Microfluidic Arrays of Three-dimensional Neuronal Culture for High-throughput Chemotactic Assays and Its Application in Neuroregeneration

Brain injuries and neurodegeneration usually cause irreversible loss of neural tissue thatdisrupts critical function of the central nervous system (CNS). As an emerging strategy torepair injured/degenerated brains, activation of endogenous neurogenesis by using engineeredconstructs are increasingly recognized as an appealing alternative. This method typicallyemploys artificial constructs with recreated cellular microenvironment to mimic thebiochemical composition of embryonic development stages. Chemotactic molecules are agroup of factors with such potential to be developed to regulate different aspects ofendogenous neurogenesis for regenerating injured brains. However, even though manydifferent neural chemotactic molecules have been discovered so far; there has been limitedsuccess in engineering these factors for regenerating brain tissues, mostly due to considerablevariety of chemotactic moclecules, and the existence of a wide range of responsive modes fordifferent molecules. Even for the same molecules, different concentrations or differentgradient steepness could lead to distinct response in neuronal cells. These variations posetremendous technical obstacles for dissecting neuronal chemotaxis to acquire sufficientquantitative information to precisely guide the engineering procedures, and thus require noveltools that can perform chemotactic assays in a high-throughput format. In this proposedproject, we aim to develop a “brain on a chip” platform that is capable of generating hundredsof concentration profiles with various gradient steepness for a specific molecule, so thatneuronal chemotactic response to the molecule can be systematically studied to in ex vivo 3Dmodels to answer the following questions: 1) what is the concentration sensitivity of aspecific chemotactic molecule; 2) how the gradient steepness affects neuronal responses; 3)how to differentiate neuronal migration or axonal projection by optimize the concentrationprofiles. Furthermore, by using the results from high-throughput chemotactic assays asinstructive inputs, we will then implement a regenerative strategy for repairing brain injuriesin an animal model. This method will be based on an engineered constructs with optimaldistribution of proper chemotactic molecules, which will be implanted to connect the injurysite and adult neurogenic regions. It is expected that successful completion of this project willnot only provide a high-throughput platform for quantitatively dissecting neuronalchemotaxis, but can also resolve valuable insights into effective mechanisms about specificmolecules, which are potentially beneficial for the treatment of brain trauma andneurodegenerative diseases.