Synergetic Use of Neural Precursor Cells and Self-assembling Peptides in Experimental Cervical Spinal Cord Injury

Klaus Zweckberger; Yang Liu; Jian Wang; Nicole Forgione; Michael G. Fehlings

doi:10.3791/52105

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Method Article

Synergetic Use of Neural Precursor Cells and Self-assembling Peptides in Experimental Cervical Spinal Cord Injury

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DOI:

10.3791/52105

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February 23rd, 2015

Klaus Zweckberger¹ , Yang Liu¹ , Jian Wang¹ , Nicole Forgione¹ , Michael G. Fehlings¹^,²^,³

¹Department of Genetics and Development, Toronto Western Research Institute and Spinal Program, University Health Network, Krembil Neuroscience Centre, ²Department of Surgery, University of Toronto, ³Institute of Medical Sciences, University of Toronto

Summary

Treating cervical spinal cord injury with both self-assembling peptides (SAP) and neural precursor cells (NPC), together with growth factors, is a promising approach to promote regeneration and recovery. A contusion/compression aneurysm clip rat model of cervical SCI and combined treatment involving SAP injection and NPC transplantation is established.

Abstract

Spinal cord injuries (SCI) cause serious neurological impairment and psychological, economic, and social consequences for patients and their families. Clinically, more than 50% of SCI affect the cervical spine¹. As a consequence of the primary injury, a cascade of secondary mechanisms including inflammation, apoptosis, and demyelination occur finally leading to tissue scarring and development of intramedullary cavities^2,3. Both represent physical and chemical barriers to cell transplantation, integration, and regeneration. Therefore, shaping the inhibitory environment and bridging cavities to create a supportive milieu for cell transplantation and regeneration is a promising therapeutic target⁴. Here, a contusion/compression model of cervical SCI using an aneurysm clip is described. This model is more clinically relevant than other experimental models, since complete transection or ruptures of the cord are rare. Also in comparison to the weight drop model, which in particular damage the dorsum columns, circumferential compression of the spinal cord appears advantageous. Clip closing force and duration can be adjusted to achieve different injury severity. A ring spring facilitates precise calibration and constancy of clip force. Under physiological conditions, synthetic self-assembling peptides (SAP) self-assemble into nanofibers and thus, are appealing for application in SCI⁵. They can be injected directly into the lesion minimizing damage to the cord. SAPs are biocompatible structures erecting scaffolds to bridge intramedullary cavities and thus, equip the damaged cord for regenerative treatments. K2(QL)6K2 (QL6) is a novel SAP introduced by Dong et al.⁶ In comparison to other peptides, QL6 self-assembles into β-sheets at neutral pH⁶.14 days after SCI, after the acute stage, SAPs are injected into the center of the lesion and neural precursor cells (NPC) are injected into adjacent dorsal columns. In order to support cell survival, transplantation is combined with continuous subdural administration of growth factors by osmotic micro pumps for 7 days.

Introduction

More than 50% of spinal cord injuries are related to the cervical spine. In the clinical setting two major pathophysiological mechanisms are described: the initial contusion of the spinal cord and subsequently, the ongoing compression caused by bone fractures, hemorrhages or tissue swelling.

The aneurysm clip contusion/compression model mimics both pathophysiological mechanisms: snapping the clip produces a contusion and the duration of clipping represents the compression component, conceding that the compression in clinical settings caused by bone fractures, hemorrhages or tissue swelling last significant longer. The used aneurysm clip is ....