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Streijger F, Kim KT, So K, Manouchehri N, Shortt K, Okon EB, Morrison C, Fong A, Gupta R, Brown AA, Tigchelaar S, Sun J, Liu E, Keung M, Daly CD, Cripton PA, Sekhon MS, Griesdale DE, Kwon BK. Duraplasty in Traumatic Thoracic Spinal Cord Injury: Impact on Spinal Cord Hemodynamics, Tissue Metabolism, Histology, and Behavioral Recovery Using a Porcine Model. J Neurotrauma 2021; 38:2937-2955. [PMID: 34011164 DOI: 10.1089/neu.2021.0084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
After acute traumatic spinal cord injury (SCI), the spinal cord can swell to fill the subarachnoid space and become compressed by the surrounding dura. In a porcine model of SCI, we performed a duraplasty to expand the subarachnoid space around the injured spinal cord and evaluated how this influenced acute intraparenchymal hemodynamic and metabolic responses, in addition to histological and behavioral recovery. Female Yucatan pigs underwent a T10 SCI, with or without duraplasty. Using microsensors implanted into the spinal cord parenchyma, changes in blood flow (ΔSCBF), oxygenation (ΔPO2), and spinal cord pressure (ΔSCP) during and after SCI were monitored, alongside metabolic responses. Behavioral recovery was tested weekly using the Porcine Injury Behavior Scale (PTIBS). Thereafter, spinal cords were harvested for tissue sparing analyses. In both duraplasty and non-animals, the ΔSCP increased ∼5 mm Hg in the first 6 h post-injury. After this, the SCP appeared to be slightly reduced in the duraplasty animals, although the group differences were not statistically significant after controlling for injury severity in terms of impact force. During the first seven days post-SCI, the ΔSCBF or ΔPO2 values were not different between the duraplasty and control animals. Over 12 weeks, there was no improvement in hindlimb locomotion as assessed by PTIBS scores and no reduction in tissue damage at the injury site in the duraplasty animals. In our porcine model of SCI, duraplasty did not provide any clear evidence of long-term behavioral or tissue sparing benefit after SCI.
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Keung MS, Streijger F, Herrity A, Ethridge J, Dougherty SM, Aslan S, Webster M, Fisk S, Deegan EG, Tessier-Cloutier B, Chen KYN, Morrison C, Okon EB, Tigchelaar S, Manouchehri N, Kim KT, Shortt K, So K, Damaser MS, Sherwood LC, Howland DR, Boakye M, Hubscher C, Stothers L, Kavanagh A, Kwon BK. Characterization of Lower Urinary Tract Dysfunction after Thoracic Spinal Cord Injury in Yucatan Minipigs. J Neurotrauma 2021; 38:1306-1326. [PMID: 33499736 DOI: 10.1089/neu.2020.7404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
There is an increasing need to develop approaches that will not only improve the clinical management of neurogenic lower urinary tract dysfunction (NLUTD) after spinal cord injury (SCI), but also advance therapeutic interventions aimed at recovering bladder function. Although pre-clinical research frequently employs rodent SCI models, large animals such as the pig may play an important translational role in facilitating the development of devices or treatments. Therefore, the objective of this study was to develop a urodynamics protocol to characterize NLUTD in a porcine model of SCI. An iterative process to develop the protocol to perform urodynamics in female Yucatan minipigs began with a group of spinally intact, anesthetized pigs. Subsequently, urodynamic studies were performed in a group of awake, lightly restrained pigs, before and after a contusion-compression SCI at the T2 or T9-T11 spinal cord level. Bladder tissue was obtained for histological analysis at the end of the study. All anesthetized pigs had bladders that were acontractile, which resulted in overflow incontinence once capacity was reached. Uninjured, conscious pigs demonstrated appropriate relaxation and contraction of the external urethral sphincter during the voiding phase. SCI pigs demonstrated neurogenic detrusor overactivity and a significantly elevated post-void residual volume. Relative to the control, SCI bladders were heavier and thicker. The developed urodynamics protocol allows for repetitive evaluation of lower urinary tract function in pigs at different time points post-SCI. This technique manifests the potential for using the pig as an intermediary, large animal model for translational studies in NLUTD.
