Raman spectroscopic platform for transcutaneous monitoring of bone quality

项目概要 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，可导致严重的患者发病率和死亡率增加。预测 骨折风险主要取决于骨矿物质密度 (BMD) 的测量，这与以下因素密切相关： 骨强度，但不存在骨折风险。另外，拉曼光谱 (RS) 是一种光学技术，可以 提供有关矿物结晶度、成分和相对矿化程度（矿物/基质）的信息 比例），以及胶原蛋白成分和交联，已成为一种有前途的技术 评估骨强度和骨折风险。我们最近证明 RS 可以检测生化 类风湿性关节炎（RA）、糖皮质激素（GC）诱导的骨质疏松症小鼠模型中发生的变化 （GIOP）和成骨不全，与生物力学强度的独立测量相关 和断裂韧性。我们还开发了仪器来实现第一个诊断敏感 对完整肢体上的小鼠骨骼进行经皮拉曼测量，并采用复杂的算法 减少来自上层软组织的光学贡献，但这些测量仅在体外进行 组织标本。在此应用中，我们将开发新的仪器和算法来适应我们的 对活体动物进行经皮 RS 测量。更重要的是，基于未公开的数据 证明骨端（骨骺）比中轴（骨干）表现出更具辨别力的 RS 差异 区域，我们将重新设计 RS 平台中的激发/收集光学器件，以提供更大范围的源- 探测器分离，采样深度多样化，最终提高光谱解析能力 解剖学和生化更复杂的骨骺中干扰软组织的贡献 地区（目标 1）。然后，我们将验证并关联区域（骨骺与骨干）经皮 拉曼光谱测量与区域和整体骨力学（骨质量测量） 幼年小鼠、骨骼成熟小鼠和老年小鼠（目标 2）。最后，研究将证明我们的 经皮 RS 平台能够灵敏地检测小鼠骨质量的纵向下降 随着时间的推移，RA 和 GIOP 模型，以及抗骨吸收和骨质量的改善 合成代谢治疗（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、非接触式光学评估骨脆性和骨折风险，这是无法检测到的 标准指标，例如 BMD。虽然这项工作的成功完成将为我们带来一种新的工具 研究工具箱，以增进我们对骨质疏松症机制的理解并评估新药物的功效 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 在不久的将来将被扩大并转化为临床实验诊断工具。

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 More importantly, based on unpublished data demonstrating that bone ends (epiphyses) exhibit more discriminate RS differences than mid-shaft (diaphysis) regions, we will redesign the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.