Multifunctional Microphysiological System Based On Patterned Nanofibers

The main reason for the high cost yet low efficiency of conventional drug development is the absence of preclinical models capable of predicting human responses to new drugs.Commonly used animal models are often inconsistent with human clinical trials with up to90%failure rate.Therefore,there is an urgent need to reestablish a novel and more representative in vitro models of human organs and diseases to speed up the screening and testing of new drugs and provide effective data for later clinical trials.With precise control of the cellular microenvironment,microphysiological system that has emerged in recent years aims to reconstruct the key features and functions of specific human tissues/organs and dynamically simulate physiological or pathological activities in tissue/organ-level context,making it gradually become recognized as the best alternative to animal models.A key factor for the construction of microphysiological system is to provide a highly biomimetic 3D microenvironment of cell and tissue.A common method is to integrate the extracellular matrix into the microphysiological system to promote the interaction between cells and matrix or between cells and cells.However,it is still a huge challenge to integrate extracellular matrices such as electrospun nanofibers and hydrogels into the microphysiological system in a precise manner.This paper proposes a multifunctional microphysiological system based on patterned nanofibers prepared by agarose hydrogel stamps,which achieve to integrate cleverly electrospun nanofibers/hydrogel into microphysiological system.The systematic study of the interaction between patterned nanofibers or patterned hydrogel to cells in microphysiological system were carried out,and preliminary attempts have been made for its possible applications in the field of drug screening.The specific research content and conclusions are as follows.（1）Preparation of microphysiological system based on patterned nanofibers:Electrospinning was used to prepare nanofibers with protein（collagen I/Laminin）and inorganic salt（calcium lactate）respectively.Both kinds of electrospun nanofibers could be micropatterned by TFEA-loaded agarose hydrogel stamps,and then they were coupled into microphysiological system with parallel channel structure.The experimental results showed that the microphysiological system has good sealing performance,and the patterned nanofibers can be fixed at any designated position of system.Furthermore,microphysiological system with complex hierarchical patterned nanofiber could be obtained by multiple cycles of electrospinning and agarose hydrogel stamp etching.（2）The microphysiological system based on patterned nanofibers regulates cell behavior:Firstly,cell enrichment in specific areas in microphysiological system could be achieved by regulating the composition of patterned nanofibers.The research results showed that cell enrichment was mainly affected by cell concentration and cell adhesion time.Secondly,aligned nanofibers could be prepared by changing the receiving device of electrospinning and then successfully patterned,thereby realizing the cells alignment in microphysiological system.The experiment found that the nucleus length ration of the aligned nanofibers group was higher than random nanofibers group,and the cell orientation distribution of the aligned nanofibers group focused on 90°±10°.（3）A microphysiological system based on patterned nanofibers forming a patterned hydrogel in situ for drug testing:Electrospinning could be used to prepared polylactic acid（PLLA）nanofibers containing calcium lactate.During the process of nanofibers forming,phase separation occurred between calcium lactate and PLLA and positively charged Ca²⁺aggregated on the outside surface of nanofibers by influence of electric field force.The patterned PLLA/calcium lactate nanofibers were prepared by agarose hydrogel stamp.When the sodium alginate solution was in contact with the PLLA/calcium lactate nanofibers,Ca²⁺released from the nanofibers could react with alginate to form patterned calcium alginate hydrogel in situ.The one-on-one patterned nanofiber/hydrogel not only improved the binding stability of the hydrogel,but also enabled cell encapsulation in situ（that is,cell patterns）to construct 3D cell culture microenvironment in specific.On this basis,this work further constructed a breast cancer model and used cisplatin as a model drug to evaluated the effect of drug concentration,drug duration time,cancer microenvironment.The experimental data showed that this microphysiological system could be used as an in vitro drug detection platform.In summary,this work used agarose hydrogel stamp to prepare patterned nanofibers,and successfully constructed microphysiological system based on patterned nanofibers/patterned hydrogel which achieve to introduce extracellular matrix into the microphysiological system in a precise manner to promote the interaction of between cells and matrix or between cells and cells,making it providing new ideas for the construction and further research of organs and disease models in vitro.