Spinal Cord Repair Research Articles

PLGA porous scaffolds by polydopamine-assisted immobilization of NGF for spinal cord injury repair

The degradable polymer biomaterials have great potential in the field of nerve regeneration, which have gradually been applied to spinal cord injury repair. In this study, a polylactic acid-glycolic acid copolymer (PLGA) porous scaffold was prepared by the process of phase inversion, then the surface of the scaffold was modified by polydopamine (PDA) as a substrate, followed by adsorption of nerve growth factor (NGF) to obtain a PDA-PLGA/NGF scaffold. The characterization and hydrophilicity of the scaffolds were evaluated by electron microscopy, EDX and contact angle measurement. The effect of PDA modification on the binding efficiency and release profile of NGF was observed by ELISA. The proliferation and differentiation of NSCs on the surface of biomaterials was evaluated by MTT, immunofluorescence staining and PCR. Subsequently, the rat T9 spinal cord transection model was established and the nerve scaffolds were implanted to injured site. Our results showed PDA modification could significantly improve the NGF adsorption capacity and provide sustained release of NGF. PDA-PLGA/NGF scaffolds could not only enhance NSCs proliferation and neuronal differentiation in vitro, but also promote recovery of spinal cord injury in vivo. Therefore, we believed that PDA-PLGA/NGF scaffolds could be a promising method to facilitate neurogenesis and repair spinal cord injury.

Inhibition of astrocytic differentiation of transplanted neural stem cells by chondroitin sulfate methacrylate hydrogels for the repair of injured spinal cord.

Neural stem cell (NSC) transplantation exerts a therapeutic effect on spinal cord injury (SCI) but is limited to an unregulated differentiation pattern by which NSCs preferentially differentiate into astrocytes, with relatively few neurons. It is well established that the increased NSC-derived astrocytes exhibit aberrant axonal sprouting associated with allodynia-like symptoms of the forepaws. Some strategies have been used to overcome this issue, such as regulation of major pathways, ex vivo gene transfer, and genetic overexpression. However, lack of efficiency, viral vector safety issues and the risk of tumorigenesis have hindered the clinical application of these treatments. Here, we show that astrocytic differentiation of NSCs in vitro and in vivo can be inhibited by encapsulation of cells in a three-dimensional chondroitin sulfate methacrylate (CSMA) hydrogel. When CSMA hydrogels were used to transplant NSCs, the combinatory implant promoted functional recovery and attenuated the hypersensitivity responses of the forepaws. Further analysis showed that transplantation of NSCs within CSMA hydrogels reduced injured cavity areas and promoted neurogenesis rather than fibroglial formation after graft implantation. Furthermore, the treatment prevented allodynia-related CGRP/GAP43-positive nociception due to fibers sprouting into inappropriate lamina regions. Taken together, these findings show that CSMA/NSCs combined transplantation helps prevent adverse side effects of NSCs treatment and promotes recovery of SCI.

ODNA: a manually curated database of noncoding RNAs associated with orthopedics.

