Despite being potential candidates to replace autografts in peripheral nerve regeneration procedures,
[1] nerve guide ducts (NGCs) are limited to repairing small gaps of no more than 1 cm.
[2] Since much of the regenerative process occurs on the surface of the NGC,
[2] our work focuses on using the layer-by-layer technique for surface modification. Through the generation of polymeric coatings, it is possible to increase the cell adhesion properties in NGCs and even to include nerve growth factor (NGF) to improve proliferation. In this research, we modified various surfaces by coating with six bilayers of the combination of heparin and collagen (HEP/COL) and studied their effects on the viability, proliferation, and morphology of human Schwann cells (hSCs) in the presence or absence of the NGF. Also, a technique based on the measurement of the electrical impedance of biosensors was used to analyze the real-time behavior and the cellular response to biosensors previously covered with HEP/COL. Viability tests with the PrestoBlue reagent showed that after six days, the coatings increase cell viability up to 2.5 times compared to the tissue culture plastic control. All the real-time monitoring tests for 6 days have allowed the identification of three stages in the cellular response to the coatings: an initial adhesion region, a proliferation region, and a cell confluence stage. Conditions with layer-by-layer coatings improved initial cell adhesion by increasing confluence in the third stage compared to control conditions of uncovered biosensors. By fluorescence microscopy, the cell morphology was determined to have a typical behavior (bipolar or tripolar cells), and cells with increased expansion were evidenced in HEP /COL films with NGF in suspension. In our previous work,
[3] we were able to determine by IR-VASE spectra that the chemical structure of collagen and heparin is present in multiple layers created on flat silicon plates. Thanks to a colorimetry method, we revealed that there is no degradation of more than 50% of the heparin content from the multilayers after 7 days, which indicates that HEP/COL films are a favorable and stable substrate for cell culture of hSCs. Layer-by-layer coatings increase cell adhesion and proliferation and can serve as reservoirs for NGF delivery. In conclusion, HEP/COL coatings are a promising strategy for surface modification of NGCs.
References:
[1] R. Ayala-caminero, L. Pinzón-herrera, C.A. Rivera Martinez, J. Almodovar, Polymeric scaffolds for three-dimensional culture of nerve cells: a model of peripheral nerve regeneration, MRS Commun. 7 (2017) 391–415. doi:10.1557/mrc.2017.90.
[2] J. Choi, J.H. Kim, J.W. Jang, H.J. Kim, S.H. Choi, S.W. Kwon, Decellularized sciatic nerve matrix as a biodegradable conduit for peripheral nerve regeneration, Neural Regen. Res. 13 (2018) 1796–1803. doi:10.4103/1673-5374.237126.
[3] D.A. Castilla-Casadiego, L. Pinzon-Herrera, M. Perez-Perez, B.A. Quiñones-Colón, D. Suleiman, J. Almodovar, Simultaneous characterization of physical, chemical, and thermal properties of polymeric multilayers using infrared spectroscopic ellipsometry, Colloids Surfaces A. 553 (2018) 155–168. doi:10.1016/j.colsurfa.2018.05.052.
