Development of in vitro osteoporosis model in minipig proximal humerus and femur: validation in histological and biomechanical study.

BACKGROUND: The minipig has been used for research in various fields of medicine, even in orthopedics. Though previous studies have already suggested other methods to create osteoporotic bone, those methods had some disadvantages for taking time and efforts. Therefore, we aimed to generate osteoporotic proximal humerus and proximal femur of minipig using EDTA solution and validate their properties through dual energy X-ray absorptiometry (DEXA), micro-CT study, histological and biomechanical ways. METHODS: Six minipigs were used. Out of a total of 12 proximal humerus (PH) and 12 proximal femurs (PF), 6 PH and 6 PF were used as the decalcified group and the opposite side as the non-decalcified group. In vitro decalcification with Ca-chelating agents (0.5 M EDTA solution, pH 7.4) was used. Area BMD (aBMD) was measured using DEXA, Volumetric BMD (vBMD), and microstructure were measured using micro-CT. Universal testing machine was used to measure ultimate load to failure (ULTF). Each group was compared using two types of suture anchors (all-suture anchor, ASA, and conventional screw type anchor, CA). RESULTS: There was a significant difference in aBMD and cortical thickness (aBMD: decalcified, 0.433 ± 0.073 g/cm2, undecalcified, 0.962 ± 0.123 g/cm2, p < 0.001; cortical thickness: decalcified, 0.33 ± 0.34 mm, undecalcified, 1.61 ± 0.45 mm, p < 0.001). In the case of ASA, the ULTF was significantly lower in the decalcified group (decalcified: 176.6 ± 74.2 N, non-decalcified: 307.7 ± 116.5 N, p = 0.003). In the case of CA, there was no significant difference (decalcified: 265.1 ± 96.0 N, undecalcified: 289.4 ± 114.5 N, p = 0.578). CONCLUSION: We demonstrated that decalcification with EDTA solution significantly decreased aBMD, vBMD, and cortical thickness. Decalcified minipig bone using EDTA resulted in similar biomechanical properties as osteoporotic human bone with respect to anchor pull-out.

Preliminary Study on Effect of Lactiplantibacillus plantarum on Osteoporosis in the Ovariectomized Rat.

Osteoporosis is a growing global health concern primarily associated with decreased estrogen in postmenopausal women. Recently, some strains of probiotics were examined for potential anti-osteoporotic effects. This study intended to evaluate the impacts of Lactiplantibacillus plantarum MGE 3038 strain (MGE 3038) in ovariectomized rats. For this purpose, twelve weeks old female Wistar rats (n=21; 250-300 g) were divided into 3 groups; ovariectomy (OVX) group, OVX/MGE 3038 group and Sham group (control). In these groups; two went through respective OVX and one had daily MGE 3038 administration through oral gavage. Prior to 16 weeks after OVX, we collected blood samples and extracted the tibiae. We scanned the extracted tibiae by in-vivo micro-computed tomography (micro-CT) and evaluated pathology by hematoxylin and eosin (H&E) and Masson's trichrome staining. The serum levels of C-telopeptide of type I collagen (CTX), osteocalcin (OC), and the receptor activator of nuclear factor-ĸB ligand (RANKL) were examined. The OVX/MGE 3038 group showed increases in bone mineral density, trabecular bone volume, trabecular number, and trabecular thickness (Tb.Th), and a decrease in trabecular spacing than the OVX group. However, OVX/MGE 3038 group and control group were measurably comparable in Tb.Th. Micro-CT, H&E, and Masson's trichrome findings exhibited increased preservation and maintenance of trabecular bone structure in the OVX/MGE 3038 group in comparison to the OVX group. In serum, the levels of CTX, OC and RANKL were significantly different between the OVX and OVX/MGE 3038 groups. Taken together, L. plantarum MGE 3038 could be helpful for the treatment of osteoporosis.

Is aryl hydrocarbon receptor antagonism after ischemia effective in alleviating acute hepatic ischemia-reperfusion injury in rats?

