Delivery Of Brain-derived Neurotrophic Factor Research Articles

Growth Factor Gene Therapy for Alzheimer's Disease.

Nervous system growth factors are natural proteins of the brain that influence neuronal survival and function throughout life, from embryonic development to old age. In animal models of Alzheimer's disease (AD), the growth factor brain derived neurotrophic factor (BDNF) prevents neuronal death, activates neuronal function, builds new synapses and improves learning and memory. Accordingly, we are determining whether gene delivery of BDNF in patients with AD will slow disease progression and improve memory. In a previous clinical trial of nerve growth factor (NGF) gene therapy in AD patients (NCT00017940, June 2001), we learned that growth factors can unequivocally elicit classic trophic responses from degenerating neurons in AD. Experience gained from the earlier NGF gene therapy trial is guiding our effort to optimize gene delivery of BDNF in our present clinical program (NCT05040217, June 2021).

Brain-Derived Neurotrophic Factor-Loaded Low-Temperature-Sensitive liposomes as a drug delivery system for repairing podocyte damage

Podocytes, cells of the glomerular filtration barrier, play a crucial role in kidney diseases and are gaining attention as potential targets for new therapies. Brain-Derived Neurotrophic Factor (BDNF) has shown promising results in repairing podocyte damage, but its efficacy via parenteral administration is limited by a short half-life. Low temperature sensitive liposomes (LTSL) are a promising tool for targeted BDNF delivery, preserving its activity after encapsulation. This study aimed to improve LTSL design for efficient BDNF encapsulation and targeted release to podocytes, while maintaining stability and biological activity, and exploiting the conjugation of targeting peptides. While cyclic RGD (cRGD) was used for targeting endothelial cells in vitro, a homing peptide (HITSLLS) was conjugated for more specific uptake by glomerular endothelial cells in vivo. BDNF-loaded LTSL successfully repaired cytoskeleton damage in podocytes and reduced albumin permeability in a glomerular co-culture model. cRGD conjugation enhanced endothelial cell targeting and uptake, highlighting an improved therapeutic effect when BDNF release was induced by thermoresponsive liposomal degradation. In vivo, targeted LTSL showed evidence of accumulation in the kidneys, and their BDNF delivery decreased proteinuria and ameliorated kidney histology. These findings highlight the potential of BDNF-LTSL formulations in restoring podocyte function and treating glomerular diseases.

Epigenetic processes associated with neonatal spinal transection.

In early development, the spinal cord in healthy or disease states displays remarkable activity-dependent changes in plasticity, which may be in part due to the increased activity of brain derived neurotrophic factor (BDNF). Indeed, BDNF delivery has been efficacious in partially ameliorating many of the neurobiological and behavioral consequences of spinal cord injury (SCI), making elucidating the role of BDNF in the normative developing and injured spinal cord a critical research focus. Recent work in our laboratory provided evidence for aberrant global and locus-specific epigenetic changes in methylation of the Bdnf gene as a consequence of SCI. In the present study, animals underwent thoracic lesions on P1, with cervical and lumbar tissue being later collected on P7, P14, and P21. Levels of Bdnf expression and methylation (exon IX and exon IV), in addition to global methylation levels were quantified at each timepoint. Results indicated locus-specific reductions of Bdnf expression that was accompanied by a parallel increase in methylation caudal to the injury site, with animals displaying increased Bdnf expression at the P14 timepoint. Together, these findings suggest that epigenetic activity of the Bdnf gene may act as biomarker in the etiology and intervention effort efficacy following SCI.

