Effect of aggregate seeding on protein stability in solution

The stability of therapeutic proteins is crucial for maintaining their efficacy and safety. Misfolded or aggregated proteins can accelerate aggregation by a seeding effect, altering protein stability and interactions. Heat-induced aggregates can pose a risk because they can have perturbed structures that expose aggregate-prone regions. This study explored seeding by heat-induced protein aggregates on the stability and aggregation of two therapeutic proteins, human growth hormone (hGH) and a monoclonal Antibody (Antibody A), during storage of two weeks at three relevant temperatures of 4 °C, room temperature (RT, 21-23 °C), and 40 °C. Grwoth of aggregates were seen in the sub-micron-sized aggregates by Dynamic Light Scattering at 4 °C or RT. Furthermore, heated Antibody A showed signs of reversibility of higher-order structure after storage. Samples stored at 4 °C and RT showed similar stability and aggregation behaviour. While two weeks of storage at 40 °C accelerated the structural degradation of both proteins, it did not accelerate aggregation or particle formation for either hGH or Antibody A.