Drug delivery, cell-based therapies, and tissue engineering approaches for spinal cord injury

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.

A Simple Modification Method to Obtain Anisotropic and Porous 3D Microfibrillar Scaffolds for Surgical and Biomedical Applications

In native tissues, cellular organization is predominantly anisotropic. Yet, it remains a challenge to engineer anisotropic scaffolds that promote anisotropic cellular organization at macroscopic length scales. To overcome this challenge, an innovative, cheap and easy method to align clinically approved non-woven surgical microfibrillar scaffolds is presented. The method involves a three-step process of coating, unidirectional stretching of scaffolds after heating them above glass transition temperature, and cooling back to room temperature. Briefly, a polymer coating is applied to a non-woven mesh that results in a partial welding of randomly oriented microfibers at their intersection points. The coated scaffold is then heated above the glass transition temperature of the coating and the scaffold polymer. Subsequently, the coated scaffold is stretched to produce aligned and three dimentional (3D) porous fibrillar scaffolds. In a proof of concept study, a polyglycolic acid (PGA) micro-fibrillar scaffold was coated with poly(4-hydroxybutirate) (P4HB) acid and subsequently aligned. Fibroblasts were cultured in vitro within the scaffold and results showed an increase in cellular alignment along the direction of the PGA fibers. This method can be scaled up easily for industrial production of polymeric meshes or directly applied to small pieces of scaffolds at the point of care.

Effective improvement of the neuroprotective activity after spinal cord injury by synergistic effect of glucocorticoid with biodegradable amphipathic nanomicelles

Dexamethasone acetate (DA) produces neuroprotective effects by inhibiting lipid peroxidation and inflammation by reducing cytokine release and expression. However, its clinical application is limited by its hydrophobicity, low biocompatibility and numerous side effects when using large dosage. Therefore, improving DA's water solubility, biocompatibility and reducing its side effects are important goals that will improve its clinical utility. The objective of this study is to use a biodegradable polymer as the delivery vehicle for DA to achieve the synergism between inhibiting lipid peroxidation and inflammation effects of the hydrophobic-loaded drugs and the amphipathic delivery vehicle. We successfully prepared DA-loaded polymeric micelles (DA/MPEG-PCL micelles) with monodispersed and approximately 25 nm in diameter, and released DA over an extended period in vitro. Additionally, in the hemisection spinal cord injury (SCI) model, DA micelles were more effective in promoting hindlimb functional recover, reducing glial scar and cyst formation in injured site, decreasing neuron lose and promoting axon regeneration. Therefore, our data suggest that DA/MPEG-PCL micelles have the potential to be applied clinically in SCI therapy.

Effect of Electro-Acupuncture on Neuroplasticity of Spinal Cord-Transected Rats

BACKGROUND This study aimed to evaluate the effects of electro-acupuncture (EA) on neuroplasticity associated with the expressions of neurotrophic factors (NTFs) and their receptors in rats subjected to spinal cord transection (SCT). MATERIAL AND METHODS A total of 144 rats were randomly divided into 3 groups (n=48 per group): sham-operated group, SCT group, and EA (electro-acupuncture) group. Rats in SCT and EA groups received spinal cord transection at T10-T11 vertebral levels. Then, EA group rats received EA treatment. Reverse transcription polymerase chain reaction was used to detect NTFs and receptors at the mRNA level. In situ hybridization (ISH) and immunohistochemistry (IHC) were used to detect the expression of NTFs and their receptors. Basso, Beattie, Bresnahan (BBB) scores and cortical somato-sensory evoked potentials (CSEP) were evaluated to assess the recovery of motor and sensory functions. We also measured BDA (Biotinylated dextran amine) axonal tracing, CGRP (Calcitonin gene-related peptide), GAP-43 (Growth-associated protein), and synaptophysin immunohistochemistry (IHC). RESULTS EA treatment led to obvious improvement in hindlimb locomotor and sensory functions. CNTF, FGF-2, and TrkB mRNA were significantly upregulated, while NGF, PDGF, TGF-b1, IGF-1, TrkA, and TrkC mRNA were concomitantly downregulated in the caudal spinal segment (CSS) following EA. Immunohistochemistry demonstrated an increased number of CGRP fibers, GAP-43, and synaptophysin profiles in the CSS in the EA rats. CONCLUSIONS EA may promote the recovery of neuroplasticity in rats subjected to SCT. This could be attributed to the systematic regulation of NTFs and their receptors after EA.

