Raman spectroscopic platform for transcutaneous monitoring of bone quality

项目摘要 在没有重大创伤的情况下发生的骨脆性骨折通常与原发性或 继发性骨质疏松症，并可导致严重的患者发病率和死亡率增加。预测 骨折风险主要依赖于骨密度(BMD)的测量，骨密度与 骨骼强度，但不存在骨折风险。或者，拉曼光谱(RS)，一种光学技术，可以 提供有关矿物结晶度、成分和矿化相对程度(矿物/基质)的信息 比率)，以及胶原成分和交联度，已经成为一种很有前途的技术 评估骨骼强度和骨折风险。我们最近已经证明RS可以检测生化 类风湿关节炎(RA)、糖皮质激素(GC)诱导的骨质疏松症小鼠模型的变化 (GIOP)和成骨不全，这与独立的生物力学强度指标相关 和断裂韧性。我们还开发了仪器，使第一个诊断敏感 对完整肢体上的鼠骨进行经皮拉曼测量，以及复杂的算法 减少覆盖软组织的光学贡献，但这些测量只在体外进行 组织标本。在此应用程序中，我们将开发新的工具和算法以适应我们的 活体动物的经皮遥感测量。更重要的是，基于未公布的数据 表明骨端(骨骺)比中段(骨干)表现出更多的区分RS差异。 我们将重新设计RS平台中的激发/收集光学元件，以提供更大范围的光源- 探测器分离，采样深度变化更大，最终提高光谱的分辨能力 干扰软组织在解剖和生化更为复杂的骨痂中的作用 区域(目标1)。然后，我们将验证并关联经皮穿入的区域(骨骺与骨干)。 用局部和整体骨力学的拉曼光谱测量(骨质量的测量) 幼年、骨骼成熟和老年小鼠(目标2)。最后，研究将证明我们的 经皮RS平台具有检测小鼠骨质量纵向减少的敏感性 随着时间的推移，RA和GIOP的模型，以及抗吸收和治疗对骨质量的改善 合成代谢疗法(目标3)。完成后，拟议的研究将验证一项颠覆性技术 用于临床前、非接触式骨脆性和骨折风险的光学评估，这些评估无法通过 标准指标，如BMD。虽然这项工作的成功完成将产生一个新的工具在我们的 研究工具箱，以促进我们对骨质疏松机制的理解，并评估新的治疗方法的疗效 临床前模型中的药物，我们希望我们在这里取得的进展将使这种非侵入性技术能够 在不久的将来，将被放大并翻译为临床上的实验性诊断工具。

Project Summary Bone fragility fractures that occur in the absence of significant trauma are often associated with primary or secondary osteoporosis, and can result in serious patient morbidity and increased mortality rates. Prediction of bone fracture risk primarily relies on measures of bone mineral density (BMD), which is strongly correlated with bone strength, but not with fracture risk. Alternatively, Raman spectroscopy (RS), an optical technique that can provide information on mineral crystallinity, composition, and relative degree of mineralization (mineral/matrix ratio), as well as collagen composition and cross-linking, has emerged as a promising technique for assessment of bone strength and fracture risk. We have recently shown that RS can detect biochemical changes that occur in mouse models of rheumatoid arthritis (RA), glucocorticoid (GC)-induced osteoporosis (GIOP), and osteogenesis imperfecta, which correlated with independent measures of biomechanical strength and fracture toughness. We have also developed instrumentation to enable the first diagnostically-sensitive transcutaneous Raman measurements of murine bone on intact limbs, along with sophisticated algorithms to reduce optical contributions from overlying soft tissue, but these measurements were only made ex vivo on tissue specimens. In this application, we will develop new instrumentation and algorithms to adapt our transcutaneous RS measurements on live animals. More importantly, based on unpublished data demonstrating that bone ends (epiphyses) exhibit more discriminate RS differences than mid-shaft (diaphysis) regions, we will redesign the excitation/collection optics in our RS platform to provide a larger range of source- detector separation, greater variety in sampling depth, and ultimately improve the ability to resolve the spectral contributions from interfering soft tissues in the more anatomically and biochemically complex epiphyses regions (Aim 1). We will then validate and correlate regional (epiphysis versus diaphysis) transcutaneous Raman spectroscopy measurements with regional and whole bone mechanics (measures of bone quality) in juvenile, skeletally mature, and aged mice (Aim 2). Finally, the studies will demonstrate that our transcutaneous RS platform has the sensitivity to detect longitudinal reductions in bone quality in mouse models of RA and GIOP over time, and improvements in bone quality in response to anti-resorptive and anabolic treatments (Aim 3). Upon completion, the proposed studies will have validated a disruptive technology for pre-clinical, non-contact optical assessment of bone fragility and fracture risk, which are undetectable by standard metrics such as BMD. While successful completion of this work will yield a new instrument in our research toolbox to advance our understanding of mechanisms of osteoporosis and to evaluate efficacy of new drugs in preclinical models, we hope that the progress we make here will allow this non-invasive technology to be scaled-up and translated in the not too distant future as an experimental diagnostic tool in the clinic.