Adenovirus vector-mediated ex vivo gene transfer of brain-derived neurotrophic factor (BDNF) tohuman umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) promotescrush-injured rat sciatic nerve regeneration.

This study was designed toinvestigate the efficacy of adenovirus vector-mediated brain-derived neurotrophic factor (BDNF) ex vivo gene transfer to human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) in a rat sciatic nerve crush injury model. BDNF protein and mRNA expression after infection was checked through an enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). Male Sprague-Dawley rats (200-250g, 6 weeks old) were distributed into threegroups (n=20 each): the control group, UCB-MSC group, and BDNF-adenovirus infected UCB-MSC (BDNF-Ad+UCB-MSC) group. UCB-MSCs (1×106cells/10µl/rat) or BDNF-Ad+UCB-MSCs (1×106cells/10µl/rat)were transplantedinto the rats at the crush site immediately after sciatic nerve injury. Cell tracking was done with PKH26-labeled UCB-MSCs and BDNF-Ad+UCB-MSCs (1×106cells/10µl/rat). The rats were monitored for 4 weeks post-surgery. Results showed that expression of BDNF at both the protein and mRNA levels was higher inthe BDNF-Ad+UCB-MSC group compared to theUCB-MSC group in vitro.Moreover, BDNF mRNA expression was higher in both UCB-MSC group and BDNF-Ad+ UCB-MSC group compared tothe control group, and BDNF mRNA expression in theBDNF-Ad+UCB-MSC group was higher than inboth other groups 5days after surgeryin vivo. Labeled neurons in the dorsal root ganglia (DRG), axon counts, axon density, and sciatic function index were significantly increased in the UCB-MSC and BDNF-Ad+ UCB-MSCgroupscompared to the controlgroup four weeksaftercell transplantation. Importantly,the BDNF-Ad+UCB-MSCgroup exhibited more peripheral nerve regeneration than the other two groups.Our results indicate thatboth UCB-MSCs and BDNF-Ad+UCB-MSCscan improve rat sciatic nerve regeneration, with BDNF-Ad+UCB-MSCsshowing a greater effectthan UCB-MSCs.

Human umbilical cord blood-derived mesenchymal stem cells promote regeneration of crush-injured rat sciatic nerves.

Several studies have demonstrated that human umbilical cord blood-derived mesenchymal stem cells can promote neural regeneration following brain injury. However, the therapeutic effects of human umbilical cord blood-derived mesenchymal stem cells in guiding peripheral nerve regeneration remain poorly understood. This study was designed to investigate the effects of human umbilical cord blood-derived mesenchymal stem cells on neural regeneration using a rat sciatic nerve crush injury model. Human umbilical cord blood-derived mesenchymal stem cells (1 × 10(6)) or a PBS control were injected into the crush-injured segment of the sciatic nerve. Four weeks after cell injection, brain-derived neurotrophic factor and tyrosine kinase receptor B mRNA expression at the lesion site was increased in comparison to control. Furthermore, sciatic function index, Fluoro Gold-labeled neuron counts and axon density were also significantly increased when compared with control. Our results indicate that human umbilical cord blood-derived mesenchymal stem cells promote the functional recovery of crush-injured sciatic nerves.

Effects of combining electrical stimulation with BDNF gene transfer on the regeneration of crushed rat sciatic nerve.

