Güttinger Martin, Padrun Vivianne, Pralong William F, Boison Detlev
Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zürich, Switzerland.
Exp Neurol. 2005 May;193(1):53-64. doi: 10.1016/j.expneurol.2004.12.012.
Adenosine is an important inhibitory modulator of brain activity. In a previous ex vivo gene therapy approach, local release of adenosine by encapsulated fibroblasts implanted into the vicinity of an epileptic focus, was sufficient to provide transient protection from seizures (Huber, A., Padrun, V., Deglon, N., Aebischer, P., Mohler, H., Boison, D., 2001. Grafts of adenosine-releasing cells suppress seizures in kindling epilepsy. Proc. Natl. Acad. Sci. U. S. A. 98, 7611-7616). Long-term seizure suppression beyond 2 weeks was precluded by limited life expectancy of the encapsulated fibroblasts. To study the feasibility for long-term seizure suppression by adenosine releasing brain implants, in the present contribution, mouse C2C12 myoblasts were engineered to release adenosine by genetic inactivation of adenosine kinase. After encapsulation, the myoblasts were grafted into the lateral brain ventricles of epileptic rats kindled in the hippocampus. While seizure activity in animals with wild-type implants remained unaltered, 1 week after grafting all rats with adenosine-releasing implants (n = 25) displayed complete protection from convulsive seizures and a corresponding reduction of afterdischarges in EEG-recordings. The duration of seizure suppression was maintained for a period of 3 weeks in 50% of the animals ranging to a maximum of 8 weeks in one animal. During the course of these experiments, adenosine A1 receptors remained responsive to selective agonists and antagonists indicating a lack of desensitization of A1 receptors after local long-term exposure to adenosine. Furthermore, local release of adenosine did not affect locomotor activity, whereas systemic application of the A1 agonist 2-chloro-N6-cyclopentyladenosine caused strong sedation. Thus, the local release of adenosine by cellular implants provides a feasible option for a potential side-effect free approach for the long-term treatment of focal epilepsies.
腺苷是脑活动的一种重要抑制性调节因子。在先前的一项离体基因治疗方法中，植入癫痫病灶附近的封装成纤维细胞局部释放腺苷，足以提供对癫痫发作的短暂保护（胡贝尔，A.，帕德鲁恩，V.，德格隆，N.，艾比舍尔，P.，莫勒，H.，博伊森，D.，2001年。释放腺苷的细胞移植抑制点燃癫痫中的癫痫发作。美国国家科学院院刊98，7611 - 7616）。封装成纤维细胞有限的寿命限制了癫痫发作抑制超过2周的长期效果。为了研究通过释放腺苷的脑植入物进行长期癫痫发作抑制的可行性，在本研究中，通过对腺苷激酶进行基因失活，使小鼠C2C12成肌细胞工程化以释放腺苷。封装后，将成肌细胞移植到海马体点燃的癫痫大鼠的侧脑室中。虽然植入野生型细胞的动物的癫痫活动未改变，但移植释放腺苷的植入物的所有大鼠（n = 25）在移植后1周均表现出对惊厥性癫痫发作的完全保护，并且脑电图记录中的后续放电相应减少。50%的动物癫痫发作抑制持续时间维持了3周，其中一只动物最长达到8周。在这些实验过程中，腺苷A1受体对选择性激动剂和拮抗剂仍有反应，表明局部长期暴露于腺苷后A1受体没有脱敏。此外，腺苷的局部释放不影响运动活动，而全身应用A1激动剂2 - 氯 - N6 - 环戊基腺苷会引起强烈的镇静作用。因此，细胞植入物局部释放腺苷为局灶性癫痫的长期治疗提供了一种可行的、潜在无副作用的方法。