Aryl hydrocarbon receptors (AhRs) have been reported to be important mediators of ischemic injury in the brain. Furthermore, the pharmacological inhibition of AhR activation after ischemia has been shown to attenuate cerebral ischemia-reperfusion (IR) injury. Here, we investigated whether AhR antagonist administration after ischemia was also effective in ameliorating hepatic IR injury. A 70% partial hepatic IR (45-min ischemia and 24-h reperfusion) injury was induced in rats. We administered 6,2',4'-trimethoxyflavone (TMF, 5 mg/kg) intraperitoneally 10 min after ischemia. Hepatic IR injury was observed using serum, magnetic resonance imaging-based liver function indices, and liver samples. TMF-treated rats showed significantly lower relative enhancement (RE) values and serum alanine aminotransferase (ALT) and aspartate aminotransferase levels than did untreated rats at 3 h after reperfusion. After 24 h of reperfusion, TMF-treated rats had significantly lower RE values, ΔT1 values, serum ALT levels, and necrotic area percentage than did untreated rats. The expression of the apoptosis-related proteins, Bax and cleaved caspase-3, was significantly lower in TMF-treated rats than in untreated rats. This study demonstrated that inhibition of AhR activation after ischemia was effective in ameliorating IR-induced liver injury in rats.

Generation of genetically engineered mice for lung cancer with mutant EGFR.

Although epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) have shown dramatic response and improvement in treating lung cancer with mutant EGFR, the emergence of drug resistance remains a major problem. In particular, some mutations including T790 M and C797S have been recognized as mechanisms of acquired resistance because they weaken binding affinity to drugs. To date, many attempts have been made to develop a new drug for overcoming acquired resistance to EGFR-TKIs, including secondary mutations. However, an appropriate animal model to evaluate in vivo efficacy during novel drug development remains lacking. In this study, we generated a novel transgenic mouse model that conditionally expresses human EGFRL858R/T790M/C797S and firefly luciferase using Cas9-mediated homology-independent targeted integration. Using a lung-specific Sftpc-CreERT2 mouse line, we induced expression of both the human EGFRL858R/T790M/C797S transgene and firefly luciferase in the lungs of adult mice. The expression of these genes and lung cancer occurrence was monitored using an in vivo imaging system and magnetic resonance imaging, respectively. Overall, our mouse model can be utilized to develop new drugs for overcoming C797S-mediated resistance to osimertinib; further, such knock-in systems for expressing oncogenes may be applied to study tumorigenesis and the development of other targeted agents.

The reversible fourth-generation EGFR tyrosine kinase inhibitor OBX02-011 overcomes C797S-mediated resistance in lung cancer.

Osimertinib is an irreversible third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that was initially developed to overcome the EGFR T790M mutation and is used as a standard therapy in patients with advanced non-small cell lung cancer (NSCLC) with EGFR-activating mutations. Despite the remarkable initial efficacy, osimertinib, like other EGFR-TKIs, is limited by the emergence of acquired resistance. As the EGFR mutation C797S has been identified as a key driver of acquired resistance to osimertinib, development of a drug that targets this clinically relevant mutation could help improve patient outcomes. Here, we report the discovery and preclinical efficacy of OBX02-011, a reversible fourth-generation EGFR TKI that overcomes the EGFR C797S mutation. Compared to approved EGFR TKIs, OBX02-011 showed potent anticancer effects and inhibited EGFR-related signaling in various models, including those harboring the EGFR C797S mutation. Additionally, in transgenic mouse models (EGFRL858R/T790M/C797S), OBX02-011 treatment effectively inhibited tumor growth and EGFR activity, leading to enhanced survival. Collectively, these results suggest that OBX02-011 may be a promising new EGFR TKI to overcome C797S-mediated resistance in NSCLC.

The Effect of Genetically Modified Lactobacillus plantarum Carrying Bone Morphogenetic Protein 2 Gene on an Ovariectomized Rat.

