Novel Sensing Technique for Stem Cells Differentiation Using Dielectric Spectroscopy of Their Proteins.

Dielectric spectroscopy (DS) is the primary technique to observe the dielectric properties of biomaterials. DS extracts complex permittivity spectra from measured frequency responses such as the scattering parameters or impedances of materials over the frequency band of interest. In this study, an open-ended coaxial probe and vector network analyzer were used to characterize the complex permittivity spectra of protein suspensions of human mesenchymal stem cells (hMSCs) and human osteogenic sarcoma (Saos-2) cells in distilled water at frequencies ranging from 10 MHz to 43.5 GHz. The complex permittivity spectra of the protein suspensions of hMSCs and Saos-2 cells revealed two major dielectric dispersions, ß and γ, offering three distinctive features for detecting the differentiation of stem cells: the distinctive values in the real and imaginary parts of the complex permittivity spectra as well as the relaxation frequency in the ß-dispersion. The protein suspensions were analyzed using a single-shell model, and a dielectrophoresis (DEP) study was performed to determine the relationship between DS and DEP. In immunohistochemistry, antigen-antibody reactions and staining are required to identify the cell type; in contrast, DS eliminates the use of biological processes, while also providing numerical values of the dielectric permittivity of the material-under-test to detect differences. This study suggests that the application of DS can be expanded to detect stem cell differentiation.

Multimodal Locomotion and Active Targeted Thermal Control of Magnetic Agents for Biomedical Applications.

Magnetic microrobots can be miniaturized to a nanometric scale owing to their wireless actuation, thereby rendering them ideal for numerous biomedical applications. As a result, nowadays, there exist several mechano-electromagnetic systems for their actuation. However, magnetic actuation is not sufficient for implementation in biomedical applications, and further functionalities such as imaging and heating are required. This study proposes a multimodal electromagnetic system comprised of three pairs of Helmholtz coils, a pair of Maxwell coils, and a high-frequency solenoid to realize multimodal locomotion and heating control of magnetic microrobots. The system produces different configurations of magnetic fields that can generate magnetic forces and torques for the multimodal locomotion of magnetic microrobots, as well as generate magnetic traps that can control the locomotion of magnetic swarms. Furthermore, these magnetic fields are employed to control the magnetization of magnetic nanoparticles, affecting their magnetic relaxation mechanisms and diminishing their thermal properties. Thus, the system enables the control of the temperature increase of soft-magnetic materials and selective heating of magnetic microrobots at different positions, while suppressing the heating properties of magnetic nanoparticles located at undesired areas.

Fabrication Techniques of Nerve Guidance Conduits for Nerve Regeneration.

Neuronal loss and axonal degeneration after spinal cord injury or peripheral injury result in the loss of sensory and motor functions. Nerve regeneration is a complicated and medical challenge that requires suitable guides to bridge nerve injury gaps and restore nerve function. Due to the hostility of the microenvironment in the lesion, multiple conditions should be fulfilled to achieve improved functional recovery. Many nerve conduits have been fabricated using various natural and synthetic polymers. The design and material of the nerve guide conduits were carefully reviewed. A detailed review was conducted on the fabrication method of the nerve guide conduit for nerve regeneration. The typical fabrication methods used to fabricate nerve conduits are dip coating, solvent casting, micropatterning, electrospinning, and additive manufacturing. The advantages and disadvantages of the fabrication methods were reported, and research to overcome these limitations was reviewed. Extensive reviews have focused on the biological functions and in vivo performance of polymeric nerve conduits. In this paper, we emphasize the fabrication method of nerve conduits by polymers and their properties. By learning from the existing candidates, we can advance the strategies for designing novel polymeric systems with better properties for nerve regeneration.

Fabrication of Polycaprolactone/Nano Hydroxyapatite (PCL/nHA) 3D Scaffold with Enhanced In Vitro Cell Response via Design for Additive Manufacturing (DfAM).

