Controlled delivery of polypeptide hormone calcitonin

描述（由申请人提供）：骨质疏松症是当今美国主要的公共卫生威胁，影响了至少4400万美国人和高达55%的50岁以上人群。据估计，30-50%的女性和15-30%的男性在其一生中会经历与骨质疏松相关的骨折，换句话说，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%。髋部、前臂和椎体骨折引起临床注意的合并终生风险约为40%，与心血管疾病的风险相等。降钙素是一种由32个氨基酸组成的多肽激素，分子量约为3500。这种激素通过抑制骨吸收参与复杂的血钙水平调节。降钙素用于治疗骨质疏松症、佩吉特病和不同原因的低钙血症。目前，多次注射降钙素是治疗上述疾病的常见做法，因为它的生物半衰期短。已经证明，鲑鱼降钙素（sCT）的日常管理有效地减少骨转换和维持骨量的男性和绝经后妇女。连续给予sCT 2个月后达到最大效果。该项目的长期目标是开发一种基于聚合物溶液的sCT控制输送系统，该系统可以在单次皮下注射后以预定的速率输送激素两个月。这种策略可以避免每天注射，并为骨质疏松症患者提供最佳的益处。我们建议研究两个具体目标：(1)。合成具有温度敏感性的聚乙二醇-聚丙交酯-共聚乙二醇-聚乙二醇-聚乙二醇-聚乙二醇-聚乙二醇三嵌段共聚物，并对其进行表征。制备了基于原位凝胶形成共聚物溶液的sCT控制递送系统，并研究了sCT的流变特性和体外释放谱。将使用傅里叶变换红外光谱、圆二色性、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、天然十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、基质辅助激光解吸/电离飞行时间质谱和高效液相色谱技术评估释放的sCT以及凝胶中的sCT的稳定性。此外，将通过MTT试验评估递送系统的体外生物相容性。(2)。目的：研究糖皮质激素诱导骨质疏松大鼠模型中sCT给药系统的体内吸收、生物测定和治疗效果。在体内生物相容性的递送系统将研究

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