BACKGROUND AND AIMS: Various techniques have been investigated to enhance peripheral nerve regeneration including the application of low-intensity electrical stimulation (ES) and the administration of growth factors, especially brain-derived neurotrophic factor (BDNF). The purpose of this study was to investigate the effects of combining short-term (ES) and recombinant adenoviral vector-mediated BDNF (BDNF-Ad) transfer, in comparison to each sole modality, on peripheral nerve regeneration in a rat model with crush-injured sciatic nerve. METHODS: Sixty male Sprague-Dawley rats (250-300 g) were equally distributed into four groups; the control group, the ES group, the BDNF-Ad group, and the combination group (n = 15 each). A standard crush injury was introduced to the sciatic nerve. The control group received no treatment after injury, the ES group received 30 minutes of low-intensity ES, the BDNF-Ad group received an injection of recombinant BDNF-Ad (concentration = 10(11) pfu/µl, 3 µl/rat) after injury, and the combination group received both ES and BDNF-Ad. The rats were followed-up for 3 weeks. RESULTS: At the end of the follow-up period, the sciatic function index (ES =-39, BDNF-Ad =-38) and number of the retrogradely labeled sensory neurons were significantly increased in the ES group and the BDNF-Ad group (ES = 326, BDNF-Ad = 264), but not in the combined treatment group, compared to the control group (SFI = -53, retrogradely labeled neurons = 229). Axonal counts were highest in the ES group (7,208 axons), axonal densities in the BDNF group (10,598 axons/mm(2)), and the myelin thickness was greater in both groups as compared to the control group. The combined treatment group showed no signs of superior recovery compared to the other groups. CONCLUSIONS: Both the ES and the BDNF-Ad treatments were effective techniques enhancing the sciatic nerve regeneration following a crush injury in rats. Nevertheless, the combined treatment with ES and BDNF-Ad produces neither a synergistic effect nor an improvement in this injury model.

Thirty minutes of low intensity electrical stimulation promotes nerve regeneration after sciatic nerve crush injury in a rat model.

We investigated whether electrical stimulation (ES) applied directly for 30 minutes after crushing injury to the sciatic nerves of rats could improve nerve regeneration. Two groups of animals were used in this study (n = 20 each): the ES group received 30 minutes of low intensity ES (20 Hz pulse rate, 2 uA amplitude) immediately after a standard crush injury, while the control group received no stimulation after injury. Both groups were followed up for three weeks. The sciatic function index (SFI) was calculated weekly. Mean conduction velocity (MCV) and peak voltage (PV) were calculated, and the sensory neurons in L4 and L5 dorsal root ganglia (DRG) were traced with Fluorogold in retrograde fashion and quantified at the end of the follow up period. Histomorphometric studies were also carried out in both groups. The ES group showed improved functional and sensory recovery compared to the control group three weeks after injury. SFI, MCV and the number of retrogradely labeled sensory neurons were significantly higher in the ES group. Additionally, axon counts, myelin thicknesses and G-ratio values were also higher in the ES group. Quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) showed an elevated expression of brain derived neurotrophic factor (BDNF) in DRG sensory neurons of the ES group five days post-injury. Here, we present the first evidence that the application of ES for 30 minutes immediately following crush injury is effective to promote nerve regeneration in a rat sciatic nerve model.

Long-term delivery enhances in vivo osteogenic efficacy of bone morphogenetic protein-2 compared to short-term delivery.

In this study, heparin-conjugated poly(l-lactide-co-glycolide) (PLGA) nanospheres (HCPNs) suspended in fibrin gel (group 1) were developed for a long-term delivery of BMP-2, and then used to address the hypothesis that a long-term delivery of BMP-2 would enhance ectopic bone formation compared to a short-term delivery at an equivalent dose. Fibrin gel containing normal PLGA nanospheres (group 2) was used for short-term delivery of BMP-2. The in vitro release of BMP-2 from group 1 was sustained for 4 weeks with no initial burst release. In contrast, 83% of BMP-2 loaded in group 2 was released only for the first 3 days. BMP-2 released from group 1 stimulated an increase in alkaline phosphatase (ALP) activity of osteoblasts for 9 days in vitro. In contrast, BMP-2 released from group 2 induced a transient increase in ALP activity for the first 5 days and a decrease thereafter. Importantly, group 1 induced bone formation to a much greater extent than did group 2, with 2.0-fold greater bone formation area and 3.5-fold greater calcium content, upon implantation into rat hind limb muscle. These results show that long-term delivery of BMP-2 enhances in vivo osteogenic efficacy of the protein compared to short-term delivery at an equivalent dose.