In this study, we investigated the dual-pore kagome-structure design of a 3D-printed scaffold with enhanced in vitro cell response and compared the mechanical properties with 3D-printed scaffolds with conventional or offset patterns. The compressive modulus of the 3D-printed scaffold with the proposed design was found to resemble that of the 3D-printed scaffold with a conventional pattern at similar pore sizes despite higher porosity. Furthermore, the compressive modulus of the proposed scaffold surpassed that of the 3D-printed scaffold with conventional and offset patterns at similar porosities owing to the structural characteristics of the kagome structure. Regarding the in vitro cell response, cell adhesion, cell growth, and ALP concentration of the proposed scaffold for 14 days was superior to those of the control group scaffolds. Consequently, we found that the mechanical properties and in vitro cell response of the 3D-printed scaffold could be improved by kagome and dual-pore structures through DfAM. Moreover, we revealed that the dual-pore structure is effective for the in vitro cell response compared to the structures possessing conventional and offset patterns.

Biomaterials and strategies for repairing spinal cord lesions.

Spinal cord injury (SCI) causes intractable disease and leads to inevitable physical, financial, and psychological burdens on patients and their families. SCI is commonly divided into primary and secondary injury. Primary injury occurs upon direct impact to the spinal cord, which leads to cell necrosis, axon disruption, and vascular loss. This triggers pathophysiological secondary injury, which has several phases: acute, subacute, intermediate, and chronic. These phases are dependent on post-injury time and pathophysiology and have various causes, such as the infiltration of inflammatory cells and release of cytokines that can act as a barrier to neural regeneration. Another unique feature of SCI is the glial scar produced from the reactive proliferation of astrocytes, which acts as a barrier to axonal regeneration. Interdisciplinary research is investigating the use of biomaterials and tissue-engineered fabrication to overcome SCI. In this review, we discuss representative biomaterials, including natural and synthetic polymers and nanomaterials. In addition, we describe several strategies to repair spinal cord injuries, such as fabrication and the delivery of therapeutic biocomponents. These biomaterials and strategies may offer beneficial information to enhance the repair of spinal cord lesions.

Combination Therapy by Tissue-Specific Suicide Gene and Bevacizumab in Intramedullary Spinal Cord Tumor.

PURPOSE: Malignant gliomas are aggressive spinal cord tumors. In this study, we hypothesized that combination therapy using an anti-angiogenic agent, bevacizumab, and hypoxia-inducible glioblastoma-specific suicide gene could reduce tumor growth. MATERIALS AND METHODS: In the present study, we evaluated the effect of combination therapy using bevacizumab and pEpo-NI2-SV-TK in reducing the proliferation of C6 cells and tumor growth in the spinal cord. Spinal cord tumor was generated by the injection of C6 cells into the T5 level of the spinal cord. Complexes of branched polyethylenimine (bPEI)/pEpo-NI2-SV-TK were injected into the spinal cord tumor. Bevacizumab was then administered by an intraperitoneal injection at a dose of 7 mg/kg. The anti-cancer effects of combination therapy were analyzed by histological analyses and magnetic resonance imaging (MRI). The Basso, Beattie and Bresnahan scale scores for all of the treatment groups were recorded every other day for 15 days to assess the rat hind-limb strength. RESULTS: The complexes of bPEI/pEpo-NI2-SV-TK inhibited the viability of C6 cells in the hypoxia condition at 5 days after treatment with ganciclovir. Bevacizumab was decreased in the cell viability of human umbilical vein endothelial cells. Combination therapy reduced the tumor size by histological analyses and MRI. The combination therapy group showed improved hind-limb function compared to the other groups that were administered pEpo-NI2-SV-TK alone or bevacizumab alone. CONCLUSION: This study suggests that combination therapy using bevacizumab with the pEpo-NI2-SV-TK therapeutic gene could be useful for increasing its therapeutic benefits for intramedullary spinal cord tumors.

