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Butler MB, Vellaiyappan SK, Bhatti F, Syed FEM, Rafati Fard A, Teh JQ, Grodzinski B, Akhbari M, Adeeko S, Dilworth R, Bhatti A, Waheed U, Robinson S, Osunronbi T, Walker B, Ottewell L, Suresh G, Kuhn I, Davies BM, Kotter MRN, Mowforth OD. The impact of phosphodiesterase inhibition on neurobehavioral outcomes in preclinical models of traumatic and non-traumatic spinal cord injury: a systematic review. Front Med (Lausanne) 2023; 10:1237219. [PMID: 37675134 PMCID: PMC10479944 DOI: 10.3389/fmed.2023.1237219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 07/31/2023] [Indexed: 09/08/2023] Open
Abstract
Study design Systematic review. Objective The objective of this study was to evaluate the impact of phosphodiesterase (PDE) inhibitors on neurobehavioral outcomes in preclinical models of traumatic and non-traumatic spinal cord injury (SCI). Methods A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and was registered with PROSPERO (CRD42019150639). Searches were performed in MEDLINE and Embase. Studies were included if they evaluated the impact of PDE inhibitors on neurobehavioral outcomes in preclinical models of traumatic or non-traumatic SCI. Data were extracted from relevant studies, including sample characteristics, injury model, and neurobehavioral assessment and outcomes. Risk of bias was assessed using the SYRCLE checklist. Results The search yielded a total of 1,679 studies, of which 22 met inclusion criteria. Sample sizes ranged from 11 to 144 animals. PDE inhibitors used include rolipram (n = 16), cilostazol (n = 4), roflumilast (n = 1), and PDE4-I (n = 1). The injury models used were traumatic SCI (n = 18), spinal cord ischemia (n = 3), and degenerative cervical myelopathy (n = 1). The most commonly assessed outcome measures were Basso, Beattie, Bresnahan (BBB) locomotor score (n = 13), and grid walking (n = 7). Of the 22 papers that met the final inclusion criteria, 12 showed a significant improvement in neurobehavioral outcomes following the use of PDE inhibitors, four papers had mixed findings and six found PDE inhibitors to be ineffective in improving neurobehavioral recovery following an SCI. Notably, these findings were broadly consistent across different PDE inhibitors and spinal cord injury models. Conclusion In preclinical models of traumatic and non-traumatic SCI, the administration of PDE inhibitors appeared to be associated with statistically significant improvements in neurobehavioral outcomes in a majority of included studies. However, the evidence was inconsistent with a high risk of bias. This review provides a foundation to aid the interpretation of subsequent clinical trials of PDE inhibitors in spinal cord injury. Systematic review registration https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=150639, identifier: CRD42019150639.
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Affiliation(s)
- Max B. Butler
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Sundar K. Vellaiyappan
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Faheem Bhatti
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Fazal-E-Momin Syed
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Amir Rafati Fard
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Jye Quan Teh
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Ben Grodzinski
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Melika Akhbari
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Sylva Adeeko
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Rory Dilworth
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Aniqah Bhatti
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Unaiza Waheed
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Sophie Robinson
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Temidayo Osunronbi
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Benn Walker
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Luke Ottewell
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Gayathri Suresh
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Isla Kuhn
- Medical Library, University of Cambridge, Cambridge, United Kingdom
| | - Benjamin M. Davies
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Mark R. N. Kotter
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Oliver D. Mowforth
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
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Zhou G, Wang Z, Han S, Chen X, Li Z, Hu X, Li Y, Gao J. Multifaceted Roles of cAMP Signaling in the Repair Process of Spinal Cord Injury and Related Combination Treatments. Front Mol Neurosci 2022; 15:808510. [PMID: 35283731 PMCID: PMC8904388 DOI: 10.3389/fnmol.2022.808510] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 01/26/2022] [Indexed: 01/03/2023] Open
Abstract
Spinal cord injury (SCI) results in multiple pathophysiological processes, including blood–spinal cord barrier disruption, hemorrhage/ischemia, oxidative stress, neuroinflammation, scar formation, and demyelination. These responses eventually lead to severe tissue destruction and an inhibitory environment for neural regeneration.cAMP signaling is vital for neurite outgrowth and axonal guidance. Stimulating intracellular cAMP activity significantly promotes neuronal survival and axonal regrowth after SCI.However, neuronal cAMP levels in adult CNS are relatively low and will further decrease after injury. Targeting cAMP signaling has become a promising strategy for neural regeneration over the past two decades. Furthermore, studies have revealed that cAMP signaling is involved in the regulation of glial cell function in the microenvironment of SCI, including macrophages/microglia, reactive astrocytes, and oligodendrocytes. cAMP-elevating agents in the post-injury milieu increase the cAMP levels in both neurons and glial cells and facilitate injury repair through the interplay between neurons and glial cells and ultimately contribute to better morphological and functional outcomes. In recent years, combination treatments associated with cAMP signaling have been shown to exert synergistic effects on the recovery of SCI. Agents carried by nanoparticles exhibit increased water solubility and capacity to cross the blood–spinal cord barrier. Implanted bioscaffolds and injected hydrogels are potential carriers to release agents locally to avoid systemic side effects. Cell transplantation may provide permissive matrices to synergize with the cAMP-enhanced growth capacity of neurons. cAMP can also induce the oriented differentiation of transplanted neural stem/progenitor cells into neurons and increase the survival rate of cell grafts. Emerging progress focused on cAMP compartmentation provides researchers with new perspectives to understand the complexity of downstream signaling, which may facilitate the clinical translation of strategies targeting cAMP signaling for SCI repair.
