Impact of Weak Vibration Generated by a Refrigerator on Protein Aggregation.

Protein aggregates and particles in biopharmaceuticals can induce adverse immune responses in patients. Thus, suppression of the formation of protein aggregates and particles is important for the successful development of therapeutic proteins. Mechanical stresses, including agitation, are widely recognized as stress factors that generate protein aggregates and particles. However, although refrigerators and storage chambers generate weak vibration, there have been no studies of the impact of such weak vibration on aggregate and particle formation during storage. In this study, monomer loss and aggregate formation of a CTLA4-Ig were evaluated during storage in a refrigerator (having a vibration acceleration less than 0.006 G) with or without three vibration isolators. The vibration isolators reduced the vibration acceleration, thereby decreasing the rate of monomer loss and nanometer-sized aggregate formation. The increase in the aggregation rate due to the weak vibration was not mitigated by adding poloxamer 188 or eliminating the air-liquid interface, which are processes known to be effective in preventing protein aggregation due to mechanical stresses. Thus, reducing vibration should be an effective way to mitigate the risk of aggregate formation.