Schwann cell-free adult canine olfactory ensheathing cell preparations from olfactory bulb and mucosa display differential migratory and neurite growth-promoting properties in vitro

Abstract

BackgroundTransplantation of olfactory ensheathing cells (OEC) and Schwann cells (SC) is a promising therapeutic strategy to promote axonal growth and remyelination after spinal cord injury. Previous studies mainly focused on the rat model though results from primate and porcine models differed from those in the rat model. Interestingly, canine OECs show primate-like in vitro characteristics, such as absence of early senescence and abundance of stable p75NTR expression indicating that this species represents a valuable translational species for further studies. So far, few investigations have tested different glial cell types within the same study under identical conditions. This makes it very difficult to evaluate contradictory or confirmatory findings reported in various studies. Moreover, potential contamination of OEC preparations with Schwann cells was difficult to exclude. Thus, it remains rather controversial whether the different glial types display distinct cellular properties.ResultsHere, we established cultures of Schwann cell-free OECs from olfactory bulb (OB-OECs) and mucosa (OM-OECs) and compared them in assays to Schwann cells. These glial cultures were obtained from a canine large animal model and used for monitoring migration, phagocytosis and the effects on in vitro neurite growth. OB-OECs and Schwann cells migrated faster than OM-OECs in a scratch wound assay. Glial cell migration was not modulated by cGMP and cAMP signaling, but activating protein kinase C enhanced motility. All three glial cell types displayed phagocytic activity in a microbead assay. In co-cultures with of human model (NT2) neurons neurite growth was maximal on OB-OECs.ConclusionsThese data provide evidence that OB- and OM-OECs display distinct migratory behavior and interaction with neurites. OB-OECs migrate faster and enhance neurite growth of human model neurons better than Schwann cells, suggesting distinct and inherent properties of these closely-related cell types. Future studies will have to address whether, and how, these cellular properties correlate with the in vivo behavior after transplantation.

Increased migration of olfactory ensheathing cells secreting the Nogo receptor ectodomain over inhibitory substrates and lesioned spinal cord

“…OEC transplantation has been shown to promote regeneration and functional recovery in lesioned spinal cord [9,10]. In that the regenerative properties of OECs are largely associated with their migration and lamellipodial dynamics (e.g., [23,69]) there is a considerable interest in enhancing OEC migratory capacity. In fact, it is assumed that OECs migrate ahead of growing axons and by secreting supporting factors (e.g., GDNF) [16,28], or with matrix metalloproteinase activity [70] aiding and promoting their elongation.…”

NT-3 attenuates the growth of human neuron cells through the ERK pathway

“…Primary damage occurs by mechanical tissue disruption immediately subsequent to trauma. Secondary damage is mediated by complex cellular and molecular processes (Roloff et al 2013). NT-3, as one of the important neurotrophic factors, modulates neuron cell growth, differentiation and survival (Brodski et al 2000).…”

Olfactory-Ensheathing Cell Transplantation for Peripheral Nerve Repair: Update on Recent Developments

“…Further analysis indicated gene expression of brain-derived neurotrophic factor (BDNF), NGF and neurotrophin-3 in both groups, but the secretion levels of these growth factors were increased in OM-OECs . Moreover, in an in vitro study, OB-OECs and SCs displayed faster migratory properties and more effective neuritic outgrowth of cocultured human NT2 neurons than OM-OECs, further indicating the physiological differences between OM-OECs and OBOECs [Roloff et al, 2014].…”

“…It was demonstrated that OM-OECs overexpress genes characteristic of wound healing and regulation of the extracellular matrix. Moreover, in an in vitro study it was demonstrated that OB-OECs and SCs displayed faster migratory properties and more effective neuritic outgrowth than OM-OECs, whereas all three glial cell types demonstrated similar phagocytic effects [Roloff et al, 2014]. With regard to their origin-dependent functional characteristics, cotransplantation of both subpopulations in a recurrent laryngeal nerve injury model resulted in enhanced functional recovery by the transplantation in combination with a reduction of synkinesia, indicating a complementary and superior effect when transplanted combined [Guérout et al, 2011a].…”

“…Moreover, in an in vitro model, phagocytosis of degenerated axon debris directly by OECs was shown to be a p38 mitogen-activated protein kinase signaling pathway with subsequent enhanced neuritic growth [He et al, 2014]. Purified cultures of OECs either from the olfactory bulb or mucosa displayed differential migratory and neurite growth-promoting properties in vitro, with a maximal neuritic growth and greater migration characteristic of OB-OECs in cocultures with human model (NT2) neurons [Roloff et al, 2014].…”