1. How it works

2. Mechanical Properties
     Bone Scaffolds    Heart Muscle Scaffolds    Spinal Cord Engineering  

3. References

Nano-scaffolding (or nanoscaffolding) is a medical process used to regrow tissue and bone, including limbs and organs. The nano-scaffold is a three-dimensional structure composed of polymer fibers very small that are scaled from a Nanometer (10⁻⁹ m) scale.^[1] Developed by the American military, the medical technology uses a microscopic apparatus made of fine polymer fibers called a scaffold.^[2] Damaged cells grip to the scaffold and begin to rebuild missing bone and tissue through tiny holes in the scaffold. As tissue grows, the scaffold is absorbed into the body and disappears completely.

Nano-scaffolding has also been used to regrow burned skin. The process cannot grow complex organs like hearts.^[3]

Historically, research on nano-scaffolds dates back to at least the late 1980s when Simon showed that electrospinning could be used to produced nano- and submicron-scale polymeric fibrous scaffolds specifically intended for use as in vitro cell and tissue substrates. This early use of electrospun fibrous lattices for cell culture and tissue engineering showed that various cell types would adhere to and proliferate upon polycarbonate fibers. It was noted that as opposed to the flattened morphology typically seen in 2D culture, cells grown on the electrospun fibers exhibited a more rounded 3-dimensional morphology generally observed of tissues in vivo.^[4]

How it works

Nano-scaffolding is very small, 100 times smaller than the human hair and is built out of biodegradable fibers. The use of this scaffolding allows more effective use of stem cells and quicker regeneration. Electrospun nanofibers are prepared using microscopic tubes that range between 100 and 200 nanometers in diameter. These entangle with each other in the form of a web as they're produced. Electrospinning allows the construction of these webs to be controlled in the sense of the tube's diameter, thickness, and the material being used.^[5] Nano-scaffolding is placed into the body at the site where the regeneration process will occur. Once injected, stem cells are added to the scaffolding. Stem cells that are attached to a scaffold are shown to be more successful in adapting to their environment and performing the task of regeneration. The nerve ends in the body will attach to the scaffolding by weaving in-between the openings. This will cause them to act as a bridge to connect severed sections. Over time the scaffolding will dissolve and safely exit the body leaving healthy nerves in its place.

This technology is the combination of stem cell research and nanotechnology. The ability to be able to repair damaged nerves is the greatest challenge and prize for many researchers as well as a huge step for the medical field.^[6] This would allow doctors to repair nerves damaged in an extreme accident, like third degree burns. The technology however, is still in its infancy and is still not capable of regenerating complex organs like a heart, although it can already be used to create skin, bone and nails.^[7] Nano scaffolding has been shown to be four to seven times more effective in keeping the stem cells alive in the body, which would allow them to perform their job more effectively. This technology can be used to save limbs that would otherwise need amputation.^[8] Nanoscaffolding provides a large surface area for the material being produced, along with changeable chemical and physical properties. This allows them to be applicable in many different types of technological fields.^[5]

Mechanical Properties

Mechanical properties are one of the most important considerations when designing scaffolds for medical use. If the mechanical properties, in particular the elastic modulus, of the scaffold do not align with those of the host tissue, the scaffold is more likely to inhibit regeneration or mechanically fail.

Bone Scaffolds

As with natural bone, the primary issue with bone scaffolds is brittle failure. They typically follow linear elastic behavior, and under compressive forces experiences a plateau and recovery reminiscent of cellular solids as well as trabecular bone.^[9] The elastic modulus of natural bone ranges from 10 to 20 GPa; it requires a high stiffness to withstand constant mechanical load.^[10] Bone scaffolds must therefore be as stiff as natural bone, or the scaffold will fail through crack nucleation and propagation before the host tissue can regenerate. However, if the scaffold is significantly stiffer than the surrounding tissue, the elastic mismatch and continuity at the scaffold boundary with cause strain in the natural bone and could create unwanted defects.

Heart Muscle Scaffolds

Cardiac muscle, on the other hand, has an elastic modulus of only around 10 MPa, 3 orders of magnitude smaller than bone. However, it experiences constant cyclic loading as the heart pumps.^[11] This means that the scaffold must be both tough and elastic, a property achieved using polymeric materials.

Spinal Cord Engineering

The spinal cord presents yet another challenge in the engineering of mechanical properties for tissue engineering. Discs in the spine are stiff like bone, and must withstand high mechanical loading; this part of the spine must be engineered with a high elastic modulus. The discs are filled with white and grey matter, which are gel-like and much less stiff. In repairing a defect in the grey matter, the modulus must be matched precisely so that the shock-absorbing properties are not affected. A mismatch in elastic modulus will also hinder contact between the regenerative material and the host grey matter as well as the exterior bone layer.^[12]

References

• Benjamin Gerrish
• Benjamin Gerritsz Cuyp
• Benjamin Geza Affleck-Boldt
• Benjamin G. Ferris
• Benjamin G. Hill
• Benjamin Gibli
• Benjamin Gibson
• Benjamin Gilad
• Benjamin Ginsberg (political scientist)
• Benjamin Girke
• Benjamin Goldwasser
• Benjamin González
• Benjamin Goodison
• Benjamin Gordon Baldwin House
• Benjamin Grant House
• Benjamin Grant Mitchell
• Benjamin Grau
• Benjamin Graydon Allmark
• Benjamin Green
• Benjamin Green (architect)
• Benjamin Green (disambiguation)
• Benjamin Greene
• Benjamin Green (merchant)
• Benjamin Griffin (alpine skier)
• Benjamin Griffin (disambiguation)