BDNF-enriched small extracellular vesicles protect against noise-induced hearing loss in mice

Noise-induced hearing loss (NIHL) is one of the most prevalent acquired sensorineural hearing loss etiologies and is characterized by the loss of cochlear hair cells, synapses, and nerve terminals. Currently, there are no agents available for the treatment of NIHL because drug delivery to the inner ear is greatly limited by the blood–labyrinth barrier. In this study, we used mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) as nanoscale vehicles to deliver brain-derived neurotrophic factor (BDNF) and evaluated their protective effects in a mouse model of NIHL. Following intravenous administration, BDNF-loaded sEVs (BDNF-sEVs) efficiently increased the expression of BDNF protein in the cochlea. Systemic application of sEVs and BDNF-sEVs significantly attenuated noise-induced cochlear hair cell loss and NIHL in CBA/J mice. BDNF-sEVs also alleviated noise-induced loss of inner hair cell ribbon synapses and cochlear nerve terminals. In cochlear explants, sEVs and BDNF-sEVs effectively protected hair cells against H2O2-induced cell loss. Additionally, BDNF-sEVs remarkably ameliorated H2O2-induced oxidative stress, cell apoptosis, and cochlear nerve terminal degeneration. Transcriptomic analysis revealed that many mRNAs and miRNAs were involved in the protective actions of BDNF-sEVs against oxidative stress. Collectively, our findings reveal a novel therapeutic strategy of MSC-sEVs-mediated BDNF delivery for the treatment of NIHL.

Virus‐Engineered Microsol Electrospun Scaffold Promotes the Reprogramming of Fibroblasts to Neurons

AbstractLentiviral‐vector‐based therapies, widely used for treating various diseases, face limitations because of release burst, rapid clearance, and immune activation. Herein, a lentiviral vector delivery platform is proposed utilizing a virus‐engineered microsol electrospun scaffold. Identifying a remarkable upregulation of polypyrimidine tract binding protein1 (PTB) in spinal cord injury (SCI) rats, a scaffold is constructed comprising a hyaluronic acid (HA) core encapsulating brain‐derived neurotrophic factor (BDNF) and a polydopamine (PDA)‐modified linear poly‐l‐lactic acid (PLLA) shell, with shPTB lentiviral vectors (LV‐shPTB) grafted via PDA. In vitro, the LV‐shPTB achieves an infection efficiency of 70%, and the oriented scaffolds significantly reduce the expression of inflammatory factors, induce the reprogramming of fibroblasts into neurons, and sustain the release of BDNF for over 2 weeks. In vivo, the scaffolds provide physical support and neural guidance, as well as released BDNF and LV‐shPTB. LV‐shPTB delivery leads to the reprogramming of fibroblasts into neurons, and the sustained BDNF delivery maintains the neurons’ proliferation and growth, which further promotes the recovery of neurological function in SCI rats. These results demonstrate the potential application of virus‐engineered delivery platforms in SCI treatment and other medical fields.

Intranasal delivery of BDNF-loaded small extracellular vesicles for cerebral ischemia therapy

Mesenchymal stem cells (MSCs) have shown promise for the therapy of cerebral ischemia in animal studies and clinical trials, yet their clinical application still faces many challenges. Utilizing small extracellular vesicles (sEVs) may overcome these challenges. In the study, we overexpressed brain-derived neurotrophic factor (BDNF) in cultured MSCs and purified sEVs using anion exchange chromatography. In an ischemic stroke mouse model, sEVs selectively targeted the peri-infarct region after intranasal administration, and BDNF loading enhanced the efficacy of sEVs in improved functional behavior, neural repair indicated by infarct volume reduction, increased neurogenesis, angiogenesis, synaptic plasticity, and fiber preservation, as well as decreased inflammatory-cytokine expression and glial response. Intranasal administration of sEVs and BDNF-sEVs resulted in upregulation of neuroprotection-related genes and downregulation of inflammation-related genes, and BDNF-sEVs treatment activated the BDNF/TrkB signaling in the ischemic brain. Transcriptomic and proteomic analysis of sEVs and BDNF-sEVs disclosed abundant proteins and miRNAs involved in neuroprotection and anti-inflammation, and BDNF-sEVs showed different characteristics from sEVs. In conclusion, intranasal delivery of sEVs-loaded BDNF is a promising alternative strategy for the therapy of cerebral ischemia.