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Affiliation(s)
- Gang Zhou
- Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Zhiyan Wang
- Plastic Surgery Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Shiyuan Han
- Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xiaokun Chen
- Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Zhimin Li
- Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xianghui Hu
- Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yongning Li
- Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Department of International Medical Service, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Jun Gao
- Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- *Correspondence: Jun Gao
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Stem Cell Secretome for Spinal Cord Repair: Is It More than Just a Random Baseline Set of Factors? Cells 2021; 10:cells10113214. [PMID: 34831436 PMCID: PMC8625005 DOI: 10.3390/cells10113214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 11/02/2021] [Accepted: 11/16/2021] [Indexed: 11/29/2022] Open
Abstract
Hundreds of thousands of people suffer spinal cord injuries each year. The experimental application of stem cells following spinal cord injury has opened a new era to promote neuroprotection and neuroregeneration of damaged tissue. Currently, there is great interest in the intravenous administration of the secretome produced by mesenchymal stem cells in acute or subacute spinal cord injuries. However, it is important to highlight that undifferentiated neural stem cells and induced pluripotent stem cells are able to adapt to the damaged environment and produce the so-called lesion-induced secretome. This review article focuses on current research related to the secretome and the lesion-induced secretome and their roles in modulating spinal cord injury symptoms and functional recovery, emphasizing different compositions of the lesion-induced secretome in various models of spinal cord injury.
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Lee YS, Funk LH, Lee JK, Bunge MB. Macrophage depletion and Schwann cell transplantation reduce cyst size after rat contusive spinal cord injury. Neural Regen Res 2018; 13:684-691. [PMID: 29722321 PMCID: PMC5950679 DOI: 10.4103/1673-5374.230295] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2018] [Indexed: 01/07/2023] Open
Abstract
Schwann cell transplantation is a promising therapy for the treatment of spinal cord injury (SCI) and is currently in clinical trials. In our continuing efforts to improve Schwann cell transplantation strategies, we sought to determine the combined effects of Schwann cell transplantation with macrophage depletion. Since macrophages are major inflammatory contributors to the acute spinal cord injury, and are the major phagocytic cells, we hypothesized that transplanting Schwann cells after macrophage depletion will improve cell survival and integration with host tissue after SCI. To test this hypothesis, rat models of contusive SCI at thoracic level 8 were randomly subjected to macrophage depletion or not. In rat subjected to macrophage depletion, liposomes filled with clodronate were intraperitoneally injected at 1, 3, 6, 11, and 18 days post injury. Rats not subjected to macrophage depletion were intraperitoneally injected with liposomes filled with phosphate buffered saline. Schwann cells were transplanted 1 week post injury in all rats. Biotinylated dextran amine (BDA) was injected at thoracic level 5 to evalute axon regeneration. The Basso, Beattie, and Bresnahan locomotor test, Gridwalk test, and sensory test using von Frey filaments were performed to assess functional recovery. Immunohistochemistry was used to detect glial fibrillary acidic protein, neurofilament, and green fluorescent protein (GFP), and also to visulize BDA-labelled axons. The GFP labeled Schwann cell and cyst and lesion volumes were quantified using stained slides. The numbers of BDA-positive axons were also quantified. At 8 weeks after Schwann cell transplantation, there was a significant reduction in cyst and lesion volumes in the combined treatment group compared to Schwann cell transplantation alone. These changes were not associated, however, with improved Schwann cell survival, axon growth, or locomotor recovery. Although combining Schwann cell transplantation with macrophage depletion does improve histopathology of the injury site, the effect on axon growth and behavioral recovery appears no better than what can be achieved with Schwann cell transplants alone.
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Affiliation(s)
- Yee-Shuan Lee
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Lucy H. Funk
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jae K. Lee
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Mary Bartlett Bunge
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL, USA
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May Z, Kumar R, Fuehrmann T, Tam R, Vulic K, Forero J, Lucas Osma A, Fenrich K, Assinck P, Lee MJ, Moulson A, Shoichet MS, Tetzlaff W, Biernaskie J, Fouad K. Adult skin-derived precursor Schwann cell grafts form growths in the injured spinal cord of Fischer rats. ACTA ACUST UNITED AC 2018; 13:034101. [PMID: 29068322 DOI: 10.1088/1748-605x/aa95f8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In this study, GFP+ skin-derived precursor Schwann cells (SKP-SCs) from adult rats were grafted into the injured spinal cord of immunosuppressed rats. Our goal was to improve grafted cell survival in the injured spinal cord, which is typically low. Cells were grafted in hyaluronan-methylcellulose hydrogel (HAMC) or hyaluronan-methylcellulose modified with laminin- and fibronectin-derived peptide sequences (eHAMC). The criteria for selection of hyaluronan was for its shear-thinning properties, making the hydrogel easy to inject, methylcellulose for its inverse thermal gelation, helping to keep grafted cells in situ, and fibronectin and laminin to improve cell attachment and, thus, prevent cell death due to dissociation from substrate molecules (i.e., anoikis). Post-mortem examination revealed large masses of GFP+ SKP-SCs in the spinal cords of rats that received cells in HAMC (5 out of n = 8) and eHAMC (6 out of n = 8). Cell transplantation in eHAMC caused significantly greater spinal lesions compared to lesion and eHAMC only control groups. A parallel study showed similar masses in the contused spinal cord of rats after transplantation of adult GFP+ SKP-SCs without a hydrogel or immunosuppression. These findings suggest that adult GFP+ SKP-SCs, cultured/transplanted under the conditions described here, have a capacity for uncontrolled proliferation. Growth-formation in pre-clinical research has also been documented after transplantation of: human induced pluripotent stem cell-derived neural stem cells (Itakura et al 2015 PLoS One 10 e0116413), embryonic stem cells and embryonic stem cell-derived neurons (Brederlau et al 2006 Stem Cells 24 1433-40; Dressel et al 2008 PLoS One 3 e2622), bone marrow derived mesenchymal stem cells (Jeong et al 2011 Circ. Res. 108 1340-47) and rat nerve-derived SCs following in vitro expansion for >11 passages (Funk et al 2007 Eur. J. Cell Biol. 86 207-19; Langford et al 1988 J. Neurocytology 17 521-9; Morrissey et al 1991 J. Neurosci. 11 2433-42). It is of upmost importance to define the precise culture/transplantation parameters for maintenance of normal cell function and safe and effective use of cell therapy.