Orthopedics is an important branch of medicine concerned with disorders of the bones, joints, spinal cord, peripheral nerves, muscles, connective tissue and cartilage (1). Orthopedic disorders, such as back pain and arthritis, have high incidence rates and affect the quality of life of most people at some point during their lifetime (2,3). In addition, many disorders of other body systems, including the vascular, nervous, immune and metabolic systems, may also affect the musculoskeletal system and complicate the diagnosis and treatment of orthopedic diseases (4–6). The causes of diseases involving the musculoskeletal system have not been well elucidated. Currently, multiple mechanisms, including proteomic, transcriptomic, genomic, epigenetic regulatory and environmental mechanisms, have been shown to be involved in the development of orthopedic disorders (7,8). Over the past decade, studies have revealed new classes of RNA molecules, including microRNAs (miRNAs), small nucleolar RNAs (snoRNAs), long noncoding RNAs (lncRNAs), PIWI-interacting RNAs (piRNAs) and circular RNAs (circRNAs). These noncoding RNAs (ncRNAs) not only regulate a variety of cell functions in the development of and physical processes involving skeletal muscle but also contribute to a number of orthopedic-related disorders (9–11). For example, miRNAs are believed to regulate the differentiation of osteoblasts and osteoclasts through upregulation or downregulation or sponging (12). LncRNAs have been identified as critical molecules that regulate bone and cartilage degeneration, promote bone metastases and repair spinal cord injuries. It has also been reported that the abnormal expression of lncRNAs leads to the malformation of bones and homeotic transformation (13). Differentially expressed circRNAs may play important roles in the differentiation and proliferation of stem cells. The abnormal expression of circRNAs is also involved in arthritis, osteoporosis and hereditary bone diseases (14–16). In recent years, studies on the associations between ncRNAs and orthopedic disorders have rapidly accumulated. However, the data about these associations have remained scattered. To facilitate investigations into the associations between orthopedic disorders and ncRNAs, we constructed a public database, the Orthopedic Diseases ncRNAome Atlas (ODNA), which contains manually curated data on orthopedic disease-associated, experimentally validated ncRNAs.

Attenuating Spinal Cord Injury by Conditioned Medium from Bone Marrow Mesenchymal Stem Cells.

Spinal cord injury (SCI) is a devastating neurological condition and might even result in death. However, current treatments are not sufficient to repair such damage. Bone marrow mesenchymal stem cells (BM-MSC) are ideal transplantable cells which have been shown to modulate the injury cascade of SCI mostly through paracrine effects. The present study investigates whether systemic administration of conditioned medium from MSCs (MSCcm) has the potential to be efficacious as an alternative to cell-based therapy for SCI. In neuron-glial cultures, MSC coculture effectively promoted neuronal connection and reduced oxygen glucose deprivation-induced cell damage. The protection was elicited even if neuron-glial culture was used to expose MSCcm, suggesting the effects possibly from released fractions of MSC. In vivo, intravenous administration of MSCcm to SCI rats significantly improved behavioral recovery from spinal cord injury, and there were increased densities of axons in the lesion site of MSCcm-treated rats compared to SCI rats. At early days postinjury, MSCcm treatment upregulated the protein levels of Olig 2 and HSP70 and also increased autophage-related proteins in the injured spinal cords. Together, these findings suggest that MSCcm treatment promotes spinal cord repair and functional recovery, possibly via activation of autophagy and enhancement of survival-related proteins.

Currarino syndrome: repair of the dysraphic anomalies and resection of the presacral mass in a combined neurosurgical and general surgical approach.

OBJECTIVEIt is well established that Currarino syndrome (CS) may be associated with spinal dysraphism. Here, the authors report on 10 CS patients with dysraphic anomalies who had undergone a combined neurosurgical and general surgical approach to repair the dysraphic anomalies and resect the presacral mass in a single operation. They discuss the spectrum of spinal dysraphism that may coexist in CS in the context of its developmental etiology.METHODSChildren with a confirmed CS diagnosis who had undergone the combined operative approach were identified from a departmental database. Presenting features were recorded and preoperative imaging was analyzed to record features of the presacral mass and the dysraphic anomalies. The histopathological nature of the resected presacral mass and the outcomes postoperatively and at the last follow-up were reviewed.RESULTSBetween 2008 and 2015, 10 patients presented with CS, 9 with constipation. Median age at the time of surgery was 1.3 years. Six of the 10 patients had anorectal malformation consisting of anal stenosis, rectal stenosis, or imperforate anus. Spinal anomalies included anterior meningocele (5 cases), low-lying conus (8), terminal syrinx (4), fatty filum (5), caudal lipoma (3), and intraspinal cyst (1). In all cases, the lumbosacral spinal canal was accessed via a midline approach with laminoplasty, allowing spinal cord untethering and repair of the dysraphic anomalies. Following dural closure, the incision was extended inferiorly to incorporate a posterior sagittal approach to resect the presacral mass. The histopathological nature of the mass was mature teratoma (8 cases), complex hamartomatous malformation (1), or neurenteric cyst (1). There were no new instances of neurological deterioration, with most instances of persisting morbidity related to constipation (6 cases) or neurogenic bladder dysfunction (8). There were no infective complications, no instances of cerebrospinal fluid fistula, no recurrences of the presacral mass, and no cases of retethering of the spinal cord.CONCLUSIONSAlthough not part of the original triad, spinal dysraphic anomalies are common in CS and in keeping with a disorder of secondary neurulation. Lumbosacral MRI is an essential investigation when CS is suspected. Children are at risk of sphincter impairment due to the anorectal malformation; however, both spinal cord tethering and compression from the presacral mass may further compromise long-term continence. A combined operative approach to repair the dysraphic anomalies and resect the presacral mass is described with good postoperative and long-term outcomes.

