Undesired effects of a combinatorial treatment for spinal cord injury – transplantation of olfactory ensheathing cells and BDNF infusion to the red nucleus

Abstract

Transplantations of olfactory ensheathing cells (OECs) have been reported to promote axonal regeneration and functional recovery after spinal cord injury, but have demonstrated limited growth promotion of rat rubrospinal axons after a cervical dorsolateral funiculus crush. Rubrospinal neurons undergo massive atrophy after cervical axotomy and show only transient expression of regeneration-associated genes. Cell body treatment with brain-derived neurotrophic factor (BDNF) prevents this atrophy, stimulates regeneration-associated gene expression and promotes regeneration of rubrospinal axons into peripheral nerve transplants. Here, we hypothesized that the failure of rubrospinal axons to regenerate through a bridge of OEC transplants was due to this weak intrinsic cell body response. Hence, we combined BDNF treatment of rubrospinal neurons with transplantation of highly enriched OECs derived from the nasal mucosa and assessed axonal regeneration as well as behavioral changes after a cervical dorsolateral funiculus crush. Each treatment alone as well as their combination prevented the dieback of the rubrospinal axons, but none of them promoted rubrospinal regeneration beyond the lesion/transplantation site. Motor performance in a food-pellet reaching test and forelimb usage during vertical exploration (cylinder test) were more impaired after combining transplantation of OECs with BDNF treatment. This impaired motor performance correlated with lowered sensory thresholds in animals receiving the combinatorial therapy - which were not seen with each treatment alone. Only this combinatorial treatment group showed enhanced sprouting of calcitonin gene-related peptide-positive axons rostral to the lesion site. Hence, some combinatorial treatments, such as OECs with BDNF, may have undesired effects in the injured spinal cord.

A Systematic Review of Cellular Transplantation Therapies for Spinal Cord Injury

“…or corticospinal axons across and beyond the lesion site was also not found in the studies using olfactory bulb derived OECs from adult rats (Deumens et al, 2006;Ruitenberg et al, 2003) or with OECs from the mucosa of newborn mice (Bretzner et al, 2008;. Behavioral benefits were seen when the adult bulb-derived OECs were transfected to express BDNF=NT-3 (Ruitenberg et al, 2003).…”

Lhx3-Chx10 Reticulospinal Neurons in Locomotor Circuits

“…Tissues were harvested, postfixed in 4% paraformaldehyde overnight, and subsequently cryoprotected in 30% sucrose. As previously described, immunohistochemistry was performed on cryostat cut sections mounted on slides (Bretzner et al, 2010) or microtome cut floating Figure 1. Anatomical characterization of Lhx3 and Chx10 medRF neurons.…”

“…Biotinylated dextran amine (BDA, 10 kDa, 10% in sterile water; Sigma-Aldrich) was injected in the cuneiform nucleus [CnF; n ϭ 4 mice; anteroposterior (AP), Ϫ5 mm; mediolateral (ML), 1.25 mm; depth, 1.9 mm] and the pedunculopontine nucleus (PPN; n ϭ 2 mice; AP, Ϫ4.6 mm; ML, 1.25 mm; depth, 2.25 mm) of anesthetized adult Lhx3-YFP mice, as described previously (Bretzner et al, 2008(Bretzner et al, , 2010. After 1 week, mice were perfused and tissues harvested and labeled.…”

“…The brain selects and plans the motor programs, and transmits motor commands from the brainstem to the spinal cord, which in turn translates these commands into motor action. While progress has been made in understanding motor commands in the forebrain (Drew et al, 2004;Bretzner and Drew, 2005) and integration in the spinal cord (Brownstone and Bui, 2010), less in known about the brainstem neurons that play key integrative roles in producing movement.…”

Schwann Cells Generated from Neonatal Skin-Derived Precursors or Neonatal Peripheral Nerve Improve Functional Recovery after Acute Transplantation into the Partially Injured Cervical Spinal Cord of the Rat

“…SKP-SCs (Experiments. 1 and 2), N-SCs (Experiment 2), or Fibros (Experiment 2) were transplanted into the spinal cord using procedures modified from our previous work (Bretzner et al, 2008(Bretzner et al, , 2010. Briefly, adherent cells were detached from the dish by digestion in trypsin-EDTA (0.01%), the trypsin was deactivated by adding 10% FBS, and the cells were spun down and resuspended in fresh HBSS (Invitrogen; Experiment 1) or DMEM (Experiment 2) at ϳ135,000 cells/l.…”