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DEVELOPMENT OF BIPHASIC SCAFFOLDS OF COLLAGEN TYPE I FOR PERIPHERAL NERVE REGENERATION
Biomaterials have been used to produce conduits that protect and connect sectioned peripheral nerve stumps preventing the formation of neuromas and fibrous tissue between the stumps of the nerves (Faroni A, et al. 2015). Major drawbacks of current commercial devices are the size of the injury and their low effectiveness rates and low functional recovery rates (Sarker M, et al, 2018). Often, the standard diameters of these devices cannot be adapted to the diameter of the nerve injured at the time of surgery (Kehoe S, et al. 2012). Hence, the need to develop products that provide microstructural and cellular microenvironments that accelerates axonal regeneration.
Objetivos - Metodologia - Resultados - Discussão dos Resultados/Objectives - Methodology - Results - Discussion of Results/Objetivos - Metodología - Resultados - Discusión de los resultados
This work developed biphasic scaffolds of collagen type I that can form conduits with inner unidirectional and outer multidirectional pores, which could be used for regeneration of injured peripheral nerves. The above mentioned scaffold organization was designed to mimic the orientation of collagen fibers on the peripheral nerve and to provide a mechanical barrier for migration of unwanted cells. The scaffolds prepared can be folded to form a tubular conduit adapted to the diameter of the sectioned nerve stump. The unidirectional and multidirectional sections of the scaffolds were prepared using different concentrations of collagen (5 mg/g and 8 mg/g, respectively). Scaffolds were cross-linked using different concentrations of glutaraldehyde (0.02%; 0.04%; 0.06%; 0.08% and 0.1%). Physicochemical and mechanical properties, and cytocompatibility of the obtained scaffolds were evaluated. Scanning electron microscopy analysis showed scaffolds with two different zones: one with unidirectional pores and other with multidirectional pores. The pore size in the scaffold-unidirectional zone was larger than the one in the multidirectional zone. Infrared spectra of the scaffolds showed the characteristic bands of collagen type I indicating that its native structure was preserved (León et al 2016; Suesca et al 2017). No changes were seen in the spectra of samples made with different pore orientation, different collagen concentrations, and different cross-linking percentages. All the scaffolds had water contact angles smaller than 90° indicating they are moderately hydrophilic (Yuan and Lee 2013). The hydrophilicity of the scaffolds did not depend on the concentration of collagen and the concentration of glutaraldehyde. It was found that cross-linking percentage of scaffolds decreased when collagen concentration increased and was directly proportional to the concentration of glutaraldehyde used. Data from Z potential evaluations showed that scaffold-surface negative charge increased when glutaraldehyde concentration increased. On the other hand, tensile stress data demonstrated that the elastic modulus increased proportionally when the concentration of glutaraldehyde increased. Finally, cell viability assays demonstrated the cytocompatible of the scaffolds.
Considerações Finais/Final considerations/Consideraciones finales
Overall, data suggest that the biphasic scaffolds can form conduits with inner unidirectional and outer multidirectional pores. The type I collagen scaffolds developed are biocompatible and have physicochemical and mechanical properties that can promote their bioactivity when used in regeneration of injured peripheral nerves.
Palavras-chave/Key words/Palabras clave
Biphasic scaffolds of collagen type I
DIANA MILLAN, RONALD ANDRES JIMENEZ, SOFIA SILVA, JOAO MANO, MARTA RAQUEL FONTANILLA