BDNF is altered in a brain-region specific manner and rescues deficits in Spinocerebellar Ataxia Type 1

Spinocerebellar ataxia type 1 (SCA1) is an adult-onset, dominantly inherited neurodegenerative disease caused by the expanded polyQ tract in the protein ATAXIN1 (ATXN1) and characterized by progressive motor and cognitive impairments. There are no disease-modifying treatments or cures for SCA1. Brain-derived neurotrophic factor (BDNF) plays important role in cerebellar physiology and has shown therapeutic potential for cerebellar pathology in the transgenic mouse model of SCA1, ATXN1[82Q] line that overexpress mutant ATXN1 under a cerebellar Purkinje-cell-specific promoter. Here we demonstrate decreased expression of brain derived neurotrophic factor (BDNF) in the cerebellum and medulla of patients with SCA1. Early stages of disease seem most amenable to therapy. Thus, we next quantified Bdnf expression in Atxn1154Q/2Q mice, a knock-in mouse model of SCA1, during the early symptomatic disease stage in four clinically relevant brain regions: cerebellum, medulla, hippocampus and motor cortex. We found that during the early stages of disease, Bdnf mRNA expression is reduced in the hippocampus and cerebellum, while it is increased in the cortex and brainstem. Importantly, we observed that pharmacological delivery of recombinant BDNF improved motor and cognitive performance, and mitigated pathology in the cerebellum and hippocampus of Atxn1154Q/2Q mice. Our findings demonstrate brain-region specific deficiency of BDNF in SCA1 and show that reversal of low BDNF levels offers the potential for meaningful treatment of motor and cognitive deficits in SCA1.

Inflammation-activated C/EBPβ mediates high-fat diet-induced depression-like behaviors in mice.

Depression, one of the most common causes of disability, has a high prevalence rate in patients with metabolic syndrome. Type 2 diabetes patients are at an increased risk for depression. However, the molecular mechanism coupling diabetes to depressive disorder remains largely unknown. Here we found that the neuroinflammation, associated with high-fat diet (HFD)-induced diabetes and obesity, activated the transcription factor CCAAT/enhancer binding protein β (C/EBPβ) in hippocampal neurons. This factor repressed brain-derived neurotrophic factor (BDNF) expression and caused depression-like behaviors in male mice. Besides, the loss of C/EBPβ expression in C/EBPβ heterozygous knockout male mice attenuated HFD-induced depression-like behaviors, whereas Thy1-C/EBPβ transgenic male mice (overexpressing C/EBPβ) showed depressive behaviors after a short-term HFD. Furthermore, HFD impaired synaptic plasticity and decreased surface expression of glutamate receptors in the hippocampus of wild-type (WT) mice, but not in C/EBPβ heterozygous knockout mice. Remarkably, the anti-inflammatory drug aspirin strongly alleviated HFD-elicited depression-like behaviors in neuronal C/EBPβ transgenic mice. Finally, the genetic delivery of BDNF or the pharmacological activation of the BDNF/TrkB signaling pathway by 7,8-dihydroxyflavone reversed anhedonia in a series of behavioral tests on HFD-fed C/EBPβ transgenic mice. Therefore, our findings aim to demonstrate that the inflammation-activated neuronal C/EBPβ promotes HFD-induced depression by diminishing BDNF expression.

Pridopidine rescues BDNF/TrkB trafficking dynamics and synapse homeostasis in a Huntington disease brain-on-a-chip model

Huntington disease (HD) is a neurodegenerative disorder caused by polyglutamine-encoding CAG repeat expansion in the huntingtin (HTT) gene. HTT is involved in the axonal transport of vesicles containing brain-derived neurotrophic factor (BDNF). In HD, diminished BDNF transport leads to reduced BDNF delivery to the striatum, contributing to striatal and cortical neuronal death. Pridopidine is a selective and potent sigma-1 receptor (S1R) agonist currently in clinical development for HD. The S1R is located at the endoplasmic reticulum (ER)-mitochondria interface, where it regulates key cellular pathways commonly impaired in neurodegenerative diseases. We used a microfluidic device that reconstitutes the corticostriatal network, allowing the investigation of presynaptic dynamics, synaptic morphology and transmission, and postsynaptic signaling. Culturing primary neurons from the HD mouse model HdhCAG140/+ provides a “disease-on-a-chip” platform ideal for investigating pathogenic mechanisms and drug activity. Pridopidine rescued the trafficking of BDNF and TrkB resulting in an increased neurotrophin signaling at the synapse. This increased the capacity of HD neurons to release glutamate and restored homeostasis at the corticostriatal synapse. These data suggest that pridopidine enhances the availability of corticostriatal BDNF via S1R activation, leading to neuroprotective effects.

