Hydrogel for control of 3D neurite outgrowth
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Hydrogeler till att kontrollera 3D neurit tillväxt. (Swedish)
The ability to egnineer defined 3D neural circuits within artifical materials is expected to bring new tools for understanding basic biology, for screening pharmacologic molecules important in neurogeneration as well as for developing neural tissue engineering applications.
Here we show that the Michael addition of thiols on maleimides can be used to form PEG-based hydrogels entrapping neurons. This addition reaction is already in wide use for bioconjugation because of its selectivity, high kinetics, and biocompatibility. But its use in this context is original. In such a system, the gelation time is higy tunable due to the PH-dependence, ranging from nearly instantaneous at pG 7.4 to around 30min at pH 5.0. A solution containing neurons can be stabilized to any pH in this range by adding a small amount of 2(N-morpholino)ethanesulfonic (MES) buffer.
Peptides with oe or two thiol-containing cysteine residues could be readily incorporated into the hydrogel. This alloed us to produce PEG gels with a matrix metalo-proteinase (MMP-cleavable peptide as a cross-linker and(or laminin peptides (RGD, IKVAV, YIGSE) as attachment cues. Among all these peptides, IKVAV was the only one that was found to promote cell adhesion and extensive neurite outgrowth from embryonic day 18 (E18) rat primary hippocampal neurons, while gels without any peptide prevented neurite outgrowth completely. Gels cross-linked with MMP-cleavable peptides degraded in a few days due to enzymatic degradation, while gels cross-linked with PEG-dithiol degraded lver the course of a few weeks, which dould be attributed to the reversibility of the addition of thiols on maleimides. Both gels promoted neurite outgrowth for macromer content below 1.6%(w/v). For the future, we envision that inductive and repulsive hydrogels can be patterned in three dimensional space, thereby providing a system for creating complex neural networks.
Place, publisher, year, edition, pages
Hydrogels, neurites, 3D neural circuits, PEG gels, peptides, laminin, neurite outgrowth
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-149660OAI: oai:DiVA.org:kth-149660DiVA: diva2:744700