Figure 1. Structure of human serum albumin ^[1] 

 3.Application of Recombinant Serum Albumin

3.1. Albumin is a serum-free culture medium supplement

Albumin is an important component of many serum-free cell culture systems, such as those for hybridoma cells and Chinese hamster ovary (CHO) cells.Albumin can be incorporated into cell scaffolds to provide cells with essential nutrients and a source of growth factors, promoting cell survival and proliferation. Human serum albumin is used as a cell culture medium supplement to maintain the growth and health of cells used in the production of monoclonal antibodies, recombinant proteins, and other biological products. Albumin can also make the cell culture environment more stable and controllable, reducing the batch-to-batch variability and contamination risks associated with animal-derived serum.

3.2. Mammalian cell culture

Albumin binds a wide range of bioactive substances making it a key transport molecule. Albumin also scavenge reactive oxygen species that are detrimental to cell survival. These properties make albumin an excellent choice for promoting cell growth and maintaining a variety of eukaryotic cells in vitro. Recombinant human albumin is well suited for a variety of different stem, primary and production cell types including immune cells, VERO, mesenchymal stem cells, HEK293, diploid cells, CHO and other cell types. 

3.3. Vaccine production and preparation 

HSA is an important component for stabilizing vaccines, providing multiple benefits for a variety of vaccine types, including live attenuated viruses, inactivated or killed viruses, virus-like particles, and subunit vaccines. One of the notable properties of HSA is its ability to coat both hydrophobic and hydrophilic surfaces, thereby preventing undesirable nonspecific adsorption of vaccines throughout their life cycle, from production to formulation to storage. Through its binding ability, capable of both ionic and hydrophobic interactions, HSA can protect exposed vaccine surfaces from unwanted aggregation and particle formation, which could otherwise compromise vaccine efficacy. 

3.4. In vitro/in vivo disease diagnosis

 HSA is a biomarker for a variety of diseases, including cancer, rheumatoid arthritis, ischemia, liver disease, obesity, and diabetes. 

3.5 Application of human serum albumin in stem cell therapy 

Albumin has long been an essential component of cell culture media. Its ability to promote the growth of a variety of cell types is well documented, including mesenchymal stem cells (MSCs), embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and immune cells. In cell culture, albumin is more than just a nutrient source. It acts as a multifunctional reservoir, protecting essential metals and other molecular entities, thereby creating an optimal environment for continued cell growth and viability.

In addition to its application in cell culture, albumin can also be used for stem cell cryopreservation. Albumin's surface coating ability ensures the safety of cells during the freezing process. In addition, albumin's buffering ability maintains the pH balance necessary for cell integrity, while its stabilizing ability keeps cells in suspension, thereby extending their viability during cryopreservation.

In addition, albumin can also be used as a drug carrier to prolong the circulation time of drugs in the body and enhance drug efficacy. 

4.Mechanism of action of Albumin in culture medium 

4.1 Bounding fatty acids

Albumin is a carrier for 99% of the non-esterified fatty acids (FA) in plasma. Albumin has 7 high-affinity and more than 20 low-affinity FA binding sites. Fatty acids such as linoleic acid, linolenic acid, and oleic acid are insoluble in aqueous solution and must be delivered to cells via carrier molecules. Circulating albumin can usually carry 1 or 2 free fatty acids. The binding of fatty acids also helps stabilize albumin. As a cell culture additive, the activity of albumin depends in part on the specific fatty acids it binds and delivers to cells.

4.2 Binding of Metal Ions

Metal ions are essential components for cell culture. HSA is a key transporter for the key metal ions Cu 2+ and Zn 2+. In addition, copper atoms can undergo monovalent redox reactions and catalyze the generation of free radicals, making copper cytotoxic. In vivo, extracellular copper ions bind to albumin, weakening the potential toxicity of copper. Each albumin molecule has a high-affinity copper binding site, and when copper is bound to this site, it will not participate in free radical-related redox reactions. Albumin can also bind other divalent cations such as Ca, Mg, Mn, Cd, Co and Ni.

4.3 Antioxidant properties of HSA

The antioxidant activity of HSA is mainly attributed to the redox properties of four major metal binding sites. Free Cu 2+, Fe 2+ and other metal ions react with oxygen to generate ROS , which can also interact with H2O2 to produce harmful hydroxyl radicals. On the other hand, the binding of albumin to metal ions limits the ability of these ions to participate in ROS generation.

Industrial-scale eukaryotic cell cultures carried out in bioreactors contain dissolved oxygen and free metals such as iron, copper, cobalt and nickel, which produce ROS that degrade cell membranes. Addition of BSA or HSA reduces ROS pressure, resulting in healthy cell cultures. On the other hand, the binding of albumin to these metals, especially copper, zinc, vanadium and selenium, promotes the uptake of these metals by cells, stimulates culture growth and significantly improves the production of recombinant proteins in eukaryotic cells.

4.4 Binding pyridoxal

Amino acids are key components of cell culture media. Pyridoxal and its derivative 5' pyridoxal phosphate (PLP) can react non-enzymatically with amino acids and form Schiff bases. These Schiff bases are very unstable and when in contact with metal ions, they lead to amino acid degradation and cell growth inhibition. The free pyridoxal fraction is sequestered by binding to albumin, which prevents pyridoxal from reacting with amino acids in vitro and destroying them.

4.5 Binding riboflavin

Riboflavin is another factor that reacts with free amino acids and degrades them. In aqueous solution, riboflavin can bind to tryptophan to form a complex. Under light conditions, this complex decomposes into toxic products. Albumin can bind to riboflavin and its phosphate (flavin monophosphate) and protect them from degradation. Albumin has a single tryptophan binding site.

5.Product Features 

Yeasen provides a variety of recombinant serum albumin, including human, mouse, rat, monkey and other species.