Angelini, T. E. | bioRxiv Science

bioRxiv2021

Embedded 3D printing in self-healing annealable composites for functional patterning of human neural constructs

Human in vitro models of neural tissue with controllable cellular identity, tunable microenvironment, and defined spatial arrangement are needed to facilitate studies of brain development and disease. Towards this end, embedded printing in jammed microgel supports (i.e., granular gels) holds great promise as it allows precise and programmable patterning of extremely soft and compliant tissue constructs. However, in contrast to the vast material landscape available for bulk hydrogels, granular printing support formulations are restricted to a handful of materials without the ability for facile adjustment of biofunctional properties of the cellular microenvironment. Therefore, there has been a need for novel materials that take advantage of versatile biomimicry of bulk hydrogels while providing high-fidelity support for embedded printing akin to granular gels. To address this need, we present a modular platform for bioengineering of neuronal networks via direct embedded 3D printing of human stem cells inside Self-Healing Annealable Particle-Extracellular matrix (SHAPE) composites. SHAPE composites consist of soft microgels immersed in viscous extracellular-matrix solution to enable precise freeform patterning of human stem cells and consequent generation and long-term maintenance of mature subtype-specific neurons that extend projections within the volume of the annealed support. The developed approach further allows multi-ink deposition, live spatial and temporal monitoring of oxygen levels, as well as creation of vascular channels. Due to its modularity, SHAPE biomanufacturing toolbox not only offers a solution for functional modeling of mechanically sensitive neural constructs, but also has potential to be applied to a wide range of biomaterials with different crosslinking mechanisms to model tissues and diseases where recapitulation of complex architectural features and topological cues is essential.

bioengineering↗

bioRxiv2020

Human CD8+ T-cells Require Glycolysis to Elicit Effector Function

Targeting human T-cell metabolism for modulating immune function requires an understanding of macronutrient utilization. Using metabolic inhibition during activation of human naive CD8+ T-cells, we demonstrate blocking glycolysis or mitochondrial respiration prevents T-cell proliferation. However, after activation and differentiation, the metabolic program changes. Inhibition of glycolysis abolished cytotoxic T-lymphocyte (CTL) activity, whereas mitochondrial inhibition had no effect on CTL lytic function. Studies with uniformly labeled 13C-glucose confirmed CTL convert the majority of glucose to lactate. The role of glycolysis in CTL function was assessed using NOD models of Type 1 diabetes (T1D). Treatment of NOD models with a glycolysis inhibitor resulted in reduced and delayed T1D incidence and significantly preserved {beta}-cell mass. We conclude glycolysis and mitochondrial ATP production are essential for efficient T-cell activation, but only glycolysis is essential for CTL lytic function. These data suggest targeting glycolysis in CTLs is a promising pathway to prevent T-cell-mediated autoimmunity.

immunology↗