Fabrication of Three-Dimensional Composite Scaffold for Simultaneous Alveolar Bone Regeneration in Dental Implant Installation.

Dental implant surgeries involve the insertion of implant fixtures into alveolar bones to replace missing teeth. When the availability of alveolar bone at the surgical site is insufficient, bone graft particles are filled in the insertion site for successful bone reconstruction. Bone graft particles induce bone regeneration over several months at the insertion site. Subsequently, implant fixtures can be inserted at the recipient site. Thus, conventional dental implant surgery is performed in several steps, which in turn increases the treatment period and cost involved. Therefore, to reduce surgical time and minimize treatment costs, a novel hybrid scaffold filled with bone graft particles that could be combined with implant fixtures is proposed. This scaffold is composed of a three-dimensionally (3D) printed polycaprolactone (PCL) frame and osteoconductive ceramic materials such as hydroxyapatite (HA) and ß-tricalcium phosphate (ß-TCP). Herein, we analyzed the porosity, internal microstructure, and hydrophilicity of the hybrid scaffold. Additionally, Saos-2 cells were used to assess cell viability and proliferation. Two types of control scaffolds were used (a 3D printed PCL frame and a hybrid scaffold without HA/ß-TCP particles) for comparison, and the fabricated hybrid scaffold was verified to retain osteoconductive ceramic particles without losses. Moreover, the fabricated hybrid scaffold had high porosity and excellent microstructural interconnectivity. The in vitro Saos-2 cell experiments revealed superior cell proliferation and alkaline phosphatase assay results for the hybrid scaffold than the control scaffold. Hence, the proposed hybrid scaffold is a promising candidate for minimizing cost and duration of dental implant surgery.

A cationic amphiphilic co-polymer as a carrier of nucleic acid nanoparticles (Nanps) for controlled gene silencing, immunostimulation, and biodistribution.

Programmable nucleic acid nanoparticles (NANPs) provide controlled coordination of therapeutic nucleic acids (TNAs) and other biological functionalities. Beyond multivalence, recent reports demonstrate that NANP technology can also elicit a specific immune response, adding another layer of customizability to this innovative approach. While the delivery of nucleic acids remains a challenge, new carriers are introduced and tested continuously. Polymeric platforms have proven to be efficient in shielding nucleic acid cargos from nuclease degradation while promoting their delivery and intracellular release. Here, we venture beyond the delivery of conventional TNAs and combine the stable cationic poly-(lactide-co-glycolide)-graft-polyethylenimine with functionalized NANPs. Furthermore, we compare several representative NANPs to assess how their overall structures influence their delivery with the same carrier. An extensive study of various formulations both in vitro and in vivo reveals differences in their immunostimulatory activity, gene silencing efficiency, and biodistribution, with fibrous NANPs advancing for TNA delivery.

Suicide Gene Therapy By Amphiphilic Copolymer Nanocarrier for Spinal Cord Tumor.

Spinal cord tumors (SCT) are uncommon neoplasms characterized by irregular growth of tissue inside the spinal cord that can result in non-mechanical back pain. Current treatments for SCT include surgery, radiation therapy, and chemotherapy, but these conventional therapies have many limitations. Suicide gene therapy using plasmid encoding herpes simplex virus-thymidine kinase (pHSV-TK) and ganciclovir (GCV) has been an alternative approach to overcome the limitations of current therapies. However, there is a need to develop a carrier that can deliver both pHSV-TK and GCV for improving therapeutic efficacy. Our group developed a cationic, amphiphilic copolymer, poly (lactide-co-glycolide) -graft-polyethylenimine (PgP), and demonstrated its efficacy as a drug and gene carrier in both cell culture studies and animal models. In this study, we evaluated PgP as a gene carrier and demonstrate that PgP can efficiently deliver reporter genes, pGFP in rat glioma (C6) cells in vitro, and pß-gal in a rat T5 SCT model in vivo. We also show that PgP/pHSV-TK with GCV treatment showed significantly higher anticancer activity in C6 cells compared to PgP/pHSV-TK without GCV treatment. Finally, we demonstrate that PgP/pHSV-TK with GCV treatment increases the suicide effect and apoptosis of tumor cells and reduces tumor size in a rat T5 SCT model.

