Development and characterization of nanofibrous membrane for the treatment of congenital diaphragmatic hernia
Résumé
Congenital Diaphragmatic Hernia (CDH) is a rare malformation, a hole in the diaphragm is formed early in the embryogenesis. For the most severe cases of CDH, a prosthesis is necessary to fill the hole in the diaphragm. The major issue is that the currently used prosthesis cannot follow the growth of the child. Their mechanical properties are not suitable in terms of stretchability and rigidity, leading to the break of the stretches and recidivism of the hernia. We aim to change the paradigm by designing a biocompatible prosthesis adapted to the disease with two distinct faces: one smooth side to impair the intestine adherence on the abdominal side and one fibrous side to enhance the cellular colonization to improve the integration of the prosthesis to the diaphragm. To follow the growth of the child, the mechanical specifications are the following: a 300 % minimum stretchability and a rigidity similar to the muscle. A medical grade elastomeric thermoplastic polyurethane (TPU) was processed using electrospinning. A semi-diluted entangled polymer solution is stretched in a jet-like form, under a strong electric field, leading to the formation of a nano-fibrous membrane on a grounded collector. Electrospinning formulation and process parameters, using a 4-needles setup , were studied to obtain fibrous membranes. Then, the preparation of bilayered membrane with a smooth film layer and a rough fibrous layer was investigated. To avoid delamination between the two layers, the membranes were fabricated in a continuous process by varying the flow rate of the solution during electrospinning. A 4-needles emiter was used to increase the production yield and its translation was optimized to ensure the thickness homogeneity of the membrane (Figure 1). It was shown that mechanical properties are impacted by the ratio of film to total thickness. A panel of membranes was thus designed varying this ratio from 0 (only fibers) to 1 (only film) allowing to modulate the mechanical properties of the membrane (tensile strength, elongation at break, Young modulus, Figure 2). The membrane exhibiting the best mechanical properties was compared with the current prosthesis. The specifications in terms of stretchability were successfully doubled (600 %) and the rigidity was considerably lowered (2.5 MPa). Further biological and mechanical tests, such as uniaxial tensile tests on the stretched membrane or bi-axial tensile tests, are currently ongoing to complete the study.
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