Co-Transplantation of Neural Stem Cells and NT-3-Overexpressing Schwann Cells in Transected Spinal Cord

Abstract

Spinal cord transection results in severe neurological sequelae, and to date, there is no effective treatment. Because of the limited capacity for axonal regeneration in the spinal cord, recovery is minimal. Recently, efforts have been made to establish, by grafting neural tissue, a functional relay-station between the severed stumps of the injured cord. Previously, we used co-transplantation of neural stem cells (NSCs) and Schwann cells (SCs) to improve functional recovery of transected spinal cord. However, this effort has been partially impeded by limited neuronal differentiation of transplanted NSCs. To circumvent this problem, we have pre-differentiated NSCs toward neurons in vitro with the application of retinoic acid (RA) prior to cell grafting. Further, we genetically modified SCs to overexpress human neurotrophin-3 (hNT-3). When these cells were co-transplanted into the transected spinal cord of rats, injured animals had partial improvement (both functionally and structurally), including improved Basso, Beattie, and Bresnahan (BBB) scores, increased axonal regeneration/remyelination, and reduced neuronal loss. However, this pre-differentiation of NSCs in vitro only mildly improved neuronal differentiation of NSCs in vivo.

Coseeded Schwann cells myelinate neurites from differentiated neural stem cells in neurotrophin-3-loaded PLGA carriers

“…24 Exogenous NSCs transplantation was proposed to be a strategy for spinal cord regeneration. 3,12,21 However, whether these grafted cells are able to survive, differentiate into neurons, form myelin structures, and then re-establish a functioning neuronal network, remains unknown. In this study, we cocultured NSCs and SCs in NT-3-loaded PLGA carriers, and systemically investigated the survival and differentiation of cultured cells in relation to the nature of the scaffold matrix.…”

“…12 Sciatic nerves were harvested with 0.25% trypsin for 15 minutes at 37°C followed by 0.16% collagenase (both trypsin and collagen; Sigma-Aldrich, St Louis, MO) for 20 minutes. Following harvest, cells were centrifuged at 1000 rpm for 5 minutes, resuspended in DMEM/F12 with 10% fetal bovine serum (FBS) (Invitrogen) and plated on poly-L-lysine 0.01% (Sigma-Aldrich)-coated plates at 1 × 10 5 cells/mL.…”

“…[11][12][13] However, effectiveness of NSC transplantation in CNS trauma remains limited for two reasons: firstly, grafted NSCs rarely differentiate into mature neurons in spinal cord lesions, 14,15 and secondly, NSCs survive poorly when transplanted, which attenuates their effect on the restoration of neural circuits. 16,17 Therefore, in order to adequately evaluate the therapeutic potential of NSCs in bridging a lesion gap in SCI, it is necessary to investigate regimens that further augment the survival and differentiation of transplanted NSCs.…”

Hypoxia-specific GM-CSF-overexpressing neural stem cells improve graft survival and functional recovery in spinal cord injury

“…20,21 However, recent studies have indicated that cell transplantation can be more successful when combined with gene therapy. 22,23 The goal of this study was to increase the viability and potential therapeutic value of transplanted NSCs following SCI. We observed that GM-CSF overexpression in NSCs, carried out by a hypoxia-inducible vector, enhanced NSC survival both in vitro and in vivo.…”

Effect of Low-Intensity Pulsed Ultrasound on Nerve Repair

“…It has been documented that NT-3 has a strong effect on neurite outgrowth (Markus, Patel et al 2002;Sahenk, Nagaraja et al 2005). Additionally, some studies using genetically modified Schwann cells to overexpress the NT-3 gene have examined the role of NT-3 in the neuron survival and axonal regeneration/remyelination (Zhang, Zeng et al 2007;Pettingill, Minter et al 2008). It has been reported that Schwann cells transduced ex vivo with adenoviral (AdV) or lentiviral www.intechopen.com (LV) vectors encoding a functional NT-3 molecule led to the presence of a significantly increased number of axons in the contusion site (Golden, Pearse et al 2007).…”