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Cheung A, Streijger F, So K, Okon EB, Manouchehri N, Shortt K, Kim KT, Keung MSM, Chan RM, Fong A, Sun J, Griesdale DE, Sehkon MS, Kwon BK. Relationship between Early Vasopressor Administration and Spinal Cord Hemorrhage in a Porcine Model of Acute Traumatic Spinal Cord Injury. J Neurotrauma 2020; 37:1696-1707. [PMID: 32233727 DOI: 10.1089/neu.2019.6781] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Current practice guidelines for acute spinal cord injury (SCI) recommend augmenting mean arterial blood pressure (MAP) for the first 7 days post-injury. After SCI, the cord may be compressed by the bone/ligaments of the spinal column, limiting regional spinal cord blood flow. Following surgical decompression, blood flow may be restored, and can potentially promote a "reperfusion" injury. The effects of MAP augmentation on the injured cord during the compressed and decompressed conditions have not been previously characterized. Here, we used our porcine model of SCI to examine the impact of MAP augmentation on blood flow, oxygenation, hydrostatic pressure, metabolism, and intraparenchymal (IP) hemorrhage within the compressed and then subsequently decompressed spinal cord. Yucatan mini-pigs underwent a T10 contusion injury followed by 2 h of sustained compression. MAP augmentation of ∼20 mm Hg was achieved with norepinephrine (NE). Animals received MAP augmentation either during the period of cord compression (CP), after decompression (DCP), or during both periods (CP-DCP). Probes to monitor spinal cord blood flow (SCBF), oxygenation, pressure, and metabolic responses were inserted into the cord parenchyma adjacent to the injury site to measure these responses. The cord was harvested for histological evaluation. MAP augmentation increased SCBF and oxygenation in all groups. In the CP-DCP group, spinal cord pressure steadily increased and histological analysis showed significantly increased hemorrhage in the spinal cord at and near the injury site. MAP augmentation with vasopressors may improve blood flow and reduce ischemia in the injured cord but may also induce undesirable increases in IP pressure and hemorrhage.
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Kim KT, Streijger F, Manouchehri N, So K, Shortt K, Okon EB, Tigchelaar S, Cripton P, Kwon BK. Review of the UBC Porcine Model of Traumatic Spinal Cord Injury. J Korean Neurosurg Soc 2018; 61:539-547. [PMID: 30196652 PMCID: PMC6129752 DOI: 10.3340/jkns.2017.0276] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/28/2018] [Indexed: 02/01/2023] Open
Abstract
Traumatic spinal cord injury (SCI) research has recently focused on the use of rat and mouse models for in vivo SCI experiments. Such small rodent SCI models are invaluable for the field, and much has been discovered about the biologic and physiologic aspects of SCI from these models. It has been difficult, however, to reproduce the efficacy of treatments found to produce neurologic benefits in rodent SCI models when these treatments are tested in human clinical trials. A large animal model may have advantages for translational research where anatomical, physiological, or genetic similarities to humans may be more relevant for pre-clinically evaluating novel therapies. Here, we review the work carried out at the University of British Columbia (UBC) on a large animal model of SCI that utilizes Yucatan miniature pigs. The UBC porcine model of SCI may be a useful intermediary in the pre-clinical testing of novel pharmacological treatments, cell-based therapies, and the “bedside back to bench” translation of human clinical observations, which require preclinical testing in an applicable animal model.