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Affiliation(s)
- Zacnicte May
- Department of Physical Therapy, Faculty of Rehabilitation Medicine, and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada
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Führmann T, Anandakumaran PN, Shoichet MS. Combinatorial Therapies After Spinal Cord Injury: How Can Biomaterials Help? Adv Healthc Mater 2017; 6. [PMID: 28247563 DOI: 10.1002/adhm.201601130] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 12/05/2016] [Indexed: 12/31/2022]
Abstract
Traumatic spinal cord injury (SCI) results in an immediate loss of motor and sensory function below the injury site and is associated with a poor prognosis. The inhibitory environment that develops in response to the injury is mainly due to local expression of inhibitory factors, scarring and the formation of cystic cavitations, all of which limit the regenerative capacity of endogenous or transplanted cells. Strategies that demonstrate promising results induce a change in the microenvironment at- and around the lesion site to promote endogenous cell repair, including axonal regeneration or the integration of transplanted cells. To date, many of these strategies target only a single aspect of SCI; however, the multifaceted nature of SCI suggests that combinatorial strategies will likely be more effective. Biomaterials are a key component of combinatorial strategies, as they have the potential to deliver drugs locally over a prolonged period of time and aid in cell survival, integration and differentiation. Here we summarize the advantages and limitations of widely used strategies to promote recovery after injury and highlight recent research where biomaterials aided combinatorial strategies to overcome some of the barriers of spinal cord regeneration.
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Affiliation(s)
- Tobias Führmann
- The Donnelly Centre for Cellular and Biomolecular Research; 160 College Street, Room 514 Toronto ON M5S 3E1 Canada
- Department of Chemical Engineering and Applied Chemistry; 200 College Street Toronto ON M5S 3E5 Canada
| | - Priya N. Anandakumaran
- The Donnelly Centre for Cellular and Biomolecular Research; 160 College Street, Room 514 Toronto ON M5S 3E1 Canada
- Institute of Biomaterials and Biomedical Engineering; 164 College Street Toronto ON M5S 3G9 Canada
| | - Molly S. Shoichet
- The Donnelly Centre for Cellular and Biomolecular Research; 160 College Street, Room 514 Toronto ON M5S 3E1 Canada
- Department of Chemical Engineering and Applied Chemistry; 200 College Street Toronto ON M5S 3E5 Canada
- Institute of Biomaterials and Biomedical Engineering; 164 College Street Toronto ON M5S 3G9 Canada
- Department of Chemistry; University of Toronto; 80 St George St Toronto ON M5S 3H6 Canada
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7
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Hodgetts SI, Harvey AR. Neurotrophic Factors Used to Treat Spinal Cord Injury. VITAMINS AND HORMONES 2016; 104:405-457. [PMID: 28215303 DOI: 10.1016/bs.vh.2016.11.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
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.
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Affiliation(s)
- S I Hodgetts
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Perth, WA, Australia; Western Australian Neuroscience Research Institute, Perth, WA, Australia.
| | - A R Harvey
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Perth, WA, Australia; Western Australian Neuroscience Research Institute, Perth, WA, Australia
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The efficacy of Schwann cell transplantation on motor function recovery after spinal cord injuries in animal models: A systematic review and meta-analysis. J Chem Neuroanat 2016; 78:102-111. [PMID: 27609084 DOI: 10.1016/j.jchemneu.2016.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/09/2016] [Accepted: 09/04/2016] [Indexed: 12/31/2022]
Abstract
AIM This article aimed to assess the efficacy of Schwann cell transplantation on motor function recovery in animal model of spinal cord injuries via meta-analysis. METHODS An extended search was carried out in the electronic databases of Medline (via PubMed), EMBASE (via OvidSP), CENTRAL, SCOPUS, Web of Science (BIOSIS), and ProQuest. Finally, 41 eligible studies conducted on 1046 animals including 517 control animals and 529 transplanted animals were included in the meta-analysis. Pooled standardized mean difference (SMD) and odds ratio (OR) with 95% confidence interval (95% CI) were reported. RESULTS The findings showed that treatment with Schwann cells leads to a modest motor function recovery after spinal cord injury (SMD=0.85; 95% CI: 0.63-1.07; p<0.001). Transplantation of these cells in acute phase of the injury (immediately after the injury) (OR=4.30; 95% CI: 1.53-12.05; p=0.007), application of mesenchymal/skin-derived precursors (OR=2.34; 95% CI: 1.28-4.29; p=0.008), and cells with human sources are associated with an increase in efficacy of Schwann cells (OR=10.96; 95% CI: 1.49-80.77; p=0.02). Finally, it seems that the efficacy of Schwann cells in mice is significantly lower than rats (OR=0.03; 95% CI: 0.003-0.41; p=0.009). CONCLUSION Transplantation of Schwann cells can moderately improve motor function recovery. It seems that inter-species differences might exist regarding the efficacy of this cells. Therefore, this should be taken into account when using Schwann cells in clinical trials regarding spinal cord injuries.