Rolipram-Loaded Polymeric Micelle Nanoparticle Reduces Secondary Injury after Rat Compression Spinal Cord Injury.

Among the complex pathophysiological events following spinal cord injury (SCI), one of the most important molecular level consequences is a dramatic reduction in neuronal cyclic adenosine monophosphate (cAMP) levels. Many studies shown that rolipram (Rm), a phosphodiesterase IV inhibitor, can protect against secondary cell death, reduce inflammatory cytokine levels and immune cell infiltration, and increase white matter sparing and functional improvement. Previously, we developed a polymeric micelle nanoparticle, poly(lactide-co-glycolide)-graft-polyethylenimine (PgP), for combinatorial delivery of therapeutic nucleic acids and drugs for SCI repair. In this study, we evaluated PgP as an Rm delivery carrier for SCI repair. Rolipram's water solubility was increased ∼6.8 times in the presence of PgP, indicating drug solubilization in the micelle hydrophobic core. Using hypoxia as an in vitro SCI model, Rm-loaded PgP (Rm-PgP) restored cAMP levels and increased neuronal cell survival of cerebellar granular neurons. The potential efficacy of Rm-PgP was evaluated in a rat compression SCI model. After intraspinal injection, 1,1'-dioctadecyl-3,3,3',3'-tetramethyl indotricarbocyanine Iodide-loaded PgP micelles were retained at the injection site for up to 5 days. Finally, we show that a single injection of Rm-PgP nanoparticles restored cAMP in the SCI lesion site and reduced apoptosis and the inflammatory response. These results suggest that PgP may offer an efficient and translational approach to delivering Rm as a neuroprotectant following SCI.

Physicochemical stability and transfection efficiency of cationic amphiphilic copolymer/pDNA polyplexes for spinal cord injury repair.

Multiple age-related and injury-induced characteristics of the adult central nervous system (CNS) pose barriers to axonal regeneration and functional recovery following injury. In situ gene therapy is a promising approach to address the limited availability of growth-promoting biomolecules at CNS injury sites. The ultimate goal of our work is to develop, a cationic amphiphilic copolymer for simultaneous delivery of drug and therapeutic nucleic acids to promote axonal regeneration and plasticity after spinal cord injury. Previously, we reported the synthesis and characterization of a cationic amphiphilic copolymer, poly (lactide-co-glycolide)-graft-polyethylenimine (PgP) and its ability to efficiently transfect cells with pDNA in the presence of serum. We also demonstrated the efficacy of PgP as a therapeutic siRhoA carrier in a rat compression spinal cord injury model. In this work, we show that PgP/pDNA polyplexes provide improved stability in the presence of competing polyanions and nuclease protection in serum relative to conventional branched polyethylenimine control. PgP/pDNA polyplexes maintain bioactivity for transfection after lyophilization/reconstitution and during storage at 4 °C for up to 5 months, important features for commercial and clinical application. We also demonstrate that PgP/pDNA polyplexes loaded with a hydrophobic fluorescent dye are retained in local neural tissue for up to 5 days and that PgP can efficiently deliver pß-Gal in a rat compression SCI model.

RhoA knockdown by cationic amphiphilic copolymer/siRhoA polyplexes enhances axonal regeneration in rat spinal cord injury model.

