3D patterns in alginate hydrogel degradation spatially guide YAP nuclear translocation and hMSC osteogenic differentiation

Abstract

AbstractTissue engineering involves assembling functional cells tailored to perform specific functions. Biological tissues are anisotropic and present spatial gradients in architecture and composition. This study explores a novel approach to guide human mesenchymal stromal cells (hMSCs) behavior by encapsulation in photopatterned alginate hydrogels. Two different crosslinked sections, degradable (Deg) vs. non-degradable (noDeg), are created dependent on the light exposure (UV and crosslinking with matrix metalloprotease (MMP) sensitive peptide vs. nonUV and click crosslinking). The patterned alginate hydrogels harbor a Deg phase, with cell spreading, collective cell alignment and preferential osteogenic differentiation; and a noDeg phase, with rounded cells, no preferential alignment and higher adipogenic differentiation. The previous patterns in cell behavior are observed under growth media (in absence of biochemical stimuli) and potentiated in the presence of specific conditioned media. We confirm the involvement of mechanotransduction pathways by the integrin-mediated yes-associated protein (YAP) nuclear translocation within degradable zones, while a homogeneous cytoplasmic/nuclear distribution is evident in non-degradable zones. The patterns in cell morphology are dependent on matrix degradation and integrin-binding, as no patterns are seen using an MMP-scramble peptide or no-RGD materials. Thus, 3D patterns in hydrogel degradation spatially guide YAP nuclear translocation and hMSC osteogenic differentiation. The spatial patterns in degradation bring us a step closer to mimicking the 3D anisotropy of tissues, by allowing to segregate cell behavior. This opens new opportunities for fundamental understanding of guided collective cell behavior and tissue engineering applications.Statement of significancePatterned materials allow to integrate multiple characteristics in a single material which better mimic the anisotropy found in tissues. The role of extracellular matrix (ECM) degradation is a crucial step in regeneration and disease. Engineered biomaterials have been used to study how degradability impacts cell behavior. This research takes a step further by spatially segregating the biophysical properties to mimic the complex ECM architecture in tissues. We aim to understand cell-matrix interaction in patterned degradable/non-degradable alginate hydrogels and the interphase between them by evaluating primary hMSC morphology, collective cell alignment and differentiation. The results advance our understanding of the cell microenvironment and tissue anisotropy, knowledge that can be applied to fundamental studies and tissue engineering applications.Figure 0:Graphical abstract