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theses

Despite the innate regenerative potential of the peripheral nervous system, functional recovery is often limited. The goal of this dissertation was to develop a clinically relevant biomaterial strategy to (1) encourage the regrowth of axons and (2) direct them down their appropriate motor tracts. To this end, we use peptide mimics of two glycans, polysialic acid (PSA) and an epitope first discovered on human natural killer cells (HNK-1), to functionalize type I collagen hydrogels. Previous studies have shown that these molecules, in their glycan and glycomimetic form, are associated with acceleration of neurite outgrowth, glial cell proliferation, and motoneuron targeting. In vitro, we demonstrated the retained functionality of the peptide glycomimetics after conjugation to a type I collagen backbone. While HNK-functionalized collagen increased motor neurite outgrowth, PSA-functionalized collagen encouraged motor and sensory neurite outgrowth and Schwann cell extension and proliferation. When we introduce these glycomimetic-functionalized collagen hydrogels into a critical gap femoral nerve model, we show that both PSA and HNK-functionalized hydrogels yielded a significant increase in functional recovery when compared to saline, native and scramble-coupled hydrogels. However, there was an interesting divergence in the morphological results: PSA-functionalized hydrogels increased axon count and HNK-functionalized hydrogels increased motoneuron targeting and myelination. We believed that these differences may be attributed to distinct mechanisms by which the glycomimetics impart their benefit. Interestingly, however, we found no synergistic gain in recovery with the use of our composite hydrogels which we speculated may be due to an inadequate dose of the individual glycomimetic. To address this possibility, we show that increasing the amount of functionalized peptide functionalized in our composite hydrogels led to increases in axon count and area of regeneration, but does not affect the degree of functional recovery. Finally, in order to assess potential mechanisms by which our glycomimetics impart benefit, we describe a novel platform for studying neural cell/biomaterial interaction through the use of two types of motoneuron cultures, dissociated spinal cord neurons and organotypic spinal cord slices. We show promising evidence that this strategy can be used to probe signaling pathways potentially involved in the action of these bioactives.

ETD_4497

Ph.D.

Includes bibliographical references

Includes vita

by Shirley Narain Masand

http://hdl.rutgers.edu/1782.1/rucore10001600001.ETD.000067804

doi:10.7282/T3V69H9K

ETD doctoral

The author owns the copyright to this work.