Bioactive Nanofibers: Synergistic Effects of Nanotopography and Chemical Signaling on Cell Guidance
In this paper, the authors look at the ability of bioactive nanofiber scaffolds to guide cells. The authors specifically investigated the capability of these scaffolds to affect neuronal outgrowth and skin cell migration. Neuronal outgrowth is of particular interest because directed neuronal regeneration has vast medical potential. Skin cell migration is an important component of wound healing, another process of medical interest.
By aligning nanofibers, researchers created a nanotopography that the cells responded to. Compared to random fibers, aligned fibers had much improved neuronal outgrowth and skin cell migration. In addition, by immobilizing specific growth factors on the nanofibers, researchers further increased neuronal outgrowth and skin cell migration.
The experimenters used at ex vivo model to measure neuronal outgrowth, culturing harvested dorsal root ganglia on the scaffold in media. The synergistic effect of nanofiber alignment and growth factor immobilization can be seen in the attached figure from the paper.
On random fibers with no growth factors (A), there was no neurite outgrowth. On aligned, untreated fibers (B), moderate neuronal outgrowth occurred in the direction of alignment. For aligned, bioactive fibers (C), neuronal outgrowth was the greatest. These results demonstrate the importance of both nanotopography and cell signaling for neuronal outgrowth.
An in vitro model was used to measure dermal fibroblast migration. Cells were seeded as monolayers on the nanofiber sheets, and a wound was simulated along the length of the sheet. Researchers then recorded the migration of the dermal fibroblasts into the "wound" site. Cell migration was greatly increased along the axis of alignment. Again, bioactive fibers added to the effect, but not as extensively as in the case of neuronal outgrowth.
This paper is of interest to my group as we will be using nanofibers as a scaffold in our project. We will also be using growth factors, though we will use solubilized growth factors because it is more simple and more effective. This paper uses techniques for visualization that we might find useful for our own project, as we will be using the same scaffolding material, and demonstrates methods for growing cells on nanofiber sheets. In addition, the results of the paper are interesting to me because they offer a viable method of controlling cell migration and neuronal outgrowth, which could be useful in many tissue engineering applications.
4 comments:
It is interesting to find that the bioactive nanofiber scaffolding successfully resulted in neuronal outgrowth in this study; however, it'd been nice to know whether these neuronal outgrowth had any effects on the actual properties of the neurites. For instance, are these neurites expressing the usual molecular markers on their surfaces to allow proper axon/dentiritic guidances to occur in the presence of nanofiber scaffolds? Ultimately, we want to ensure the novel functionalities of neurons - ie. whether they extend to the complementary synapses, whether the growth of one axon still maintains the negative feedback system within the neuron to signal other neurites from further growing, etc. It'd been an awesome experiment if they stained the newly-grown neurites in the presence of nanofiber scaffolds for maybe Tau and MAP-2 (microtubule binding proteins that are prominent in axon and dentrites, respectively) to see if any of these novel properties of neurites were, indeed, conserved.
Very much interested in what you guys find in your group's project using nanofiber scaffold! Thanks for posting the paper! :^)
Hey Adam, I don't know where the supporting figures so I don't know if I missed something, but the graphs on page 4 and 6 with the bar graphs of the various groups are missing a graph for laminin AND bFGF. Shyam is missing a positive control for the experiment, but I can't think of something that should work all the time for this particular study, but I'm glad he did use a negative control in every aspect of the experiment (attachment of bFGF, neurite outgrowth, and cell migration). I also don't know if it's just this journal's particular format, but I found the article to be a bit frustrating because of a lack of organization. Methods, materials, and results are all jumbled together with no clear structure, so I found it difficult to read. Anyways, I think this is an extremely interesting paper and am wondering if the future of this project is going towards recreating native ECM in the nanofiber scaffolds (since adding bFGF and laminin is just a baby step towards this). Thanks Adam (and go fill out your commencement forms)
There's a lot of research going on with nanofibers, in order to make them more functionally useful, and investigating their potential with various cell types (stem cells, etc). I think that Shyam is concentrating on making nerve conduits through the use of bioactive aligned nanofiber tubes.
It sounds interesting that by aligning fibers orderly they had much improved neuronal outgrowth and skin cell migration. Perhaps due to the similar arrangement in real life? And I am wondering what these nanofibers are made of.
Post a Comment