Recent progress in the fabrication techniques of 3D scaffolds for tissue engineering.

Significant advances have been made in the field of tissue engineering (TE), especially in the synthesis of three-dimensional (3D) scaffolds for replacing damaged tissues and organs in laboratory conditions. However, the gaps in knowledge in exploiting these techniques in preclinical trials and beyond and, in particular, in practical scenarios (e.g., replacing real body organs) have not been discussed well in the existing literature. Furthermore, it is observed in the literature that while new techniques for the synthesis of 3D TE scaffold have been developed, some of the earlier techniques are still being used. This implies that the advantages offered by a more recent and advanced technique as compared to the earlier ones are not obvious, and these should be discussed in detail. For example, one needs to be aware of the reason, if any, behind the superiority of traditional electrospinning technique over recent advances in 3D printing technique for the production of 3D scaffolds given the popularity of the former over the latter, indicated by the number of publications in the respective areas. Keeping these points in mind, this review aims to demonstrate the ongoing trend in TE based on the scaffold fabrication techniques, focusing mostly, on the two most widely used techniques, namely, electrospinning and 3D printing, with a special emphasis on preclinical trials and beyond. In this context, the advantages, disadvantages, flexibilities and limitations of the relevant techniques (electrospinner and 3D printer) are discussed. The paper also critically analyzes the applicability, restrictions, and future demands of these techniques in TE including their applications in generating whole body organs. It is concluded that combining these knowledge gaps with the existing body of knowledge on the preparation of laboratory scale 3D scaffolds, would deliver a much better understanding in the future for scientists who are interested in these techniques.