Superoxide Dismutase-Loaded Porous Polymersomes as Highly Efficient Antioxidants for Treating Neuropathic Pain

A highly efficient antioxidant is developed by encapsulating superoxide dismutase (SOD) within the aqueous interior of porous polymersomes. The porous polymersomes provide a permeable membrane that allows free superoxide radicals to pass into the aqueous interior and interact with the encapsulated antioxidant enzyme SOD. In vivo studies in the rat demonstrate that administration of SOD-encapsulated porous polymersomes can prevent neuropathic pain after nerve root compression more effectively than treatment with free antioxidant enzyme alone.

Nanofiber Scaffolds as Drug Delivery Systems to Bridge Spinal Cord Injury

The complex pathophysiology of spinal cord injury (SCI) may explain the current lack of an effective therapeutic approach for the regeneration of damaged neuronal cells and the recovery of motor functions. A primary mechanical injury in the spinal cord triggers a cascade of secondary events, which are involved in SCI instauration and progression. The aim of the present review is to provide an overview of the therapeutic neuro-protective and neuro-regenerative approaches, which involve the use of nanofibers as local drug delivery systems. Drugs released by nanofibers aim at preventing the cascade of secondary damage (neuro-protection), whereas nanofibrous structures are intended to re-establish neuronal connectivity through axonal sprouting (neuro-regeneration) promotion, in order to achieve a rapid functional recovery of spinal cord.

Three-Dimensional Hyaluronic Acid Hydrogel-Based Models for In Vitro Human iPSC-Derived NPC Culture and Differentiation

Human induced pluripotent stem cell-derived neural progenitor cells (hiPSC-NPCs) are considered as a promising cell source for transplantation and have been used for organoid fabrication to recapitulate central nervous system (CNS) diseases in vitro. The establishment of three-dimensional (3D) in vitro model with hiPSC-NPCs and control of their differentiation is significantly critical for understanding biological processes and CNS disease and regeneration. Here we implemented 3D methacrylated hyaluronic acid (Me-HA) hydrogels with encapsulation of hiPSC-NPCs as in vitro culture models and further investigated the role of the hydrogel rigidity on the cell behavior of hiPSC-NPCs. We first encapsulated single dispersive hiPSC-NPCs within both soft and stiff Me-HA hydrogel and found that hiPSC-NPCs gradually self-assembled and aggregated to form 3D spheroids. Then, the hiPSC-NPCs were laden into Me-HA hydrogels in the form of spheroids to evaluate their spontaneous differentiation in response to hydrogel rigidity. The soft Me-HA hydrogel-encapsulated hiPSC-NPCs displayed robust neurite outgrowth and showed high levels of spontaneous neural differentiation. We further encapsulated Down Syndrome (DS) patient-specific hiPSC-derived NPCs (DS-NPCs) spheroids within our hydrogels. DS-NPCs remained excellent cell viability in both soft and stiff Me-HA hydrogels. Similarly, soft hydrogels promoted neural differentiation of DS-NPCs by significantly upregulating neural maturation markers. This study demonstrates that soft matrix promotes neural differentiation of hiPSC-NPCs and HA-based hydrogels with hiPSC-NPCs or DS-NPCs are effective 3D models for CNS disease study.

