3D printing of tissue engineering scaffolds:a focus on vascular regeneration

Tissue engineering is an emerging means for resolving the problems of tissue repair and organ replacement in regenerative medicine.Insufficient supply of nutrients and oxygen to cells in large-scale tissues has led to the demand to prepare blood vessels.Scaffold-based tissue engineering approaches are effective methods to form new blood vessel tissues.The demand for blood vessels prompts systematic research on fabrication strategies of vascular scaffolds for tissue engineering.Recent advances in 3D printing have facilitated fabrication of vascular scaffolds,contributing to broad prospects for tissue vascularization.This review presents state of the art on modeling methods,print materials and preparation processes for fabrication of vascular scaffolds,and discusses the advantages and application fields of each method.Specially,significance and importance of scaffold-based tissue engineering for vascular regeneration are emphasized.Print materials and preparation processes are discussed in detail.And a focus is placed on preparation processes based on 3D printing technologies and traditional manufacturing technologies including casting,electrospinning,and Lego-like construction.And related studies are exemplified.Transformation of vascular scaffolds to clinical application is discussed.Also,four trends of 3D printing of tissue engineering vascular scaffolds are presented,including machine learning,near-infrared photopolymerization,4D printing,and combination of self-assembly and 3D printing-based methods.

Bioscaffolds embedded with regulatory modules for cell growth and tissue formation:A review

The demand for artificial organs has greatly increased because of various aging-associated diseases and the wide need for organ transplants.A recent trend in tissue engineering is the precise reconstruction of tissues by the growth of cells adhering to bioscaffolds,which are three-dimensional(3D)structures that guide tissue and organ formation.Bioscaffolds used to fabricate bionic tissues should be able to not only guide cell growth but also regulate cell behaviors.Common regulation methods include biophysical and biochemical stimulations.Biophysical stimulation cues include matrix hardness,external stress and strain,surface topology,and electromagnetic field and concentration,whereas biochemical stimulation cues include growth factors,proteins,kinases,and magnetic nanoparticles.This review discusses bioink preparation,3D bioprinting(including extrusion-based,inkjet,and ultraviolet-assisted 3D bioprinting),and regulation of cell behaviors.In particular,it provides an overview of state-of-the-art methods and devices for regulating cell growth and tissue formation and the effects of biophysical and biochemical stimulations on cell behaviors.In addition,the fabrication of bioscaffolds embedded with regulatory modules for biomimetic tissue preparation is explained.Finally,challenges in cell growth regulation and future research directions are presented.