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

• Published in: Pharmaceutics Vol. 13; no. 4; p. 582
• Main Authors: Sundermann, Julius, Sydow, Steffen, Burmeister, Laura, Hoffmann, Andrea, Menzel, Henning, Bunjes, Heike
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 19.04.2021; MDPI
• Subjects: Acids; BMP-2; bone morphogenetic protein 2; chitosan; Electrolytes; Experiments; Growth factors; matrix effects; Nanoparticles; Physiology; Product development; Proteins; release quantification; Transplants & implants; United States > US; Germany; release quantification; chitosan; bone morphogenetic protein 2; BMP-2; matrix effects
• ISSN: 1999-4923; 1999-4923
• DOI: 10.3390/pharmaceutics13040582

Chitosan nanogel-coated polycaprolactone (PCL) fiber mat-based implant prototypes with tailored release of bone morphogenic protein 2 (BMP-2) are a promising approach to achieve implant-mediated bone regeneration. In order to ensure reliable release results, the robustness of a commercially available ELISA for -derived BMP-2 and the parallel determination of BMP-2 recovery using a quantitative biological activity assay were investigated within a common release setup, with special reference to solubility and matrix effects. Without bovine serum albumin and Tween 20 as solubilizing additives to release media buffed at physiological pH, BMP-2 recoveries after release were notably reduced. In contrast, the addition of chitosan to release samples caused an excessive recovery. A possible explanation for these effects is the reversible aggregation tendency of BMP-2, which might be influenced by an interaction with chitosan. The interfering effects highlighted in this study are of great importance for bio-assay-based BMP-2 quantification, especially in the context of pharmaceutical release experiments.