Magnetic Delivery of Therapeutic Nanoparticles to the Dental Pulp

描述（由申请人提供）：牙髓炎症或牙髓炎是一种常见、痛苦且昂贵的全球公共卫生问题，影响患者的生活质量。在大多数情况下，牙髓炎是中度或晚期龋齿（蛀牙）的结果，龋齿是世界上最常见的慢性疾病。牙髓炎也可由对敏感牙齿的反复热损伤、牙齿磨损、创伤、牙齿修复的微渗漏和牙周炎（支撑牙齿的组织的炎症）引起。牙髓炎的特征是由热刺激引起的尖锐的刺痛（可逆性牙髓炎）或使人衰弱的、钝的、搏动性的疼痛 自发发生或可由机械或热刺激诱发，并在刺激停止后持续，需要紧急护理（不可逆牙髓炎）。疼痛的性质和严重程度与细菌和其他病因的刺激程度相关。诊断可能很复杂，因为疼痛可能涉及其他口面结构，或邻近的牙齿。我们最近发明了一种新技术，可以将治疗剂输送到牙髓，而不会影响牙髓腔的完整性。为此，我们利用天然存在的牙本质小管（~0.3 - 2？牙本质中直径为20 μ m的通道），并使用磁力将治疗性磁性颗粒引导到牙髓中。初步实验表明，使用我们设计的磁体阵列，在大约30分钟内将100-500 nm的淀粉涂层颗粒有效递送到提取的人牙齿的髓室。在这项申请中，我们寻求资金，使我们能够开发这种创新技术，并测试其对牙髓组织和牙齿周围组织的影响。我们的目标：目标1。检测生物相容性纳米颗粒通过牙本质小管进入牙髓的磁动力学和药代动力学。我们将使用一种体外制备的新鲜拔除的人牙，并研究：（1）递送到牙髓中的最佳粒度;（2）多糖涂层的效果（淀粉与壳聚糖）对颗粒向纸浆递送的影响;（3）治疗药物的量（泼尼松龙或氧氟沙星），以及在停止施加磁力后这些治疗剂的持续释放速率。纳米颗粒浓度将使用电感耦合等离子体原子发射光谱法（ICP-AES）测定，药物水平将使用高效液相色谱-质谱法定量。目标2.为了量化药物缀合的纳米颗粒在体内向牙髓的递送，并评估这些纳米颗粒的作用， 纳米颗粒在正常和病理条件下对牙髓组织的作用。我们将在大鼠的臼齿上制备不同深度的洞。我们将应用纳米颗粒与多糖或结合泼尼松龙，或氧氟沙星涂层（粒度将基于目标1的结果）和：（1）评估在将多糖包被的纳米颗粒应用于大鼠磨牙中实验制备的洞之后牙髓生物学和周围牙齿组织的变化;（2）检测药物结合纳米粒（泼尼松龙和氧氟沙星）对直接或间接损伤牙髓的作用。我们将使用组织学检查来测试 牙髓生物学的变化、牙髓和牙齿周围组织中的炎性细胞浸润、牙周膜（牙齿周围组织）的厚度。我们还将使用ICP-AES来确定牙齿内的纳米颗粒浓度。

DESCRIPTION (provided by applicant): Inflammation of the dental pulp, or pulpitis, is a common, painful, and costly global public health problem that affects quality of life of patients. n most cases, pulpitis is a consequence of moderate or advanced dental caries (tooth decay), the most common chronic disease in the world. Pulpitis can also result from repeated thermal insults to a sensitive tooth, tooth attrition, trauma, microleakage of dental restorations, and periodontitis (inflammation of tissues supporting the teeth). Pulpitis is characterized by sharp shooting pain evoked by thermal stimuli (reversible pulpitis) or debilitating, dull, throbbing pain that occurs spontaneously or can be evoked by mechanical or thermal stimuli and lingers after cessation of the stimulus, necessitating emergency care (irreversible pulpitis). The quality and severity of the pain correlates with the extent of irritation from bacteria and other etiologies. Diagnosis can be complicated because the pain can be referred to other orofacial structures, or to adjacent teeth. We recently invented a new technique to deliver therapeutic agents to the pulp without affecting the integrity of the pulp chamber. To do so, we take advantage of naturally occurring dentinal tubules (~0.3 - 2 ?m diameter channels in dentin), and use magnetic forces to direct therapeutic magnetic particles into the tooth pulp. Preliminary experiments demonstrated efficient delivery of 100-500 nm starch-coated particles to the pulp chamber of extracted human teeth in approximately 30 minutes, using magnet arrays of our design. In this application, we seek funds to allow us to develop this innovative technique and to test its effect on pulpal tissues and tissues surrounding the teeth. We aim: Aim 1. To test the magneto-dynamics and pharmacokinetics of biocompatible nanoparticles guided to the pulp through dentinal tubules. We will use an in vitro preparation of freshly extracted human teeth and investigate: (1) The optimum particle size for delivery into the pulp; (2) The effect of polysaccharide coating (starch vs. chitosan) on the delivery of particles to the pulp; and (3) The amount of therapeutic medication (prednisolone or ofloxacin) that can be delivered to the pulp and the rate of sustained release of these therapeutic agents after magnetic force application is stopped. Nanoparticle concentrations will be determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and drug levels will be quantified using high performance liquid chromatography coupled with mass spectrometry. Aim 2. To quantify delivery of drug-conjugated nanoparticles to the pulp in vivo, and to evaluate the effects of these nanoparticles on pulpal tissues under normal and pathologic conditions. We will prepare cavities of various depths in the molar teeth of rats. We will apply nanoparticles coated with polysaccharides or conjugated to prednisolone, or ofloxacin (particle size will be based on results from Aim 1) and: (1) Assess changes in pulpal biology and surrounding dental tissues after the application of polysaccharide-coated nanoparticles to experimentally prepared cavities in rat molars; and (2) Test the effect of drug-conjugated nanoparticles (prednisolone, and ofloxacin) on directly or indirectly injured pulp. We will use histological examination to test for changes in pulpal biology, inflammatory cell infiltration in the pulp and tissues surrounding the tooth, thickness of periodontal ligament (tissues surrounding the tooth). We will also use ICP-AES to determine nanoparticle concentration within the teeth.