Porous Silicon Nanoparticles Targeted to the Extracellular Matrix for Therapeutic Protein Delivery in Traumatic Brain Injury.

Traumatic brain injury (TBI) is a major cause of disability and death among children and young adults in the United States, yet there are currently no treatments that improve the long-term brain health of patients. One promising therapeutic for TBI is brain-derived neurotrophic factor (BDNF), a protein that promotes neurogenesis and neuron survival. However, outstanding challenges to the systemic delivery of BDNF are its instability in blood, poor transport into the brain, and short half-life in circulation and brain tissue. Here, BDNF is encapsulated into an engineered, biodegradable porous silicon nanoparticle (pSiNP) in order to deliver bioactive BDNF to injured brain tissue after TBI. The pSiNP carrier is modified with the targeting ligand CAQK, a peptide that binds to extracellular matrix components upregulated after TBI. The protein cargo retains bioactivity after release from the pSiNP carrier, and systemic administration of the CAQK-modified pSiNPs results in effective delivery of the protein cargo to injured brain regions in a mouse model of TBI. When administered after injury, the CAQK-targeted pSiNP delivery system for BDNF reduces lesion volumes compared to free BDNF, supporting the hypothesis that pSiNPs mediate therapeutic protein delivery after systemic administration to improve outcomes in TBI.

Intranasal Administration of Brain-Derived Neurotrophic Factor Rescues Depressive-Like Phenotypes in Chronic Unpredictable Mild Stress Mice.

IntroductionMajor depression disorder is the most common diagnosed mental illnesses, and it bring a high social and economic burden. However, the current treatment for depression has limitations with side effects. Hence, there is an urgent need to search more effective treatment for major depressive disorder. Brain-derived neurotrophic factor (BDNF) is a neurotrophin that is vital to the survival, growth, and maintenance of neurons.MethodsWe administered BDNF into chronic unpredictable mild stress (CUMS)-induced depression mice and assessed the effects of intranasal delivery of BDNF in depression by the tail suspension test, forced swimming test, novelty suppressed feeding test, and open-field test.ResultsWe find that the intranasal administration of BDNF reversed the depressive-like behaviors in CUMS mice as measured Further analyses suggested that BDNF treatment reduced pro-inflammatory cytokine (IL-6, TNF-α, iNOS and IL-1β) expressions in the hippocampus of CUMS mice. In addition, our results showed that BDNF markedly reduced oxidative stress in the hippocampus and blood of CUMS mice. Moreover, our data suggested that BDNF treatment increased neurogenesis in the hippocampus of CUMS mice.DiscussionTaken together, our results for the first time demonstrated that intranasal delivery of BDNF protein exhibited anti-depressant-like effects in mice, and therefore may represent a new therapeutic strategy for major depressive disorder.

7,8-Dihydroxyflavone accelerates recovery of Brown-Sequard syndrome in adult female rats with spinal cord lateral hemisection

Background7,8-Dihydroxyflavone (DHF) mimicks the physiological action of brain-derived neurotrophic factor (BDNF). Since local BDNF delivery to the injured spinal cord enhanced diaphragmatic respiratory function, we aimed to ascertain whether DHF might have similar beneficial effects after Brown-Sequard Syndrome in a rat model of spinal cord lateral hemisection (HX) at the 9th thoracic (T9) vertebral level. MethodsThree sets of adult female rats were included: sham+vehicle group, T9HX+vehicle group and T9HX+DHF group. On the day of surgery, HX+DHF group received DHF (5 mg/kg) while HX+vehicle group received vehicle. Neurobehavioral function, morphology of motor neurons innervating the tibialis anterior muscle and the transmission in descending motor pathways were evaluated. ResultsAdult female rats received T9 HX had paralysis and loss of proprioception on the same side as the injury and loss of pain and temperature on the opposite side. We found that, in this model of Brown-Sequard syndrome, reduced cord dendritic arbor complexity, reduced cord motoneuron numbers, enlarged cord lesion volumes, reduced motor evoked potentials, and cord astrogliosis and microgliosis were noted after T9HX. All of the above-mentioned disorders showed recovery by Day 28 after surgery. Therapy with DHF significantly accelerated the electrophysiological, histological and functional recovery in these T9HX animals. ConclusionsOur data provide a biological basis for DHF as a neurotherapeutic agent to improve recovery after a Brown-Sequard syndrome. Such an effect may be mediated by synaptic plasticity and glia-mediated inflammation in the spared lumbar motoneuron pools to a T9HX.

