Controlled delivery of polypeptide hormone calcitonin

描述(申请人提供)：骨质疏松症是当今美国一个主要的公共健康威胁，影响着至少4400万美国人和高达55%的50岁以上的人。据估计，30%-50%的女性和15%-30%的男性会在一生中遭受与骨质疏松相关的骨折，也就是说，三分之一的女性和五分之一的男性会经历骨质疏松性骨折。到2050年，全球髋部骨折的发病率预计将增加约300%。引起临床关注的髋部、前臂和脊椎骨折的终生风险合计约为40%，相当于心血管疾病的风险。降钙素是一种含有32个氨基酸的多肽激素，分子质量约为3500。这种激素通过抑制骨吸收参与血钙水平的复杂调节。降钙素用于治疗骨质疏松症、Paget病和不同来源的低钙血症。目前，多次注射降钙素是治疗上述疾病的常用方法，因为其生物半衰期较短。已经证明，每天服用鲑鱼降钙素(SCT)可以有效地降低男性和绝经后女性的骨转换并保持骨量。SCT连续用药2个月后效果最好。该项目的长期目标是开发一种基于聚合物溶液的SCT控制释放系统，该系统可以在单次皮下注射后以预定的速度释放激素两个月。这一策略将避免每日注射，并为骨质疏松症患者提供最佳益处。我们建议研究两个具体目标：(1)。合成和表征随PLGA链长增加的聚乙二醇-聚丙交酯-聚乙交酯三嵌段共聚物(PEGPLGA-PEG3)。将制备基于原位凝胶形成共聚溶液的SCT控释系统，并研究SCT的流变性和体外释放特性。使用傅立叶变换红外光谱、圆二色谱、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法、天然十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法、基质辅助激光解吸/电离飞行时间质谱仪和高效液相色谱技术对释放的SCT以及SCT在凝胶中的稳定性进行评价。此外，将通过四甲基偶氮唑盐比色法评价缓释系统的体外生物相容性。(2)。目的：研究SCT缓释系统对激素性骨质疏松大鼠的体内吸收、生物测定及治疗效果。给药系统的体内生物相容性将在#年研究 对注射部位切除的组织进行光镜观察。建议的努力将极大地促进以可注射溶液的形式的温度敏感型聚合物给药系统的开发，以便在单次皮下注射后以受控速度在较长时间(~2个月)内给药SCT。开发这样一种新的治疗系统对于成功治疗骨病，特别是男性和绝经后女性的骨质疏松症，以提高患者的生活质量至关重要。 公共卫生相关性：骨质疏松性骨折是导致男性和绝经后女性残疾的严重原因。骨质疏松症在死亡率、发病率和经济成本方面给社会造成了巨大的负担。据国际骨质疏松症基金会统计，骨质疏松症每年导致数百万人骨折。骨质疏松症是当今美国一个主要的公共健康威胁，影响着至少4400万美国人和高达55%的50岁以上的人。目前，多次注射鲑鱼降钙素是治疗骨骼疾病的常见做法。本申请中提出的研究将研究热敏性三嵌段共聚物的合成及其表征。这些共聚物将用于开发注射溶液形式的受控释放系统，以便在SINLE皮下注射后以受控速度提供降钙素，持续时间更长(~2个月)。这项研究将在体外和体内进行动物模型。PHS 398/2590(05/01版)页面续格式页面

DESCRIPTION (provided by applicant): Osteoporosis is a major public health threat in the U.S. today affecting at least 44 million Americans and up to 55% of people over 50 years of age. It is estimated that 30-50% of women and 15-30% of men will suffer a fracture related to osteoporosis in their lifetime, in other words, 1 in 3 women and 1 in 5 men will experience an osteoporotic fracture. By the year 2050, the worldwide incidence of hip fracture is projected to increase by ~300%. The combined lifetime risk for hip, forearm, and vertebral fractures coming to clinical attention is ~40%, which is equal to the risk for cardiovascular disease. Calcitonin isa polypeptide hormone with 32 amino acids and has a molecular mass of about 3500. This hormone is involved in the complex regulation of blood calcium level by inhibiting bone resorption. Calcitonin is used therapeutically for the treatment of osteoporosis, Paget's disease, and hypocalcaemia of different origin. Currently, multiple injections of calcitonin is a common practice in treating the above conditions due to its short biological half-life. It has been demonstrated that daily administration of salmon calcitonin (sCT) effectively reduces bone turnover and maintains bone mass in men and postmenopausal women. The maximum effect is reached after 2 months of continuous administration of sCT. The long-term goal of this project is to develop a polymer solution based controlled delivery system of sCT, which can deliver the hormone at a predefined rate for two months after a single subcutaneous injection. This strategy would avoid daily injections and provide optimum benefits to the osteoporotic patients. We propose to study two specific aims: (1). To synthesize and characterize temperature sensitive poly (ethylene glycol) - poly (lactide-co-glycolide) - poly (ethylene glycol) (PEG-PLGA-PEG) triblock copolymers with increasing PLGA chain length. In situ gel forming copolymer solution based controlled delivery systems of the sCT will be prepared and studied for rheological characteristics and in vitro release profiles of sCT. The stability of the released sCT as well as sCT in the gel will be evaluated using Fourier transform infrared spectroscopy, circular dichroism, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, native sodium dodecyl sulfate-polyacrylamide gel electrophoresis, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and high performance liquid chromatography techniques. Further, in vitro biocompatibility of the delivery systems will be evaluated by MTT assay. (2). To study in vivo absorption, bioassay, and therapeutic efficacy of sCT delivery systems in the glucocorticoid induced osteoporosis rat model. In vivo biocompatibility of the delivery systems will be studied in rats by light microscopic studies of the excised tissue from the injection site. The proposed efforts will significantly contribute to the development of temperature sensitive polymer based delivery systems in the form of injectable solution to deliver sCT at a controlled rate for a longe duration (~ 2 months) after a single subcutaneous injection. Development of such a novel therapeutic system is critical for successful treatment of bone diseases, especially osteoporosis in men and postmenopausal women, in order to improve patient quality of life. PUBLIC HEALTH RELEVANCE: Osteoporotic fractures are a serious cause of disability in men and postmenopausal women. Osteoporosis causes a great burden to society in terms of mortality, morbidity, and economic costs. According to the statistics from International Osteoporosis Foundation, osteoporosis causes millions of fractures annually. Osteoporosis is a major public health threat in the U.S. today affecting at least 44 million Americans and up to 55% of people over 50 years of age. Currently, multiple injections of salmon calcitonin is a common practice in treating bone diseases. The research proposed in this application would investigate the synthesis of thermosensitive triblock copolymers and their characterization. The copolymers will be used to develop controlled delivery systems in the form of injectable solutions to deliver calcitonin at a controlled rate for a longer duration (~ 2 months) after a sinle subcutaneous injection. The study would be conducted in vitro and in vivo in animal model. PHS 398/2590 (Rev. 05/01) Page Continuation Format Page