Laser Assisted Bioprinting of laminin on biodegradable PLGA substrates: Effect on neural stem cell adhesion and differentiation

Laser Assisted Bioprinting (LAB) is recognized to be an enabling and versatile microfabrication technology for regenerative medicine and artificial tissue engineering. Current bioprinting concentrates on a layer-by-layer approach to print cells in consecutive stacks or nets, to recreate specialized tissue functions with a top-down approach. This synthering of proximal cells however reduces the long range correlation of tissue parenchyma and stroma given by natural development, as result of cells mobility and signaling. In this work, laminin, one of the main components of brain extracellular matrix is deposited by LAB on a biodegradable scaffold made of poly(lactic-co-glycolic acid) (PLGA), providing chemical cues for the adhesion and differentiation of neural stem cells NE-4C induced by retinoic acid. Surface roughness and LAB induced aggregates promote the initial adhesion of neuronal stem cells to the PLGA substrate and influence the formation of clusters and interconnection between them. The amount of laminin delivered inside the spot area may be controlled down to sub-monolayer coverage and a positive correlation between the laminin spots and soma of trafficking cells is demonstrated, also by computational modelling. Anisotropic orientation of neurite outgrowth is induced upon differentiation, up to 70% of processes protruding from stem cell clusters. The comparative analysis shows that the topological cue plays a major role in enhabling cluster formation on the scaffold, but the bioprinted laminin spots appear to be regulating the strength of connection between them, opening the way to control the functional morphology of artificial neural tissue constructs.