Biomaterials for Local, Controlled Drug Delivery to the Injured Spinal Cord

Affecting approximately 17,000 new people each year, spinal cord injury (SCI) is a devastating injury that leads to permanent paraplegia or tetraplegia. Current pharmacological approaches are limited in their ability to ameliorate this injury pathophysiology, as many are not delivered locally, for a sustained duration, or at the correct injury time point. With this review, we aim to communicate the importance of combinatorial biomaterial and pharmacological approaches that target certain aspects of the dynamically changing pathophysiology of SCI. After reviewing the pathophysiology timeline, we present experimental biomaterial approaches to provide local sustained doses of drug. In this review, we present studies using a variety of biomaterials, including hydrogels, particles, and fibers/conduits for drug delivery. Subsequently, we discuss how each may be manipulated to optimize drug release during a specific time frame following SCI. Developing polymer biomaterials that can effectively release drug to target specific aspects of SCI pathophysiology will result in more efficacious approaches leading to better regeneration and recovery following SCI.

Biomimetic nanofibrous scaffolds for neural tissue engineering and drug development

Neural tissue engineering aims to develop functional substitutes for damaged tissues, creating many promising opportunities in regeneration medicine and drug discovery. Biomaterial scaffolds routinely provide nerve cells with a physical support for cell growth and regeneration, yielding 3D extracellular matrix to mimic the in vivo cellular microenvironment. Among the various types of cellular scaffolds for reconstruction, biomimetic nanofibrous scaffolds are recognized as appropriate candidates by precisely controlling morphology and shape. Here, we review the current techniques in fabricating biomimetic nanofibrous scaffolds for neural tissue engineering, and describe the impact of nanofiber components on the properties of scaffolds and their uses in therapeutic models and drug development. We also discuss the current challenges and future directions of applying 3D printing and microfluidic technologies in neural tissue engineering.

A Thermosensitive Heparin-Poloxamer Hydrogel Bridges aFGF to Treat Spinal Cord Injury

Acidic fibroblast growth factor (aFGF) exerts a protective effect on spinal cord injury (SCI) but is limited by the lack of physicochemical stability and the ability to cross the blood spinal cord barrier (BSCB). As promising biomaterials, hydrogels contain substantial amounts of water and a three-dimensional porous structure and are commonly used to load and deliver growth factors. Heparin can not only enhance growth factor loading onto hydrogels but also can stabilize the structure and control the release behavior. Herein, a novel aFGF-loaded thermosensitive heparin-poloxamer (aFGF-HP) hydrogel was developed and applied to provide protection and regeneration after SCI. To assess the effects of the aFGF-HP hydrogel, BSCB restoration, neuron and axonal rehabilitation, glial scar inhibition, inflammatory response suppression, and motor recovery were studied both in vivo and in vitro. The aFGF-HP hydrogels exhibited sustained release of aFGF and protected the bioactivity of aFGF in vitro. Compared to groups intravenously administered either drug-free HP hydrogel or aFGF alone, the aFGF-HP hydrogel group revealed prominent and attenuated disruption of the BSCB, reduced neuronal apoptosis, reactive astrogliosis, and increased neuron and axonal rehabilitation both in vivo and in vitro. This work provides an effective approach to enhance recovery after SCI and provide a successful strategy for SCI protection.

β-hairpin peptide hydrogels for package delivery

The underlying challenge of drug delivery is the safe, controlled transport of a supply of therapeutic agent to its intended location at its effective dose. New and expanding solutions to payload delivery are being discovered in the field of hydrogels. Hydrogels are highly hydrated polymer networks that vary greatly depending on the underlying molecular structure. The subgroup of hydrogels that will be the focus of this chapter is the β-hairpin peptide hydrogel. These peptide-based materials are formed through a molecular self-assembly mechanism that only occurs after desired triggering of intramolecular peptide folding. Once folded, the β-hairpins assemble intermolecularly into a nanofibrillar network. The physical properties of the hydrogel network and its peptide foundation result in advantageous material properties which can be used for multiple biomedical applications including drug delivery. As a shear thinning solid that is easily injectable, cytocompatible, customizable, and well characterized, β-hairpin hydrogels are an exciting candidate as a drug delivery vehicle.

