| 학회 | 한국고분자학회 |
| 학술대회 | 2004년 가을 (10/08 ~ 10/09, 경북대학교) |
| 권호 | 29권 2호, p.121 |
| 발표분야 | 생체적합성 유ㆍ무기 입자소재 |
| 제목 | Receptor-Mediated Molecular Imaging Using Tc-99m Labeled Chitosan Conjugates |
| 초록 | Non-invasive nuclear imaging is one of important tools for evaluating various pathologic conditions such as inflammation and cancer in living subjects. The need to develop target-specific MRI contrast agents to aid disease diagnosis remains highly essential. Nearly 80 % of all radiopharmaceuticals used in nuclear medicine are 99mTc-labeled compounds. The reason for such a preeminent position of Tc-99m in clinical use is its extremely favorable physical and radiation characteristics. The 6-hr physical half-life and the little amount of electron emission permit the administration of millicurie amounts of Tc-99m radioactivity without significant radiation dose to the patient. Macromolecular contrast agents due to their larger size enable longer imaging times and possess higher relaxation times. Also, it can be applied as a quantitative non-invasive way to monitor the location, magnitude, and persistence of gene expression over time. Recently, nuclear physicians and researchers have interested in organ and tissue targeted molecular imaging using receptor-specific ligand. Asialoglycoprotein receptors (ASGPR) and transferrin receptors are useful ligands for hepatocytes, and inflammatory cells, respectively. Mammalian hepatocytes are the only cells that possess large numbers of high affinity cell-surface receptors that can bind asialoglycoproteins bearing therminal galactose group. Transferrin receptors were expressed on the surfaces of tumor and inflammatory cells. In tumor cells which rapidly proliferate, transferrin receptors are upregulated due to the need for increasing non-hem iron to catalyze the first and rate-limiting step of DNA synthesis. Thus rapidly proliferating tumors with a high level of DNA synthesis would have a higher number of transferrin receptors. In inflammatory site, transferrin leaked from vessels due to vascular permeability bind to transferrin receptor on leukocytes and bacteria. Transferrin is thought to be a major ligand to find tumor cells and inflammatory foci through such these mechanisms. For in vivo ASGPR and transferrin receptor imaging in animal model, we designed galactosylated chitosan and transferrin / chitosan conjugate and bound bifunctional chelating agents to chitosan for labelling with Tc-99m. We also checked the possibility of a novel diagnostic radiopharmaceutical of specific ligand-conjugated chitosan derivatives for tumor and inflammation imaging as well as liver imaging. Acknowledgements This research was supported by the grant of Nuclear Energy R & D Program from the Ministry of Science and Technology of Korea (M20203200028-02A0702-00411). |
| 저자 | 박인규1, 정환정2, 김은미2, 범희승3, Toshihiro Akaike4, 조종수1 |
| 소속 | 1서울대, 2원광대, 3전남대, 4동경공대 생체분자공학과 |
| 키워드 | Molecular imaging; chitosan; hepatocyte; ASGPR; inflammation site; transferrin; gene delivery |