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Streijger F, So K, Manouchehri N, Gheorghe A, Okon EB, Chan RM, Ng B, Shortt K, Sekhon MS, Griesdale DE, Kwon BK. A Direct Comparison between Norepinephrine and Phenylephrine for Augmenting Spinal Cord Perfusion in a Porcine Model of Spinal Cord Injury. J Neurotrauma 2018; 35:1345-1357. [PMID: 29338544 DOI: 10.1089/neu.2017.5285] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Current clinical guidelines recommend elevating the mean arterial blood pressure (MAP) to increase spinal cord perfusion in patients with acute spinal cord injury (SCI). This is typically achieved with vasopressors such as norepinephrine (NE) and phenylephrine (PE). These drugs differ in their pharmacological properties and potentially have different effects on spinal cord blood flow (SCBF), oxygenation (PO2), and downstream metabolism after injury. Using a porcine model of thoracic SCI, we evaluated how these vasopressors influenced intraparenchymal SCBF, PO2, hydrostatic pressure, and metabolism within the spinal cord adjacent to the injury site. Yorkshire pigs underwent a contusion/compression SCI at T10 and were randomized to receive either NE or PE for MAP elevation of 20 mm Hg, or no MAP augmentation. Prior to injury, a combined SCBF/PO2 sensor, a pressure sensor, and a microdialysis probe were inserted into the spinal cord adjacent to T10 at two locations: a "proximal" site and a "distal" site, 2 mm and 22 mm from the SCI, respectively. At the proximal site, NE and PE resulted in little improvement in SCBF during cord compression. Following decompression, NE resulted in increased SCBF and PO2, whereas decreased levels were observed for PE. However, both NE and PE were associated with a gradual decrease in the lactate to pyruvate (L/P) ratio after decompression. PE was associated with greater hemorrhage through the injury site than that in control animals. Combined, our results suggest that NE promotes better restoration of blood flow and oxygenation than PE in the traumatically injured spinal cord, thus providing a physiological rationale for selecting NE over PE in the hemodynamic management of acute SCI.
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Streijger F, So K, Manouchehri N, Tigchelaar S, Lee JHT, Okon EB, Shortt K, Kim SE, McInnes K, Cripton P, Kwon BK. Changes in Pressure, Hemodynamics, and Metabolism within the Spinal Cord during the First 7 Days after Injury Using a Porcine Model. J Neurotrauma 2017; 34:3336-3350. [PMID: 28844181 DOI: 10.1089/neu.2017.5034] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Traumatic spinal cord injury (SCI) triggers many perturbations within the injured cord, such as decreased perfusion, reduced tissue oxygenation, increased hydrostatic pressure, and disrupted bioenergetics. While much attention is directed to neuroprotective interventions that might alleviate these early pathophysiologic responses to traumatic injury, the temporo-spatial characteristics of these responses within the injured cord are not well documented. In this study, we utilized our Yucatan mini-pig model of traumatic SCI to characterize intraparenchymal hemodynamic and metabolic changes within the spinal cord for 1 week post-injury. Animals were subjected to a contusion/compression SCI at T10. Prior to injury, probes for microdialysis and the measurement of spinal cord blood flow (SCBF), oxygenation (in partial pressure of oxygen; PaPO2), and hydrostatic pressure were inserted into the spinal cord 0.2 and 2.2 cm from the injury site. Measurements occurred under anesthesia for 4 h post-injury, after which the animals were recovered and measurements continued for 7 days. Close to the lesion (0.2 cm), SCBF levels decreased immediately after SCI, followed by an increase in the subsequent days. Similarly, PaPO2 plummeted, where levels remained diminished for up to 7 days post-injury. Lactate/pyruvate (L/P) ratio increased within minutes. Further away from the injury site (2.2 cm), L/P ratio also gradually increased. Hydrostatic pressure remained consistently elevated for days and negatively correlated with changes in SCBF. An imbalance between SCBF and tissue metabolism also was observed, resulting in metabolic stress and insufficient oxygen levels. Taken together, traumatic SCI resulted in an expanding area of ischemia/hypoxia, with ongoing physiological perturbations sustained out to 7 days post-injury. This suggests that our clinical practice of hemodynamically supporting patients out to 7 days post-injury may fail to address persistent ischemia within the injured cord. A detailed understanding of these pathophysiological mechanisms after SCI is essential to promote best practices for acute SCI patients.