Self-Assembled Nanoscale Materials for Neuronal Regeneration: A Focus on BDNF Protein and Nucleic Acid Biotherapeutic Delivery.

Enabling challenging applications of nanomedicine and precision medicine in the treatment of neurodegenerative disorders requires deeper investigations of nanocarrier-mediated biomolecular delivery for neuronal targeting and recovery. The successful use of macromolecular biotherapeutics (recombinant growth factors, antibodies, enzymes, synthetic peptides, cell-penetrating peptide–drug conjugates, and RNAi sequences) in clinical developments for neuronal regeneration should benefit from the recent strategies for enhancement of their bioavailability. We highlight the advances in the development of nanoscale materials for drug delivery in neurodegenerative disorders. The emphasis is placed on nanoformulations for the delivery of brain-derived neurotrophic factor (BDNF) using different types of lipidic nanocarriers (liposomes, liquid crystalline or solid lipid nanoparticles) and polymer-based scaffolds, nanofibers and hydrogels. Self-assembled soft-matter nanoscale materials show favorable neuroprotective characteristics, safety, and efficacy profiles in drug delivery to the central and peripheral nervous systems. The advances summarized here indicate that neuroprotective biomolecule-loaded nanoparticles and injectable hydrogels can improve neuronal survival and reduce tissue injury. Certain recently reported neuronal dysfunctions in long-COVID-19 survivors represent early manifestations of neurodegenerative pathologies. Therefore, BDNF delivery systems may also help in prospective studies on recovery from long-term COVID-19 neurological complications and be considered as promising systems for personalized treatment of neuronal dysfunctions and prevention or retarding of neurodegenerative disorders.

Neural stem cell-derived exosome as a nano-sized carrier for BDNF delivery to a rat model of ischemic stroke

Our previous study demonstrated the potential therapeutic role of human neural stem cell-derived exosomes (hNSC-Exo) in ischemic stroke. Here, we loaded brain-derived neurotrophic factor (BDNF) into exosomes derived from NSCs to construct engineered exosomes (BDNF-hNSC-Exo) and compared their effects with those of hNSC-Exo on ischemic stroke both in vitro and in vivo. In a model of H2O2-induced oxidative stress in NSCs, BDNF-hNSC-Exo markedly enhanced cell survival. In a rat middle cerebral artery occlusion model, BDNF-hNSC-Exo not only inhibited the activation of microglia, but also promoted the differentiation of endogenous NSCs into neurons. These results suggest that BDNF can improve the function of NSC-derived exosomes in the treatment of ischemic stroke. Our research may support the clinical use of other neurotrophic factors for central nervous system diseases.

Localized delivery of brain-derived neurotrophic factor from PLGA microspheres promotes peripheral nerve regeneration in rats