OBJECTIVE: Osteoporosis result from age-related decline in the number of osteoblast progenitors in the bone marrow. Probiotics have beneficial effects on the host, when administered in appropriate amounts. This study investigated the effects of probiotics expressing specific genes, especially the effects of genetically modified bone morphogenetic protein (BMP)-2-expressing Lactobacillus plantarum CJNU 3003 (LP) on ovariectomized rats. METHODS: Twenty-eight female Wistar rats (250-300 g, 12 weeks old) were divided into four groups : the sham (control), the ovariectomy (OVX)-induced osteoporosis group (OVX), the OVX and LP (OVX/LP), OVX and genetically modified BMP-2-expressing LP (OVX/LP with BMP) groups. The three groups underwent bilateral OVX and two of these groups were administered two different types of LP via oral gavage daily. At 16 weeks post-OVX, blood was collected from the heart and the bilateral tibiae were extracted and were scanned by ex-vivo micro-computed tomography and stained with hematoxylin-and-eosin (H&E) and Masson's trichrome stain for pathological assessment. The serum levels of osteocalcin (OC), rat C-telopeptide of type I collagen (CTX-I), BMP-2, and receptor activator of nuclear factor-ĸB ligand (RANKL) were measured. RESULTS: The 3D-micro-computed tomography images showed that the trabecular structure in the OVX/LP with BMP group was maintained compared with OVX and OVX/LP groups. No significant differences were detected in trabecular thickness (Tb.Th) between control and OVX/LP with BMP groups (p>0.05). Furthermore, a tendency toward increased BMD, trabecular bone volume, Tb.Th, and trabecular number and decreased trabecular separation was found in rats in the OVX/LP with BMP groups when compared with the OVX and OVX/LP groups (p>0.05). The H&E and Masson's trichrome stained sections showed a thicker trabecular bone in the OVX/LP with BMP group compared with the OVX and OVX/LP groups. There was no difference in serum levels of OC, CTX and RANKL control and OVX/LP with BMP groups (p>0.05). In contrast, significant differences were found in OC and CTX-1 levels between the OVX and OVX/LP with BMP groups (p<0.05). CONCLUSION: Our results showed that the expression of genetically modified BMP-2 showed inhibition effect for bone loss in a rat model of osteoporosis.

Bone formation effect of highly concentrated tricalcium phosphate biocomposite screws in a rabbit osteoporosis model.

The purpose of this study was to determine the efficacy of highly concentrated tricalcium phosphate (TCP) biocomposite screws on local bone formation in a rabbit model of osteoporosis induced by bilateral ovariohysterectomy (OHE). Fourteen 24-week-old female New Zealand rabbits (weight, 3-3.5 kg) were divided into two groups: (1) OHE and biodegradable poly(lactic-co-glycolic acid) (PLGA) without ß-TCP plate or screw insertion (OHE/Bio ScRew [BSR]) group and (2) OHE and biocomposite PLGA with highly concentrated ß-TCP plate and screw insertion (OHE/highly concentrated ß-triCalcium phosphate [HCCP]). Both groups underwent bilateral OHE and had two different types of screws and plates inserted at the proximal tibia. Bilateral tibiae were extracted at 25 weeks post-OHE. The extracted tibiae were scanned with ex vivo microcomputed tomography (micro-CT). Parameters including bone mineral density (BMD), trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb. Th), and trabecular separation (Tb. Sp) were evaluated after staining the tibial samples with hematoxylin and eosin (H&E) and Masson's trichrome. We then performed pathological assessments. Micro-CT images revealed improved new bone formation near the implant in the OHE/HCCP group with higher values of BMD, BV/TV, and Tb.N but lower values of Tb. Th and Tb. Sp than the OHE/BSR group. Analyses of H&E and Masson's trichrome staining showed better new bone formation around the implant in the OHE/HCCP group than in the OHE/BSR group. The use of highly concentrated TCP biocomposite screw and plate might improve local bone formation and facilitate osteoconductivity in an osteoporotic rabbit model.