Stem cells for spinal cord injury: Strategies to inform differentiation and transplantation

The complex pathology of spinal cord injury (SCI), involving a cascade of secondary events and the formation of inhibitory barriers, hampers regeneration across the lesion site and often results in irreversible loss of motor function. The limited regenerative capacity of endogenous cells after SCI has led to a focus on the development of cell therapies that can confer both neuroprotective and neuroregenerative benefits. Stem cells have emerged as a candidate cell source because of their ability to self-renew and differentiate into a multitude of specialized cell types. While ethical and safety concerns impeded the use of stem cells in the past, advances in isolation and differentiation methods have largely mitigated these issues. A confluence of work in stem cell biology, genetics, and developmental neurobiology has informed the directed differentiation of specific spinal cell types. After transplantation, these stem cell-derived populations can replace lost cells, provide trophic support, remyelinate surviving axons, and form relay circuits that contribute to functional recovery. Further refinement of stem cell differentiation and transplantation methods, including combinatorial strategies that involve biomaterial scaffolds and drug delivery, is critical as stem cell-based treatments enter clinical trials. Biotechnol. Bioeng. 2017;114: 245-259. © 2016 Wiley Periodicals, Inc.

Peptide-Tethered Hydrogel Scaffold Promotes Recovery from Spinal Cord Transection via Synergism with Mesenchymal Stem Cells

Spinal cord injury (SCI) is one of the most devastating injuries. Treatment strategies for SCI are required to overcome comprehensive issues. Implantation of biomaterial scaffolds and stem cells has been demonstrated to be a promising strategy. However, a comprehensive recovery effect is difficult to achieve. In the comprehensive treatment process, the specific roles of the implanted scaffolds and of stem cells in combined strategy are usually neglected. In this study, a peptide-modified scaffold is developed based on hyaluronic acid and an adhesive peptide PPFLMLLKGSTR. Synchrotron radiation micro computed tomography measurement provides insights to the three-dimensional inner topographical property and perspective porous structure of the scaffold. The modified scaffold significantly improves cellular survival and adhesive growth of mesenchymal stem cells during 3D culture in vitro. After implantation in transected spinal cord, the modified scaffold and mesenchymal stems are found to function in synergy to restore injured spinal cord tissue, with respective strengths. Hindlimb motor function scores exhibit the most significant impact of the composite implant at 2 weeks post injury, which is the time secondary injury factors begin to take hold. Investigation on the secondary injury factors including inflammatory response and astrocyte overactivity at 10 days post injury reveals the possible underlying reason. Implants of the scaffold, cells, and especially the combination of both elicit inhibitory effects on these adverse factors. The study develops a promising implant for spinal cord tissue engineering and reveals the roles of the scaffold and stem cells. More importantly, the results provide the first understanding of the bioactive peptide PPFLMLLKGSTR concerning its functions on mesenchymal stem cells and spinal cord tissue restoration.

Double conjugated nanogels for selective intracellular drug delivery

One of the most important drawbacks of nanomedicine is related to the unwanted rapid diffusion of drugs loaded within nanocarriers towards the external biological environment, according to the high clearance of body fluids.

Design and criteria of electrospun fibrous scaffolds for the treatment of spinal cord injury

The complex pathophysiology of spinal cord injury may explain the current lack of an effective therapeutic approach for the regeneration of damaged neuronal cells and the recovery of motor functions. Many efforts have been performed to design and develop suitable scaffolds for spinal cord regeneration, keeping in mind that the reconstruction of a pro-regenerative environment is the key challenge for an effective neurogenesis. The aim of this review is to outline the main features of an ideal scaffold, based on biomaterials, produced by the electrospinning technique and intended for the spinal cord regeneration. An overview of the polymers more investigated in the production of neural fibrous scaffolds is also provided.

