Determination Of GBCAs' Stability And Studies Of Their Effects On Gadolinium Deposition And Kupffer Cells In Rats

GBCAs are a class of MRI contrast agents widely used in the clinical diagnosis and related studies of diseases.According to the structure of gadolinium ion-bound ligands,GBCAs can be divided into linear and macrocyclic types.Generally,the chemical stability of macrocyclic complex is relatively higher than the linear one.According to the different charged properties of the ligands forming gadolinium complexes,gadolinium contrast agents can be divided into ionic and non-ionic types.After intravenous injection,GBCAs were quickly distributed to the systemic vascular system and then dispersed to the extracellular space of the blood vessels,and soon reached the equilibrium stage.Theoretically,all GBCAs are rapidly excreted by the kidneys in prototype form within a day of intravenous administration.However,in recent years,studies have shown that GBCAs can cause gadolinium deposition in various organs of human body to different degrees after repeated use,and the gadolinium deposition degree is closely related to the type of gadolinium contrast agent.Why is gadolinium contrast agent deposition related to gadolinium contrast agent type?In which organs does GBCAs mainly deposit?Does gadolinium contrast deposition affect organ morphology and function?Current research has yet to definitively answer these questions.Therefore,this paper analyses the types of GBCAs relation with gadolinium deposition,investigates the main parts of gadolinium deposition and its effect on the body function of each organ and uses the kupffer cells to preliminarily explore the effect of gadolinium deposition in body's immune system.In the first part of the study,we established the AKTA purifier Coupled with ICP-MS system and successfully detected the free concentration of Gd³⁺in GBCAs in vitro.The release rate of Gd³⁺in deionized aqueous solution,human plasma and renal failure plasma was compared.In deionized aqueous solution,the Gd³⁺release rate of all kinds of GBCAs was less than 1%,which did not change with time.In 37?human plasma,the Gd³⁺release rate of macrocyclic GBCAs t remained below 0.5%and did not change with time.The Gd³⁺release rate of ion linear GBCAs increased with time,and finally remained between 3%and4%.The Gd³⁺release rate of non-ionic linear GBCAs increased with time,and finally reached 15%.In renal failure plasma,the Gd³⁺release rate of non-ionic linear GBCAs increased with time,eventually reaching 25%.The Gd³⁺release rate of ion linear and macrocyclic GBCAs was no significantly difference between normal plasma and renal failure plasma.The results show that the stability of GBCAs is good in aqueous solution.The stability of GBCAs in human plasma,macrocyclic>ion linear>non-ionic linear.Renal failure has great effect on the stability of non-ionic linear GBCAs,but had little effect on ionic linear and macrocyclic GBCAs.In the second part of the study,we investigated the deposition of different gadolinium in each organ of rats by injecting GBCAs for several times,and analyzed the influence of gadolinium deposition on the morphology of each organ of rats by HE staining.At the same time,we successfully established a rat renal failure model and investigated the effect of renal failure on gadolinium deposition.The results showed that GBCAs were deposited in many organs of rats,but the deposition was most obvious in liver,spleen and kidney.HE staining showed that GBCAs deposition did not cause morphological changes in rat organs.As an independent risk factor,renal failure can aggravate gadolinium deposition in each organ of rats.The degree of gadolinium deposition is depand on the type of GBCAs?macrocyclic<ionic linear<non-ionic linear?.The more stable GBCAs is,the less likely it is to lead to gadolinium deposition.In the third part of the study,we injected GBCAs or gadolinium chloride solution into rat vein to investigate the effect of different GBCAs on the activity of kupffer cells in liver.The toxicity of gadolinium contrast agents on kupffer cells was detected by cck-8 kit.In addition,the rat Th1/Th2 cytokine kit was used to detect the effects of various GBCAs on the release of cytokines from kupffer cells,so as to analyze the possible risks of gadolinium deposition.The results showed that after continuous injection of GBCAs,the number of kupffer cells all decreased,and the most remarkable reduction was found in the rat kupffer cells after the injection of gadolinium chloride.CCK-8 results showed that the cytotoxicity of all reagents to kupffer cells is gadolinium chloride solution>non-ionic linear>ion linear>macrocyclic.GBCAs toxicity was related to the release of Gd³⁺concentration.Cytokine testing found that linear GBCAs tended to increase the levels of IL-6 and TNF released by kupffer cells,both of which are involved in the body's inflammatory response.Therefore,repeated use of linear GBCAs is more likely to cause the Th1 inflammatory response,which may increase the risk of patients suffering from inflammatory reactions-related diseases.In conclusion,this study successfully established a method to analyze Gd³⁺release rate of GBCAs in vitro,and tested the stability of different types of GBCAs.GBCAs deposition mainly concentrated in the liver,kidney,spleen and other organs.Using GBCAs Repeatedly,especially linear GBCAs,leads to a decrease in the number of immune cells in body,such as kupffer cells,and an increase in the release of IL-6 and TNF,which may increase the risk of patients developing inflammatory reactivity related diseases.The degree of gadolinium deposition,the number of kupffer cells,and the changes in the cytokines released were all correlated with the stability of GBCAs.Therefore,macrocyclic GBCAs should be chosen in clinic optimally.Before using gadolinium,health workers should assess the kidney function of patients.