Optimal Ratio of Wnt3a Expression in Human Mesenchymal Stem Cells Promotes Axonal Regeneration in Spinal Cord Injured Rat Model.

OBJECTIVE: Through our previous clinical trials, the demonstrated therapeutic effects of MSC in chronic spinal cord injury (SCI) were found to be not sufficient. Therefore, the need to develop stem cell agent with enhanced efficacy is increased. We transplanted enhanced Wnt3asecreting human mesenchymal stem cells (hMSC) into injured spines at 6 weeks after SCI to improve axonal regeneration in a rat model of chronic SCI. We hypothesized that enhanced Wnt3a protein expression could augment neuro-regeneration after SCI. METHODS: Thirty-six Sprague-Dawley rats were injured using an Infinite Horizon (IH) impactor at the T9-10 vertebrae and separated into five groups : 1) phosphate-buffered saline injection (injury only group, n=7); 2) hMSC transplantation (MSC, n=7); 3) hMSC transfected with pLenti vector (without Wnt3a gene) transplantation (pLenti-MSC, n=7); 4) hMSC transfected with Wnt3a gene transplantation (Wnt3a-MSC, n=7); and 5) hMSC transfected with enhanced Wnt3a gene (1.7 fold Wnt3a mRNA expression) transplantation (1.7 Wnt3a-MSC, n=8). Six weeks after SCI, each 5×105 cells/15 µL at 2 points were injected using stereotactic and microsyringe pump. To evaluate functional recovery from SCI, rats underwent Basso-Beattie-Bresnahan (BBB) locomotor test on the first, second, and third days post-injury and then weekly for 14 weeks. Axonal regeneration was assessed using growth-associated protein 43 (GAP43), microtubule-associated protein 2 (MAP2), and neurofilament (NF) immunostaining. RESULTS: Fourteen weeks after injury (8 weeks after transplantation), BBB score of the 1.7 Wnt3a-MSC group (15.0±0.28) was significantly higher than that of the injury only (10.0±0.48), MSC (12.57±0.48), pLenti-MSC (12.42±0.48), and Wnt3a-MSC (13.71±0.61) groups (p<0.05). Immunostaining revealed increased expression of axonal regeneration markers GAP43, MAP2, and NF in the Wnt3a-MSC and 1.7 Wnt3a-MSC groups. CONCLUSION: Our results showed that enhanced gene expression of Wnt3a in hMSC can potentiate axonal regeneration and improve functional recovery in a rat model of chronic SCI.

Aryl hydrocarbon receptor antagonism before reperfusion attenuates cerebral ischaemia/reperfusion injury in rats.

Aryl hydrocarbon receptor (AhR) antagonism can mitigate cellular damage associated with cerebral ischaemia and reperfusion (I/R) injury. This study investigated the neuroprotective effects of AhR antagonist administration before reperfusion in a rat stroke model and influence of the timing of AhR antagonist administration on its neuroprotective effects. Magnetic resonance imaging (MRI) was performed at baseline, immediately after, and 3, 8, and 24 h after ischaemia in the sham, control (I/R injury), TMF10 (trimethoxyflavone [TMF] administered 10 min post-ischaemia), and TMF50 (TMF administered 50 min post-ischaemia) groups. The TMF treatment groups had significantly fewer infarcts than the control group. At 24 h, the relative apparent diffusion coefficient values of the ischaemic core and peri-infarct region were significantly higher and relative T2 values were significantly lower in the TMF10 groups than in the control group. The TMF treatment groups showed significantly fewer terminal deoxynucleotidyl transferase dUTP nick-end labelling positive (+) cells (%) in the peri-infarct region than the control group. This study demonstrated that TMF treatment 10 or 50 min after ischaemia alleviated brain damage. Furthermore, the timing of AhR antagonist administration affected the inhibition of cellular or vasogenic oedema formation caused by a transient ischaemic stroke.

Optogenetic inactivation of the entopeduncular nucleus improves forelimb akinesia in a Parkinson's disease model.

