Periodic Reporting for period 3 - HERMES (Hybrid Enhanced Regenerative Medicine Systems)
Período documentado: 2022-01-01 hasta 2023-06-30
The overall goal of HERMES is to provide the proof-of-concept that a restorative dialogue between bioengineered and mammalian brain tissue can be established and controlled to heal brain damage effectively and safely. To overcome the limitations of biological approaches for brain regeneration, HERMES fosters the emergence of the novel field of enhanced regenerative medicine. This paradigm is rooted in the establishment of biohybrid neuronics (neural electronics), in which the symbiotic integration of bioengineered brain tissue, neuromorphic microelectronics and artificial intelligence (AI) effectively pursues a controlled self-repair process of dysfunctional brain circuits.
In pursuing the proof-of-concept, we will focus on temporal lobe epilepsy (TLE), the most common epileptic syndrome and the most frequently unresponsive to medications. As the hippocampus is primarily stricken in TLE, we aim at replacing its damaged portion by bioengineered hippocampal tissue.
Along its roadmap, HERMES also promotes interdisciplinary cross-fertilization beyond the Consortium; it extends the concepts of enhanced brain regeneration to philosophy, ethics, policy and society, ultimately fostering the establishment of highly versatile intelligent biohybrids that will potentially be compliant to adapt to cure any brain disorder linked to brain damage, beyond epilepsy.
In pursuing the proof-of-concept, we will focus on temporal lobe epilepsy (TLE), the most common epileptic syndrome and the most frequently unresponsive to medications. As the hippocampus is primarily stricken in TLE, we aim at replacing its damaged portion by bioengineered hippocampal tissue.
Along its roadmap, HERMES also promotes interdisciplinary cross-fertilization beyond the Consortium; it extends the concepts of enhanced brain regeneration to philosophy, ethics, policy and society, ultimately fostering the establishment of highly versatile intelligent biohybrids that will potentially be compliant to adapt to cure any brain disorder linked to brain damage, beyond epilepsy.
HERMES is a complex polyhedral project, requiring the parallel development of biological and artificial components, and their convergence in the functional biohybrid. The latter was achieved during this third reporting period.
Bioengineered brain tissue graft – We have established a reproducible protocol to obtain bioengineered organoids with hippocampal signature from rodent neural stem cells (NSCs), and developed a bioactive biopolymer-based extracellular matrix (ECM) for in vivo co-injection with NSCs, to support their in vivo differentiation in hippocampal neurons. In this context, we have also established the key turning point for fluid pre-tissue grafting to avoid excessive stemness (hence uncontrolled proliferation), and provide a favorable microenviroment for NSCs differentiation. Further, we have established the minimally invasive closed-skull neurosurgery technique to ablate the sclerotic hippocampal tissue in epileptic rodents along the lines of hippocampal ablation in TLE patients. In parallel, we have developed spheroids and alginate hydrogels of primary hippocampal cells as hippocampal tissue replicas recapitulating the final NCS differentiation in mature grafts. These replicas demonstrated robust and reliable electrical activity and offer the opportunity of testing the biohybrid interplay in two distinct biological scenarios. Namely, the spheroids revealed their ictogenic potential, substantiating the basic assumption of HERMES, i.e. the risk of a purely biological brain regeneration; on the other hand, hydrogels never generate ictal activity, suggesting an anti-ictogenic potential.
Neuromorphic engineering – The neuromorphic computing system (NCS) will guide the functional graft-host integration. To achieve it, we have designed and fabricated the CMOS-neuron chip, the analogue front-end, and the memristor array. For the latter, we have selected materials based on their specific suitability to address the required biologically plausible plasticity. These components have been integrated in a desktop system for in vitro use, for which we have implemented custom communication hardware to interface the NCS with a commercial microelectrode array (MEA) recording system. In addition to the memristor-based NCS (here, MXBAR), we have developed an emulator based on a microcontroller and implementing a model of the MXBAR. We have also developed a new algorithm for memristor-based seizure prediction, termed 'memristor transform'. In addition to the MXBAR system originally foreseen by the project, we have developed new MoS2-based memristor devices for a memristor-only NCS, as well as two memristorless NCS designs (one fully analog CMOS-based, the other fully digital). All these systems have been succesfully tested with MEA recording of epileptiform patterns generated by brain slices or hippocampal spheroids, achieving the recognition of different epileptiform events and, in some instances, seizure prediction.
Aiming at the in vivo setting, we have finalized the flexible probe design and the implantation technique, and we have tested the implanted probes via benchmark tests and in vivo recording and stimulation.
Artificial Intelligence – We have developed the computational models and signal processing tools aiding the AI algorithms design. For the latter, we have achieved a two-AI agent design, wherein agent 1 pursues seizure prediction (prediction agent) and agent 2 monitors and trains the NCS (reinforcement learning control agent).
Bioengineered brain tissue graft – We have established a reproducible protocol to obtain bioengineered organoids with hippocampal signature from rodent neural stem cells (NSCs), and developed a bioactive biopolymer-based extracellular matrix (ECM) for in vivo co-injection with NSCs, to support their in vivo differentiation in hippocampal neurons. In this context, we have also established the key turning point for fluid pre-tissue grafting to avoid excessive stemness (hence uncontrolled proliferation), and provide a favorable microenviroment for NSCs differentiation. Further, we have established the minimally invasive closed-skull neurosurgery technique to ablate the sclerotic hippocampal tissue in epileptic rodents along the lines of hippocampal ablation in TLE patients. In parallel, we have developed spheroids and alginate hydrogels of primary hippocampal cells as hippocampal tissue replicas recapitulating the final NCS differentiation in mature grafts. These replicas demonstrated robust and reliable electrical activity and offer the opportunity of testing the biohybrid interplay in two distinct biological scenarios. Namely, the spheroids revealed their ictogenic potential, substantiating the basic assumption of HERMES, i.e. the risk of a purely biological brain regeneration; on the other hand, hydrogels never generate ictal activity, suggesting an anti-ictogenic potential.
