LAUSR

PURPOSE This systematic review focus on the application of bilayer scaffolds as an engaging structure for the engineering of multilayered tissues, including vascular and osteochondral tissues, skin, nerve, and urinary bladder. This article provides a concise literature review of different types of bilayer scaffolds to understand their efficacy in targeted tissue engineering. METHODS To this aim, electronic search in the English language was performed in PMC, NBCI, and PubMed from April 2008 to December 2019 based on the PRISMA guidelines. Animal studies, including the "bilayer scaffold" and at least one of the following items were examined: osteochondral tissue, bone, skin, neural tissue, urinary bladder, vascular system. The articles which didn't include "tissue engineering" and just in vitro studies were excluded. RESULTS Totally, 600 articles were evaluated; related articles were 145, and 35 full-text English articles met all the criteria. Fifteen articles in soft tissue engineering and twenty items in hard tissue engineering were the results of this exploration. Based on selected papers, it was revealed that the bilayer scaffolds were used in the regeneration of the multilayered tissues. The highest multilayered tissue regeneration has been achieved when bilayer scaffolds were used with mesenchymal stem cells and differentiation medium before implanting. Among the studies being reported in this review, bone marrow mesenchymal stem cells are the most studied mesenchymal stem cells. Among different kinds of multilayer tissue, the bilayer scaffold has been most used in osteochondral tissue engineering in which collagen and PLGA have been the most frequently used biomaterials. After osteochondral tissue engineering, bilayer scaffolds were widely used in skin tissue engineering. CONCLUSION The current review aimed to manifest the researcher and surgeons to use a more sophisticated bilayer scaffold in combinations of appropriate stem cells, and different can improve multilayer tissue regeneration. This systematic review can pave a way to design a suitable bilayer scaffold for a specific target tissue and conjunction with proper stem cells.