Department of Medicine, UCLA, Los Angeles, CA 90024, USA.
Brain Res. 2010 Nov 11;1360:193-7. doi: 10.1016/j.brainres.2010.09.009. Epub 2010 Sep 9.
Erythropoietin (EPO) is a potent neuroprotective agent that could be developed as a new treatment for stroke. However, the blood-brain barrier (BBB) is intact in the early hours after stroke when neuroprotection is still possible, and EPO does not cross the intact BBB. To enable BBB transport, human EPO was re-engineered as an IgG-EPO fusion protein, wherein the IgG part is a monoclonal antibody (MAb) against the human insulin receptor (HIR). The HIRMAb acts as a BBB molecular Trojan horse to ferry the fused EPO across the BBB via transport on the BBB insulin receptor. The HIRMAb part of the HIRMAb-EPO fusion protein does not recognize the rat insulin receptor. However, the EPO part of the fusion protein does recognize the rat EPO receptor. Therefore, the neuroprotective properties of the HIRMAb-EPO fusion protein were investigated with a permanent middle cerebral artery occlusion model in the rat. The HIRMAb-EPO fusion protein was injected into the ipsilateral brain under stereotaxic guidance. High doses of the HIRMAb-EPO fusion protein (61pmol) completely eliminated both cortical and sub-cortical infarction. Lower doses of the fusion protein (4.5pmol) eliminated the cortical infarct with no significant effect on sub-cortical infarct. The neurologic deficit was reduced by 35% and 90%, respectively, by the 4.5 and 61pmol doses of the HIRMAb-EPO fusion protein. In conclusion, these studies demonstrate the biological activity of the HIRMAb-EPO fusion protein in the brain in vivo, and that EPO retains neuroprotective properties following fusion to the HIRMAb BBB Trojan horse.
促红细胞生成素（EPO）是一种有效的神经保护剂，可开发为治疗中风的新方法。然而，在中风发生后的早期，血脑屏障（BBB）是完整的，此时仍有可能进行神经保护，而 EPO 不能穿过完整的 BBB。为了使 BBB 转运，将人 EPO 重新设计为 IgG-EPO 融合蛋白，其中 IgG 部分是针对人胰岛素受体（HIR）的单克隆抗体（MAb）。HIRMAb 作为 BBB 分子特洛伊木马，通过 BBB 胰岛素受体上的转运将融合的 EPO 运过 BBB。HIRMAb-EPO 融合蛋白的 HIRMAb 部分不识别大鼠胰岛素受体。然而，融合蛋白的 EPO 部分确实识别大鼠 EPO 受体。因此，使用大鼠永久性大脑中动脉闭塞模型研究了 HIRMAb-EPO 融合蛋白的神经保护特性。在立体定向引导下将 HIRMAb-EPO 融合蛋白注入同侧大脑。高剂量的 HIRMAb-EPO 融合蛋白（61pmol）完全消除了皮质和皮质下梗死。较低剂量的融合蛋白（4.5pmol）消除了皮质梗死，对皮质下梗死没有明显影响。融合蛋白的 4.5 和 61pmol 剂量分别使神经功能缺损减少了 35%和 90%。总之，这些研究证明了 HIRMAb-EPO 融合蛋白在体内大脑中的生物活性，并且 EPO 在融合到 HIRMAb BBB 木马后保留了神经保护特性。
