Bone Morphogenetic Protein 2 (BMP-2) Aggregates Can be Solubilized by Albumin—Investigation of BMP-2 Aggregation by Light Scattering and Electrophoresis

Abstract

Bone morphogenetic protein 2 (BMP-2) has a high tendency to aggregate at physiological pH and physiological ionic strength, which can complicate the development of growth factor delivery systems. The aggregation behavior in differently concentrated BMP-2 solutions was investigated using dynamic and static light scattering. It was found that at higher concentrations larger aggregates are formed, whose size decreases again with increasing dilution. A solubilizing effect and therefore less aggregation was observed upon the addition of albumin. Imaged capillary isoelectric focusing and the simulation of the surface charges of BMP-2 were used to find a possible explanation for the unusually low solubility of BMP-2 at physiological pH. In addition to hydrophobic interactions, attractive electrostatic interactions might be decisive in the aggregation of BMP-2 due to the particular distribution of surface charges. These results help to better understand the solubility behavior of BMP-2 and thus support future pharmaceutical research and the development of new strategies for the augmentation of bone healing.

ELISA- and Activity Assay-Based Quantification of BMP-2 Released In Vitro Can Be Biased by Solubility in “Physiological” Buffers and an Interfering Effect of Chitosan

“…Tween 20 and BSA apparently had a solubilizing effect on BMP-2 and prevented its precipitation at pH 7.2. Previous studies have shown that albumin influences the size of BMP-2 aggregates [ 23 ]. It was also found that BMP-2 still largely remained in the form of redissolvable aggregates despite the addition of BSA and Tween 20.…”

“… Schematic presentation of the proposed effect of chitosan on the aggregation tendency of BMP-2. Left (without chitosan): Ionic BMP-2 self-interaction, leading to BMP-2 aggregation [ 23 ]. Right: Binding of chitosan to the negatively charged tips of BMP-2 [ 27 ], potentially leading to a decreased aggregation tendency.…”

“…BMP-2 has an isoelectric point (pI) of about 8.5 after chaotropic denaturation [ 21 ] and the tendency to form redissolvable aggregate particles of native protein with a pI of 7.7–8.3 at physiologic ionic strength and pH [ 22 , 23 ]. We were interested in the potential influence of poor BMP-2 solubility in physiological buffers like PBS [ 24 ] on the outcome of in vitro release tests.…”

Evaluation of the potential immunogenicity of recombinant human bone morphogenetic proteins

“…Известно, что BMPs, в частности BMP-2, имеет высокую склонность к агрегации при физиологических pH, что может усложнить разработку систем доставки данных белков [21]. Как правило, образование антител происходит либо зависимым от Т-клеток, либо независимым от Т-клеток образом.…”

Applications of capillary electrophoresis for biopharmaceutical product characterization

“…The method was proposed as a simple, rapid, and economical alternative to LC-based approaches. Additional methods were also developed for analyzing the charge heterogeneity and aggregation/solubility of cytokines [113,114].…”