Current tissue engineering and novel therapeutic approaches to axonal regeneration following spinal cord injury using polymer scaffolds

Respir Physiol Neurobiol, 2009 · DOI: 10.1016/j.resp.2009.08.015 · Published: November 30, 2009

Spinal Cord Injury Regenerative Medicine Biomedical

Simple Explanation

This review discusses tissue engineering and therapeutic approaches for axonal regeneration after spinal cord injury, focusing on 3D polymer scaffolds. The aim is to derive new neuronal tissue from the surrounding, healthy cord that will be guided by the polymer implant through the injured area to make functional reconnections. Structural support of axonal regeneration is combined with integrated polymeric and cellular delivery systems for therapeutic drugs and for neurotrophic molecules to regionalize growth of specific nerve populations.

Study Duration

Not specified

Participants

Not specified

Evidence Level

Review

Key Findings

1
Axonal growth is supported by inherent properties of the selected polymer, the architecture of the scaffold, permissive microstructures such as pores, grooves or polymer fibres, and surface modifications to provide improved adherence and growth directionality.
2
Open path designs were improvements over the other three designs in terms of regenerative capacity, but also that the other more closed designs adversely affected the surrounding cord, doubling the defect length.
3
Microgrooves can be placed in the polymer surface by laser etching, affecting contact guidance and alignment of neurites.

Research Summary

This review highlights current tissue engineering and novel therapeutic approaches to axonal regeneration following spinal cord injury. Restoration of respiratory function will be a critical application for biomaterial approaches given the degree of mortality and morbidity associated with respiratory compromise after spinal cord injury. The integration of Schwann cells, olfactory ensheathing cells and neural stem cells into the polymer structures have improved their regenerative capacity, as has the use of scaffolds as delivery devices for therapeutic agents, particularly neurotrophic factors.

Practical Implications

Scaffold Design

Scaffold architecture, porosity, and micro/macroengineering influence axonal regeneration, suggesting tailored designs can optimize nerve growth.

Polymer Selection

The choice of natural or synthetic polymers affects biocompatibility, degradation, and drug delivery potential, implying careful material selection is crucial.

Cellular Therapies

Integrating Schwann cells, olfactory ensheathing cells, and neural stem cells into polymer scaffolds enhances regenerative capacity, indicating a promising avenue for cell-based therapies.

Study Limitations

1
Investigation of many possible combinations of material, geometry, functionalization strategies, and integrated drug or cell based therapies will need to be properly controlled and systematic.
2
Despite these approaches to augment neurotrophic support and phenotypic selection, there remains no convincing evidence that axonal populations are extending beyond the cellular or polymer bridges to form lasting functional connections.
3
The absence of their use has the influenced development of alternate stem cell types for scaffolds including mesenchymal stem cells and induced pluripotent stem cells (iPSCs) as potential sources both of new neurons as well as drug delivery cells.

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