Hair-Follicle-Associated Pluripotent (HAP) Stem Cells Encapsulated on Polyvinylidene Fluoride Membranes (PFM) Promote Functional Recovery from Spinal Cord Injury.

Our previous studies showed that nestin-expressing hair follicle-associated-pluripotent (HAP) stem cells, which reside in the bulge area of the hair follicle, could restore injured nerve and spinal cord and differentiate into cardiac muscle cells. Here we transplanted mouse green fluorescent protein (GFP)-expressing HAP stem-cell colonies enclosed on polyvinylidene fluoride membranes (PFM) into the severed thoracic spinal cord of nude mice. After seven weeks of implantation, we found the differentiation of HAP stem cells into neurons and glial cells. Our results also showed that PFM-captured GFP-expressing HAP stem-cell colonies assisted complete reattachment of the thoracic spinal cord. Furthermore, our quantitative motor function analysis with the Basso Mouse Scale for Locomotion (BMS) score demonstrated a significant improvement in the implanted mice compared to non-implanted mice with a severed spinal cord. Our study also showed that it is easy to obtain HAP stem cells, they do not develop teratomas, and do not loose differentiation ability when cryopreserved. Collectively our results suggest that HAP stem cells could be abetter source compared to induced pluripotent stem cells (iPS) or embryonic stem (ES) cells for regenerative medicine, specifically for spinal cord repair.

Matrigel uses in cell biology and for the identification of thymosin β4, a mediator of tissue regeneration

The thin extracellular matrix that is found basally in epithelial and endothelial cells and around smooth muscle, peripheral nerves, and fat cells is known as the basement membrane. A murine tumor matrix extract, termed Matrigel, has provided an abundant source of basement membrane proteins (laminin, collagen IV, heparan sulfate, etc.). Matrigel gels at room temperature into a structure similar to the authentic matrix. Embryonic tissue explants, stem cells, and various cell types differentiate when cultured on Matrigel. Matrigel has been used in various in vitro assays for angiogenesis, cell invasion, spheroid formation, organoid formation from a single cell, etc. In vivo Matrigel improves/promotes tumor xenograft growth and is used to measure angiogenesis, improve heart and spinal cord repair, increase tissue transplant take, etc. Endothelial cells plated on top of Matrigel form capillary-like tubules. The gene for thymosin beta 4 was induced at 4 h after plating endothelial cells on Matrigel, and when the thymosin beta 4 protein was added exogenously to the culture, tubule formation was accelerated. Thymosin beta 4, a small 43 kDa protein present in all body fluids and cells, has multiple biological activities, including reducing inflammation, apoptosis, and cytotoxicity while increasing cell migration, stem cell recruitment and differentiation, and tissue repair. Thymosin beta 4 was subsequently found to promote angiogenesis in vivo and to improve dermal and ocular healing in experimental injury models. It has regenerative activity in animal models of traumatic brain injury, stroke, multiple sclerosis, heart attack, peripheral neuropathy, liver and kidney fibrosis, and hair growth. Clinical trials have demonstrated its efficacy for both stasis and pressure ulcers and for both dry eye and a rare ocular disease. This mini review will discuss the development of Matrigel and the discovery of thymosin beta 4 as a regenerative protein that is upregulated when endothelial cells are plated on Matrigel.

