McGoldrick Samantha J, Woo Bokyung, Kohn David H
Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA.
J Biomed Mater Res B Appl Biomater. 2025 Jul;113(7):e35612. doi: 10.1002/jbm.b.35612.
Bone morphogenetic proteins (BMPs) are widely recognized for their therapeutic efficacy in bone regeneration, but one side effect of these therapies is ectopic mineralization. Previous work identified a mineral-binding peptide (pVTK, VTKHNLQI(pS)Q(pS)Y; where pS denotes a phosphoserine) with the ability to inhibit mineralization in osteoblasts. This study investigated the application of pVTK for inhibiting ectopic mineralization secondary to BMP delivery in vitro and in vivo. It was hypothesized that a mineral binding peptide could be delivered alongside BMP to limit unwanted mineralization without limiting the pro-osteogenic effects of the BMP signaling pathway. In vitro, pVTK reduced BMP-stimulated mineral deposition in an osteoblast cell line, as determined by a significant reduction in extracellular matrix calcium deposition with > 300 μM pVTK (p < 0.0001) (at 50 ng/mL BMP2). Importantly, pVTK inhibited mineral deposition without competing with the BMP ligand or diminishing the osteogenic phenotype of the cells in response to BMP stimulation, as demonstrated by no changes in intracellular/extracellular osteogenic protein levels with addition of pVTK. In vivo, pVTK reduced ectopic mineralization of BMP-loaded subcutaneous implants by 92% (p = 0.0101) compared to PBS-treated controls. In an acellular model of spontaneous mineralization, pVTK disrupted mineral deposition and reduced crystallinity and crystal organization (as measured via Raman spectroscopy), demonstrating that pVTK is not solely reliant on cell mechanisms for inhibiting mineralization. These findings support the use of a mineral binding peptide for controlling ectopic mineralization secondary to BMP therapies without interfering with the BMP osteogenic pathway, which is necessary for a regenerative effect.
骨形态发生蛋白（BMPs）因其在骨再生中的治疗效果而被广泛认可，但这些疗法的一个副作用是异位矿化。先前的研究发现了一种矿物结合肽（pVTK，VTKHNLQI(pS)Q(pS)Y；其中pS表示磷酸丝氨酸），它能够抑制成骨细胞中的矿化。本研究调查了pVTK在体外和体内抑制BMP递送继发的异位矿化的应用。研究假设，一种矿物结合肽可以与BMP一起递送，以限制不必要的矿化，同时不限制BMP信号通路的促骨生成作用。在体外，pVTK减少了成骨细胞系中BMP刺激的矿物质沉积，在50 ng/mL BMP2时，>300 μM pVTK可使细胞外基质钙沉积显著减少（p<0.0001）。重要的是，pVTK抑制矿物质沉积，而不与BMP配体竞争，也不削弱细胞对BMP刺激的成骨表型，添加pVTK后细胞内/外成骨蛋白水平无变化即证明了这一点。在体内，与PBS处理的对照组相比，pVTK使负载BMP的皮下植入物的异位矿化减少了92%（p=0.0101）。在自发矿化的无细胞模型中，pVTK破坏了矿物质沉积，降低了结晶度和晶体组织（通过拉曼光谱测量），表明pVTK并非完全依赖细胞机制来抑制矿化。这些发现支持使用一种矿物结合肽来控制BMP疗法继发的异位矿化，而不干扰BMP成骨途径，这对再生效果是必要的。
