Rudich S M, Zhou S, Srivastava R, Escobedo J A, Perez R V, Manning W C
Department of Surgery, University of California, Sacramento, California 95817, USA.
J Surg Res. 2000 May 15;90(2):102-8. doi: 10.1006/jsre.2000.5859.
Anemia is a significant problem in many disease states. Erythropoietin (Epo) has been used in the treatment of anemia associated with numerous chronic diseases. This study investigates the dose-response profiles of a single intramuscular (im) injection of a recombinant adeno-associated virus vector (rAAV) containing the Epo gene with the goal of achieving a sustained elevation of hematocrit (Hct).
Cynomolgus (cm) monkeys were given single injections of different doses of rAAV-cm-Epo. The biological effect of Epo gene expression was monitored by determining the Hct levels and circulating hormone levels by ELISA. Antibody to the rAAV capsid protein was also measured over the 41-week period of the experiment.
Epo expression was noted only when 2 x 10(11) or more particles were injected. Epo was noted to be increased as soon as 1 week postinjection and was maximum in 6 to 8 weeks. This level of expression remained constant for nearly 20 weeks. Animals given the highest dose of rAAV developed a higher Hct over the first 8 weeks postinjection than those given an intermediate dose. However, the maximum levels of hemoglobin were the same. There was a weak correlation between amount of rAAV injected and capsid antibody response.
AAV vectors are able to transduce skeletal muscle and are capable of achieving sustained expression and systemic delivery of a therapeutic protein following a single im administration. Dose responses to rAAV-Epo are achievable, although a threshold inoculum of virus is necessary to produce an effect and the therapeutic window is narrow.
贫血在许多疾病状态中都是一个重要问题。促红细胞生成素（Epo）已被用于治疗与多种慢性疾病相关的贫血。本研究调查单次肌内注射含Epo基因的重组腺相关病毒载体（rAAV）的剂量反应情况，目的是实现血细胞比容（Hct）的持续升高。
给食蟹猴单次注射不同剂量的rAAV - 食蟹猴 - Epo。通过ELISA测定Hct水平和循环激素水平来监测Epo基因表达的生物学效应。在实验的41周期间还检测了针对rAAV衣壳蛋白的抗体。
仅当注射2×10¹¹或更多颗粒时才观察到Epo表达。注射后1周Epo即开始升高，6至8周时达到最高水平。这种表达水平在近20周内保持恒定。在注射后的前8周，给予最高剂量rAAV的动物比给予中等剂量的动物Hct更高。然而，血红蛋白的最高水平相同。注射的rAAV量与衣壳抗体反应之间存在弱相关性。
AAV载体能够转导骨骼肌，单次肌内给药后能够实现治疗性蛋白质的持续表达和全身递送。对rAAV - Epo的剂量反应是可以实现的，尽管产生效果需要一定的病毒接种阈值且治疗窗口较窄。