Neurotrophic Factors Used to Treat Spinal Cord Injury

The application of neurotrophic factors as a therapy to improve morphological and behavioral outcomes after experimental spinal cord injury (SCI) has been the focus of many studies. These studies vary markedly in the type of neurotrophic factor that is delivered, the mode of administration, and the location, timing, and duration of the treatment. Generally, the majority of studies have had significant success if neurotrophic factors are applied in or close to the lesion site during the acute or the subacute phase after SCI. Comparatively fewer studies have administered neurotrophic factors in order to directly target the somata of injured neurons. The mode of delivery varies between acute injection of recombinant proteins, subacute or chronic delivery using a variety of strategies including osmotic minipumps, cell-mediated delivery, delivery using polymer release vehicles or supporting bridges of some sort, or the use of gene therapy to modify neurons, glial cells, or precursor/stem cells. In this brief review, we summarize the state of play of many of the therapies using these factors, most of which have been undertaken in rodent models of SCI.

The effects of different amounts of drug microspheres on the vivo and vitro performance of the PLGA/β-TCP scaffold

OIC-A006 (BMPs osteogenesis compounds), can stimulate bone marrow mesenchymal stem cells ALP, OPN, OC, Cbfal expression. To stimulate new bone formation in the body. We postulate different amounts of drug microspheres on the PLGA/β-CPT scaffold can produce the effects on performance and sustained release characteristics. In this paper, through adding different amount of carrier drug microsphere, three concentrations scaffolds which are 12.5, 18.75 and 25 μmol/L are prepared by adding different amounts of drug-loaded microspheres. Hereafter called OICM/CPT-200, OICM/CPT-300, OICM/CPT-400. We implant them in rat femur diameter 3 mm depth of 3 mm hole for eight weeks. The degradation, microsphere, delivery properties, with X-ray, micro-CT and histology are tested. Results show that the contain carrier drug microsphere scaffolds become radiopaque, and the gaps between the scaffold and radial cut ends are often invisible. This preliminary study reveals that different carrier drug microsphere has a corresponding effect the performance of stent body, OICM/CPT – 200 scaffolds induction effect is best. Illustrates that the low concentration load OIC-A006 microspheres can promote bone healing, and high concentration of OIC-A006 micro ball is played a inhibitory effect on bone healing process.

Changes in the Expression of miR-34a and its Target Genes Following Spinal Cord Injury In Rats

Background

Results from DNA microarray experiments have shown that the expression of miR-34s undergoes significant changes following spinal cord injury (SCI). The present study was designed to detect changes in the expression of miR-34s and its target genes during the acute and sub-acute stages of SCI.

Material/Methods

Luxol fast blue (LFB) staining for myelin was used to observe the differences in the general morphology of the spinal cord after SCI in a contusion model in rats. qPCR was carried out to determine the expression variation of miR-34s and its target genes during the acute and sub-acute stages of SCI. The mimic technique was used to further confirm the regulatory effect of miR-34a on the potential target genes.

Results

The expression level of miR-34a decreased immediately after SCI and persisted for 21 days after SCI. The expression level of miR-34c began decreasing at day 1 after SCI and persisted until day 14. The expression level of miR-34b did not undergo significant change after SCI. The results of double immunofluorescence and in-situ hybridization suggested that miR-34a was highly expressed in spinal cord neurons. Based on our bioinformatics analysis, we postulated that miR-34a might participate in post-SCI cell apoptosis by regulating the target gene Notch1, and likely participated in the inflammatory response and glial scar formation by regulating the candidate genes Csf1r and PDGFRα, respectively. The expression levels of the candidate genes Csf1r and PDGFRα were consistent with Notch1 after SCI. The mimic technique further confirmed the regulatory effect of miR-34a on the aforementioned target genes.