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Myers SA, Bankston AN, Burke DA, Ohri SS, Whittemore SR. Does the preclinical evidence for functional remyelination following myelinating cell engraftment into the injured spinal cord support progression to clinical trials? Exp Neurol 2016; 283:560-72. [PMID: 27085393 DOI: 10.1016/j.expneurol.2016.04.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 02/08/2023]
Abstract
This article reviews all historical literature in which rodent-derived myelinating cells have been engrafted into the contused adult rodent spinal cord. From 2500 initial PubMed citations identified, human cells grafts, bone mesenchymal stem cells, olfactory ensheathing cells, non-myelinating cell grafts, and rodent grafts into hemisection or transection models were excluded, resulting in the 67 studies encompassed in this review. Forty five of those involved central nervous system (CNS)-derived cells, including neural stem progenitor cells (NSPCs), neural restricted precursor cells (NRPs) or oligodendrocyte precursor cells (OPCs), and 22 studies involved Schwann cells (SC). Of the NSPC/NPC/OPC grafts, there was no consistency with respect to the types of cells grafted and/or the additional growth factors or cells co-grafted. Enhanced functional recovery was reported in 31/45 studies, but only 20 of those had appropriate controls making conclusive interpretation of the remaining studies impossible. Of those 20, 19 were properly powered and utilized appropriate statistical analyses. Ten of those 19 studies reported the presence of graft-derived myelin, 3 reported evidence of endogenous remyelination or myelin sparing, and 2 reported both. For the SC grafts, 16/21 reported functional improvement, with 11 having appropriate cellular controls and 9/11 using proper statistical analyses. Of those 9, increased myelin was reported in 6 studies. The lack of consistency and replication among these preclinical studies are discussed with respect to the progression of myelinating cell transplantation therapies into the clinic.
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Affiliation(s)
- Scott A Myers
- 511 S. Floyd St., MDR 623, Kentucky Spinal Cord Injury Research Center and Department of Neurological Surgery, University of Louisville, School of Medicine, Louisville, KY 40202, USA
| | - Andrew N Bankston
- 511 S. Floyd St., MDR 623, Kentucky Spinal Cord Injury Research Center and Department of Neurological Surgery, University of Louisville, School of Medicine, Louisville, KY 40202, USA
| | - Darlene A Burke
- 511 S. Floyd St., MDR 623, Kentucky Spinal Cord Injury Research Center and Department of Neurological Surgery, University of Louisville, School of Medicine, Louisville, KY 40202, USA
| | - Sujata Saraswat Ohri
- 511 S. Floyd St., MDR 623, Kentucky Spinal Cord Injury Research Center and Department of Neurological Surgery, University of Louisville, School of Medicine, Louisville, KY 40202, USA
| | - Scott R Whittemore
- 511 S. Floyd St., MDR 623, Kentucky Spinal Cord Injury Research Center and Department of Neurological Surgery, University of Louisville, School of Medicine, Louisville, KY 40202, USA.
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Hodgetts SI, Edel M, Harvey AR. The State of Play with iPSCs and Spinal Cord Injury Models. J Clin Med 2015; 4:193-203. [PMID: 26237027 PMCID: PMC4470248 DOI: 10.3390/jcm4010193] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/08/2014] [Indexed: 01/10/2023] Open
Abstract
The application of induced pluripotent stem cell (iPSC) technologies in cell based strategies, for the repair of the central nervous system (with particular focus on the spinal cord), is moving towards the potential use of clinical grade donor cells. The ability of iPSCs to generate donor neuronal, glial and astrocytic phenotypes for transplantation is highlighted here, and we review recent research using iPSCs in attempts to treat spinal cord injury in various animal models. Also discussed are issues relating to the production of clinical grade iPSCs, recent advances in transdifferentiation protocols for iPSC-derived donor cell populations, concerns about tumourogenicity, and whether iPSC technologies offer any advantages over previous donor cell candidates or tissues already in use as therapeutic tools in experimental spinal cord injury studies.
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Affiliation(s)
- Stuart I Hodgetts
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia.
| | - Michael Edel
- Control of Pluripotency Laboratory, Department of Physiological Sciences I, Faculty of Medicine, University of Barcelona, Hospital Clinic, Casanova 143, Barcelona 08036, Spain.
- Faculty of Medicine, The University of Sydney Medical School, Division of Pediatrics and Child Health, Westmead Children's Hospital, Sydney 2010, Australia.
- School of Anatomy, Physiology and Human Biology, and the Harry Perkins Institute for Medical Research (CCTRM), The University of Western Australia, Western Australia 6009, Australia.
| | - Alan R Harvey
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia.
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Abstract
Stem cell-based interventions aim to use special regenerative cells (stem cells) to facilitate neuronal function beyond the site of the injury. Many studies involving animal models of spinal cord injury (SCI) suggest that certain stem cell-based therapies may restore function after SCI. Currently, in case of spinal cord injuries, new discoveries with clinical implications have been continuously made in basic stem cell research, and stem cell-based approaches are advancing rapidly toward application in patients. There is a huge base of preclinical evidence in vitro and in animal models which suggests the safety and clinical efficacy of cellular therapies after SCI. Despite this, data from clinical studies is not very encouraging and at times confounding. Here, we have attempted to cover preclinical and clinical evidence base dealing with safety, feasibility and efficacy of cell based interventions after SCI. The limitations of preclinical data and the reasons underlying its failure to translate in a clinical setting are also discussed. Based on the evidence base, it is suggested that a multifactorial approach is required to address this situation. Need for standardized, stringently designed multi-centric clinical trials for obtaining validated proof of evidence is also highlighted.
