Optimizing the Treatment Method of Arterial Tissue to be Used as Acellular Scaffolds for Vascular Reconstruction
Burl, Rayanne B.
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Arterial reconstruction is a necessary treatment for damaged arterial tissue. While materials such as biodegradable cell-seeded scaffolds and collagen-gel matrices have successfully been used to reconstruct arteries, they are not without complications and research is still being done to find the most biocompatible method that is successfully able to mimic the structural, chemical, and mechanical characteristics of a native blood vessel. Scaffolds made from the decellularized arterial tissue of a donor are a promising method as the scaffold is comprised of the native extracellular matrix proteins of an arterial vessel. These scaffolds then recruit native cells from surround tissue. However when implanted, this leaves the collagen-containing basal lamina as the blood contacting surface of the graft. The collagen activates white blood cells in the host and causes cell adhesion and clotting. Instead, research has proposed using the internal arterial elastic laminae as the blood contacting surface as it has been shown to have anti-inflammatory and anti-thrombogenic properties. This requires tissue treatment to not only decellularize the tissue, but remove the luminal basal lamina to expose the elastic laminae in the media of the vessel. In this study, we used excised rat aortic tissue and attempted to optimize their treatment with sodium hydroxide (NaOH) to expose the elastic lamina for the blood contacting surface, but also retain enough collagen in the adventita of the vessel that the scaffold remains structurally sound. Five different treatment methods were used; each one was an improvement on the one before when the results were unsuccessful. These treatment methods are referred to as numbered trials. Trial 1 consisted of simply placing aortic tissue in 0.1 M NaOH. In Trial 2, tissue was placed on a vortex mixer in NaOH to agitate tissue during treatment. Trial 3 placed tissue in NaOH on a shake table to agitate tissue, and then tissue was placed in PBS and put back on the shake table for three hours. Trial 4 followed the same treatment as Trial 3 and following this treatment, a cell treatment was added using sodium chloride, sodium dodecyl sulfate, and fetal bovine serum to decellularize tissue. In Trial 5, a pump system was implemented that ran NaOH through the lumen of the vessel only and the same cell treatment described in Trial 4 was use post-treatment. Trials using only NaOH failed to decellularized the tissue. The cell treatment used in Trials 4 and 5 successfully decellularized the tissue, and the NaOH treatment in Trial 5 was the most successful at removing the collagen of the basal lamina while preserving the collagen in the adventitia. These observations suggest that Trial 5 is a promising treatment method to produce a decellularized scaffold from native arterial tissue that has the internal elastic laminae as the blood contacting surface. Future research should attempt to optimize the length of treatment for the Trial 5 method, use immunofluorescent labeling to better visualize the treated blood-contacting surface, and test the scaffolds treated with this method in vivo. This research brings us one step closer to finding the most biocompatible material for vascular reconstruction.