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Streijger F, Lee JH, Manouchehri N, Melnyk AD, Chak J, Tigchelaar S, So K, Okon EB, Jiang S, Kinsler R, Barazanji K, Cripton PA, Kwon BK. Responses of the Acutely Injured Spinal Cord to Vibration that Simulates Transport in Helicopters or Mine-Resistant Ambush-Protected Vehicles. J Neurotrauma 2016; 33:2217-2226. [DOI: 10.1089/neu.2016.4456] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Streijger F, Lee JH, Manouchehri N, Okon EB, Tigchelaar S, Anderson LM, Dekaban GA, Rudko DA, Menon RS, Iaci JF, Button DC, Vecchione AM, Konovalov A, Sarmiere PD, Ung C, Caggiano AO, Kwon BK. The Evaluation of Magnesium Chloride within a Polyethylene Glycol Formulation in a Porcine Model of Acute Spinal Cord Injury. J Neurotrauma 2016; 33:2202-2216. [DOI: 10.1089/neu.2016.4439] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Streijger F, Lee JH, Chak J, Dressler D, Manouchehri N, Okon EB, Anderson LM, Melnyk AD, Cripton PA, Kwon BK. The Effect of Whole-Body Resonance Vibration in a Porcine Model of Spinal Cord Injury. J Neurotrauma 2015; 32:908-21. [DOI: 10.1089/neu.2014.3707] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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Jones CF, Lee JHT, Burstyn U, Okon EB, Kwon BK, Cripton PA. Cerebrospinal Fluid Pressures Resulting From Experimental Traumatic Spinal Cord Injuries in a Pig Model. J Biomech Eng 2013; 135:101005. [DOI: 10.1115/1.4025100] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/29/2013] [Indexed: 12/21/2022]
Abstract
Despite considerable effort over the last four decades, research has failed to translate into consistently effective treatment options for spinal cord injury (SCI). This is partly attributed to differences between the injury response of humans and rodent models. Some of this difference could be because the cerebrospinal fluid (CSF) layer of the human spine is relatively large, while that of the rodents is extremely thin. We sought to characterize the fluid impulse induced in the CSF by experimental SCIs of moderate and high human-like severity, and to compare this with previous studies in which fluid impulse has been associated with neural tissue injury. We used a new in vivo pig model (n = 6 per injury group, mean age 124.5 days, 20.9 kg) incorporating four miniature pressure transducers that were implanted in pairs in the subarachnoid space, cranial, and caudal to the injury at 30 mm and 100 mm. Tissue sparing was assessed with Eriochrome Cyanine and Neutral Red staining. The median peak pressures near the injury were 522.5 and 868.8 mmHg (range 96.7–1430.0) and far from the injury were 7.6 and 36.3 mmHg (range 3.8–83.7), for the moderate and high injury severities, respectively. Pressure impulse (mmHg.ms), apparent wave speed, and apparent attenuation factor were also evaluated. The data indicates that the fluid pressure wave may be sufficient to affect the severity and extent of primary tissue damage close to the injury site. However, the CSF pressure was close to normal physiologic values at 100 mm from the injury. The high injury severity animals had less tissue sparing than the moderate injury severity animals; this difference was statistically significant only within 1.6 mm of the epicenter. These results indicate that future research seeking to elucidate the mechanical origins of primary tissue damage in SCI should consider the effects of CSF. This pig model provides advantages for basic and preclinical SCI research due to its similarities to human scale, including the existence of a human-like CSF fluid layer.
