A. Jagielska, K. Kowsari
Artificial Axon Labs Inc.,
Keywords: artificial axons, 3D printing, microstereolithography, in vitro myelination
Summary:MS is a demyelinating disease of the central nervous system (CNS) characterized by immune-mediated loss of myelin and the death of the myelin producing oligodendrocyte cells (OLs), which leads to axonal damage and neuronal death. Drugs that promote endogenous remyelination are highly sought after as therapeutics for MS. All current MS therapies rely on immuno-modulators aimed at preventing myelin damage, but they fail to promote remyelination, and prevent disability in progressive patients. Despite the search for myelinating agents that complement the anti-inflammatory treatments, there are currently no approved medicines that can stimulate myelin repair in MS. Artificial Axon Labs Inc. (AAL) ,an MIT spinout, is developing a transformative drug discovery platform to discover first-in-class remyelinating therapies for currently incurable myelin diseases such as multiple sclerosis. One of the major roadblocks in the discovery of remyelinating drugs is the lack of biomimetic drug screening tools that can model the process of myelination in the disease relevant environment. Current approaches fall into two categories: 1) biofidelic 3D models such as organoids or organotypic tissue models, which are too complex for high throughput drug discovery, and 2) oversimplified but highly scalable 2D assays that can only evaluate compounds’ potential to stimulate differentiation of oligodendrocytes but not an actual process of myelin wrapping, which requires 3D axon-like structures. Moreover, animal models often do not sufficiently represent human neurodegenerative diseases. As a result, drug candidates discovered with today’s inadequate tools had limited success in the clinic. There is an urgent unmet need for the tools that can model myelination in biomimetic axon-like environment and at the same time allow for high throughput predictive drug screening. To address this urgent need, our company developed a novel phenotypic drug discovery platform, Artificial Axons, building upon technology developed by the company founders at MIT, which uses state-of-the-art 3D printing to create axon mimics that can be myelinated by living oligodendrocytes. We demonstrated scalable 3D printing of axon mimics with the unmatched combination of micrometer scale diameters (2-8 µm), and free-standing axon-like geometry with ultra-low stiffness (< 1 kPa elastic moduli) matching the biological axons. By allowing for direct, fast quantification of 3D myelination around axon mimics, our platform delivers critical advantages over existing assays, which make it a superior tool for the discovery of remyelinating compounds. We have demonstrated that our unique Artificial Axons platform enables direct quantification of 3D myelination in response to known pro-myelinating compounds, delivering first dose-response data for compounds myelination efficacy in the biofidelic axon-like environment, not achievable with other platforms. The unique ability to tune Artificial Axons’ biophysical properties enabled by flexible 3D printing allows us to mimic distinct conditions observed in MS lesions. As we demonstrated, the variations of these features, which often occur in MS lesions (e.g., changes of axon stiffness, diameter and density) can affect the extent of remyelination. This enables drug discovery that will be more predictive of therapeutic outcomes.