BackgroundRepair of peripheral nerve defect presents a considerable challenge for reconstructive surgeons. The aim of this study is to develop a brain-derived neurotrophic factor (BDNF) from poly(D,L-lactide-co-glycolide) (PLGA) microspheres for the treatment of the peripheral nerve defect.MethodBDNF microspheres were prepared by using an oil-in-water emulsification-solvent evaporation method. The morphology, particle size, encapsulation efficiency, drug loading and sustained release performance of microspheres was observed and calculated. Adipose mesenchymal stem cells (ADSCs) were isolated and expanded. ADSCs were divided into four groups: control, BDNF, blank microsphere and BDNF microsphere groups. Cell count kit-8 (CCK-8) assays were used to assess cell proliferation. Cell migration was determined by Transwell assays. Twenty-eight male Sprague–Dawley rats underwent transection damage model on the right sciatic nerve. The wet weight ratio of the gastrocnemius muscle was calculated by comparing the weight of the gastrocnemius muscle from the operated side to that of the normal side. Neuroelectrophysiological testing was performed to assess nerve function recovery. Nerve regeneration was evaluated by histological analysis and immunohistochemical staining.ResultsThe microspheres were spherical and had uniform size (46.38 ± 1.00 μm), high encapsulation efficiency and high loading capacity. In vitro release studies showed that BDNF-loaded microspheres had good sustained release characteristics. The duration of BDNF release was extended to more than 50 days. BDNF or BDNF microsphere promote the proliferation and migration of ADSCs than control group (P < 0.05). Compared with control group, BDNF significantly decreased the nerve conduction velocity (NCV) and compound amplitude (AMP) (P < 0.05). The nerve fibers in the BDNF microsphere group were closely arranged and uniformly distributed than control group.ConclusionBDNF/PLGA sustained-release microsphere could promote the migration of ADSCs and promoted neural differentiation of ADSCs. Moreover, BDNF/PLGA sustained-release microsphere ameliorated nerve conduction velocity and prevented neuralgic amyotrophy.

Liquid crystalline lipid nanoparticles for combined delivery of curcumin, fish oil and BDNF: In vitro neuroprotective potential in a cellular model of tunicamycin-induced endoplasmic reticulum stress

We develop multidrug-loaded cubosome and spongosome lipid nanoparticles for targeting of endoplasmic reticulum stress as a potential emerging therapeutic strategy against neuronal degeneration. The multicompartment organization of the liquid crystalline nanoparticles (LCNPs), fabricated by self-assembly, was characterized by cryogenic transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS). Monoolein-based cubosome and spongosome LCNPs co-encapsulated the natural plant-derived antioxidant curcumin, fish oil rich in ω-3 polyunsaturated fatty acids (PUFA), and the neurotrophin brain-derived neurotrophic factor (BDNF), which is of vital need for neurogenesis. The neuroprotective properties of the nanoparticles were in vitro investigated in a cellular model of tunicamycin-induced endoplasmic reticulum (ER) stress using differentiated human neuroblastoma SH-SY5Y cells deprieved from serum. The intracellular accumulation of aggregates of misfolded proteins, typical for the ER stress process, was analyzed by fluorescence microscopy co-localization imaging and ER staining. The performed cellular bioassays established that the BDNF-loaded LCNPs enhanced the neuronal cell survival. The diminution of the tunicamycin-induced ER stress upon internalization of neuroprotective nanoparticles was quantified via the changes in the Thioflavin T fluorescence, which is a sensitive marker of protein aggregation. LCNPs with multi-drug loading appear to be promising candidates to face the challenges in neuroprotective nanomedicine development by exploiting ER-stress targeting mechanisms.

Gold nanoparticle-assisted delivery of brain-derived neurotrophic factor to cerebral organoids

Gold nanoparticle-assisted delivery of brain-derived neurotrophic factor to cerebral organoids

Rescue of BDNF expression by the thalamic parafascicular nucleus with chronic treatment with the mGluR2/3 agonist LY379268 may contribute to the LY379268 rescue of enkephalinergic striatal projection neurons in R6/2 Huntington’s disease mice

We have found that daily subcutaneous injection with a maximum tolerated dose of the mGluR2/3 agonist LY379268 (20 mg/kg) beginning at 4 weeks of age dramatically improves the motor, neuronal and neurochemical phenotype in R6/2 mice, a rapidly progressing transgenic model of Huntington’s disease (HD). We also previously showed that the benefit of daily LY379268 in R6/2 mice was associated with increases in corticostriatal brain-derived neurotrophic factor (BDNF), and in particular was associated with a reduction in enkephalinergic striatal projection neuron loss. In the present study, we show that daily LY379268 also rescues expression of BDNF by neurons of the thalamic parafascicular nucleus in R6/2 mice, which projects prominently to the striatum, and this increase too is linked to the rescue of enkephalinergic striatal neurons. Thus, LY379268 may protect enkephalinergic striatal projection neurons from loss by boosting BDNF production and delivery via both the corticostriatal and thalamostriatal projection systems. These results suggest that chronic treatment with mGluR2/3 agonists may represent an approach for slowing enkephalinergic neuron loss in HD, and perhaps progression in general.

