process of cryopreservation is not without its challenges. The most significant issue is the formation of ice crystals during freezing, which can damage cell structures and lead to decreased viability upon thawing. Ice crystals can rupture cell membranes, disrupt cellular organelles, and cause osmotic stress, all of which can have severe consequences for the preserved samples.

Another issue is the potential toxicity of cryoprotectants, the chemical compounds used to prevent ice crystal formation. While cryoprotectants are necessary to protect cells during freezing, they can be harmful if used in excessive amounts or if not properly removed during the thawing process.

Solutions to Cryopreservation Challenges

Over the years, scientists and researchers have developed innovative strategies to address the challenges of cryopreservation. These solutions have evolved alongside advancements in our understanding of cell biology, chemistry, and material science.

The Basic Formula

The development of a cryopreservation medium involves carefully crafting a solution that balances cryoprotection and cell compatibility. The basic formula of a cryopreservation medium typically includes the following components:

1. Cryoprotectants: Cryoprotectants are the cornerstone of any cryopreservation medium. These compounds reduce the freezing point of the solution, thereby preventing ice crystal formation. Glycerol, dimethyl sulfoxide (DMSO), and ethylene glycol are common cryoprotectants used in various formulations.

2. Buffering Agents: To maintain a stable pH level during freezing and thawing, buffering agents are essential. Common choices include HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) and phosphate buffers.

3. Serum or Albumin: Adding serum or bovine serum albumin (BSA) to the medium can provide additional protection and nutrients to the cells during the cryopreservation process. These components support cell health and reduce damage during freezing and thawing.

4. Salts and Nutrients: Essential salts and nutrients are often included to sustain cell health and metabolism during the frozen state. These may include sodium chloride, potassium phosphate, and various vitamins and amino acids.

5. Antioxidants:  Antioxidants such as ascorbic acid and tocopherol are incorporated into some formulations to protect cells from oxidative damage, which can occur during the cryopreservation process.

6. Preservatives: Small amounts of preservatives, such as antibiotics or antifungal agents, are added to prevent microbial contamination of the medium during storage.

The specific formulation and concentration of these components can vary based on the type of cells, tissues, or organs being preserved and the specific goals of the cryopreservation process. Optimizing the composition is a crucial step in developing an effective cryopreservation medium.

The Key Changes in This Field

The field of cryopreservation medium development has seen significant changes and advancements over time. Several key changes have shaped the evolution of this critical technology.

1. Cryobiology as a Science

The development of cryobiology as a scientific discipline played a pivotal role in advancing cryopreservation techniques. Researchers in cryobiology explored the fundamental principles of freezing and thawing, leading to a deeper understanding of the cellular and molecular processes involved. This knowledge paved the way for the development of more effective cryopreservation media.

In a notable paper, "Cryobiology: A History," Meryman (2002) highlighted the historical progression of cryobiology, from early trial and error methods to the systematic approach we see today. This systematic approach has been instrumental in optimizing cryopreservation media.

2. Cryopreservation of Specific Cell Types

Advancements in cell and tissue engineering have increased the need for cryopreservation techniques tailored to specific cell types. This has led to the development of specialized cryopreservation media that are optimized for the unique requirements of various cell lines.

For example, a study by Pollock et al. (2004) titled "Cryopreservation of Adipose-Derived Stem Cells" demonstrates the formulation of a cryopreservation medium specifically designed for adipose-derived stem cells, taking into consideration their unique characteristics and requirements.

3. Innovations in Cryoprotectant Chemistry

The chemistry of cryoprotectants has evolved, with researchers continually exploring new compounds and methods to enhance their effectiveness while minimizing toxicity. Studies like "Recent Developments in Cryopreservation of Gametes and Embryos of Marine Animals" by Holt et al. (2011) have delved into the use of novel cryoprotectants in marine animal reproductive cells.

4. The Role of Controlled Rate Freezers

The introduction of controlled rate freezers has revolutionized the freezing process in cryopreservation. These devices enable precise control of the cooling rate, reducing the formation of ice crystals and improving cell viability upon thawing. Research papers such as "Optimization of Controlled Rate Freezing Protocols for Cynomolgus Monkey (Macaca fascicularis) Sperm" by Chang et al. (2015) have demonstrated the importance of controlled rate freezers in optimizing cryopreservation protocols for specific applications.

Key Brands in the Market

The field of cryopreservation has seen the emergence of several key brands that have become synonymous with reliable cryopreservation solutions. These companies have been at the forefront of developing and commercializing cryopreservation media and related products. Some notable brands in the market include:

1. Thermo Fisher Scientific:

 Thermo Fisher Scientific offers a wide range of cryopreservation media and related products, catering to various cell types and applications. Their cryopreservation solutions are trusted by researchers and laboratories worldwide.

2. STEMCELL Technologies

  STEMCELL Technologies is known for its innovative products in the field of cell culture and cryopreservation. They provide a variety of cryopreservation media designed to maintain cell viability and functionality.

3. Sigma-Aldrich (now part of MilliporeSigma):

  Sigma-Aldrich has a long history of providing high-quality chemicals and reagents, including cryopreservation media and cryoprotectants. Their products are widely used in research and biotechnology.

4. Merck KGaA (EMD Millipore)

  Merck KGaA offers a comprehensive range of cryopreservation media and reagents to support cell preservation and biobanking efforts. Their solutions are designed for maximum cell viability and recovery.

5. Corning

  Corning is a well-known provider of laboratory products, including cryopreservation media and cryovials. They offer a variety of solutions to support researchers in cell preservation and storage.

These brands have made significant contributions to the development of cryopreservation media and continue to drive innovation in the field. Their products are used by scientists and institutions worldwide for various applications, from stem cell research to biobanking.

6. Yocon Biology Technology Company

Yocon offers a GMP grade cell freezing medium for cryopreservation cells. It's a chemically-defined without DMSO and protein-free. This media can be transport and stroage in room temperature.