Synthetic and Nature-derived Lipid Nanoparticles for Nerve Regeneration
medicine is a promising approach for the treatment of nerve injuries. Soluble growth
factors are commonly used to promote neuronal cell proliferation and differentiation.
However, there remain some issues associated with the use of growth factors alone.
Exosomes are lipid nanovesicles secreted by many types of cells and used for
intercellular communication. Since exosome ... read morecontains RNA and proteins, they could be a
useful alternative to growth factors for promoting tissue regeneration. We hypothesized
that exosomes derived from differentiating cells provide clues about the active
components promoting cell differentiation and proliferation. In this thesis, we used
PC12 cells, a neuronal cell line as a model. We investigated the role of exosomes
derived from PC12 cells at various stages of neuronal differentiation in promoting the
differentiation of mesenchymal stem cells (MSCs) towards a neuronal lineage. After the
treatment with exosomes, MSCs developed a neuron-like morphology, and the gene and
protein expressions of neuronal markers were upregulated. Microarray and proteomics
analyses identified active components including miRNAs and proteins that play a role in
neurite extension and neuronal differentiation. These results suggest that the exosome
may be delivering necessary signals, such as RNA and protein molecules, involved in
functional nerve regeneration. In addition, we took the first step in building exosome
mimics using synthetic lipid-based nanoparticles with defined miRNA cargo to induce
neuronal differentiation of MSCs. We performed screening assays to optimize the chemical
structure of bioreducible lipids for miRNA delivery. Then, we used the optimal lipid to
deliver miR-9, a known signaling molecule in neuronal differentiation, to MSCs. We
observed that the delivery of miR-9 induced morphological changes and upregulation of
neuronal marker genes in the MSCs. We believe these lipid nanoparticles, exosomes and
bioreducible lipids, have potential applications for nerve tissue
Thesis (Ph.D.)--Tufts University, 2016.
Submitted to the Dept. of Biomedical Engineering.
Advisor: Qiaobing Xu.
Committee: David Kaplan, Shoji Takeuchi, and Emmanuel Tzanakakis.
Keywords: Biomedical engineering, Molecular biology, and Cellular biology.read less