Despite electrospinning having multiple advantages over other methods such as creating materials with a superfine fiber diameter, high specific surface area, and good mechanical properties, the pore diameter of scaffolds prepared directly using conventional electrospinning is often smaller than a few tens of microns, which may not be suitable for three-dimensional (3-D) cell culture and tissue growth. In order to achieve satisfactory results for use in tissue engineering, the pore size of the scaffold should be increased to a size dependent on the specific cells being cultured. Many methods for enlarging the pore size of electrospun scaffolds have been described in the literature. In the present review, we have summarized the preparation of macroporous electrospun scaffold techniques for the skin, blood vessels, bone, cartilage and nerve tissue engineering for different applications, and further discuss the influence of changing pore-enlarging process parameters on the properties of the scaffolds, such as mechanical properties, and hydrophilicity and hydrophobicity, etc. We believe that changes in scaffold pore size and related physical properties can have a profound impact on cell behavior, such as adhesion, proliferation and infiltration, and the significance of their influence on applications of electrospun tissue engineering scaffolds is worthy of further investigation in the future.

Endogenous electric fields (EFs) are capable of regulating the behaviors of skin cells in wound healing. However, majority of current dressings are primarily engaged in the passive repair of defective tissue, as they lack the ability to actively respond to physiological electrical signals. In this work, a series of nanofibrous membranes (NFMs) were fabricated by coaxial electrospinning, combining the good mechanical properties of poly(ε-caprolactone) (PCL), the bioactivity of gelatin and the electroactivity of Ti₃C₂T_x MXene, as electroactive and antibacterial dressings for cutaneous wound healing. The obtained NFMs exhibited suitable mechanical properties and hydrophilicity, excellent electroactivity, antibacterial activity, and biocompatibility. Especially, Ti₃C₂T_x MXene/PCL/gelatin-6 (MPG-6, 6 wt.% of Ti₃C₂T_x MXene in sheath spinning liquids) showed the optimal conductivity and antibacterial activity. Excitingly, this scaffold significantly promoted the adhesion, proliferation, and migration of NIH 3T3 cells under the electrical stimulation (ES). The in vivo evaluation in a full-thickness wounds defect model demonstrated that the MPG-6 films significantly accelerated wound closure, increased granulation tissue formation, increased collagen deposition, and promoted wound vascularization. In summary, the versatile scaffold is expected to be an ideal candidate as wound dressings due to its ability to promote the transmission of physiological electrical signals and thus improved the therapeutic outcomes of wound regeneration.

In situ tissue regeneration approach aims to exploit the body’s own biological resources and reparative capability and recruit host cells by utilizing cell-instructive biomaterials. In order to immobilize and release bioactive factors in biomaterials, it is important to engineer the load effectiveness, release kinetics and cell recruiting capabilities of bioactive molecules by using suitable bonding strategies. Stromal cell-derived factor 1α (SDF-1α) is one of the most potent chemokines for stem cell recruitment, and SDF-1α-loaded scaffolds have been used for the regeneration of many types of tissues. This review summarizes the strategies to incorporate SDF-1α into scaffolds, including direct loading or adsorption, polyion complexes, specific heparin-mediated interaction and particulate system, which may be applied to the immobilization of other chemokines or growth factors. In addition, we discuss the application of these strategies in the regeneration of tissues such as blood vessel, myocardium, cartilage and bone.