Near infrared three-dimensional nonlinear optical monitoring of stem cell differentiation

Abstract

Under certain conditions, embryonic stem cells (ESCs) can be induced to differentiate into cartilage cells (chondrocytes), neuronal cells and pancreatic cells to a state suitable for transplantation to treat disorders/lesions in a clinical setting. Currently, this involves culturing cells either in the form of a monolayer (2D culture) or in a scaffold (3D culture), which may improve the formation of extracellular matrix. In this chapter, we attempt to compare the differentiation kinetics of ESCs using noninvasive near infrared nonlinear optical imaging (NLOI) for vital 3D monitoring of stem cell differentiation. In particular, we describe experimental and NLOI data pertaining to mouse embryonic stem cells (mESCs) induced to differentiate into chondrocytes, neuronal and pancreatic cells via embryoid bodies (EBs) formation either (a) on 2D plastic coverslips, (b) in 3D by suspending them in culture medium, (c) or growing them in collagen type-I-based 3D scaffolds. It was found that NLOI comprising two-photon excitation (TPE) and second harmonic generation (SHG) can be used as a versatile tool to simultaneously monitor morphological features of differentiating mESCs, as well as the formation of collagen fibres at various stages of differentiation.