## 5 Other Hybrid Approaches with MEW
In the study of [PERSON] et al., they combined MEW with solution electrospinning to acquire micro-nano fibers, mimicking the ECM structure for further application in tissue engineering [125]. PCL was utilized for MEW process to manufacture a mesh-like structure, and a PCL/collagen blend was used for SE, as shown in Figure 8. The hybrid MEW-SE scaffold was fabricated in a two-step manner. The patterned microlayers were melt electrospun, and PCL/collagen nanofibers were deposited between the layers by electrospinning. Three different combinations of MEW and SE were used with varying the number of PCL/collagen layers. Afterwards, bovine chondrocytes were seeded, and cell adhesion and proliferation were investigated for 10 days of incubation on different hybrid scaffold designs. The results demonstrated that the scaffolds containing more layers of PCL/collagen had 2.5 folds higher cell attachment and 2.7 times more cell number than the melt electrospun PCL scaffold. The amide groups of PCL/collagen nanofibers with improvement in its hydrophilicity with the help of its rough surface and higher surface area enhanced the cell attachment, and the ECM like architecture of the hybrid structure enhanced its cell proliferation. Figure 7: Attachment of human umbilical vein endothelial cells (HUVECs) on the fibronectin coated PCL fiber networks with different pore size. Scale bar represents 200 \(\upmu\)m [122] Copyright 2018 by Wiley-VCH Verlag GmbH & Co. KGaA Weinheim. Reprinted by permission of John Wiley and Sons. Another study was performed by developing a hybrid MEW-SE setup for neural applications. [PERSON] et al., melt electrospun two different micro-patterns of PCL as loop mesh and biaxial aligned structures and functionalized them with retinoic acid (RA) encapsulated PCL while using SE. The scaffolds were then seeded with neural progenitors that were derived from human induced pluripotent stem cells (iPSCs). The promotion and differentiation of iPSCs were evaluated, and the effect of different geometries was explored as well. Cell viability, immunohistochemistry, neurite extension, and real-time quantitative PCR analysis were performed. Electrospinning of RA encapsulated PCL increased cell attachment due to expanding the available surface area for cells to adhere. The cells were able to adhere, align, and migrate along the fibers in the loop mesh scaffolds with lower fiber diameters. Biaxial aligned fibers showed more promising results in terms of cell viability, proliferation, elongation, and neurite outgrowth. In general, melt electrospun structures induced the expression of neural markers in the cells, and hybrid structures showed the highest expression of neural markers as compared to loop mesh and biaxial aligned scaffolds. Melt electrospinning could be favorable for neural tissue engineering, since the geometry of the fabricated structure strongly influences the cell alignments and cell response. Moreover, by integrating it with other techniques, it can serve as a promising strategy to fulfill the requirements of the designed scaffold. The modification of melt electrospun structures by solution electrospinning utilizing benign solvents or water with a variety of polymers encapsulated with drugs, nanoparticles, and biomolecules could enrich its application for different tissue engineering purposes.