Transplanted enteric neural stem cells integrate within the developing chick spinal cord: implications for spinal cord repair.

Spinal cord injury (SCI) causes paralysis, multisystem impairment and reduced life expectancy, as yet with no cure. Stem cell therapy can potentially replace lost neurons, promote axonal regeneration and limit scar formation, but an optimal stem cell source has yet to be found. Enteric neural stem cells (ENSC) isolated from the enteric nervous system (ENS) of the gastrointestinal (GI) tract are an attractive source. Here, we used the chick embryo to assess the potential of ENSC to integrate within the developing spinal cord. In vitro, isolated ENSC formed extensive cell connections when co-cultured with spinal cord (SC)-derived cells. Further, qRT-PCR analysis revealed the presence of TuJ1+ neurons, S100+ glia and Sox10+ stem cells within ENSC neurospheres, as well as expression of key neuronal subtype genes, at levels comparable to SC tissue. Following ENSC transplantation to an ablated region of chick embryo SC, donor neurons were found up to 12days later. These neurons formed bridging connections within the SC injury zone, aligned along the anterior/posterior axis, and were immunopositive for TuJ1. These data provide early proof of principle support for the use of ENSCs for SCI, and encourage further research into their potential for repair.

Mechanical Mapping of Spinal Cord Growth and Repair in Living Zebrafish Larvae by Brillouin Imaging

The mechanical properties of biological tissues are increasingly recognized as important factors in developmental and pathological processes. Most existing mechanical measurement techniques either necessitate destruction of the tissue for access or provide insufficient spatial resolution. Here, we show for the first time to our knowledge a systematic application of confocal Brillouin microscopy to quantitatively map the mechanical properties of spinal cord tissues during biologically relevant processes in a contact-free and nondestructive manner. Living zebrafish larvae were mechanically imaged in all anatomical planes during development and after spinal cord injury. These experiments revealed that Brillouin microscopy is capable of detecting the mechanical properties of distinct anatomical structures without interfering with the animal’s natural development. The Brillouin shift within the spinal cord remained comparable during development and transiently decreased during the repair processes after spinal cord transection. By taking into account the refractive index distribution, we explicitly determined the apparent longitudinal modulus and viscosity of different larval zebrafish tissues. Importantly, mechanical properties differed between tissues in situ and in excised slices. The presented work constitutes the first step toward an in vivo assessment of spinal cord tissue mechanics during regeneration, provides a methodical basis to identify key determinants of mechanical tissue properties, and allows us to test their relative importance in combination with biochemical and genetic factors during developmental and regenerative processes.

Regulation of Inflammatory Cytokines for Spinal Cord Injury Repair Through Local Delivery of Therapeutic Agents.

The balance of inflammation is critical to the repair of spinal cord injury (SCI), which is one of the most devastating traumas in human beings. Inflammatory cytokines, the direct mediators of local inflammation, have differential influences on the repair of the injured spinal cord. Some inflammatory cytokines are demonstrated beneficial to spinal cord repair in SCI models, while some detrimental. Various animal researches have revealed that local delivery of therapeutic agents efficiently regulates inflammatory cytokines and promotes repair from SCI. Quite a few clinical studies have also shown the promotion of repair from SCI through regulation of inflammatory cytokines. However, local delivery of a single agent affects only a part of the inflammatory cytokines that need to be regulated. Meanwhile, different individuals have differential profiles of inflammatory cytokines. Therefore, future studies may aim to develop personalized strategies of locally delivered therapeutic agent cocktails for effective and precise regulation of inflammation, and substantial functional recovery from SCI.

