Transplantation of canine olfactory ensheathing cells producing chondroitinase ABC promotes chondroitin sulphate proteoglycan digestion and axonal sprouting following spinal cord injury

Abstract

Olfactory ensheathing cell (OEC) transplantation is a promising strategy for treating spinal cord injury (SCI), as has been demonstrated in experimental SCI models and naturally occurring SCI in dogs. However, the presence of chondroitin sulphate proteoglycans within the extracellular matrix of the glial scar can inhibit efficient axonal repair and limit the therapeutic potential of OECs. Here we have used lentiviral vectors to genetically modify canine OECs to continuously deliver mammalian chondroitinase ABC at the lesion site in order to degrade the inhibitory chondroitin sulphate proteoglycans in a rodent model of spinal cord injury. We demonstrate that these chondroitinase producing canine OECs survived at 4 weeks following transplantation into the spinal cord lesion and effectively digested chondroitin sulphate proteoglycans at the site of injury. There was evidence of sprouting within the corticospinal tract rostral to the lesion and an increase in the number of corticospinal axons caudal to the lesion, suggestive of axonal regeneration. Our results indicate that delivery of the chondroitinase enzyme can be achieved with the genetically modified OECs to increase axon growth following SCI. The combination of these two promising approaches is a potential strategy for promoting neural regeneration following SCI in veterinary practice and human patients.

Methods of olfactory ensheathing cell harvesting from the olfactory mucosa in dogs

“…The optimal proportion of mucosal olfactory ensheathing cell to promote axonal regeneration and improve functions following SCI is currently unknown and variable proportions of mucosal olfactory ensheathing cell have been used in rodent models [34,35,56–60]. A recent report described that higher proportions of olfactory mucosal ensheathing cells tended to lead to successful functional recovery after transplantation, while lower proportions (~10%) did not [57].…”

Stem Cell Conditioned Medium Treatment for Canine Spinal Cord Injury: Pilot Feasibility Study

“…Bone marrow was isolated from healthy adult dogs ( n = 2) after informed consent of the owners was obtained. Procedure for isolating bone marrow was the same as described in our previous study [ 20 ].…”

“…Mesenchymal stem cells (MSCs) generated from adult and neonatal tissues have been enrolled for experimental treatment of canine SCI [ 18 , 19 ]. In addition, extracellular vesicles have emerged as an important bioactive component of the MSC conditioned media which may be useful for intervention treatment [ 20 ]. Olfactory ensheathing cells (OECs) revealing persistent neurogenesis seem to be another good candidate for treatment of canine experimental and naturally-occurring SCI [ 20 , 21 ].…”

“…In addition, extracellular vesicles have emerged as an important bioactive component of the MSC conditioned media which may be useful for intervention treatment [ 20 ]. Olfactory ensheathing cells (OECs) revealing persistent neurogenesis seem to be another good candidate for treatment of canine experimental and naturally-occurring SCI [ 20 , 21 ]. Dogs treated with OECs showed better coordination and increased pelvic limb movement when compared with controls [ 22 , 23 ].…”

Survival and Integration of Transplanted Olfactory Ensheathing Cells are Crucial for Spinal Cord Injury Repair: Insights from the Last 10 Years of Animal Model Studies

“…None of the studies in which OEC survival was calculated assessed or analyzed the inflammatory status of the injury site. Two studies mentioned intermingling of surviving OECs with reactive astrocytes at the injury site 29,32 . Only one of the studies discussed migration of OECs away from site of injection into the cord tissue and disappearance of the transplanted cells from the lesion site at 8 weeks following transplantation 33 .…”