The Joint Research Center of Guangzhou University and Keele University for Gene Interference and Application, School of Life Sciences, Guangzhou University, Guangzhou 510006, China.
Int J Mol Sci. 2022 Sep 4;23(17):10144. doi: 10.3390/ijms231710144.
Understanding interactions between bone morphogenetic proteins (BMPs) and biomaterials is of great significance in preserving the structure and bioactivity of BMPs when utilized in clinical applications. Currently, bone morphogenetic protein-2 (BMP-2) is one of the most important growth factors in bone tissue engineering; however, atomistic interactions between BMP-2 and zinc-substituted hydroxyapatite (Zn-HAP, commonly used in artificial bone implants) have not been well clarified until now. Thus, in this work, the interaction energies, binding/debinding states, and molecular structures of BMP-2 upon a series of Zn-HAP surfaces (Zn-HAPs, 1 at%, 2.5 at%, 5 at%, and 10 at% substitution) were investigated by hybrid molecular dynamics (MD) and steered molecular dynamics (SMD) simulations. Meanwhile, cellular studies including alkaline phosphatase (ALP) activity and reverse transcription-polymerase chain reaction (RT-PCR) assay were performed to verify the theoretical modeling findings. It was found that, compared to pure HAP, Zn-HAPs exhibited a higher binding affinity of BMP-2 at the adsorption process; meanwhile, the detachment of BMP-2 upon Zn-HAPs was more difficult at the desorption process. In addition, molecular structures of BMP-2 could be well stabilized upon Zn-HAPs, especially for Zn10-HAP (with a 10 at% substitution), which showed both the higher stability of cystine-knots and less change in the secondary structures of BMP-2 than those upon HAP. Cellular studies confirmed that higher ALP activity and osteogenic marker gene expression were achieved upon BMP-2/Zn-HAPs than those upon BMP-2/HAP. These findings verified that Zn-HAPs favor the adsorption of BMP-2 and leverage the bioactivity of BMP-2. Together, this work clarified the interaction mechanisms between BMP-2 and Zn-HAPs at the atom level, which could provide new molecular-level insights into the design of BMP-2-loaded biomaterials for bone tissue engineering.
了解骨形态发生蛋白（BMPs）与生物材料之间的相互作用对于在临床应用中保持 BMPs 的结构和生物活性具有重要意义。目前，骨形态发生蛋白-2（BMP-2）是骨组织工程中最重要的生长因子之一；然而，BMP-2 与锌取代羟基磷灰石（Zn-HAP，常用于人工骨植入物）之间的原子相互作用至今仍未得到很好的阐明。因此，在这项工作中，通过混合分子动力学（MD）和导向分子动力学（SMD）模拟研究了 BMP-2 与一系列 Zn-HAP 表面（Zn-HAP，1%、2.5%、5%和 10%取代）的相互作用能、结合/解吸状态和分子结构。同时，进行了包括碱性磷酸酶（ALP）活性和逆转录-聚合酶链反应（RT-PCR）测定的细胞研究，以验证理论建模结果。结果发现，与纯 HAP 相比，Zn-HAP 在吸附过程中对 BMP-2 具有更高的结合亲和力；同时，在解吸过程中，BMP-2 从 Zn-HAP 上的脱附更加困难。此外，BMP-2 的分子结构在 Zn-HAP 上可以得到很好的稳定，尤其是对于 Zn10-HAP（取代度为 10%），其半胱氨酸结的稳定性更高，BMP-2 的二级结构变化更小。细胞研究证实，BMP-2/Zn-HAP 上的 ALP 活性和成骨标志物基因表达均高于 BMP-2/HAP。这些发现证实了 Zn-HAP 有利于 BMP-2 的吸附，并利用了 BMP-2 的生物活性。总之，这项工作在原子水平上阐明了 BMP-2 与 Zn-HAP 之间的相互作用机制，为骨组织工程中负载 BMP-2 的生物材料的设计提供了新的分子水平见解。
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