We performed optogenetic inactivation of rats' entopeduncular nucleus (EP, homologous to primates' globus pallidus interna (GPi)) and investigated the therapeutic effect in a rat model of PD. 6-Hydroxydopamine (6-OHDA)-induced hemiparkinsonian rats were injected with either a virus for halorhodopsin expression that is used to inactivate GABAergic neurons or a control virus injection and received optic fiber insertion. All the rats were illuminated by 590 nm of light. Each rat was then subjected to sequential sessions of stepping tests under controlled illumination patterns. The stepping test is a reliable evaluation method for forelimb akinesia. The number of adjusting steps was significantly higher in experimental (optogene with reporter gene expression) (5Hz - 10ms: 15.7 ±â€¯1.9, 5Hz - 100ms: 16.0 ±â€¯1.8, continuous: 21.6 ±â€¯1.9) than control rats (reporter gene expression) (5Hz-10ms: 1.9 ±â€¯1.1, 5Hz-100ms: 2.6 ±â€¯1.0, continuous: 2.5 ±â€¯1.2) (p < 0.001). Continuous EP illumination showed a significantly higher improvement of forelimb akinesia than other illumination patterns (p < 0.01). Optogene expression in the GABAergic neurons of the EP was confirmed by immunohistochemistry. Optogenetic inhibition of EP was effective to improve contralateral forelimb akinesia. However, further studies using prolonged illumination are needed to investigate the best illumination pattern for optogenetic stimulation.

Biodegradable Screws Containing Bone Morphogenetic Protein-2 in an Osteoporotic Rat Model.

OBJECTIVE: The aim of this study was to evaluate the effect for biodegradable screws containing bone morphogenetic protein-2 (BMP-2) in an osteoporotic rat model. METHODS: Twenty-four female Wistar rat (250-300 g, 12 weeks of age) were randomized into four groups. Three groups underwent bilateral ovariectomy (OVX). Biodegradable screws with or without BMP-2 were inserted in the proximal tibia in two implantation groups. The extracted proximal metaphysis of the tibiae were scanned by exo-vivo micro-computed tomography. Evaluated parameters included bone mineral density (BMD), trabecular bone volume (BV/TV), trabecular number, trabecular thickness, and trabecular separation (Tb.Sp). The tibia samples were pathologically evaluated by staining with by Hematoxylin and Eosin, and trichrome. RESULTS: Trabecular formation near screw insertion site was evident only in rats receiving BMP-2 screws. BMD and BV/TV significantly differed between controls and the OVX and OVX with screw groups. However, there were no significant differences between control and OVX with screw BMP groups. Tb.Sp significantly differed between control and OVX and OVX with screw groups (p<0.05), and between the OVX and OVX with screw BMP group (p<0.05), with no statistically significant difference between control and OVX with screw BMP groups. Over the 12 weeks after surgery, bone lamellae in direct contact with the screw developed more extensive and thicker trabecular bone around the implant in the OVX with screw BMP group compared to the OVX with screw group. CONCLUSION: Biodegradable screws containing BMP-2 improve nearby bone conditions and enhance ostoeintegration between the implant and the osteoporotic bone.

A Novel Animal Model of Parkinson's Disease Using Optogenetics: Representation of Various Disease Stages by Modulating the Illumination Parameter.

BACKGROUND: The classic animal model of Parkinson's disease (PD) using neurotoxin can only simulate fixed stages of the disease by causing irreversible damage to the nigrostriatal system. OBJECTIVES: To develop an optogenetic PD model that can modulate the severity of disease by optical stimulation by introducing the halorhodopsin (NpHR) gene into the substantia nigra compacta. METHODS: Fifteen rats received injections of engineered AAV with NpHR-YFP gene into the substantia nigra. They were then subjected to illumination of 590-nm light wavelengths with 3 optical stimulation conditions, i.e., frequency-width: 5 Hz-10 ms (n = 5), 5 Hz-100 ms (n = 5), and 50 Hz-10 ms (n = 5). Eleven rats received 6-hydroxydopamine injections to establish the conventional PD model. RESULTS: The optogenetic models showed characteristic PD manifestations, similar to those of the conventional models; the severity of forelimb akinesia correlated with the total illumination value (frequency × width). The group with a low illumination value (5 Hz-10 ms) was comparable to the conventional partial model whereas the groups with high illumination values (5 Hz-100 ms and 50 Hz-10 ms) were similar to the conventional complete model. CONCLUSIONS: An optogenetic PD model has the advantage of more appropriately representing various PD stages by controlling illumination parameters.

