3D nerve integrated tissue on a chip and organoid models for exploring mechanotransduction and gene expression

The ever-growing need to understand and engineer biological and biochemical mechanisms of cells and materials that aim to study, restore, maintain, and improve the treatment of disease has led to the emergence of in vitro models in the field of tissue engineering. The evolution of tissue-engineered models holds promise for mimicking the responses of biological functionality of physiological systems. Such tissue models involve the combination of cells, engineering, materials methods, and suitable biochemical and biophysical factors, allowing the microenvironmental signals to be in uenced by their three-dimensional (3D) surroundings, including the extracellular matrix (ECM) scaffold architectures. This distinct, complex organization enables a versatile design and distinctive advantages over foundational 2D studies. 3D ECM systems and 3D ECM scaffold systems provide more complex cellto- cell communication, realistic cell-ECM interaction, and spatial organization. Engineered tissue models, encompassing methods such as brain models with neurons, hold promise in providing more predictive, robust, and physiologically relevant platforms to ?nd and study disease, in ammation, and injured states.

Despite its potential to revolutionize diagnostics, therapeutics, treatment, and healing protocols, our present understanding of neural activity response to mechanical loading on neurons in vitro is mainly limited to local stimulation of single or multiple neurons cultured over planar substrates. To better simulate neuron response in 3D to mechanics, we developed a neuron-like nerve integrated tissue on a chip (NITC) system embedded within a collagen matrix that, once subjected to our mechanical excitation test-bed (MET) system, converts mechanical stimuli into bio-active cues shifting intracellular signals. To accomplish this, we designed the MET system incorporating a voice coil actuator (VCA) with custom printed 3D parts controlled by a power supply and function generator synchronized with live image capture. 

This work then studies high-throughput biology integration of the MET system to aid in rapid testing. Here we demonstrate an increase in the number of independent parameters that define the functional configuration and automating the input parameters that govern the applied external mechanical stimuli to NITC devices. Here, we observed a molecular signature, calcium, is expressed as a function of the applied strain rate. This work was further enhanced by building upon the reductionist organ-on-a-chip approach by using cerebral organoids with the MET system to validate neural identity and activity, explore the impact of neuroprotective strategies, and analyze the transcriptome of gene expression within RNA. 

We believe the on-chip approach and the cerebral organoid model combined with the MET system will have implications in various areas, including tissue on-chip systems, bio-materials,neuromechanics, cellular dynamics, gene expression, regeneration, and fundamental findings associating the genome with external mechanics.