Developing Methods for Directing Neurite Growth in 3-Dimensional Collagen Gels

Following nerve injuries, such as peripheral nerve atrophy or spinal cord injury, spontaneous nerve regeneration is limited, arising the need to develop growth-promoting technologies for enhancing neuronal regeneration. One promising approach is the through tissue-engineered scaffolds that can be implanted in the injured site, giving mechanical and biochemical support for growing neurons. Designing scaffolds with a structure and composition similar to the natural neuronal environment, and specifically, the utilization of scaffolds with aligned features, have demonstrated enhanced and directed neuronal growth. Methodologies to fabricate aligned scaffolds often include long preparation time, incorporation of toxic chemical agents, and require specific configuration based design for implantation. We designed collagen hydrogel as 3D scaffolds for neuronal regeneration, and developed methods to control collagen matrix structure and collagen fiber orientation. Firstly, we show the application of directed mechanical strain resulted in highly aligned gel matrices and facilitated enhanced and directed neuronal growth. Secondly, we developed a new method to orient collagen fibers as an injectable 3D collagen platform through magnetic forces. Embedded with magnetic nano particles (MNP) our collagen platform can be aligned in situ dynamically and remotely in response to an external magnetic field. This model overcomes the need for pre-fabrication of scaffolds, and shows superb orientation of fibers and subsequent directional neuronal regrowth. We report the enrichment of the gel platform with biomolecules conjugated MNPs for a multifunctional aligned collagen gel system presenting controlled delivery of biomolecules, together with integral fiber-guidance cues. We examine the aligned gel platform for peripheral nerve repair and fabricated an implantable scaffold conduit. 

* PhD supervised by: Prof. Orit Shefi