electrospinning & nanofibres in nerve regeneration- diptyajit das

Electrospinning & Nanofibers in Nerve Regeneration

Artificial Organs II

Diptyajit Das

Matrikel Nr. 3058259Date: 20.04.2016

© FH AACHEN UNIVERSITY OF APPLIED SCIENCES 28. April 2023 | 2

Overview

Introduction Structure of Nerve fiber Classification of nerve injury Nanotechnology & Nanofibres Nanofibre Production: Electrospinning Current research and development Discussion


Introduction

Nerve: Bundle of enclosed fibres in the body that transmits impulses of sensation to the brain or spinal cord, and impulses from these to the muscles and organs.

• Nerves are collection of neurons, which are the individual nerve cells.

Where are the nerves located?Our nerves are located throughout our bodies from our skin, through and round our organs and towards their centre, the brain.


Background

Which types of nerves exist?

The main 2 types of nerves are -sensory nerves and motor nerves.

• Sensory nerves also known as afferent nerves, carry impulses from sensory receptors towards the brain.

• Motor nerves also known as efferent nerves, carry impulses away from the brain to muscles and glands.


Structure of Nerve Fibre

Neuron Structure Nerve Fibres structure (PNS)


Overview of Nervous System

Diptyajit Das

Nervous system:The network of nerve cells and fibres which transmits nerve impulses between parts of the body.


Classification of Nerve Injury

Based on types of pain:• Acute: Peripheral nerve injury, spinal cord injury, traumatic

brain injury.• Chronic: Neurodegeneration (Alzheimer’s disease,

Parkinson’s disease).

Based on types of damage in neurons:• Neurapraxia : Myelin sheath is compressed only

(Demyelination).


Nerve Injury…

• Axonotmesis: (Demyelination+ Axon loss)

• Neurotmesis: (Demyelination+ Axon loss + one of the following: a)damage of endoneurium- fair growth b) damage of perineurium- poor growth c)damage of epineurium - no growth)

Note: Axon can grow back in presence of cell body.


CNS nerve fibres• Clear up process is

very slow• Environment is not

optimal• Oligodendrocytes

inhibit regeneration

Remarks: Nerve fibers do not regenerate

Comparison between CNS & PNS nerve fibers

PNS nerve fibres• Clean up process is

quick- macrophage .• Schwaan cells assist in

regeneration.

Remarks: Nerve fibers can regenerate


Nanotechnology & Nanofibers

• Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers.

• Nanofibers are defined as fibers with diameters less than 100 nanometers.

Physicist Richard Feynman is known as the father of nanotechnology.


Ideal properties of Nanofibers for nerve regeneration• Large specific surface area• High porosity• Small pore size• Diameter range (50 – 1000) nm• Biodegradable and biocompatible• Permissive for cell growth

Sometimes neurotrophic factors, such as neural growth factor (i.e.BDNF) will be included in nanofibers.


Materials for Nanofibers

• Mainly polymer solutions or melts• More than 30 polymers, including polyethylene oxide,

polyaniline have been electrospun.

• Natural polymers: (proteins, collagens) PVA, PS, PAN, but also peptide amphiphiles or cellulose. Lower immunogenicity, inherent biodegradability but

expensive and harder to produce in industry level.

• Synthetic polymers: Polyglycolide (PGA), poly(L-lactide) (PLA), and their copolymer poly(D,L-lactide-co-glycolide) (PLGA) etc.

relatively good mechanical strength , biocompatible, biodegradable and easier to produce.


Nanofiber Production

• What is electrospinning?Electrospinning is the process using electrostatic forces to form a fine filament of the polymer solution.

Why do we need electrospinning? • It fabricates porous and highly spatially interconnected micro-

and nano-scale polymer fibers, both natural and synthetic.• It produces highly aligned electrospun fibers which can

provide guidance cues for glial cells (e.g., Schwann cells) growth.

• Much easier (one single step) to incorporate those essential factors.

Modified Electrospinning Setup for alligned nanofibres

• Voltage applied to the needle: 12 kV• Syringe pump feeding rate: 1ml/h• Tip diameter of the needle: 0.4mm• Distance between collector and needle

tip: 10cm

c) SEM image of electrospun poly(L-lactide) (PLA) fibers using a rotating disk 8 wt%

Optical micrograph of PLGA (10:90) polymer, electrospun at different concentrations: (a) 5 wt%1000×; (b)7 wt% 1000×


Current research and development

NNGC (nanofibre nerve guide conduits) implantation:

Implantation site: Wistar rat’s (weighing 200–250 g) right sciatic nerve (a 3 cm long skin incision on the thigh), no. of rats: 11

Length of the implant NNGC: 14 mm

Nanofibre’s material: PLGA

Perineural suturing to NNGC: 10-0 times

The surgery was performed under an Olympus operating microscope.


Observation after one month

a) Macrograph of the regenerated cable one month after implantation

• Eight out of eleven rats had a regenerated cable inside the conduits.

• Positive reflex responses in 45% of the rats with a PLGA nanofibre NGC.

• Numerous myelinated nerve fibres had regenerated. Distributions of both myelinated and unmyelinated axons were observed.

• The regenerated axons varied in axonal diameter.


Discussion

• Electrospinning has been widely used to produce nano-fibrous scaffolds which mimic the structure of the natural extracellular matrix. The alignment of the fibres is important for achieving

directed cell growth.

• The quality of nerve regeneration in the nano-fibre conduits can be improved by introducing nerve growth factors or Schwann cells into the conduit lumen.


References

• Burger, Christian, Benjamin S. Hsiao, and Benjamin Chu. "Nanofibrous Material and Their Applications." Review. 25 Apr. 2006. Web. 14 Feb. 2010.

• Hunley, Matthew T., and Timothy E. Long. "Electrospinning Functional Nanoscale Fibers: a Perspective for the Future." Polymer International 57 (2008): 385-89. Web. 7 Mar. 2010.

• Xie, Jingwei, Matthew R. MacEwan, Andrea G. Schwartz, and Younan Xia. "Electrospin Nanofibers for Neural Tissue Engineering." Nanoscale 2 (2010): 35-44. Print.

• http://iopscience.iop.org/article/10.1088/0957-4484/15/11/014/pdf• www.mdpi.com/2073-4360/3/4/1684/pdf• http://www.brain.hku.hk/f/page/1157/Wu-nanomedicine.pdf• http://bmcbiotechnol.biomedcentral.com/articles/10.1186/1472-6750-8-39• http://www.differencebetween.net/science/difference-between-nerve-and-n

euron/

http://iopscience.iop.org/article/10.1088/0957-4484/15/11/014/pdf

http://www.mdpi.com/2073-4360/3/4/1684/pdf

http://www.brain.hku.hk/f/page/1157/Wu-nanomedicine.pdf

http://bmcbiotechnol.biomedcentral.com/articles/10.1186/1472-6750-8-39

http://www.differencebetween.net/science/difference-between-nerve-and-neuron/

http://www.differencebetween.net/science/difference-between-nerve-and-neuron/

Thank you for the Attention!

Question please?

electrospinning & nanofibres in nerve regeneration- diptyajit das

Documents