On the progress of 3D-printed hydrogels for tissue engineering

This is the authors' abstract. We don't add key points for this paper.

Tissue engineering involves the use of materials engineering and life sciences concepts to regenerate, restore, replace, improve, and maintain tissues damaged by injury, disease, or congenital disabilities. [ 1 ] Not only can these procedures be done using basic understanding of the structural and functional relationships of natural and pathologic mammalian tissues, but the development of biosubstitutes can also be achieved. [ 2 , 3 ] Particularly, by harvesting cells from a living organism (or other compatible sources), and seeding the cells onto a tissue scaffold (which becomes the cell-scaffold construct), the construct tends to become a functional construction after maturation. Subsequently, it can be implanted into a human body to help regenerate or repair any damaged tissues. [ 4 ] For successful implants and proper tissue scaffold designs, a good understanding of the composition and organization of tissue scaffolds is desirable. Suitable architectural designs and materials capable of mimicking the properties of natural tissues must also be selected. [ 5 ] Likewise, proper design towards cell proliferation, cell differentiation, vascularization, and sustainable growth should be implemented. Several groups have recently studied different architectures, materials, growth factors, cell types, and other supporting components to create functional constructs. [ 6 , 7 , 8 , 9 ] While these attempts need further improvement in mimicking complex tissue structures, challenges of cell differentiation in hierarchical locations or orientation have also been identified. [ 10 ]