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Affiliation(s)
- Harvinder Singh Chhabra
- Spine Service, Indian Spinal Injuries Centre, Vasant Kunj, New Delhi, India,Address for correspondence: Dr. Harvinder Singh Chhabra, Indian Spinal Injuries Centre, Sector C, Vasant Kunj, New Delhi - 110 070, India. E-mail:
| | - Kanchan Sarda
- Spine Service, Indian Spinal Injuries Centre, Vasant Kunj, New Delhi, India
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12
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Harvey AR, Lovett SJ, Majda BT, Yoon JH, Wheeler LPG, Hodgetts SI. Neurotrophic factors for spinal cord repair: Which, where, how and when to apply, and for what period of time? Brain Res 2014; 1619:36-71. [PMID: 25451132 DOI: 10.1016/j.brainres.2014.10.049] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/20/2014] [Accepted: 10/23/2014] [Indexed: 12/22/2022]
Abstract
A variety of neurotrophic factors have been used in attempts to improve morphological and behavioural outcomes after experimental spinal cord injury (SCI). Here we review many of these factors, their cellular targets, and their therapeutic impact on spinal cord repair in different, primarily rodent, models of SCI. A majority of studies report favourable outcomes but results are by no means consistent, thus a major aim of this review is to consider how best to apply neurotrophic factors after SCI to optimize their therapeutic potential. In addition to which factors are chosen, many variables need be considered when delivering trophic support, including where and when to apply a given factor or factors, how such factors are administered, at what dose, and for how long. Overall, the majority of studies have applied neurotrophic support in or close to the spinal cord lesion site, in the acute or sub-acute phase (0-14 days post-injury). Far fewer chronic SCI studies have been undertaken. In addition, comparatively fewer studies have administered neurotrophic factors directly to the cell bodies of injured neurons; yet in other instructive rodent models of CNS injury, for example optic nerve crush or transection, therapies are targeted directly at the injured neurons themselves, the retinal ganglion cells. The mode of delivery of neurotrophic factors is also an important variable, whether delivered by acute injection of recombinant proteins, sub-acute or chronic delivery using 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. Neurotrophic factors are often used in combination with cell or tissue grafts and/or other pharmacotherapeutic agents. Finally, the dose and time-course of delivery of trophic support should ideally be tailored to suit specific biological requirements, whether they relate to neuronal survival, axonal sparing/sprouting, or the long-distance regeneration of axons ending in a different mode of growth associated with terminal arborization and renewed synaptogenesis. This article is part of a Special Issue entitled SI: Spinal cord injury.
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Affiliation(s)
- Alan R Harvey
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
| | - Sarah J Lovett
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Bernadette T Majda
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Jun H Yoon
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Lachlan P G Wheeler
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Stuart I Hodgetts
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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14
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Saunders NR, Noor NM, Dziegielewska KM, Wheaton BJ, Liddelow SA, Steer DL, Ek CJ, Habgood MD, Wakefield MJ, Lindsay H, Truettner J, Miller RD, Smith AI, Dietrich WD. Age-dependent transcriptome and proteome following transection of neonatal spinal cord of Monodelphis domestica (South American grey short-tailed opossum). PLoS One 2014; 9:e99080. [PMID: 24914927 PMCID: PMC4051688 DOI: 10.1371/journal.pone.0099080] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 05/09/2014] [Indexed: 01/08/2023] Open
Abstract
This study describes a combined transcriptome and proteome analysis of Monodelphis domestica response to spinal cord injury at two different postnatal ages. Previously we showed that complete transection at postnatal day 7 (P7) is followed by profuse axon growth across the lesion with near-normal locomotion and swimming when adult. In contrast, at P28 there is no axon growth across the lesion, the animals exhibit weight-bearing locomotion, but cannot use hind limbs when swimming. Here we examined changes in gene and protein expression in the segment of spinal cord rostral to the lesion at 24 h after transection at P7 and at P28. Following injury at P7 only forty genes changed (all increased expression); most were immune/inflammatory genes. Following injury at P28 many more genes changed their expression and the magnitude of change for some genes was strikingly greater. Again many were associated with the immune/inflammation response. In functional groups known to be inhibitory to regeneration in adult cords the expression changes were generally muted, in some cases opposite to that required to account for neurite inhibition. For example myelin basic protein expression was reduced following injury at P28 both at the gene and protein levels. Only four genes from families with extracellular matrix functions thought to influence neurite outgrowth in adult injured cords showed substantial changes in expression following injury at P28: Olfactomedin 4 (Olfm4, 480 fold compared to controls), matrix metallopeptidase (Mmp1, 104 fold), papilin (Papln, 152 fold) and integrin α4 (Itga4, 57 fold). These data provide a resource for investigation of a priori hypotheses in future studies of mechanisms of spinal cord regeneration in immature animals compared to lack of regeneration at more mature stages.
