Directing Axonal Growth: A Review on the Fabrication of Fibrous Scaffolds That Promotes the Orientation of Axons

Tissues are commonly defined as groups of cells that have similar structure and uniformly perform a specialized function. A lesser-known fact is that the placement of these cells within these tissues plays an important role in executing its functions, especially for neuronal cells. Hence, the design of a functional neural scaffold has to mirror these cell organizations, which are brought about by the configuration of natural extracellular matrix (ECM) structural proteins. In this review, we will briefly discuss the various characteristics considered when making neural scaffolds. We will then focus on the cellular orientation and axonal alignment of neural cells within their ECM and elaborate on the mechanisms involved in this process. A better understanding of these mechanisms could shed more light onto the rationale of fabricating the scaffolds for this specific functionality. Finally, we will discuss the scaffolds used in neural tissue engineering (NTE) and the methods used to fabricate these well-defined constructs.

Cell-Incorporated Bioactive Tissue Engineering Scaffolds made by Concurrent Cell Electrospinning and Emulsion Electrospinning

Electrospun fibrous scaffolds attract great attention in tissue engineering owing to their high similarity in architecture to the extracellular matrix (ECM) that support cell attachment and growth in human bodies. Although they have shown superiority in promoting cell attachment and proliferation on their surfaces and hence, hold great promise for the regeneration of body tissues, the research still faces a great challenge of three-dimensional (3D) cell incorporation in electrospun scaffolds to form thick and cell-dense constructs because deep cell infiltration is hard to achieve in conventional electrospun scaffolds that normally have very small diameters of interconnected pores. Such hindrance has severely limited the clinical application of electrospun fibrous scaffolds to repair/regenerate various body tissues, particularly those with complex anatomies. To address this challenge, we have developed a concurrent cell electrospinning and emulsion electrospinning technique for fabricating bioactive bio-hybrid scaffolds with 3D and high-density cell incorporation. Through concurrent electrospinning, cell-encapsulated hydrogel fibers (“cell fibers”) and growth factor-containing ultrafine fibers are simultaneously deposited to form two-component scaffolds (i.e., scaffolds composed of two types of fibers) according to the design. With the breakup of cell fibers, live cells with well-preserved cell viability are released in situ inside the scaffolds, resulting in the creation of cell-incorporated bioactive scaffolds with ECM-mimicking fibrous architectures and 3D and high-density incorporation of cells. The growth and functions of incorporated cells in the scaffolds can be enhanced by the released growth factor from the emulsion electrospun fibrous component. The bioactive bio-hybrid scaffolds fabricated via concurrent electrospinning mimic the cell-matrix organization of body tissues and therefore have great potential for regenerating body tissues such as tendon and ligament.

Electrospun Composite Nanofibers Based on Poly (ε-caprolactone) and Styrax Liquidus (Liquidambar Orientalis Miller) as a Wound Dressing: Preparation, Characterization, Biological and Cytocompatibility Results

In this study, styrax liquidus (sweet gum balsam) extracted from Liquidambar orientalis Mil. incorporated PCL fibrous scaffolds were prepared using the electrospinning method. The effects of the styrax liquidus content on the prepared scaffolds were investigated using different physico-chemical and morphological analyses. Then, the styrax-loaded nanofibers were examined for their antioxidant activity, anti-biofilm, metal chelating, antimicrobial and DNA cleavage properties. The results obtained from these studies showed that the nanofibers exhibited effective biological activity depending on the weight ratio of the styrax liquidus. In light of the data obtained from the characterization and biological studies, a sample with high ratio of balsam was built for determining the cytocompatibility analysis in vitro. The cytotoxicity studies of the selected membrane were conducted using mouse embryonic fibroblast cells. The fibrous scaffolds lead to increase the cell number as a result of high viability. According to the results, we propose a novel biocompatible electrospun hybrid scaffold with antioxidant and antimicrobial properties that can be used as wound healing material for potential tissue engineering applications.