One of the human body’s most amazing qualities is its ability to regenerate itself. Everything from paper cuts to broken bones can be healed through time, but there are limits. Once damage gets too extensive, it can never regenerate. And sometimes, the regenerative wait can be agonizing.
Nerve damage is a perfect example. It can occur any number of ways, from the dramatic gunshot to the mundane falling down the stairs, and the damage can last a lifetime. Using a technique known as electrospinning, scientists can create what are known as “3D nanofiber scaffolds” which could prove vital for creating 3D neural tissue constructs to rebuild bodies. Their findings have been published May 12 in the Applied Physics Review.
"Electrospinning is a technology to produce nanofiber membranes," says co-author Jingwei Xie, at the University of Nebraska Medical Center, speaking in a press statement. "The physics principle behind it involves applying an electrical force to overcome the surface tension of a solution to elongate a solution jet into continuous and ultrafine fibers after solvent evaporation."
Here is electrospinning at its most basic: imagine a syringe, with a battery below it, pointed at a screen. The syringe is filled with a polymer solution. Electrospinning uses high voltages from the battery to create an electric field between the syringe and the screen. As the syringe pushes out the polymer solution, the electrostatic force shapes the solution like a cone, and eventually forces a jet of solution onto the screen and dries. That leaves a group of randomly oriented solid nanofibers onto the screen, ready to be collected and used.
Electrospinning can reduce a 12 hour process to a single hour.
Xie’s team has demonstrated that the nanofibers gleaned from electrospinning can create “3D neural tissue constructs with an ordered structure.”
“Many different scenarios could benefit from tissue regeneration/repair using the methods described in this study,” Xie tells Inverse. “For example, cylindrical shaped nanofiber scaffolds could be used for peripheral nerve regeneration as the scaffolds exhibit the similar structure as the decellularized native tissue.” Peripheral nerves exist outside of our central nervous system, and comprise the nerves that connect the parts of our face, like our eyes, noses, and mouths, to our brain.
There were challenges to get electrospinning to create 3D neural tissue. When the jet lands on the collection screen, it’s more likely that 2D membranes from dense structures and small pore sizes. These are tiny, smaller than human cells.
While small can often be good in terms of innovation, in this case it “greatly inhibits the applications of electrospun nanofibers, because cells fail to seed or penetrate throughout the nanofiber membranes, which is undesirable," Xie says in the press statement. Using what’s known as gas foaming, which blends together various chemicals, Xie’s team can manipulate the polymers into useful shapes within an hour. Other methods can take up to twelve hours.
“There are several different strategies” for the regeneration process, Xie tells Inverse. “The simplest one is to use the 3D scaffolds alone for tissue repair/regeneration without incorporation of biological factors and living cells. In this case, the 3D scaffolds can be applied as medical devices/implants for promoting endogenous cell infiltration and recruitment to form new tissues, resulting in tissue repair/regeneration.” Endogenous cell infiltration, when cells move from one part of the body to another, can be crucial for tissue repair.
Xie expects that “3D scaffolds alone could be translated into clinical applications for tissue repair/regeneration in the next 5-10 years.” Like regeneration itself, it’s a development that will hopefully be worth the wait.
Abstract: The ability to transform two-dimensional (2D) structures into three-dimensional (3D) structures leads to a variety of applications in fields such as soft electronics, soft robotics, and other biomedical-related fields. Previous reports have focused on using electrospun nanofibers due to their ability to mimic the extracellular matrix. These studies often lead to poor results due to the dense structures and small poor sizes of 2D nanofiber membranes. Using a unique method of combining innovative gas-foaming and molding technologies, we report the rapid transformation of 2D nanofiber membranes into predesigned 3D scaffolds with biomimetic and oriented porous structure. By adding a surfactant (pluronic F-127) to poly(ε-caprolactone) (PCL) nanofibers, the rate of expansion is dramatically enhanced due to the increase in hydrophilicity and subsequent gas bubble stability. Using this novel method together with molding, 3D objects with cylindrical, hollow cylindrical, cuboid, spherical, and irregular shapes are created. Interestingly, these 3D shapes exhibit anisotropy and consistent pore sizes throughout entire object. Through further treatment with gelatin, the scaffolds become superelastic and shape-recoverable. Additionally, gelatin-coated, cube-shaped scaffolds were further functionalized with polypyrrole coatings and exhibited dynamic electrical conductivity during cyclic compression. Cuboid-shaped scaffolds have been demonstrated to be effective for compressible hemorrhage in a porcine liver injury model. In addition, human neural progenitor cells can be uniformly distributed and differentiated into neurons throughout the cylinder-shaped nanofiber scaffolds, forming ordered 3D neural tissue constructs. Taken together, the approach presented in this study is very promising in the production of pre-molded 3D nanofiber scaffolds for many biomedical applications.