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Okon EB, Streijger F, Lee JHT, Anderson LM, Russell AK, Kwon BK. Intraparenchymal Microdialysis after Acute Spinal Cord Injury Reveals Differential Metabolic Responses to Contusive versus Compressive Mechanisms of Injury. J Neurotrauma 2013; 30:1564-76. [DOI: 10.1089/neu.2013.2956] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Lee JHT, Jones CF, Okon EB, Anderson L, Tigchelaar S, Kooner P, Godbey T, Chua B, Gray G, Hildebrandt R, Cripton P, Tetzlaff W, Kwon BK. A novel porcine model of traumatic thoracic spinal cord injury. J Neurotrauma 2013; 30:142-59. [PMID: 23316955 DOI: 10.1089/neu.2012.2386] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spinal cord injury (SCI) researchers have predominately utilized rodents and mice for in vivo SCI modeling and experimentation. From these small animal models have come many insights into the biology of SCI, and a growing number of novel treatments that promote behavioral recovery. It has, however, been difficult to demonstrate the efficacy of such treatments in human clinical trials. A large animal SCI model that is an intermediary between rodent and human SCI may be a valuable translational research resource for pre-clinically evaluating novel therapies, prior to embarking upon lengthy and expensive clinical trials. Here, we describe the development of such a large animal model. A thoracic spinal cord injury at T10/11 was induced in Yucatan miniature pigs (20-25 kg) using a weight drop device. Varying degrees of injury severity were induced by altering the height of the weight drop (5, 10, 20, 30, 40, and 50 cm). Behavioral recovery over 12 weeks was measured using a newly developed Porcine Thoracic Injury Behavior Scale (PTIBS). This scale distinguished locomotor recovery among animals of different injury severities, with strong intra-observer and inter-observer reliability. Histological analysis of the spinal cords 12 weeks post-injury revealed that animals with the more biomechanically severe injuries had less spared white matter and gray matter and less neurofilament immunoreactivity. Additionally, the PTIBS scores correlated strongly with the extent of tissue sparing through the epicenter of injury. This large animal model of SCI may represent a useful intermediary in the testing of novel pharmacological treatments and cell transplantation strategies.
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Kwon BK, Okon EB, Tsai E, Beattie MS, Bresnahan JC, Magnuson DK, Reier PJ, McTigue DM, Popovich PG, Blight AR, Oudega M, Guest JD, Weaver LC, Fehlings MG, Tetzlaff W. A grading system to evaluate objectively the strength of pre-clinical data of acute neuroprotective therapies for clinical translation in spinal cord injury. J Neurotrauma 2010; 28:1525-43. [PMID: 20507235 DOI: 10.1089/neu.2010.1296] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The past three decades have seen an explosion of research interest in spinal cord injury (SCI) and the development of hundreds of potential therapies that have demonstrated some promise in pre-clinical experimental animal models. A growing number of these treatments are seeking to be translated into human clinical trials. Conducting such a clinical trial, however, is extremely costly, not only for the time and money required to execute it, but also for the limited resources that will then no longer be available to evaluate other promising therapies. The decision about what therapies have sufficient pre-clinical evidence of efficacy to justify testing in humans is therefore of utmost importance. Here, we have developed a scoring system for objectively grading the body of pre-clinical literature on neuroprotective treatments for acute SCI. The components of the system include an evaluation of a number of factors that are thought to be important in considering the "robustness" of a therapy's efficacy, including the animal species and injury models that have been used to test it, the time window of efficacy, the types of functional improvements effected by it, and whether efficacy has been independently replicated. The selection of these factors was based on the results of a questionnaire that was performed within the SCI research community. A modified Delphi consensus-building exercise was then conducted with experts in pre-clinical SCI research to refine the criteria and decide upon how to score them. Finally, the grading system was applied to a series of potential neuroprotective treatments for acute SCI. This represents a systematic approach to developing an objective method of evaluating the extent to which the pre-clinical literature supports the translation of a particular experimental treatment into human trials.
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Kwon BK, Okon EB, Plunet W, Baptiste D, Fouad K, Hillyer J, Weaver LC, Fehlings MG, Tetzlaff W. A systematic review of directly applied biologic therapies for acute spinal cord injury. J Neurotrauma 2010; 28:1589-610. [PMID: 20082560 DOI: 10.1089/neu.2009.1150] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
An increasing number of therapies for spinal cord injury (SCI) are emerging from the laboratory and seeking translation into human clinical trials. Many of these are administered as soon as possible after injury with the hope of attenuating secondary damage and maximizing the extent of spared neurologic tissue. In this article, we systematically reviewed the available preclinical research on such neuroprotective therapies that are administered in a non-invasive manner for acute SCI. Specifically, we reviewed treatments that have a relatively high potential for translation due to the fact that they are already used in human clinical applications or are available in a form that could be administered to humans. These included: erythropoietin, NSAIDs, anti-CD11d antibodies, minocycline, progesterone, estrogen, magnesium, riluzole, polyethylene glycol, atorvastatin, inosine, and pioglitazone. The literature was systematically reviewed to examine studies in which an in vivo animal model was utilized to assess the efficacy of the therapy in a traumatic spinal cord injury paradigm. Using these criteria, 122 studies were identified and reviewed in detail. Wide variations exist in the animal species, injury models, and experimental designs reported in the preclinical literature on the therapies reviewed. The review highlights the extent of investigation that has occurred in these specific therapies, and points out gaps in our knowledge that would be potentially valuable prior to human translation.
