Designing synthetic matrices for enhanced organoid development: A step towards better disease understanding

Lead Research Organisation: King's College London
Department Name: Craniofacial Dev and Stem Cell Biology

Abstract

The severely debilitating effects of neuropathology, from neurodegenerative disorders, like Alzheimer's to neuro-inflammatory autoimmune conditions, such as Multiple Sclerosis, and traumatic damage to the nervous system continue to profoundly affect the lives of many. These illnesses are poorly understood at present, resulting in limited therapeutics to be available and many good quality life years lost.
Understanding human brain development is of paramount importance to create pathways to effective approaches that amend these pathologies. However, current in vitro models of the human brain are too crude, given the marked distinctions In comparison to in vivo models they currently possess. Improving our knowledge in this domain, holds promise for comprehending neurodevelopmental disorders and provide a way to mitigate its effects through improved understanding of neural tissue regeneration.

At present, my research is focused on modelling early brain development to advance understanding of neuropathologies. The model is based on neuroepithelial organoids generated from hiPSCs. To mimic the natural conditions of the surrounding brain tissue, I embed these organoids in a synthetic tunable hydrogel, which I've developed and optimized in the past two years. In this way, the organoids microenvironment is more relevant to that of in vivo conditions, allowing tunability, controlling organoid morphology, and serving as a potent instrument for probing the intricacies of brain development.
Early brain development begins with the formation of the neural tube, wherein the neural plate undergoes folding and closure to eventually give rise to the brain and spinal cord. As the brain matures, it displays a heterogeneous structure, with distinct regions exhibiting varying degrees of stiffness. We postulate that this gradient of stiffness, combined with the three-dimensional environment, plays a key role in recreating neural tube patterning. Additionally, the Wnt signaling/beta-catenin pathway is critical in patterning this process. The Wnt gradient is indispensable for anterior-posterior differentiation. Moreover, the activation of Wnt can be influenced by increased stiffness of the extracellular matrix. Hence, establishing a model that allows precise control of stiffness gradients, material softening, and the targeted release of biomolecules is critical for constructing in vitro models.

Taking part in this exchange program and integrating a controlled stiffness gradient with precise control of Wnt signaling will result in a more robust and reliably reproducible model for studying brain development and disease modelling.
Benefits to UK-Canada:

In the near future, we anticipate publishing a manuscript that builds upon our preliminary data regarding how ECM stiffness impacts neuron generation in neuroepithelial organoids from Gentleman's lab. Our upcoming research will focus on determining whether a stiffness gradient can activate WNT signaling and influence organoid patterning. Subsequently, we will further investigate WNT patterning using controlled release with microbeads in uniform hydrogels.

Looking ahead, we aim to advance the development of optimal disease-specific models. For instance, the study of disorders involving extracellular matrix irregularities, such as myelin degeneration, is best conducted using fully synthetic biomaterials. Combining 3D printing with synthetic matrices and organoid technologies holds great promise for creating a more effective model in this context.

This deeper understanding will pave the way for developing regenerative strategies for damaged tissue, particularly in areas where bioprinting shows groundbreaking promise.

Technical Summary

Early brain development initiates with neural tube formation, involving folding and closure of the neural plate to form the brain and spinal cord.
As the brain matures, it displays a heterogeneous structure, with distinct regions exhibiting varying degrees of stiffness. Posterior regions of the brain tend to be softer, while anterior areas exhibit greater rigidity. We postulate that this gradient of stiffness, combined with the three-dimensional environment, plays a key role in recreating neural tube patterning. Additionally, the Wnt signalling/beta-catenin pathway is critical in patterning this process. The Wnt gradient is indispensable for anterior-posterior differentiation. Moreover, the activation of Wnt can be influenced by increased stiffness of the extracellular matrix. Hence, establishing a model that allows precise control of stiffness gradients, material softening, and the targeted release of biomolecules is critical for constructing in vitro models.
We aim to investigate how stiffness gradients and Wnt signaling play a role in neural tissue patterning. Collaborations with Gentleman and Willerth labs offer promising avenues for progress.
Aim 1: To determine if bioprinting a stiffness gradient using PEG-based bioinks can serve as a guide for hiPSC-derived neurons.
Aim 2: To compare the performance of the PEG gradients versus fibrin-based ink gradients
Aim 3: To evaluate how controlled release of growth factors can induce localized Wnt signalling.
In the near future, we anticipate publishing a manuscript that builds upon our preliminary data regarding how ECM stiffness impacts neuron generation in neuroepithelial organoids. Our upcoming research will focus on determining whether a stiffness gradient can activate WNT signalling and influence organoid patterning. Subsequently, we will further investigate WNT patterning using controlled release with microbeads in uniform hydrogels.

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