The Effect of Biocomposite Screws on Bone Regeneration in a Rat Osteoporosis Model.

OBJECTIVE: To evaluate the efficacy of biocomposite screws used in ovariectomy (OVX)-induced osteoporotic rats. METHODS: Twenty-four female Wistar rats (250-300 g, 12 weeks old) were divided into 4 groups: sham group (control), OVX-induced osteoporosis group (OVX), OVX and biodegradable poly(lactic-co-glycolic acid) (PLGA) without tricalcium phosphate (ß-TCP) screw insertion group (OVX/BSR), and OVX and biocomposite (PLGA with ß-TCP) screw insertion group (OVX/CSR). Three groups underwent bilateral OVX, and of these, 2 groups had 2 different types of screw inserted at the proximal tibia. At 25 weeks after OVX, the bilateral tibias were extracted. The extracted tibiae were scanned by ex vivo micro-computed tomography (CT) and stained with hematoxylin and eosin (H&E) and with Masson's trichrome stain for pathological assessment. RESULTS: Compared with the ovariectomized groups, the control group had the highest values for bone mineral density (BMD), bone volume (BV)/total volume (TV), and trabecular number (Tb.N) and the lowest values for trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp). In the pairwise comparison among ovariectomized groups, the OVX/CSR group had significantly higher BMD, BV/TV, and Tb.N values than the other 2 groups (OVX and OVX/BSR) and significantly lower Tb.Sp. Micro-CT scans showed clear evidence of new trabecular formation near the screw insertion site in the OVX/CSR group only. Analyses of H&E- and Masson's trichrome-stained sections showed more and thicker trabecular bone around the implant in the OVX/CSR group compared with the OVX and OVX/BSR groups. CONCLUSIONS: Biocomposite screws can improve local bone quality and facilitate osteoconductivity in an osteoporotic rat model.

Is There Additive Therapeutic Effect When GCSF Combined with Adipose-Derived Stem Cell in a Rat Model of Acute Spinal Cord Injury?

OBJECTIVE: Functional and neural tissue recovery has been reported in many animal studies conducted with stem cells. However, the combined effect of cytokines and stem cells has not yet been adequately researched. Here, we analyzed the additive effects of granulocyte colony-stimulating factor (GCSF) on adipose-derived stem cells (ADSCs) infusion in the treatment of acute spinal cord injury (SCI) in rats. METHODS: Four days after intrathecal infusion tubes implantation in Sprague-Dawley rats, SCI was induced with an infinite horizon impactor. In the Sham group (n=5), phosphate-buffered saline was injected 3, 7, and 14 days after SCI. GCSF, ADSCs, and ADSCs with GCSF were injected at the same time in the GCSF (n=8), ADSC (n=8), and ADSC+GCSF groups (n=7), respectively. RESULTS: The ADSC and ADSC+GCSF groups, but not the GCSF group, showed significantly higher Basso-Beattie-Bresnahan scores than the Sham group during 8 weeks (p<0.01), but no significant difference between the ADSC and ADSC+GCSF groups. In the ladder rung test, all four groups were significantly different from each other, with the ADSC+GCSF group showing the best improvement (p<0.01). On immunofluorescent staining (GAP43, MAP2), western blotting (GAP43), and reverse transcription polymerase chain reaction (GAP43, nerve growth factor), the ADSC and ADSC+GCSF groups showed higher levels than the Sham and GCSF groups. CONCLUSION: Our analyses suggest that the combination of GCSF and ADSCs infusions in acute SCI in the rat does not have a significant additive effect. Hence, when combination agents for SCI stem cell therapy are considered, molecules other than GCSF, or modifications to the methodology, should be investigated.