Conclusions

We postulate that miR-34a and miR-34c might participate in multiple aspects of cytobiological activities following SCI. MiR-34a in particular may participate in cell apoptosis, inflammatory response, and glial scar formation by regulating the target gene Notch1 and candidate target genes Csf1r and PDGFRα respectively.

Oriented growth of rat Schwann cells on aligned electrospun poly(methyl methacrylate) nanofibers

Transplanted Schwann cells have the potential to serve as a support for regenerating neurites after spinal cord injury. However, implanted Schwann cells die off rapidly once transplanted partly owing to the absence of a proper matrix support, with a glia scar and a cavity being present instead at the injury site. For this report, we evaluated aligned electrospun poly(methyl methacrylate) nanofibers as a Schwann cell-loading scaffold in vitro. By monitoring the fluorescence of green fluorescence protein-containing Schwann cells cultured on nanofibers, we found that aligned nanofibers provided better support for the cells than did non-aligned nanofibers. The cells elongated along the long axes of the aligned nanofibers and formed longer cell processes than when the substrate was non-aligned nanofibers. By coculturing Schwann cells with dorsal root ganglion neurons, it was also found that Schwann cells and neurites of dorsal root ganglion neurons could share and both elongate along the orientation of aligned nanofibers and thus they had a higher chance of colocalization than cocultured on film and non-aligned fibers, which might be beneficial to the ensuring process of myelination. The results of the study indicate that aligned electrospun nanofibers may serve as a Schwann cell-loading scaffold for future implantation research.

Radially Aligned Electrospun Fibers with Continuous Gradient of SDF1α for the Guidance of Neural Stem Cells

Repair of spinal cord injury will require enhanced recruitment of endogenous neural stem cells (NSCs) from the central canal region to the lesion site to reestablish neural connectivity. The strategy toward this goal is to provide directional cues, e.g., alignment topography and biological gradients from the rostral and caudal ends toward the center. This study demonstrates a facile method for fabrication of continuous gradients of stromal-cell-derived factor-1α (SDF1α) embedded in the radially aligned electrospun collagen/poly (ε-caprolactone) mats. Gradients can be readily produced in a controllable and reproducible fashion by adjusting the collection time and collector size during electrospinning. To get a long-term gradient, the SDF1α is fused with a unique peptide of collagen-binding domain (CBD), which can bind to collagen specifically. Aligned CBD-SDF1α gradients show stable, sustained, and gradual release during 7 d. Further, the effect of aligned CBD-SDF1α gradients on the guidance of NSCs is investigated. It is found that the CBD-SDF1α gradient scaffolds direct and enhance NSC migration from the periphery to the center along the aligned electrospun fibers. Taken together, the tubular conduits based on radially aligned electrospun fibers with continuous SDF1α gradient show great potential for guiding nerve regeneration.

Gold Nanoparticle-Decorated Scaffolds Promote Neuronal Differentiation and Maturation

Engineered 3D neuronal networks are considered a promising approach for repairing the damaged spinal cord. However, the lack of a technological platform encouraging axonal elongation over branching may jeopardize the success of such treatment. To address this issue we have decorated gold nanoparticles on the surface of electrospun nanofiber scaffolds, characterized the composite material, and investigated their effect on the differentiation, maturation, and morphogenesis of primary neurons and on an immature neuronal cell line. We have shown that the nanocomposite scaffolds have encouraged a longer outgrowth of the neurites, as judged by the total length of the branching trees and the length and total distance of neurites. Moreover, neurons grown on the nanocomposite scaffolds had less neurites originating out of the soma and lower number of branches. Taken together, these results indicate that neurons cultivated on the gold nanoparticle scaffolds prefer axonal elongation over forming complex branching trees. We envision that such cellular constructs may be useful in the future as implantable cellular devices for repairing damaged neuronal tissues, such as the spinal cord.

