Comparative Study On Developmental Toxicity In Vitro Mouse Whole Embryo By Three Kinds Nano- And Micro-scale Materials

Comparing to macro-sizes material, nano-sizes material has special physico-chemical characteristics, and may lead to changes of biological activity and biodynamics process which might be unknown potential hazards for human health. Nanotoxicology has become a new research fields. Developmental toxicity is an important part of safety evaluation of toxicology. There are two question to be answered: it is suitable for evaluating the developmental toxicity of nanometerials using the existing safety evaluation method? And what is the difference in effect of developmental toxicity between nano and macro meterials.Objective: Compared to macro-sizes material with same chemical constituents, the aim of this research is to examine the effects of nano materials on embryonic development, in view of the embryonic growth and morphological differentiation. The characteristic recognition of developmental toxicity of nano materials on whole embryo cultured in vitro is to be revealed. The results of this experiment is hoped to provide some experimental basis and theoretical basis for safety evaluation.Method: The post-implantation whole embryo culture(WEC)system was used to observe the effects of three nano oxides on cultured mouse embryo in vitro. The isolated ICR mouse embryos(8.5 day,2-5 somites) at organogenesis stage were cultured for 48 hours in immediately centrifugal serum(ICS) with different nano size and concentration(Nano-TiO₂, Nano-SiO₂, Nano-ZnO),and the same composition chemical macro material morphodifferentiation of tissues and organs Neubert scoreResults1,There is no obvious toxicity observed under the experimental conditions for macro TiO₂. It is found that there was distribution of nano particles showing on the surface of the yolk sac under the dose up to 100--200.0μg/m, but not found using macro TiO₂. Embryotoxity and teratogenicity are generally found under three different nanometers size of TiO₂, performance including hypoevolutismus of VYS and embryos, the low Neubert′s score morphodifferentiation of tissues and organs of mouse embryos,malformation (morphological abnormality of hear (small head); Dysplasia of auditory system; Dysplasia of olfactory system; Dysplasia of branchial arch; Dysplasia of heart (relatively small, pericardial effusion, rested on heart tube stage); ysplasia of neural tube (deletion, incomplete spontaneous); Mini fore limb or no; limb bud missing; Dysplasia of brain; Detardation.). From sensitivity of development perspective, morphological differentiation of nervous system is most evident, even only under the dose of 50.0μg/ml. More dose, more severe effect to organs, tissue and development, while morphological abnormality for mice embryo under the dose of 100.0μg/ml and death under 200.0μg/ml. In addition, the effect to development of embryo became more severe with time. The severity of toxicity of TiO₂ of three different nanometers is different. It was shown that smaller size means more severity.2, There is no obvious toxicity observed under the experimental conditions for macro SiO₂. But for nanometer SiO₂, it could lead to the smaller VYS diameter,crown-rump length,head length and segment numbers et al ,and low Neubert score of morphodifferentiation of tissues and organs of mouse embryos. when the dose exceeding 100.0μg/ml. The teratogenicity would appear for 50nmSiO₂when exceeding 100μg/ml. As for 15, 30 and 100 nm TiO₂, the teratogenicity would appear when exceeding 200.0μg/ml. Morphological abnormality is obvious. Death would appear when the dose exceeded 200.0μg/ml for 50nm SiO₂. This phenomenon of damage would be more serious with more dose or longer time. Among of different size of nano SiO₂, 50nm SiO₂ has most toxic and 100nm SiO₂ has least toxicity.3, There is no obvious toxicity observed under the experimental conditions for macro ZnO. It was generally found under three different nanometers size of ZnO that there was a decrease in score of VYS diameter,crown-rump length,head length and segment numbers et al development and morphodifferentiation of tissues and organs of mouse embryos.Teratogenicity and lethality were found under 50.0μg/ml for 30,50nmZnO and 100.0μg/ml for 100nmZnO. The damage for organs, tissue and development would be more serious when more dose or longer time. It was seen that 30nm ZnO led to more serious damage to embryo development and death than other sizes ZnO. As for performance to organ differentiation and embryonic mortality, it was found that 30nm ZnO had the most severe influence and 100nm ZnO had the least influence.Conclusions:1,The difference is evident between toxicity performance of three nano materials and macro material. There is an obvious toxicity to ICR mice embryo of nano Nano-TiO₂, Nano-SiO₂ and Nano-ZnO. But there was no toxicity observed for corresponding macro material under same dose level.2,Embryo toxicity and teratogenicity were generally found for three nano materials under different dose level. With more dose and longer time, the number organs effected would increase, and the damage would be more severe even death. There is an obvious dose-effect relationship and time-effect relationship. The effect led by three nano materials is widely and no target organ with significantly specific variation was observed. The dose which is effective to embryo development is also effective to development of VYS. The toxicity of nano-ZnO is more toxic than that of other two nano materials, and the toxicity will be obvious for 30 nm ZnO when exceeding 25.0μg/ml while 50.0μg/ml for 50 and 100nm nano-ZnO. As for different sizes of nano TiO₂ and Nano-SiO₂, the development toxicity would obvious only under the dose of 100.0μg/ml or more.3,It is different for development toxicity under different sizes of oxide. More serious damage would appear with less size of nano Nano-TiO₂ and Nano-ZnO, manifested as effect on mice embryo development in vitro and organ differentiation. But the size effect of nano-SiO₂ is not obvious, furthermore, the toxicity of 50nm SiO₂ is most severe among 15, 30, 50 and 100nm SiO₂.