Recording nerve signals in canine sciatic nerves with a flexible penetrating microelectrode array.

OBJECTIVE: Previously, we presented the fabrication and characterization of a flexible penetrating microelectrode array (FPMA) as a neural interface device. In the present study, we aim to prove the feasibility of the developed FPMA as a chronic intrafascicular recording tool for peripheral applications. APPROACH: For recording from the peripheral nerves of medium-sized animals, the FPMA was integrated with an interconnection cable and other parts that were designed to fit canine sciatic nerves. The uniformity of tip exposure and in vitro electrochemical properties of the electrodes were characterized. The capability of the device to acquire in vivo electrophysiological signals was evaluated by implanting the FPMA assembly in canine sciatic nerves acutely as well as chronically for 4 weeks. We also examined the histology of implanted tissues to evaluate the damage caused by the device. MAIN RESULTS: Throughout recording sessions, we observed successful multi-channel recordings (up to 73% of viable electrode channels) of evoked afferent and spontaneous nerve unit spikes with high signal quality (SNR > 4.9). Also, minor influences of the device implantation on the morphology of nerve tissues were found. SIGNIFICANCE: The presented results demonstrate the viability of the developed FPMA device in the peripheral nerves of medium-sized animals, thereby bringing us a step closer to human applications. Furthermore, the obtained data provide a driving force toward a further study for device improvements to be used as a bidirectional neural interface in humans.

Enhanced axonal regeneration by transplanted Wnt3a-secreting human mesenchymal stem cells in a rat model of spinal cord injury.

BACKGROUND: While pure mesenchymal stem cell (MSC) treatment for spinal cord injury (SCI) is known to be safe, its efficacy is insufficient. Therefore, gene-modified stem cells are being developed to enhance the effect of pure MSCs. We investigated the effect of stem cell therapy through the transfection of a Wnt3a-producing gene that stimulates axonal regeneration. METHOD: MSCs obtained from the human umbilical cord blood (hMSCs) were multiplied, cultivated, and transfected with the pLenti-Wnt3a-GFP viral vector to produce Wnt3a-secreting hMSCs. A total of 50 rats were injured with an Infinite Horizon impactor at the level of the T7-8 vertebrae. Rats were divided into five groups according to the transplanted material: (1) phosphate-buffered saline injection group (sham group, n = 10); (Pertz et al. Proc Natl Acad Sci USA 105:1931-1936, 39) Wnt3a protein injection group (Wnt3a protein group, n = 10); (3) hMSC transplantation group (MSC group, n = 10); (4) hMSCs transfected with the pLenti vector transplantation group (pLenti-MSC group, n = 10); (5) hMSCs transfected with the pLenti+Wnt3a vector transplantation group (Wnt3a-MSC group, n = 10). Behavioral tests were performed daily for the first 3 days after injury and then weekly for 8 weeks. The injured spinal cords were extracted, and axonal regeneration markers including choline acetyltransferase (ChAT), growth-associated protein 43 (GAP43), and microtubule-associated protein 2 (MAP2) were investigated by immunofluorescence, RT-PCR, and western blotting. RESULTS: Seven weeks after the transplantation (8 weeks after SCI), rats in the Wnt3a-MSC group achieved significantly higher average scores in the motor behavior tests than those in the other groups (p < 0.05). Immunofluorescent stains showed greater immunoreactivity of ChAT, GAP43, and MAP2 in the Wnt3a-MSC group than in the other groups. RT-PCR and western blots revealed greater expression of these proteins in the Wnt3a-MSC group than in the other groups (p < 0.05). CONCLUSIONS: Wnt3a-secreting hMSC transplantation considerably improved neurological recovery and axonal regeneration in a rat SCI model.