Spinal cord injury (SCI) results in permanent loss of motor and sensory function due to developmentally-related and injured-induced changes in the extrinsic microenvironment and intrinsic neuronal biochemistry that limit plasticity and axonal regeneration. Our long term goal is to develop cationic, amphiphilic copolymers (poly (lactide-co-glycolide)-g-polyethylenimine, PgP) for combinatorial delivery of therapeutic nucleic acids (TNAs) and drugs targeting these different barriers. In this study, we evaluated the ability of PgP to deliver siRNA targeting RhoA, a critical signaling pathway activated by multiple extracellular inhibitors of axonal regeneration. After generation of rat compression SCI model, PgP/siRhoA polyplexes were locally injected into the lesion site. Relative to untreated injury only, PgP/siRhoA polyplexes significantly reduced RhoA mRNA and protein expression for up to 4 weeks post-injury. Histological analysis at 4 weeks post-injury showed that RhoA knockdown was accompanied by reduced apoptosis, cavity size, and astrogliosis and increased axonal regeneration within the lesion site. These studies demonstrate that PgP is an efficient non-viral delivery carrier for therapeutic siRhoA to the injured spinal cord and may be a promising platform for the development of combinatorial TNA/drug therapy.

Cationic, amphiphilic copolymer micelles as nucleic acid carriers for enhanced transfection in rat spinal cord.

Spinal cord injury commonly leads to permanent motor and sensory deficits due to the limited regenerative capacity of the adult central nervous system (CNS). Nucleic acid-based therapy is a promising strategy to deliver bioactive molecules capable of promoting axonal regeneration. Branched polyethylenimine (bPEI: 25kDa) is one of the most widely studied nonviral vectors, but its clinical application has been limited due to its cytotoxicity and low transfection efficiency in the presence of serum proteins. In this study, we synthesized cationic amphiphilic copolymers, poly (lactide-co-glycolide)-graft-polyethylenimine (PgP), by grafting low molecular weight PLGA (4kDa) to bPEI (25kDa) at approximately a 3:1 ratio as an efficient nonviral vector. We show that PgP micelle is capable of efficiently transfecting plasmid DNA (pDNA) and siRNA in the presence of 10% serum in neuroglioma (C6) cells, neuroblastoma (B35) cells, and primary E8 chick forebrain neurons (CFN) with pDNA transfection efficiencies of 58.8%, 75.1%, and 8.1%, respectively. We also show that PgP provides high-level transgene expression in the rat spinal cord in vivo that is substantially greater than that attained with bPEI. The combination of improved transfection and reduced cytotoxicity in vitro in the presence of serum and in vivo transfection of neural cells relative to conventional bPEI suggests that PgP may be a promising nonviral vector for therapeutic nucleic acid delivery for neural regeneration. STATEMENT OF SIGNIFICANCE: Gene therapy is a promising strategy to overcome barriers to axonal regeneration in the injured central nervous system. Branched polyethylenimine (bPEI: 25kDa) is one of the most widely studied nonviral vectors, but its clinical application has been limited due to cytotoxicity and low transfection efficiency in the presence of serum proteins. Here, we report cationic amphiphilic copolymers, poly (lactide-co-glycolide)-graft-polyethylenimine (PgP) that are capable of efficiently transfecting reporter genes and siRNA both in the presence of 10% serum in vitro and in the rat spinal cord in vivo. The combination of improved transfection and reduced cytotoxicity in the presence of serum as well as transfection of neural cells in vivo suggests PgP may be a promising nucleic acid carrier for CNS gene delivery.

Therapeutic Use of 3ß-[N-(N',N'-Dimethylaminoethane) Carbamoyl] Cholesterol-Modified PLGA Nanospheres as Gene Delivery Vehicles for Spinal Cord Injury.

