Gene and cell therapy: combining two approaches to promote neuroprotection and neuroregeneration in a model of optic nerve injury

Abstract

Purpose : After injury, the axons in central nervous system (CNS) do not regenerate great distances and permanently lose their connections to the brain. Two promising approaches to revert this challenging condition are gene and cell therapies. In the present work, we evaluated the neuroprotective and neuroregenerative potential of pigment epithelium derived factor (PEDF) gene therapy together with human mesenchymal stem cells (hMSCs) therapy in retinal ganglion cells (RGC) survival and axonal outgrowth in a model of optic nerve injury.

Methods : Adult (3-4 months old) Lister-Hooded rats underwent unilateral optic nerve crush 30 days after AAV.PEDF or AAV.GFP unilateral injection into the vitreous body. Immediately after crush, hMSCs derived from umbilical cord Wharton's Jelly were also injected unilaterally into vitreous body. Twenty-eight days after injury, RGC survival and axonal outgrowth were evaluated assessing the estimated number of Tuj1-positive cells in flat-mounted retinas and the number of axons anterogradely labeled with cholera toxin B subunit conjugated with Alexa 488 (CTB-488), respectively.

Results : Twenty-eight days after crush, the combined therapy with intravitreal administration of both hMSC and PEDF gene therapy through adeno-associated viral vectors (AAV2.PEDF/hMSCs) significantly (p<0.05) increased the number of Tuj1-positive cells/retina (50.646 ± 4.661) when compared to control (AAV2.GFP/hMSC) (31.966 ± 2.239). Furthermore, we noticed a significantly (p<0.001) higher number of axons/nerve in AAV2.PEDF/hMSCs group (1340 ± 180.0) when compared to AAV2.GFP/hMSCs (626.7 ± 72.57), 0.25 mm beyond the lesion site.

Conclusions : The combined gene and cell therapy (AAV2.PEDF/hMSCs) showed an expressive neuroprotective potential and was able to protect a higher number of RGC from death after injury, when compared to control. Additionally, the axonal regeneration of these surviving cells was higher in the treated group, 0.25 mm beyond the lesion site. The molecular mechanisms by which PEDF and hMSC are acting to promote these striking effects are now under investigation.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.