A Modular Assembly of Spinal Cord-Like Tissue Allows Targeted Tissue Repair in the Transected Spinal Cord.

Tissue engineering–based neural construction holds promise in providing organoids with defined differentiation and therapeutic potentials. Here, a bioengineered transplantable spinal cord–like tissue (SCLT) is assembled in vitro by simulating the white matter and gray matter composition of the spinal cord using neural stem cell–based tissue engineering technique. Whether the organoid would execute targeted repair in injured spinal cord is evaluated. The integrated SCLT, assembled by white matter–like tissue (WMLT) module and gray matter–like tissue (GMLT) module, shares architectural, phenotypic, and functional similarities to the adult rat spinal cord. Organotypic coculturing with the dorsal root ganglion or muscle cells shows that the SCLT embraces spinal cord organogenesis potentials to establish connections with the targets, respectively. Transplantation of the SCLT into the transected spinal cord results in a significant motor function recovery of the paralyzed hind limbs in rats. Additionally, targeted spinal cord tissue repair is achieved by the modular design of SCLT, as evidenced by an increased remyelination in the WMLT area and an enlarged innervation in the GMLT area. More importantly, the pro‐regeneration milieu facilitates the formation of a neuronal relay by the donor neurons, allowing the conduction of descending and ascending neural inputs.

Geoffrey Raisman. 28 June 1939—27 January 2017

Geoffrey Raisman was a neuroscientist whose particular love was the microanatomy and ultrastructure of the nervous system. From his anatomical studies came discoveries in synaptic plasticity, neuroendocrinology, axon regeneration, spinal cord repair and glaucoma. His studies of the anatomy of synapses after denervation led to his concept of plasticity, where synapses compete for targets and can replace those that are lost. This discovery persuaded him, against the dominant view of the time, that some repair of the damaged nervous system should be possible. His studies of the events following damage to the nervous system led to the pathway hypothesis; axon regeneration is blocked by scar tissue formed of glial cells around injuries. Finding that the newly born olfactory neurons that are created throughout life grow axons into the brain with the assistance of specialized olfactory glia, he realized that these glial cells might also assist regenerating axons to bridge the scar tissue blocking axon regeneration. Preliminary trials of this treatment in human spinal cord injuries have shown some clinical promise. He recently developed a new energy theory of glaucoma.

Aligned fibrous PVDF-TrFE scaffolds with Schwann cells support neurite extension and myelination in vitro

Objective. Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), which is a piezoelectric, biocompatible polymer, holds promise as a scaffold in combination with Schwann cells (SCs) for spinal cord repair. Piezoelectric materials can generate electrical activity in response to mechanical deformation, which could potentially stimulate spinal cord axon regeneration. Our goal in this study was to investigate PVDF-TrFE scaffolds consisting of aligned fibers in supporting SC growth and SC-supported neurite extension and myelination in vitro. Approach. Aligned fibers of PVDF-TrFE were fabricated using the electrospinning technique. SCs and dorsal root ganglion (DRG) explants were co-cultured to evaluate SC-supported neurite extension and myelination on PVDF-TrFE scaffolds. Main results. PVDF-TrFE scaffolds supported SC growth and neurite extension, which was further enhanced by coating the scaffolds with Matrigel. SCs were oriented and neurites extended along the length of the aligned fibers. SCs in co-culture with DRGs on PVDF-TrFE scaffolds promoted longer neurite extension as compared to scaffolds without SCs. In addition to promoting neurite extension, SCs also formed myelin around DRG neurites on PVDF-TrFE scaffolds. Significance. This study demonstrated PVDF-TrFE scaffolds containing aligned fibers supported SC-neurite extension and myelination. The combination of SCs and PVDF-TrFE scaffolds may be a promising tissue engineering strategy for spinal cord repair.