Differential effects of rat ADSCs encapsulation in fibrin matrix and combination delivery of BDNF and Gold nanoparticles on peripheral nerve regeneration

BackgroundFibrin as an extracellular matrix feature like biocompatibility, creates a favorable environment for proliferation and migration of cells and it can act as a reservoir for storage and release of growth factors in tissue engineering.MethodsIn this study, the inner surface of electrospun poly (lactic-co-glycolic acid) (PLGA) nanofibrous conduit was biofunctionalized with laminin containing brain derived neurotrophic factor (BDNF) and gold nanoparticles in chitosan nanoparticle. The rats were randomly divided into five groups, including autograft group as the positive control, PLGA conduit coated by laminin and filled with DMEM/F12, PLGA conduit coated by laminin and filled with rat-adipose derived stem cells (r-ADSCs), PLGA conduit coated by laminin containing gold-chitosan nanoparticles (AuNPs-CNPs), BDNF-chitosan nanoparticles (BDNF-CNPs) and filled with r-ADSCs or filled with r-ADSCs suspended in fibrin matrix, and they were implanted into a 10 mm rat sciatic nerve gap. Eventually, axonal regeneration and functional recovery were assessed after 12 weeks.ResultsAfter 3 months post-surgery period, the results showed that in the PLGA conduit filled with r-ADSCs without fibrin matrix group, positive effects were obtained as compared to other implanted groups by increasing the sciatic functional index significantly (p < 0.05). In addition, the diameter nerve fibers had a significant difference mean in the PLGA conduit coated by laminin and conduit filled with r-ADSCs in fibrin matrix groups relative to the autograft group (p < 0.001). However, G-ratio and amplitude (AMP) results showed that fibrin matrix might have beneficial effects on nerve regeneration but, immunohistochemistry and real-time RT-PCR outcomes indicated that the implanted conduit which filled with r-ADSCs, with or without BDNF-CNPs and AuNPs-CNPs had significantly higher expression of S100 and MBP markers than other conduit implanted groups (p < 0.05).ConclusionsIt seems, in this study differential effects of fibrin matrix, could be interfered it with other factors thereby and further studies are required to determine the distinctive effects of fibrin matrix combination with other exogenous factors in peripheral nerve regeneration.

Injectable, macroporous scaffolds for delivery of therapeutic genes to the injured spinal cord.

Biomaterials are being developed as therapeutics for spinal cord injury (SCI) that can stabilize and bridge acute lesions and mediate the delivery of transgenes, providing a localized and sustained reservoir of regenerative factors. For clinical use, direct injection of biomaterial scaffolds is preferred to enable conformation to unique lesions and minimize tissue damage. While an interconnected network of cell-sized macropores is necessary for rapid host cell infiltration into—and thus integration of host tissue with—implanted scaffolds, injectable biomaterials have generally suffered from a lack of control over the macrostructure. As genetic vectors have short lifetimes in vivo, rapid host cell infiltration into scaffolds is a prerequisite for efficient biomaterial-mediated delivery of transgenes. We present scaffolds that can be injected and assembled in situ from hyaluronic acid (HA)-based, spherical microparticles to form scaffolds with a network of macropores (∼10 μm). The results demonstrate that addition of regularly sized macropores to traditional hydrogel scaffolds, which have nanopores (∼10 nm), significantly increases the expression of locally delivered transgene to the spinal cord after a thoracic injury. Maximal cell and axon infiltration into scaffolds was observed in scaffolds with more regularly sized macropores. The delivery of lentiviral vectors encoding the brain-derived neurotrophic factor (BDNF), but not neurotrophin-3, from these scaffolds further increased total numbers and myelination of infiltrating axons. Modest improvements to the hindlimb function were observed with BDNF delivery. The results demonstrate the utility of macroporous and injectable HA scaffolds as a platform for localized gene therapies after SCI.