Analysis of equivalent parameters of two spinal cord injury devices: the New York University impactor versus the Infinite Horizon impactor.

BACKGROUND CONTEXT: The New York University (NYU) impactor and the Infinite Horizon (IH) impactor are used to create spinal cord injury (SCI) models. However, the parameters of these two devices that yield equivalent SCI severity remain unclear. PURPOSE: To identify equivalent parameters, rats with SCIs induced by either device set at various parameters were subjected to behavioral and histologic analyses. STUDY DESIGN: This is an animal laboratory study. METHODS: Groups of eight rats acquired SCIs by dropping a 10 g rod from a height of 25 mm or 50 mm by using the NYU device or by delivering a force of 150 kdyn, 175 kdyn, 200 kdyn, or 250 kdyn by using the IH impactor. All injured rats were tested weekly for 8 weeks by using the Basso, Beattie, and Bresnahan (BBB) test and the ladder rung test. On the 10th week, the lesion volume of each group was measured by using a 9.4 Tesla magnetic resonance imaging (MRI), and the spinal cords were subjected to histologic analysis using anterograde biotinylated dextran amine (BDA) tracing and immunofluorescence staining with an anti-protein kinase C-gamma (PKC-γ) antibody. RESULTS: Basso, Beattie, and Bresnahan test scores between the 25 mm and the 200 kdyn groups as well as between the 50 mm and and 250 kdyn groups were very similar. Although it was not statistically significant, the mean scores of the ladder rung test in the 200 kdyn group were higher than the 25 mm group at all assessment time points. There was a significantly different cavity volume only between the 50 mm and the 200 kdyn groups. Midline sagittal images of the spinal cord on the MRI revealed that the 25 mm group predominantly had dorsal injuries, whereas the 200 kdyn group had deeper injuries. Anterograde tracing with BDA showed that in the 200 kdyn group, the dorsal corticospinal tract of the caudal area of the lesion was labeled. Similar labeling was not observed in the 25 mm group. Immunofluorescence staining of PKC-γ also revealed strong staining of the dorsal corticospinal tract in the 200 kdyn group but not in the 25 mm group. CONCLUSIONS: The 25 mm injuries generated by the NYU impactor are generally equivalent to the 200 kdyn injuries generated by using the IH impactor. However, differences in the ladder rung test scores, MRI images, BDA traces, and PKC-γ staining demonstrate that the two devices exert qualitatively different impacts on the spinal cord.

Optogenetic Inhibition of the Subthalamic Nucleus Reduces Levodopa-Induced Dyskinesias in a Rat Model of Parkinson's Disease.

BACKGROUND: The inhibition of neuronal activity by electrical deep brain stimulation is one of the mechanisms explaining the amelioration of levodopa-induced dyskinesia. However, electrical deep brain stimulation cannot specifically activate or inactivate selected types of neurons. OBJECTIVES: We applied optogenetics as an alternative treatment to deep brain stimulation for levodopa-induced dyskinesia, and also to confirm that the mechanism of levodopa-induced dyskinesia amelioration by subthalamic nucleus deep brain stimulation is mediated through neuronal inhibition. METHODS: 6-hydroxydopamine-induced hemiparkinsonian rats received injections of hSynapsin1-NpHR-YFP adeno-associated virus (AAV) or hSynapsin1-YFP AAV. Two weeks after viral injections, all rats were treated with daily injections of levodopa. Then, the optic fiber was implanted into the ipsilateral subthalamic nucleus. We performed various behavioral tests to evaluate the changes in levodopa-induced dyskinesias after optogenetic expression and illumination in the subthalamic nucleus. RESULTS: The behavioral tests revealed that optical inhibition of the subthalamic nucleus significantly ameliorated levodopa-induced dyskinesia by reducing the duration of the dyskinesias as well as the severity of axial dyskinesia. CONCLUSIONS: These findings will provide a useful foundation for the future development of optogenetic modulation systems that could be considered as an approach to dyskinesia therapy.