Regulatory mechanisms and regeneration strategies of the soft-hard tissue interface in the human periodontium

The soft-hard tissue interface of the human periodontium is responsible for periodontal homeostasis and is essential for normal oral activities.This softhard tissue interface is formed by the direct insertion of fibrous ligaments into the bone tissue.It differs from the unique four-layer structure of the fibrocartilage interface.This interface is formed by a combination of physical,chemical,and biological factors.The physiological functions of this interface are regulated by different signaling pathways.The unique structure of this soft-hard tissue interface has inspired scientists to construct biomimetic gradient structures.These biomimetic systems include nanofiber scaffolds,cell sheets,and hydrogels.Exploring methods to repair this soft-hard tissue interface can help solve clinically unresolved problems.The present review examines the structure of the soft-hard tissue interface of the periodontium and the factors that influence the development of this interface.Relevant regulatory pathways and biomimetic reconstruction methods are also presented to provide ideas for future research on interfacial tissue engineering.

Multi‑compartment Organ‑on‑a‑Chip Based on Electrospun Nanofber Membrane as In Vitro Jaundice Disease Model

Organ-on-a-chip(OOC)is now becoming a potential alternative to the classical preclinical animal models,which reconstitutes in vitro the basic function of specifc human tissues/organs and dynamically simulates physiological or pathological activities in tissue and organ level.Despite of the much progress achieved so far,there is still an urgent need to explore new biomaterials to construct a reliable and efcient tissue-tissue interface and a general fabrication strategy to expand from single-organ OOC to multi-organ OOC in an easy manner.In this paper,we propose a novel strategy to prepare doublecompartment organ-on-a-chip(DC-OOC)using electrospun poly(l-lactic acid)/collagen I(PLLA/Col I)nanofber membrane as tissue-tissue interface.The unique features of PLLA/Col I nanofber membrane like excellent biocompatibility,strong afnity to multiple cells,adjustable orientation,controllable thickness and porosity endow the tissue-tissue interface with excellent semi-permeability,appropriate mechanical support,inducible cell orientation,good cell adhesion and proliferation.The integration of 3D printing technology during the fabrication process enables precise size control of the tissue-tissue interface and stable bonding with microfuidic channels.More importantly,our fabrication strategy and OOC confguration makes it easy to extend from DC-OOC to multi-compartment organ-on-a-chip(MC-OOC).To show its possible application,in vitro jaundice disease model is established by constructing blood vessel/skin/liver/lung organ-on-a-chip via MC-OOC.The downward trends of the cell viability after perfusion of bilirubin,the variation in cell sensitivity to bilirubin for diferent type of cells and recovery of cell viability after blue light therapy prove the feasibility of this jaundice disease model.We believe this general strategy of constructing tissue-tissue interface and multi-organ OOC can be used for many other in vitro physiological and pathological models.