Gene delivery holds therapeutic promise for the treatment of neurological diseases and spinal cord injury. Although several studies have investigated the use of non-viral vectors, such as polyethylenimine (PEI), their clinical value is limited by their cytotoxicity. Recently, biodegradable poly (lactide-co-glycolide) (PLGA) nanospheres have been explored as non-viral vectors. Here, we show that modification of PLGA nanospheres with 3ß-[N-(N',N'-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol) enhances gene transfection efficiency. PLGA/DC-Chol nanospheres encapsulating DNA were prepared using a double emulsion-solvent evaporation method. PLGA/DC-Chol nanospheres were less cytotoxic than PEI both in vitro and in vivo. DC-Chol modification improved the uptake of nanospheres, thereby increasing their transfection efficiency in mouse neural stem cells in vitro and rat spinal cord in vivo. Also, transgene expression induced by PLGA nanospheres was higher and longer-lasting than that induced by PEI. In a rat model of spinal cord injury, PLGA/DC-Chol nanospheres loaded with vascular endothelial growth factor gene increased angiogenesis at the injury site, improved tissue regeneration, and resulted in better recovery of locomotor function. These results suggest that DC-Chol-modified PLGA nanospheres could serve as therapeutic gene delivery vehicles for spinal cord injury.

Multifunctional nanoparticles for gene delivery and spinal cord injury.

Methylprednisolone (MP) is a glucocorticoid that is used as an anti-inflammatory agent to the treat spinal cord injury (SCI). A low molecular weight chitosan was used to synthesize chitosan-MP conjugate, which was used to evaluate the gene therapy, anti-inflammatory and anti-apoptotic effects of MP. The cytotoxicity of chitosan-MP nanoparticles and the transfection efficiency of plasmid DNA were evaluated by MTT and luciferase assays. A chitosan-MP/pDNA complexes was injected into injured spinal cord to evaluate the anti-inflammatory and anti-apoptotic effects of these complexes using terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL) and ED1 staining, respectively. In addition, to evaluate the distribution of chitosan-MP/pDNA complexes, pß-gal encapsulated chitosan-MP was injected into the injected site. Cell survival was similar in cells treated with chitosan-MP conjugate and untreated cells. Luciferase expression was higher in cells treated with the chitosan-MP/pDNA than cells treated with the chitosan/pDNA. The chitosan-MP/pDNA complexes also reduced apoptosis and inflammation at the injury site. These results suggest that chitosan-MP conjugation is an effective gene delivery system to treat SCI.

Effect of combined bevacizumab and temozolomide treatment on intramedullary spinal cord tumor.

STUDY DESIGN: C6 glioma cells and an intramedullary spinal cord tumor model were used to evaluate the effect of bevacizumab (Avastin) or temozolomide (TMZ). OBJECTIVE: In this study, we hypothesized that treatment with bevacizumab accelerates the therapeutic effect of TMZ on intramedullary gliomas in an animal model. SUMMARY OF BACKGROUND DATA: Recently therapies for the management of intramedullary malignant gliomas include surgery, chemotherapy, and radiotherapy. Concurrent or adjuvant TMZ has been considered an emerging new treatment for intramedullary malignant gliomas; however, high-dose application of TMZ has limitation of side effect. METHODS: C6 glioma cells were injected into the T5 level of the spinal cord, and TMZ and bevacizumab were administered 5 days after C6 inoculation (n = 7 for each group). Tumor size was analyzed using histology and magnetic resonance imaging at 13 days after tumor inoculation. RESULTS: Histological analyses and magnetic resonance imaging findings showed that combined treatment with TMZ and bevacizumab reduced tumor mass. The tumor volume of control group was 2.8-fold higher than combined therapy (P < 0.05). Neurological outcomes demonstrated that combined therapy improved hind limb function more than TMZ-alone group or control group (P < 0.05). CONCLUSION: This study shows that bevacizumab could be useful in combination with TMZ to increase the therapeutic benefits of TMZ for intramedullary spinal cord tumors. LEVEL OF EVIDENCE: N/A.

Chitosan/TPP-hyaluronic acid nanoparticles: a new vehicle for gene delivery to the spinal cord.

