Construction Of Heart On A Chip For Evaluating The Cardiotoxicity Of Natural Herbs

Traditional Chinese medicine(TCM)is a valuable wealth of thousands years of medical experience in China,and as the life expectancy of Chinese citizens increases and the quality of life improves,the using of TCM has become popular in the field of daily health care.Although we have long a long experience in drug use and has a qualitative understanding of the toxicity of various prescriptions and medicinal materials,due to the lack of dose effect toxicity relationship in modern pharmacology,the reports of various adverse reactions caused by the use of traditional Chinese medicine are increasing in recent years.That is to say,the traditional ancient books’ classification for the toxicity of traditional Chinese medicine-"hypertoxic","poisonous","slight toxicity",can ’ t meet the requirements of the modernization of traditional Chinese.The quantitative toxicity evaluation of various natural drug components in traditional Chinese medicine for various target organs is undoubtedly an important step for the development of national medicine.In the preclinical toxicity test of drugs,cardiotoxicity is a very important evaluation index.Cardiotoxicity is a biological process in which drugs enter the heart through blood circulation and act on various cells in the heart,causing cell damage or even death,which can be manifested clinically as arrhythmia,myocarditis,heart failure and myocardial necrosis.The current in vitro model to detect the cardiotoxicity of drugs is the well plate model.Simulating the interaction between cells in the real organism,and maintaining the microenvironment stable is a hard work in well plates model.To solve the problems above,this paper proposes a microfluidic cardiovascular organ chip,which simulates the vascular barrier function of the heart and avoids the direct exposure of cardiomyocytes to the drug solution,so this chip can simulate the process of drug interaction with cardiomyocytes through the vascular barrier in human body.This experiment also explores the bionic nature of the chip,and the comparison can reveal that this organ model has better tolerance to drug toxicity in cardiomyocytes inside the chip compared to the pore plate model,presumably because of the role of vascular barrier function.This platform is expected to be a new in vitro model for the detection and evaluation of drug cardiotoxicity.The organ chip body is fabricated from polydimethylsiloxane(PDMS),and the silicon template for each layer structure in the chip is obtained by mask-photocuring-channel etching technique.PDMS is poured onto the template and cured,and then peeled off.The heart chip model consists of two PDMS substrates sandwiched by two polycarbonate membranes with 10 μm pore size,and the complete heart chip is obtained by assembly and sealing.In this experiment,a two-channel differential velocity of flow microfluidic organ model was constructed,and primary vascular endothelial cells and cardiomyocytes from SD rats were grown in the upper and lower culture chambers of the chip,respectively.The experimental results showed that the cells grew well in the chip.The video tracking software developed for the chip can analyze the cell beating videos.The software can monitor the cell videos to obtain changes in the frequency and intensity of cardiomyocyte beats before and after drug addition,and this software visually and qualitatively characterizes the toxic effects of drugs on cardiomyocytes.The extent of myocardial cell damage can be quantitatively characterized by detecting specific biomarkers of damage such as troponin(c Tn I)and lactate dehydrogenase(LDH)in the effluent of chip.In this experiment,we used this microarray to evaluate the myocardial volume temporal toxicity relationship of three natural drug components:triptolide,nitidine chloride and anisodamine.Similar to the positive control drug adriamycin,all three natural drugs caused significant changes in biomarker secretion from cardiac myocytes at certain concentrations in the chip,and it was determined from the changes in the amount of live cell death that all of three natural drugs can cause damage to cardiac myocytes.By comparing the toxicity evaluation results of the chip and the plate,it was found that the cardiomyocytes in the chip had better drug tolerance.The chip can simulate the vascular barrier function of capillary in the heart,avoid the direct exposure of myocardial cells to drug solution,and better simulate the process of drug interaction with myocardial cells through the vascular barrier in the body.It is expected to become a new in vitro model to evaluate the cardiac toxicity of drugs.