Osborne W R, Ramesh N, Lau S, Clowes M M, Dale D C, Clowes A W
Department of Pediatrics, University of Washington, Seattle 98195, USA.
Proc Natl Acad Sci U S A. 1995 Aug 15;92(17):8055-8. doi: 10.1073/pnas.92.17.8055.
The injection of recombinant erythropoietin (Epo) is now widely used for long-term treatment of anemia associated with chronic renal failure, cancer, and human immunodeficiency virus infections. The ability to deliver this hormone by gene therapy rather than by repeated injections could provide substantial clinical and economic benefits. As a preliminary approach, we investigated in rats the expression and biological effects of transplanting autologous vascular smooth muscle cells transduced with a retroviral vector encoding rat Epo cDNA. Vector-derived Epo secretion caused increases in reticulocytes, with peak levels of 7.8-9.6% around day 10 after implantation. The initial elevation in reticulocytes was followed by clinically significant increases in hematocrit and hemoglobin for up to 11 weeks. Ten control and treated animals showed mean hematocrits of 44.9 +/- 0.4% and 58.7 +/- 3.1%, respectively (P < 0.001), and hemoglobin values of 15.6 +/- 0.1 g/dl and 19.8 +/- 0.9 g/dl, respectively (P < 0.001). There were no significant differences between control and treated animals in the number of white blood cells and platelets. Kidney and to a lesser extent liver are specific organs that synthesize Epo in response to tissue oxygenation. In the treated animals, endogenous Epo mRNA was largely down regulated in kidney and absent from liver. These results indicate that vascular smooth muscle cells can be genetically modified to provide treatment of anemias due to Epo deficiency and suggest that this cell type may be targeted in the treatment of other diseases requiring systemic therapeutic protein delivery.
重组促红细胞生成素（Epo）注射目前广泛用于长期治疗与慢性肾衰竭、癌症及人类免疫缺陷病毒感染相关的贫血。通过基因疗法而非反复注射来递送这种激素，可能会带来显著的临床和经济效益。作为初步方法，我们在大鼠中研究了移植用编码大鼠Epo cDNA的逆转录病毒载体转导的自体血管平滑肌细胞的表达及生物学效应。载体衍生的Epo分泌导致网织红细胞增加，植入后第10天左右达到峰值水平7.8 - 9.6%。网织红细胞最初升高后，血细胞比容和血红蛋白在长达11周内出现临床上显著增加。10只对照动物和治疗动物的平均血细胞比容分别为44.9±0.4%和58.7±3.1%（P<0.001），血红蛋白值分别为15.6±0.1 g/dl和19.8±0.9 g/dl（P<0.001）。对照动物和治疗动物在白细胞和血小板数量上无显著差异。肾脏以及程度较轻的肝脏是响应组织氧合而合成Epo的特定器官。在治疗动物中，内源性Epo mRNA在肾脏中大量下调，在肝脏中未检测到。这些结果表明，血管平滑肌细胞可通过基因改造来治疗因Epo缺乏导致的贫血，并提示这种细胞类型可能是治疗其他需要全身递送治疗性蛋白质的疾病的靶点。