Gene delivery offers therapeutic promise for the treatment of neurological diseases and spinal cord injury. Several studies have offered viral vectors as vehicles to deliver therapeutic agents, yet their toxicity and immunogenicity, along with the cost of their large-scale formulation, limits their clinical use. As such, non-viral vectors are attractive in that they offer improved safety profiles compared to viruses. Poly(ethylene imine) (PEI) is one of the most extensively studied non-viral vectors, but its clinical value is limited y its cytotoxicity. Recently, chitosan/DNA complex nanoparticles have een considered as a vector for gene delivery. Here, we demonstrate that DNA nanoparticles made of hyaluronic acid (HA) and chitosan have low cytotoxicity and induce high transgene expression in neural stem cells and organotypic spinal cord slice tissue. Chitosan-TPP/HA nanoparticles were significantly less cytotoxic than PEI at various concentrations. Additionally, chitosan-TPP/HA nanoparticles with pDNA induced higher transgene expression in vitro for a longer duration than PEI in neural stem cells. These results suggest chitosan-TPP/HA nanoparticles may have the potential to serve as an option for gene delivery to the spinal cord.

Hypoxia-specific VEGF-expressing neural stem cells in spinal cord injury model.

We established three stable neural stem cell (NSC) lines to explore the possibility of using hypoxia-specific vascular endothelial growth factor (VEGF) expressing NSC lines (EpoSV-VEGF NSCs) to treat spinal cord injury. The application of EpoSV-VEGF NSCs into the injured spinal cord after clip compression injury not only showed therapeutic effects such as extended survival and angiogenesis, but also displayed its safety profile as it did not cause unwanted cell proliferation or angiogenesis in normal spinal cord tissue, as EpoSV-VEGF NSCs consistently showed hypoxia-specific VEGF expression patterns. This suggests that our EpoSV-VEGF NSCs are both safe and therapeutically efficacious for the treatment of spinal cord injury. Furthermore, this hypoxia-inducible gene expression system may represent a safe tool suitable for gene therapy.

Hypoxia-induced expression of VEGF in the organotypic spinal cord slice culture.

We used the erythropoietin enhancer and Simian virus-40 promoter to create a hypoxia-inducible gene expression system to investigate the effect of vascular endothelial growth factor (VEGF) gene therapy on neuroprotection and neurogenesis in organotypic spinal cord slice culture. The organotypic spinal cord slice culture transfected with pEpo-SV-VEGF expressed the highest amount of VEGF under hypoxic conditions and showed decreased apoptosis and increased proliferation, and evidence of neurogenesis. Our results show that the hypoxia-induced VEGF expression in an organotypic spinal cord slice culture may lead to an optimal treatment for spinal cord injury.

Cotransplantation of mouse neural stem cells (mNSCs) with adipose tissue-derived mesenchymal stem cells improves mNSC survival in a rat spinal cord injury model.

The low survival rate of graft stem cells after transplantation into recipient tissue is a major obstacle for successful stem cell therapy. After transplantation into the site of spinal cord injury, the stem cells face not only hypoxia due to low oxygen conditions, but also a lack of nutrients caused by damaged tissues and poor vascular supply. To improve the survival of therapeutic stem cells after grafting into the injured spinal cord, we examined the effects of cotransplanting mouse neural stem cells (mNSCs) and adipose tissue-derived mesenchymal stem cells (AT-MSCs) on mNSC viability. The viability of mNSCs in coculture with AT-MSCs was significantly increased compared to mNSCs alone in an in vitro injury model using serum deprivation (SD), hydrogen peroxide (H(2)O(2)), and combined (SD + H(2)O(2)) injury mimicking the ischemic environment of the injured spinal cord. We demonstrated that AT-MSCs inhibited the apoptosis of mNSCs in SD, H(2)O(2), and combined injury models. Consistent with these in vitro results, mNSCs transplanted into rat spinal cords with AT-MSCs showed better survival rates than mNSCs transplanted alone. These findings suggest that cotransplantation of mNSCs with AT-MSCs may be a more effective transplantation protocol to improve the survival of cells transplanted into the injured spinal cord.