Modification of the hTERT promoter by heat shock elements enhances the efficiency and specificity of cancer targeted gene therapy

PURPOSE

One of the current challenges facing cancer gene therapy is the tumour-specific targeting of therapeutic genes. Effective targeting in gene therapy requires accurate spatial and temporal control of gene expression. To develop a sufficient and accurate tumour-targeting method for cancer gene therapy, we have investigated the use of hyperthermia to control the expression of a transgene under the control of the human telomerase reverse transcriptase (hTERT) promoter and eight heat shock elements (8HSEs).

MATERIALS AND METHODS

Luciferase reporters were constructed by inserting eight HSEs and the hTERT promoter (8HSEs-hTERTp) upstream of the pGL4.20 vector luciferase gene. The luciferase activity of the hTERT promoter and 8HSEs-hTERT promoter were then compared in the presence and absence of heat. The differences in luciferase activity were analysed using dual luciferase assays in SW480 (high hTERT expression), MKN28 and MRC-5 cells (low hTERT expression). The luciferase activity of the Hsp70B promoter was also compared to the 8HSEs-hTERT promoter in the above listed cell lines. Lentiviral vector and heat-induced expression of EGFP expression under the control of the 8HSEs-hTERT promoter in cultured cells and mouse tumour xenografts was measured by reverse transcription polymerase (RT-PCR), Western blot and immunofluorescence assays.

RESULTS

hTERT promoter activity was higher in SW480 cells than in MKN28 or MRC-5 cells. At 43 °C, the luciferase activity of the 8HSEs-hTERT promoter was significantly increased in SW480 cells, but not in MKN28 or MRC-5 cells. Importantly, the differences in luciferase activity were much more obvious in both high (SW480) and low (MKN28 and MRC-5) hTERT expressing cells when the activity of the 8HSEs-hTERT promoter was compared to the Hsp70B promoter. Moreover, under the control of 8HSEs-hTERT promoter in vitro and in vivo, EGFP expression was obviously increased by heat treatment in SW480 cells but not in MKN28 or MRC-5 cells, nor was expression increased under normal temperature conditions.

CONCLUSIONS

The hTERT promoter is a potentially powerful tumour-specific promoter and gene therapy tool for cancer treatment. Incorporating heat-inducible therapeutic elements (8HSEs) into the hTERT promoter may enhance the efficiency and specificity of cancer targeting gene therapy under hyperthermic clinical conditions.

Human bone marrow-derived and umbilical cord-derived mesenchymal stem cells for alleviating neuropathic pain in a spinal cord injury model

BACKGROUND

Stem cell therapy can be used for alleviating the neuropathic pain induced by spinal cord injuries (SCIs). However, survival and differentiation of stem cells following their transplantation vary depending on the host and intrinsic factors of the cell. Therefore, the present study aimed to determine the effect of stem cells derived from bone marrow (BM-MSC) and umbilical cord (UC-MSC) on neuropathic pain relief.

METHODS

A compression model was used to induce SCI in a rat model. A week after SCI, about 1 million cells were transplanted into the spinal cord. Behavioral tests, including motor function recovery, mechanical allodynia, cold allodynia, mechanical hyperalgesia, and thermal hyperalgesia, were carried out every week for 8 weeks after SCI induction. A single unit recording and histological evaluation were then performed.

RESULTS

We show that BM-MSC and UC-MSC transplantations led to improving functional recovery, allodynia, and hyperalgesia. No difference was seen between the two cell groups regarding motor recovery and alleviating the allodynia and hyperalgesia. These cells survived in the tissue at least 8 weeks and prevented cavity formation due to SCI. However, survival rate of UC-MSC was significantly higher than BM-MSC. Electrophysiological evaluations showed that transplantation of UC-MSC brings about better results than BM-MSCs in wind up of wide dynamic range neurons.

CONCLUSIONS

The results of the present study show that BM-MSC and UC-MSC transplantations alleviated the symptoms of neuropathic pain and resulted in subsequent motor recovery after SCI. However, survival rate and electrophysiological findings of UC-MSC were significantly better than BM-MSC.