Speaker
Description
Since synthetic vascular prosthesis perform poorly in small diameter revascularization, biological vascular substitutes are being developed as an alternative. Although their in vivo results are promising, their productions involve tissue engineering methods that are long, complex and expensive. To overcome these limitations, we propose an innovative approach that combines the human amniotic membrane (HAM), which is a widely available and cost-effective biological raw material, with a rapid and robust textile-inspired assembly strategy. [1] Fetal membranes were collected after cesarean deliveries at term. Once isolated by dissection, HAM sheets were cut in ribbons that could be further processed, by twisting, into threads. Characterization of HAM yarns (both ribbons and threads) showed that their physical and mechanical properties could easily be tuned. Since our clinical strategy will be to provide an off-the-shelf, allogeneic implant, we studied the effects of decellularization and / or gamma sterilization on the histological, mechanical, and biological properties of HAM ribbons. Decellularization had little effect of HAM yarn mechanical properties other than a small increase in strain at failure. However, gamma sterilization of the dried and decellularized HAM caused a decrease in rehydrated yarn diameter, an increase in ultimate tensile strength and a decrease in strain at failure. Gamma irradiation of hydrated (and decellularized) HAM largely avoided these mechanical changes and the process did not interfere with the ability of the matrix to support endothelium formation in vitro. Finally, HAM-based, woven, tissue-engineered vascular grafts (TEVGs) showed clinically relevant mechanical properties with a burst pressure of over 8000 mmHg (at a diameter of 4.4 mm), suture retention strength of over 5 N, and a transmural permeability of 1 ml·min-1·cm-2 Thus, this study demonstrates that human, completely biological, allogeneic, small diameter TEVGs can be produced from HAM, thereby avoiding costly manufacturing strategies based on cell culture and complex bioreactors.
[1] Magnan, L., Labrunie, G., Fenelon, M., Dusserre, N., Foulc, M.P., Lafourcade, M., Svahn, I., Gontier, E., Velez, V.J., McAllister, T.N., and L'Heureux, N. Human textiles: A cell-synthesized yarn as a truly "bio" material for tissue engineering applications. Acta Biomater, (105), 111-120, doi: 10.1016/j.actbio.2020.01.037 (2020).
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