Electrospun Nano-architectures for Tissue Engineering and Regenerative Medicine

Abstract

Skin consists of three layers, namely, epidermis, dermis, and hypodermis. In case of partial injury to the epidermis layer, the body has the ability to heal itself naturally, but in case of deep dermal injuries, skin substitutes are required. This skin transplantation can be done by using either allograft or autograft or xenograft. However, these techniques are associated with drawbacks like high cost, limited availability, and disease transmission. In order to mitigate these challenges, tissue-engineered skin grafts can be used. Nowadays, researchers are trying to engineer artificial organs which will help patients facing organ failure and would end the hassle of finding a suitable donor. This rapidly emerging field of science is known as regenerative medicine. Regenerative medicine involves repairing or engineering human tissues and organs by culturing normal cells or stem cells on scaffolds. To ensure the growth of cells, these scaffolds must be porous, should have good water-holding capacity, and should allow easy permeation of gases and metabolites. Nanofibers due to their unique properties like large surface area, high porosity, and increased mechanical strength are considered as ideal material for scaffold preparation. It has been found that nanofibers help in promoting adherence, growth, and proliferation of seeded cells and successful development of tissue-engineered constructs. Electrospinning is a cost-effective, simple, and versatile method which can be used for fabrication of a variety of nanofibers at a large scale. By changing various parameters like voltage, concentration of solution, tip to collector distance, feed rate, speed of collector drum, and viscosity, the orientation and diameter of nanofibers can be fine-tuned to match the desired end applications. Orientation of nanofibers, porosity, pore size, and nanophase surface roughness are some of the factors that have a great influence on cell growth. It has been observed that smaller size of fibers than the cell size facilitates the orientation of the cells around the fiber. Pore size has also been found to affect the cell morphology. On decreasing the pore size of randomly oriented nanofibrous membrane, the cell morphology changes from spherical to elongated, whereas in the case of aligned fiber membrane, on decreasing the pore area, the cell remains in elongated state and is found to spread along the direction of alignment of fiber. Although significant amount of work has been carried out to study the role of ‘nanofibers diameter’ on the adherence, growth, and proliferation. The effect of fiber orientation and pore size on cell adhesion is still not fully explored. In this chapter, we review (1) general properties of nanofibers and biopolymers, (2) electrospinning process and its types, (3) parameters which affect the electrospinning process, (4) applications of the electrospun nanofibers in the field of regenerative medicine, and (5) existing regenerative medicine products in the market. The major applications discussed are tissue engineering and drug delivery, and a detailed discussion regarding regeneration of different types of tissues has been carried out. A comprehensive list of electrospun and co-spun biopolymers along with their spinning condition and potential applications has been tabulated by thorough literature analysis. This review aims to identify the research gap in this field and to highlight the future prospects of this efficient technology in the field of medicine.