Dmitriy Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Ministry of Healthcare, Samory Mashela str., 1, GSP-7, Moscow, 117997, Russia.
Faculty of Physics, Moscow State University, Leninskie Gory, 1, build. 2, GSP-1, Moscow, 119991, Russia.
Sci Rep. 2019 Feb 6;9(1):1455. doi: 10.1038/s41598-018-37828-5.
Increased blood ammonium concentrations cause neurological complications. Existing drugs are not always sufficiently effective. Alternatively, erythrocytes-bioreactors (EBRs) loaded with enzymes utilizing ammonium, were suggested for ammonium removal from blood. However all they worked only for a short period of time. The reasons for this were not investigated. In this study, EBR mathematical models were developed and analysed based on the reactions of glycolysis and different enzymes utilizing ammonium, which showed that the efficiency and duration of EBRs' functioning could be limited due to low permeability of the cell membrane for some key substrates and products. A new enzyme system including glutamate dehydrogenase and alanine aminotransferase was proposed and realised experimentally, which was not limited by cell membrane permeability for glutamate and α-ketoglutarate due to creating metabolic pathway where these metabolites were produced and consumed cyclically. New bioreactors removed ammonium in vitro at the rate of 1.5 mmol/h × l (for human bioreactors) and in vivo in a model of hyperammoniemia in mice at the rate of 2.0 mmol/h × l (for mouse bioreactors), which correlated with model calculations. Experimental studies proved the proposed mathematical models are correct. Mathematical simulation of erythrocyte-bioreactors opens new opportunities for analysing the efficiency of any enzyme included in erythrocytes.
血液中氨浓度的增加会导致神经系统并发症。现有的药物并不总是非常有效。作为替代方案，有人提出使用载有利用氨的酶的红细胞生物反应器（EBR）从血液中去除氨。然而，它们的作用时间都很短。对此原因尚未进行研究。在这项研究中，根据糖酵解和利用氨的不同酶的反应，开发并分析了 EBR 的数学模型，结果表明，EBR 功能的效率和持续时间可能会受到限制，这是由于细胞膜对某些关键底物和产物的通透性低所致。提出并实验验证了一种新的酶系统，包括谷氨酸脱氢酶和丙氨酸氨基转移酶，由于创建了这些代谢物循环产生和消耗的代谢途径，因此该酶系统不受谷氨酸和α-酮戊二酸透过细胞膜的限制。新型生物反应器以 1.5mmol/h·l（对于人用生物反应器）的速率在体外去除氨，以 2.0mmol/h·l（对于鼠用生物反应器）的速率在小鼠高氨血症模型中体内去除氨，这与模型计算结果相符。实验研究证明了所提出的数学模型是正确的。红细胞生物反应器的数学模拟为分析任何包含在红细胞中的酶的效率开辟了新的机会。
