Multi-compartment Organ-on-a-chip Based On Electrospun Nanofiber Membrane As In Vitro Jaundice Disease Model

Organ-on-a-chip(OOC)is a simplified microphysiological system based on microfluidic technology and integrated with biology,material science,physics,chemistry,microelectromechanical and other disciplines,which is constructed on the in vitro chip to simulate the main structure or function of human tissues or organs.The microphysiological system can simulate the physiological activities of the human body in vitro and predict the response of the human body to external stimuli(including drugs).It has extensive application value in the construction of physiological / pathological models,the development of new drugs and other fields.it even has the potential to replace the current preclinical animal trials of new drugs.Tissue interface is the key part of organ-to-organ interaction in OOC.At present,the construction methods of tissue interface mainly include microchannel,polymer membrane,hydrogel and so on.However,there are some problems in these tissue interfaces,such as complex and lengthy preparation process,distorted construction of microenvironment,lack of system scalability and so on,which also restrict the large-scale application of OOC and the accuracy of predicting the response to external stimuli.A tissue interface based on electrospun poly(L-lactic acid)/ type I collagen(PLLA/Col I)nanofiber membrane is reported in this paper.this kind of tissue interface has the characteristics of excellent biocompatibility,good semi-permeability,suitable mechanical support strength,inducing cell orientation and enhancing cell adhesion and proliferation.In addition,3D printing technology is used to print PDMS prepolymer onto the surface of nanofiber membrane for OOC sealing instead of mechanical fixation,which avoids fluid leakage caused by poor sealing between nanofiber membrane and PDMS microchannel.More importantly,this electrospun nanofiber membrane manufacturing strategy supplemented by 3D printing can be easily extended from single-organ chips to multi-organ chips.The main contents and conclusions of this work are as follows:(1)Construction of tissue interface of double-compartment OOC(DC-OOC)and multi-compartment OOC(MC-OOC)by electrospun nanofiber membrane combined with 3D printing technology.Nanofiber membranes with different double-sided orientations are obtained by secondary spinning.High-precision 3D printing technology can accurately print PDMS at the predetermined position of the nanofiber membrane to form a tissue interface with a specific pattern.It is sealed with the pre-prepared upper and lower layers of PDMS chip substrate in an oxygen-plasma gas environment with a "sandwich" structure to form an OOC with a specific structure.Through the preliminary evaluation of common high temperature,high pressure and ultraviolet environment,the tightness of the OOC prepared by the above strategy meets the requirements.(2)Verifaction of basic function of OOC.Taking the DC-OOC as an example,it was tested by water perfusion,laminar flow simulation,cell adhesion,cell co-culture,cell proliferation,cell orientation induction and vascular endothelial barrier characterization.The results indicate that the OOC on electrospun nanofiber membrane meets the requirements in all tests.To be exact,the results show that the tissue interface of the OOC has good semi-permeability,suitable mechanical support,different cell orientation,good cell adhesion and proliferation ability.In addition,vascular endothelial cells can form a good endothelial barrier under the condition of dynamic perfusion,which further shows that the tissue interface we prepared can meet the real tissue interface in vivo.(3)the blood vessel / skin / liver / lung OOC was used as the in vitro jaundice model and the function of bilirubin perfusion and phototherapy was verified.Blood vessel / skin / liver /lung OOC was constructed by culturing vascular endothelial cells,fibroblasts,hepatocytes and lung cells in MC-OOC.The change trend of cell viability and the sensitivity of different cells to bilirubin were investigated by infusing bilirubin.On this basis,the blue light irradiation on OOC was further used to simulate the clinical phototherapy in the treatment of jaundice.The recovery of cell viability after blue light irradiation proved the feasibility of our jaundice model.It is also proved that small molecular biochemical signals(bilirubin)can affect the behavior of multiple organs and tissues through vascular transport and tissue interface infiltration.In short,a new type of MC-OOC with electrospun nanofiber membrane as tissue interface was reported in this paper,and the in vitro jaundice model was successfully established.We believe that this general strategy of constructing tissue interface and multi-organ chip is also suitable for the construction of other physiological and pathological models in vitro,and helps to strengthen our understanding of the internal mechanism of human physiological phenomena.it also has potential application prospects in drug evaluation and screening.