Neuromorphic engineering – The neuromorphic computing system (NCS) will guide the functional graft-host integration. To achieve it, we have designed and fabricated the CMOS-neuron chip, the analogue front-end, and the memristor array. For the latter, we have selected materials based on their specific suitability to address the required biologically plausible plasticity. These components have been integrated in a desktop system for in vitro use, for which we have implemented custom communication hardware to interface the NCS with a commercial microelectrode array (MEA) recording system. In addition to the memristor-based NCS (here, MXBAR), we have developed an emulator based on a microcontroller and implementing a model of the MXBAR. We have also developed a new algorithm for memristor-based seizure prediction, termed 'memristor transform'. In addition to the MXBAR system originally foreseen by the project, we have developed new MoS2-based memristor devices for a memristor-only NCS, as well as two memristorless NCS designs (one fully analog CMOS-based, the other fully digital). All these systems have been succesfully tested with MEA recording of epileptiform patterns generated by brain slices or hippocampal spheroids, achieving the recognition of different epileptiform events and, in some instances, seizure prediction.
Aiming at the in vivo setting, we have finalized the flexible probe design and the implantation technique, and we have tested the implanted probes via benchmark tests and in vivo recording and stimulation.
Artificial Intelligence – We have developed the computational models and signal processing tools aiding the AI algorithms design. For the latter, we have achieved a two-AI agent design, wherein agent 1 pursues seizure prediction (prediction agent) and agent 2 monitors and trains the NCS (reinforcement learning control agent).
The method for rodent hippocampal organoid generation overcomes the drawbacks of rodent NSC manipulation and the lack of specific reference work. The new biocompatible, bioactive ECM may have significant translational impact in tissue bioengineering, beyond brain regeneration. We have also discovered the unexpected ictogenic potential of spheroids of primary hippocampal cells let free to self-assemble, as opposed to hippocampal hydrogels, which never generate ictal activity, but a recurrent pattern of short events resembling hippocampal interictal activity, thus being potentially anti-ictogenic.
The NCS concept is the first two-way learning system, where the biological and artificial synapses learn from each other. The several designs have demonstrated capable of detecting interictal events and seizures, and, in some instances, of seizure prediction. The AFE brings further novelty to the NCS and broadly to neural recording device engineering by enabling detection of action potentials and local field potentials in a wide amplitude range with >250 times input impedance improvement versus other structures.
The established closed-skull neurosurgery strategy for deep brain organoid grafting outclasses current procedures limited to the cortical surface. The approach may also be highly relevant for the combined ablation/replacement of damaged brain tissue in humans.
The microprobe uses a previously unconsidered combination of biocompatible substrate, encapsulation polymers, and stiffeners.
The methods for detection/prediction of brain-state changes and the modular simulation framework to realistically model the biohybrid interplay bring additional novelty, being based on a general framework rather than on detailed brain function biophysics; we expect them to find wider use in neuroscience research as well as in clinical diagnostic tools and brain prosthetics. In this context, the two-AI agent system is a novelty with respect to the original work plan, bringing cooperative AI agents for more target AI task allocation. The foreseen AI hardware implementation will be a first step toward a novel AI-based implantable device for seizure prediction and control.
By the end of the project, the developed technologies will positively impact the fields of biomaterials, brain tissue bioengineering, NCS design, deep brain recording, AI, and enhanced brain regeneration overall. In this, we are fostering an innovation eco-system via a constant dialog with society under a philosophical and ethical perspective, supported by a strong digital presence and focus groups.
The NCS concept is the first two-way learning system, where the biological and artificial synapses learn from each other. The several designs have demonstrated capable of detecting interictal events and seizures, and, in some instances, of seizure prediction. The AFE brings further novelty to the NCS and broadly to neural recording device engineering by enabling detection of action potentials and local field potentials in a wide amplitude range with >250 times input impedance improvement versus other structures.
The established closed-skull neurosurgery strategy for deep brain organoid grafting outclasses current procedures limited to the cortical surface. The approach may also be highly relevant for the combined ablation/replacement of damaged brain tissue in humans.
The microprobe uses a previously unconsidered combination of biocompatible substrate, encapsulation polymers, and stiffeners.
The methods for detection/prediction of brain-state changes and the modular simulation framework to realistically model the biohybrid interplay bring additional novelty, being based on a general framework rather than on detailed brain function biophysics; we expect them to find wider use in neuroscience research as well as in clinical diagnostic tools and brain prosthetics. In this context, the two-AI agent system is a novelty with respect to the original work plan, bringing cooperative AI agents for more target AI task allocation. The foreseen AI hardware implementation will be a first step toward a novel AI-based implantable device for seizure prediction and control.
By the end of the project, the developed technologies will positively impact the fields of biomaterials, brain tissue bioengineering, NCS design, deep brain recording, AI, and enhanced brain regeneration overall. In this, we are fostering an innovation eco-system via a constant dialog with society under a philosophical and ethical perspective, supported by a strong digital presence and focus groups.