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Affiliation(s)
- Norman R. Saunders
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
- * E-mail:
| | - Natassya M. Noor
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
| | | | - Benjamin J. Wheaton
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
| | - Shane A. Liddelow
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
- Department of Neurobiology, Stanford University, Stanford, California, United States of America
| | - David L. Steer
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - C. Joakim Ek
- Department of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Mark D. Habgood
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
| | - Matthew J. Wakefield
- Walter & Eliza Hall Institute of Medical Research, Victoria, Australia
- Department of Genetics, The University of Melbourne, Victoria, Australia
| | - Helen Lindsay
- Walter & Eliza Hall Institute of Medical Research, Victoria, Australia
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Jessie Truettner
- The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
| | - Robert D. Miller
- Center for Evolutionary & Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - A. Ian Smith
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - W. Dalton Dietrich
- The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
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Abrams MB, Nilsson I, Kjell J, Lewandowski S, Codeluppi S, Eriksson U, Olson L. Response to the report, "A re-assessment of treatment with a tyrosine kinase inhibitor (imatinib) on tissue sparing and functional recovery after spinal cord injury" by Sharp et al. Exp Neurol 2014; 257:182-5. [PMID: 24825370 DOI: 10.1016/j.expneurol.2014.04.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 04/24/2014] [Accepted: 04/25/2014] [Indexed: 12/14/2022]
Affiliation(s)
- Mathew B Abrams
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Ingrid Nilsson
- Department of Medical Biochemisty and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Jacob Kjell
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Sebastian Lewandowski
- Department of Medical Biochemisty and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Simone Codeluppi
- Department of Medical Biochemisty and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Ulf Eriksson
- Department of Medical Biochemisty and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Lars Olson
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden.
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Ferguson AR, Irvine KA, Gensel JC, Nielson JL, Lin A, Ly J, Segal MR, Ratan RR, Bresnahan JC, Beattie MS. Derivation of multivariate syndromic outcome metrics for consistent testing across multiple models of cervical spinal cord injury in rats. PLoS One 2013; 8:e59712. [PMID: 23544088 PMCID: PMC3609747 DOI: 10.1371/journal.pone.0059712] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/17/2013] [Indexed: 12/13/2022] Open
Abstract
Spinal cord injury (SCI) and other neurological disorders involve complex biological and functional changes. Well-characterized preclinical models provide a powerful tool for understanding mechanisms of disease; however managing information produced by experimental models represents a significant challenge for translating findings across research projects and presents a substantial hurdle for translation of novel therapies to humans. In the present work we demonstrate a novel ‘syndromic’ information-processing approach for capitalizing on heterogeneous data from diverse preclinical models of SCI to discover translational outcomes for therapeutic testing. We first built a large, detailed repository of preclinical outcome data from 10 years of basic research on cervical SCI in rats, and then applied multivariate pattern detection techniques to extract features that are conserved across different injury models. We then applied this translational knowledge to derive a data-driven multivariate metric that provides a common ‘ruler’ for comparisons of outcomes across different types of injury (NYU/MASCIS weight drop injuries, Infinite Horizons (IH) injuries, and hemisection injuries). The findings revealed that each individual endpoint provides a different view of the SCI syndrome, and that considering any single outcome measure in isolation provides a misleading, incomplete view of the SCI syndrome. This limitation was overcome by taking a novel multivariate integrative approach for leveraging complex data from preclinical models of neurological disease to identify therapies that target multiple outcomes. We suggest that applying this syndromic approach provides a roadmap for translating therapies for SCI and other complex neurological diseases.
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Affiliation(s)
- Adam R. Ferguson
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United States of America
- * E-mail: (ARF); (MSB)
| | - Karen-Amanda Irvine
- Department of Comparative Medicine, Stanford University, Palo Alto, California, United States of America
| | - John C. Gensel
- Department of Physiology, Spinal Cord and Brain Injury Research Center (SCoBIRC), University of Kentucky, Lexington, Kentucky, United States of America
| | - Jessica L. Nielson
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United States of America
| | - Amity Lin
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United States of America
| | - Johnathan Ly
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United States of America
| | - Mark R. Segal
- Center for Bioinformatics and Molecular Biostatistics, Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, United States of America
| | - Rajiv R. Ratan
- Burke-Cornell Medical Research Institute, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, White Plains, New York, United States of America
| | - Jacqueline C. Bresnahan
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United States of America
| | - Michael S. Beattie
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United States of America
- * E-mail: (ARF); (MSB)
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Li J, Lepski G. Cell transplantation for spinal cord injury: a systematic review. BIOMED RESEARCH INTERNATIONAL 2013; 2013:786475. [PMID: 23484157 PMCID: PMC3581246 DOI: 10.1155/2013/786475] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 11/16/2012] [Accepted: 12/11/2012] [Indexed: 02/07/2023]
Abstract
Cell transplantation, as a therapeutic intervention for spinal cord injury (SCI), has been extensively studied by researchers in recent years. A number of different kinds of stem cells, neural progenitors, and glial cells have been tested in basic research, and most have been excluded from clinical studies because of a variety of reasons, including safety and efficacy. The signaling pathways, protein interactions, cellular behavior, and the differentiated fates of experimental cells have been studied in vitro in detail. Furthermore, the survival, proliferation, differentiation, and effects on promoting functional recovery of transplanted cells have also been examined in different animal SCI models. However, despite significant progress, a "bench to bedside" gap still exists. In this paper, we comprehensively cover publications in the field from the last years. The most commonly utilized cell lineages were covered in this paper and specific areas covered include survival of grafted cells, axonal regeneration and remyelination, sensory and motor functional recovery, and electrophysiological improvements. Finally we also review the literature on the in vivo tracking techniques for transplanted cells.
