Contents lists available at ScienceDirect Materials Science & Engineering C journal homepage: www.elsevier.com/locate/msec Review Recent progress in the fabrication techniques of 3D scaffolds for tissue engineering Mostafa Mabrouk a,b, ⁎ , Hanan H. Beherei a , Diganta B. Das b a Refractories, Ceramics and Building Materials Department, National Research Centre, 33El Bohouth St (Former EL Tahrirst)-Dokki, P.O. 12622, Giza, Egypt b Department of Chemical Engineering, Loughborough University, Loughborough LE113TU, Leicestershire, UK ARTICLE INFO Keywords: Tissue engineering Scaffold preparation techniques Electrospinning 3D printing ABSTRACT 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, flex- ibilities 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. 1. Introduction Tissue engineering (TE) approaches have demonstrated impressive results for the treatment and substitution of damaged tissues and organs including skin, heart, and kidney tissues, in addition to their potential to address some inherent bone defects [1–10]. When different scientific fields, e.g., materials science, biology and engineering are combined together in an interdisciplinary manner with a view to augment or re- generate malfunctioned human parts, it promises to improve the suc- cess of the TE approaches [11–16]. For the TE systems to be fruitful, the material utilized should generally be a mixture of scaffolds, growth factors, and cells. They should also most certainly be able to replace the damaged tissue and have the capacity to either work as the native tissue or mimic the native tissue [17–22]. Application of growth factors and exogenous materials with the sole aim of quickening and enhancing the body's healing procedures could improve the tissue condition. Materials that simulate the properties of extracellular matrix have been used for a long period time till now, which accomplish more advantages other than supplying the physical structure [23–25]. Biomimetic materials can induce recovery of all, and they can be utilized for transport of biomolecules, for example, growth factors that facilitate cells growth [18,20,24–26]. At first, it was thought that scaffolds are fundamental for cells' physical support, the biomaterial or scaffold can now be loaded with biological factors to facilitate tissue recovery [27–29]. Because of the diverse recovery limits of various tissues, some tissues do not demand cells but rather simply the biomaterial and biological molecules. On the other hand, other tissues have restricted recovery limits and demand the biomaterial, biomolecules, and cells for recovery to happen. There are tissues and organs with constrained or no possibility for recovery like ligament and https://doi.org/10.1016/j.msec.2020.110716 Received 23 November 2019; Received in revised form 29 January 2020; Accepted 1 February 2020 ⁎ Corresponding author at: Refractories, Ceramics and Building Materials Department, National Research Centre, 33El Bohouth St (Former EL Tahrirst)-Dokki, P.O. 12622, Giza, Egypt. E-mail address: mostafamabrouk.nrc@gamail.com (M. Mabrouk). Materials Science & Engineering C 110 (2020) 110716 Available online 03 February 2020 0928-4931/ © 2020 Published by Elsevier B.V. T