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. 2021 Apr 15;9:622524. doi: 10.3389/fbioe.2021.622524

Figure 5.

Figure 5

Images of various types of nerve neuroprosthetics. Images included of devices as fabricated (device), implanted into rodent sciatic nerves (implantation), and of the resulting FBR in tissue (FBR). (A-C) Epineurial cuff electrodes. (C) Cross-section of a rat sciatic nerve implanted with a silicone cuff 30 days post-implantation. Nerve (represented by immunoflurescently labeled axon marker NF200, green) take up a small portion of the cuff, with the rest filled with fibroblasts (vimentin, blue) due to FBR to the cuff. Dotted white line indicates approximate position of the cuff. Yellow arrowheads indicate compression of the nerve due to growing fibrotic tissue. Scale bar: 100 μm. (D–F) Intraneural electrodes, either transverse intrafascicular multichannel electrodes (TIME) (D,E) or longitudinally implanted intrafascicular electrodes (LIFE) (F). (F) Toluidine blue-stained images of nerve cross-sections. The two branches of the LIFE parylene C implant (slits in tissue) are found in close proximity to the axons (small circular structures) 1 day (1 d) post-implantation. By 8 weeks post-implantation (8 w) a fibrotic capsule (seen as a smooth ring around the implant slits) develops, displacing the axons. Scale bar: 50 μm. (G–I) Regenerative sieve (G,H) and microchannel (I) electrodes. (I) Cross-section of a rat sciatic nerve regenerated through a PDMS microchannel implant (image of a single microchannel) 12 weeks post-implantation. Nerve tissue (represented by immunoflurescently labeled axon marker NF, green; and Schwann cell S100, red) take up a small portion of the microchannel cross-section. The remainder of the microchannel is filled with other cell types (nuclear stain DAPI, blue), likely macrophages and fibroblasts as a result of FBR to the microchannel walls. The outline of the image represents the approximate position of the microchannel walls. Scale bar: 20 μm. All images reproduced under the terms of the Creative Commons Attribution License: (A) (Christie et al., 2017), (B) (Elyahoodayan et al., 2020), (C) (González-González et al., 2018), (D) (Zelechowski et al., 2020), (E) (Strauss et al., 2019), (F) (de la Oliva et al., 2018), (G,H) (MacEwan et al., 2016), (I) (Musick et al., 2015).