Fabrication of tannic acid/poly(N-vinylpyrrolidone) layer-by-layer coating on Mg-based metallic glass for nerve tissue regeneration application.

For improving recovery rates and functional outcomes in large nerve defects, a nerve guide conduit, in addition to topographic, physical and chemical cues should provide contact guidance and adequate mechanical support for cell migration and axon outgrowth. Among biomaterials, magnesium (Mg) metal has potential to support nerve regeneration owing to its electrical conductivity, biodegradation and ability to be formed into wires, filaments and ribbons. However, rapid degradation of magnesium can pose a challenge. Mg-based metallic glasses with desirable features including favorable biocompatibility, proper biodegradation and good mechanical properties are a good alternative to crystalline Mg alloys. This study investigates the biocorrosion and biocompatibility of Mg-Zn-Ca metallic glass ribbon with Mg70Zn26Ca4 composition. For controlling biocorrosion, layer-by-layer coating of tannic acid/ poly(N-vinylpyrrolidone) was applied on Mg70Zn26Ca4 ribbon and characterized by SEM and FTIR. Immersion and potentiodynamic polarization test results indicated that coating significantly improved the corrosion resistance of Mg70Zn26Ca4. Schwann cells were selected for the cytocompatibility evaluation of samples due to their key role in peripheral nerve regeneration and ability to repair spinal cord injuries. The MTT assay and cell morphology results showed good biocompatibility for Mg70Zn26Ca4 metallic glass as a promising candidate for nerve regeneration and implantable nervous prosthetic devices.

A 15-channel 30-V Neural Stimulator for Spinal Cord Repair.

This paper presents a 15-channel, 30-V, implantable current stimulator for restoring locomotion control after spinal cord injuries. The stimulator features performance specifications comparable to those of large desktop instrumentation: high linearity, high precision of the delivered currents, small channel-to-channel mismatches and a fast settling time of 0.3 μs. An ADC-based active charge balancing scheme using a digital PI (proportional-integral) controller was implemented in firmware.

Mesenchymal Stem Cell-Macrophage Choreography Supporting Spinal Cord Repair.

Spinal cord injury results in destructive events that lead to tissue loss and functional impairments. A hallmark of spinal cord injury is the robust and persistent presence of inflammatory macrophages. Mesenchymal stem cells (MSCs) are known to benefit repair of the damaged spinal cord often associated with improved functional recovery. Transplanted MSCs immediately encounter the abundance of inflammatory macrophages in the injury site. It is known that MSCs interact closely and reciprocally with macrophages during tissue healing. Here, we will review the roles of (transplanted) MSCs and macrophages in spinal cord injury and repair. Molecular interactions between MSCs and macrophages and the deficiencies in our knowledge about the underlying mechanisms will be reviewed. We will discuss possible ways to benefit from the MSC-macrophage choreography for developing repair strategies for the spinal cord.

Biomaterials for revascularization and immunomodulation after spinal cord injury

Spinal cord injury (SCI) causes immediate damage to the nervous tissue accompanied by loss of motor and sensory function. The limited self-repair competence of injured nervous tissue underscores the need for reparative interventions to recover function after SCI. The vasculature of the spinal cord plays a crucial role in SCI and repair. Ruptured and sheared blood vessels in the injury epicenter and blood vessels with a breached blood-spinal cord barrier (BSCB) in the surrounding tissue cause bleeding and inflammation, which contribute to the overall tissue damage. The insufficient formation of new functional vasculature in and near the injury impedes endogenous tissue repair and limits the prospect of repair approaches. Limiting the loss of blood vessels, stabilizing the BSCB, and promoting the formation of new blood vessels are therapeutic targets for spinal cord repair. Inflammation is an integral part of injury-mediated vascular damage, which has deleterious and reparative consequences. Inflammation and the formation of new blood vessels are intricately interwoven. Biomaterials can be effectively used for promoting and guiding blood vessel formation or modulating the inflammatory response after SCI, thereby governing the extent of damage and the success of reparative interventions. This review deals with the vasculature after SCI, the reciprocal interactions between inflammation and blood vessel formation, and the potential of biomaterials to support revascularization and immunomodulation in damaged spinal cord nervous tissue.

