A Morphological Study of a Bioresorbable Tubular Matrix of a Small Diameter from a Poly (L-lactide) for a Tissue-Engineered Vascular Implant

Nonwoven tubular bioresorbable matrices with an inner diameter of 1.1 mm were obtained by electroforming from solutions of poly (L-lactide) (PLA). Matrices were implanted into the abdominal aorta of rats as a tissue-engineering vascular implant for a period of 2 days to 16 months and showed high biocompatibility, nontoxicity, and pronounced atrombogenic properties. The total implant patency was 93%. Morphometric analysis of the dynamics of population of the matrix with cells showed that, for all observation periods in the outer half of the matrix wall, the number of cells prevails, which indicates the migration of cells from the connective tissue capsule surrounding the matrix. It is shown that two parallel processes occur in the matrix wall: bioresorption of PLA fibers and the formation of connective tissue. Complete bioresorption of matrices with replacement by native tissues, as well as formation of the endothelial and subendothelial layers, took place over the 16 months of the experiment. By this time, all the experimental animals in the reconstruction zone revealed an aneurysmal expansion that did not lead to rupture of the implant. To prevent the development of such complications, it is necessary to develop a method for additional strengthening of the matrix wall.