Building an Artificial Stem Cell Niche: Prerequisites for Future 3D-Formation of Inner Ear Structures - Towards 3D Inner Ear Biotechnology.

In recent years there has been an increased interest in stem cells for the purpose of regenerative medicine to deliver a wide range of therapies to treat many diseases. However, 2D cultures of stem cells are of limited use when studying the mechanism of pathogenesis of diseases and the feasibility of a treatment. Therefore, research is focusing on the strengths of stem cells in three-dimensional (3D) structures mimicking organs, i.e., organoids, or organ-on-chip, for modeling human biology and disease. As 3D technology advances, it is necessary to know which signals stem cells need to multiply and differentiate into complex structures. This holds especially true for the complex three-dimensional (3D) structure of the inner ear. Recent work suggests that although other factors play a role, the extra cellular matrix (ECM), including its topography, is crucial to mimic a stem cell niche in vitro and to drive stem cells towards formation of the tissue of interest. Technological developments have led to the investigation of biomaterials that closely resemble the native ECM. In the fast forward moving research of organoids and organs-on-chip, the inner ear has hardly received attention. This review aims to provide an overview, by describing the general context in which cells, matrix and morphogens cooperate in order to build a tissue, to facilitate research in 3D inner ear technology. This article is protected by copyright. All rights reserved.