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Affiliation(s)
- Jun Li
- Department of Neurosurgery, Eberhard Karls University, 72076 Tübingen, Germany
- Department of Spine Surgery, The Affiliated Hospital of Luzhou Medical College, 646000 Luzhou, China
| | - Guilherme Lepski
- Department of Neurosurgery, Eberhard Karls University, 72076 Tübingen, Germany
- Division of Neurosurgery, Department of Neurology, Faculdade de Medicina, Universidade de São Paulo, Avnida Dr. Enéas de Carvalho Aguiar 255, 05403-000 São Paulo, SP, Brazil
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Hill CE, Brodak DM, Bartlett Bunge M. Dissociated predegenerated peripheral nerve transplants for spinal cord injury repair: a comprehensive assessment of their effects on regeneration and functional recovery compared to Schwann cell transplants. J Neurotrauma 2012; 29:2226-43. [PMID: 22655857 DOI: 10.1089/neu.2012.2377] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Several recent studies suggest that predegenerated nerves (PDNs) or dissociated PDNs (dPDNs) can improve behavioral and histological outcomes following transplantation into the injured rat spinal cord. In the current study we tested the efficacy of dPDN transplantation by grafting cells isolated from the sciatic nerve 7 days after crush. We did not replicate one study, but rather assessed what appeared, based on five published reports, to be a reported robust effect of dPDN grafts on corticospinal tract (CST) regeneration and locomotor recovery. Using a standardized rodent spinal cord injury model (200 kD IH contusion) and transplantation procedure (injection of GFP⁺ cells 7 days post-SCI), we demonstrate that dPDN grafts survive within the injured spinal cord and promote the ingrowth of axons to a similar extent as purified Schwann cell (SC) grafts. We also demonstrate for the first time that while both dPDN and SC grafts promote the ingrowth of CGRP axons, neither graft results in mechanical or thermal hyperalgesia. Unlike previous studies, dPDN grafts did not promote long-distance axonal growth of CST axons, brainstem spinal axons, or ascending dorsal column sensory axons. Moreover, using a battery of locomotor tests (Basso Beattie Bresnahan [BBB] score, BBB subscore, inked footprint, Catwalk, and ladderwalk), we failed to detect any beneficial effects of dPDN transplantation on the recovery of locomotor function after SCI. We conclude that dPDN transplants are not sufficient to promote CST regeneration or locomotor recovery after SCI.
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Affiliation(s)
- Caitlin E Hill
- The Burke Medical Research Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, USA.
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Tuszynski MH, Steward O. Concepts and methods for the study of axonal regeneration in the CNS. Neuron 2012; 74:777-91. [PMID: 22681683 PMCID: PMC3387806 DOI: 10.1016/j.neuron.2012.05.006] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2012] [Indexed: 12/22/2022]
Abstract
Progress in the field of axonal regeneration research has been like the process of axonal growth itself: there is steady progress toward reaching the target, but there are episodes of mistargeting, misguidance along false routes, and connections that must later be withdrawn. This primer will address issues in the study of axonal growth after central nervous system injury in an attempt to provide guidance toward the goal of progress in the field. We address definitions of axonal growth, sprouting and regeneration after injury, and the research tools to assess growth.
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Affiliation(s)
- Mark H Tuszynski
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093-0662, USA.
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Drug-eluting microfibrous patches for the local delivery of rolipram in spinal cord repair. J Control Release 2012; 161:910-7. [PMID: 22634093 DOI: 10.1016/j.jconrel.2012.05.034] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 05/03/2012] [Accepted: 05/16/2012] [Indexed: 01/10/2023]
Abstract
Spinal cord injury (SCI) remains a major challenge for regenerative medicine. Following SCI, axon growth inhibitors and other inflammatory responses prevent functional recovery. Previous studies have demonstrated that rolipram, an anti-inflammatory and cyclic adenosine monophosphate preserving small molecule, improves spinal cord regeneration when delivered systemically. However, more recent studies showed that rolipram has some adverse effects in spinal cord repair. Here, we developed a drug-delivery platform for the local delivery of rolipram into the spinal cord. The potential of drug-eluting microfibrous patches for continuous delivery of high and low-dose rolipram concentrations was characterized in vitro. Following C5 hemisections, athymic rats were treated with patches loaded with low and high doses of rolipram. In general, animals treated with low-dose rolipram experienced greater functional and anatomical recovery relative to all other groups. Outcomes from the high-dose rolipram treatment were similar to those with no treatment. In addition, high-dose treated animals experienced reduced survival rates suggesting that systemic toxicity was reached. With the ability to control the release of drug dosage locally within the spinal cord, drug-eluting microfibrous patches demonstrate the importance of appropriate local release-kinetics of rolipram, proving their usefulness as a therapeutic platform for the study and repair of SCI.
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McCall J, Weidner N, Blesch A. Neurotrophic factors in combinatorial approaches for spinal cord regeneration. Cell Tissue Res 2012; 349:27-37. [PMID: 22526621 DOI: 10.1007/s00441-012-1388-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 02/23/2012] [Indexed: 01/09/2023]
Abstract
Axonal regeneration is inhibited by a plethora of different mechanisms in the adult central nervous system (CNS). While neurotrophic factors have been shown to stimulate axonal growth in numerous animal models of nervous system injury, a lack of suitable growth substrates, an insufficient activation of neuron-intrinsic regenerative programs, and extracellular inhibitors of regeneration limit the efficacy of neurotrophic factor delivery for anatomical and functional recovery after spinal cord injury. Thus, growth-stimulating factors will likely have to be combined with other treatment approaches to tap into the full potential of growth factor therapy for axonal regeneration. In addition, the temporal and spatial distribution of growth factors have to be tightly controlled to achieve biologically active concentrations, to allow for the chemotropic guidance of axons, and to prevent adverse effects related to the widespread distribution of neurotrophic factors. Here, we will review the rationale for combinatorial treatments in axonal regeneration and summarize some recent progress in promoting axonal regeneration in the injured CNS using such approaches.
