Background: Functionality of vascular grafts and heart valve grafts are limited of their calcification. It is assumed that decellularization the grafts can prevent their calcinosis. The aim of our study was to evaluate the effect of decellularization on the calcinosis of vascular grafts and to develop the method for prevention of vascular graft mineralization.
Material and methods: Human and pig aorta walls were used to study vascular calcinosis after decellularization. The well known model of subcutaneous implantation in rats was applied to evaluate the ability of aorta wall fragments to calcification. Histology and confocal microscopy was performed to assess decellularisation, tissue matrix damage and mineralization of aortic fragments. Calcium content in aorta fragments was determined by a spectophotometric method using the calcium-binding dye Arsenazo III. Nucleation of calcium deposits in mitochondria at early stages after implantation was evaluated by transmission electron microscopy.
Results: Decellularization with hypotonic shock, as well as with enzymatic or detergent SDS treatment did not reduce calcinosis of implanted aortic fragments. All mentioned treatments led to significant damage of tissue matrix in aorta wall fragments. The hypothesis was proposed that accumulation of calcium by mitochondria during donor cell dying may be a cause of calcinosis initiation in vascular grafts. The hypothesis was confirmed by electron microscopy study of calcinosis nucleation in aorta fragments after implantation. Based on the mitochondrial hypothesis of calcinosis nucleation, the method was developed to prevent mineralization of vascular grafts. This method has not damaging effect on the structure of the tissue matrix in aortic fragments.
Conclusion: Decellularization of aortic grafts by SDS, hypotonic shock or by enzymatic treatment does not prevent their mineralization. The method was developed for prevention of vascular graft calcinosis, which is based on the mitochondrial hypothesis of calcium deposit nucleation in dying cells.
This work was supported by grant of the Government of the Russian Federation №14.Z50.31.0028, by fellowship grant of the president of the Russian Federation (SP-6867.2013.4) and grant of the Russian Foundation of Basic Research №14-04-32191)