The Paper that Restarted Modern Central Nervous System Axon Regeneration Research

Spinal cord repair research appeared to have run out of new ideas in the 1970s. In a 1981 paper, the Aguayo Laboratory revisited an experiment by Tello and Cajal that suggested that central nervous system (CNS) axons could regenerate into peripheral nerve grafts. Using modern axon tracing methods, David and Aguayo showed that axons from neurons in the spinal cord could regenerate for long distances within peripheral nervous system (PNS) grafts, but not back into the CNS. This proved that damaged CNS tissue is inhibitory to axon regeneration while PNS tissue is permissive. The experiment sparked a research revival, leading to the identification of many inhibitory molecules that block axon growth in the mature CNS.

Grafts of Olfactory Stem Cells Restore Breathing and Motor Functions after Rat Spinal Cord Injury.

The transplantation of olfactory ecto-mesenchymal stem cells (OEMSCs) could be a helpful therapeutic strategy for spinal cord repair. Using an acute rat model of high cervical contusion that provokes a persistent hemidiaphragmatic and foreleg paralysis, we evaluated the therapeutic effect of a delayed syngeneic transplantation (two days post-contusion) of OEMSCs within the injured spinal cord. Respiratory function was assessed using diaphragmatic electromyography and neuroelectrophysiological recordings of phrenic nerves (innervating the diaphragm). Locomotor function was evaluated using the ladder-walking locomotor test. Cellular reorganization in the injured area was also studied using immunohistochemical and microscopic techniques. We report a substantial improvement in breathing movements, in activities of the ipsilateral phrenic nerve and ipsilateral diaphragm, and also in locomotor abilities four months post-transplantation with nasal OEMSCs. Moreover, in the grafted spinal cord, axonal disorganization and inflammation were reduced. Some grafted stem cells adopted a neuronal phenotype, and axonal sparing was observed in the injury site. The therapeutic effect on the supraspinal command is presumably because of both neuronal replacements and beneficial paracrine effects on the injury area. Our study provides evidence that nasal OEMSCs could be a first step in clinical application, particularly in patients with reduced breathing/locomotor movements.

Effects of Transplanted Heparin-Poloxamer Hydrogel Combining Dental Pulp Stem Cells and bFGF on Spinal Cord Injury Repair.

Spinal cord injury (SCI) is one of serious traumatic diseases of the central nervous system and has no effective treatment because of its complicated pathophysiology. Tissue engineering strategy which contains scaffolds, cells, and growth factors can provide a promising treatment for SCI. Hydrogel that has 3D network structure and biomimetic microenvironment can support cellular growth and embed biological macromolecules for sustaining release. Dental pulp stem cells (DPSCs), derived from cranial neural crest, possess mesenchymal stem cell (MSC) characteristics and have an ability to provide neuroprotective and neurotrophic properties for SCI treatment. Basic fibroblast growth factor (bFGF) is able to promote cell survival and proliferation and also has beneficial effect on neural regeneration and functional recovery after SCI. Herein, a thermosensitive heparin-poloxamer (HP) hydrogel containing DPSCs and bFGF was prepared, and the effects of HP-bFGF-DPSCs on neuron restoration after SCI were evaluated by functional recovery tests, western blotting, magnetic resonance imaging (MRI), histology evaluation, and immunohistochemistry. The results suggested that transplanted HP hydrogel containing DPSCs and bFGF had a significant impact on spinal cord repair and regeneration and may provide a promising strategy for neuron repair, functional recovery, and tissue regeneration after SCI.