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Affiliation(s)
- Julianne McCall
- Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstrasse 200 a, 69118 Heidelberg, Germany
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Ferguson AR, Stück ED, Nielson JL. Syndromics: a bioinformatics approach for neurotrauma research. Transl Stroke Res 2011; 2:438-54. [PMID: 22207883 PMCID: PMC3236294 DOI: 10.1007/s12975-011-0121-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/14/2011] [Accepted: 10/18/2011] [Indexed: 12/25/2022]
Abstract
Substantial scientific progress has been made in the past 50 years in delineating many of the biological mechanisms involved in the primary and secondary injuries following trauma to the spinal cord and brain. These advances have highlighted numerous potential therapeutic approaches that may help restore function after injury. Despite these advances, bench-to-bedside translation has remained elusive. Translational testing of novel therapies requires standardized measures of function for comparison across different laboratories, paradigms, and species. Although numerous functional assessments have been developed in animal models, it remains unclear how to best integrate this information to describe the complete translational "syndrome" produced by neurotrauma. The present paper describes a multivariate statistical framework for integrating diverse neurotrauma data and reviews the few papers to date that have taken an information-intensive approach for basic neurotrauma research. We argue that these papers can be described as the seminal works of a new field that we call "syndromics", which aim to apply informatics tools to disease models to characterize the full set of mechanistic inter-relationships from multi-scale data. In the future, centralized databases of raw neurotrauma data will enable better syndromic approaches and aid future translational research, leading to more efficient testing regimens and more clinically relevant findings.
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Affiliation(s)
- Adam R. Ferguson
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, 1001 Potrero Avenue, Building 1, Room 101, San Francisco, CA 94110 USA
| | - Ellen D. Stück
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, 1001 Potrero Avenue, Building 1, Room 101, San Francisco, CA 94110 USA
| | - Jessica L. Nielson
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, 1001 Potrero Avenue, Building 1, Room 101, San Francisco, CA 94110 USA
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Andrews EM, Richards RJ, Yin FQ, Viapiano MS, Jakeman LB. Alterations in chondroitin sulfate proteoglycan expression occur both at and far from the site of spinal contusion injury. Exp Neurol 2011; 235:174-87. [PMID: 21952042 DOI: 10.1016/j.expneurol.2011.09.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 08/29/2011] [Accepted: 09/09/2011] [Indexed: 12/24/2022]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) present an inhibitory barrier to axonal growth and plasticity after trauma to the central nervous system. These extracellular and membrane bound molecules are altered after spinal cord injuries, but the magnitude, time course, and patterns of expression following contusion injury have not been fully described. Western blots and immunohistochemistry were combined to assess the expression of four classically inhibitory CSPGs, aggrecan, neurocan, brevican and NG2, at the lesion site and in distal segments of cervical and thoracic spinal cord at 3, 7, 14 and 28 days following a severe mid-thoracic spinal contusion. Total neurocan and the full-length (250 kDa) isoform were strongly upregulated both at the lesion epicenter and in cervical and lumbar segments. In contrast, aggrecan and brevican were sharply reduced at the injury site and were unchanged in distal segments. Total NG2 protein was unchanged across the injury site, while NG2+ profiles were distributed throughout the lesion site by 14 days post-injury (dpi). Far from the lesion, NG2 expression was increased at lumbar, but not cervical spinal cord levels. To determine if the robust increase in neurocan at the distal spinal cord levels corresponded to regions of increased astrogliosis, neurocan and GFAP immunoreactivity were measured in gray and white matter regions of the spinal enlargements. GFAP antibodies revealed a transient increase in reactive astrocyte staining in cervical and lumbar cord, peaking at 14 dpi. In contrast, neurocan immunoreactivity was specifically elevated in the cervical dorsal columns and in the lumbar ventral horn and remained high through 28 dpi. The long lasting increase of neurocan in gray matter regions at distal levels of the spinal cord may contribute to the restriction of plasticity in the chronic phase after SCI. Thus, therapies targeted at altering this CSPG both at and far from the lesion site may represent a reasonable addition to combined strategies to improve recovery after SCI.
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Affiliation(s)
- Ellen M Andrews
- Department of Physiology and Cell Biology, The Ohio State University Medical Center, Columbus, OH 43210, USA
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Abstract
INTRODUCTION A large number of different cells including embryonic and adult stem cells have been transplanted into animal models of spinal cord injury, and in many cases these procedures have resulted in modest sensorimotor benefits. In October 2010 the world's first clinical trial using human embryonic stem cells began, using stem cells converted into oligodendrocyte precursor cells. SOURCES OF DATA In this review we examine some of the publically available preclinical evidence that some of these cell types improve outcome in animal models of spinal cord injury. Much evidence is not available for public scrutiny, however, being private commercial property of various stem cell companies. AREAS OF AGREEMENT Transplantation of many different types of stem and progenitor cell enhances spontaneous recovery of function when transplanted acutely after spinal cord injury in animal models. AREAS OF DISAGREEMENT: The common mechanism(s) whereby the generic procedure of cellular transplantation enhances recovery of function are not well understood, although a range of possibilities are usually cited (including preservation of tissue, remyelination, axon sprouting, glial cell replacement). Only in exceptional cases has it been shown that functional recovery depends causally on the survival and differentiation of the transplanted cells. There is no agreement about the optimal cell type for transplantation: candidate stem cells have not yet been compared with each other or with other cell types (e.g. autologous Schwann cells) in a single study. AREAS TIMELY FOR DEVELOPING RESEARCH Transplantation of cells into animals with a long lifespan is important to determine whether or not tumours will eventually form. It will also be important to determine whether long-term survival of cells is required for functional recovery, and if so, how many are optimal.
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