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Tetzlaff W, Okon EB, Karimi-Abdolrezaee S, Hill CE, Sparling JS, Plemel JR, Plunet WT, Tsai EC, Baptiste D, Smithson LJ, Kawaja MD, Fehlings MG, Kwon BK. A systematic review of cellular transplantation therapies for spinal cord injury. J Neurotrauma 2010; 28:1611-82. [PMID: 20146557 DOI: 10.1089/neu.2009.1177] [Citation(s) in RCA: 404] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cell transplantation therapies have become a major focus in pre-clinical research as a promising strategy for the treatment of spinal cord injury (SCI). In this article, we systematically review the available pre-clinical literature on the most commonly used cell types in order to assess the body of evidence that may support their translation to human SCI patients. These cell types include Schwann cells, olfactory ensheathing glial cells, embryonic and adult neural stem/progenitor cells, fate-restricted neural/glial precursor cells, and bone-marrow stromal cells. Studies were included for review only if they described the transplantation of the cell substrate into an in-vivo model of traumatic SCI, induced either bluntly or sharply. Using these inclusion criteria, 162 studies were identified and reviewed in detail, emphasizing their behavioral effects (although not limiting the scope of the discussion to behavioral effects alone). Significant differences between cells of the same "type" exist based on the species and age of donor, as well as culture conditions and mode of delivery. Many of these studies used cell transplantations in combination with other strategies. The systematic review makes it very apparent that cells derived from rodent sources have been the most extensively studied, while only 19 studies reported the transplantation of human cells, nine of which utilized bone-marrow stromal cells. Similarly, the vast majority of studies have been conducted in rodent models of injury, and few studies have investigated cell transplantation in larger mammals or primates. With respect to the timing of intervention, nearly all of the studies reviewed were conducted with transplantations occurring subacutely and acutely, while chronic treatments were rare and often failed to yield functional benefits.
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Chung AWY, Au Yeung K, Chum E, Okon EB, van Breemen C. Diabetes modulates capacitative calcium entry and expression of transient receptor potential canonical channels in human saphenous vein. Eur J Pharmacol 2009; 613:114-8. [PMID: 19393642 DOI: 10.1016/j.ejphar.2009.04.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 04/03/2009] [Accepted: 04/09/2009] [Indexed: 10/20/2022]
Abstract
Diabetes is associated with a perturbation of signaling pathways in vascular tissue, which causes vasomotor dysfunction such as hypertension. We have previously demonstrated that vessels from diabetic patients were more contractile than those from non-diabetic. However, in human vessels, the receptor-stimulated contraction is mainly due to enzymatic, rather than calcium signaling pathway. In this study, we hypothesized that the differential contractile response between diabetic and non-diabetic human vessels could be due to the receptor signaling to sarcoplasmic reticulum and the regulation of capacitative calcium entry. In saphenous vein samples (n=20) collected from diabetic patients undergoing bypass surgery, the contraction initiated by the addition of the sarco-endoplasmatic reticulum calcium ATPase blocker, cyclopiazonic acid, was significantly higher than that in the vessels from non-diabetic patients (n=26) (84.0+/-14.9% vs 44.2+/-9.2%), and this contraction was inhibited by SKF-96365, an inhibitor of store-operated calcium channels. Pre-incubation with indomethacin reduced the cyclopiazonic acid-induced contraction in the non-diabetic veins, but had no effect on the diabetic ones. The gene expression of transient receptor potential canonical channels (TRPC)4 was upregulated by 22% in the diabetic vessels compared with the non-diabetic ones. However, the protein expression of TRPC1 and TRPC6 was downregulated in the diabetic group by 50%. We concluded that diabetes would modulate the capacitative calcium entry likely through the store-operated calcium channel specifically via the regulation of TRPC.
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Okon EB, Chung AW, Hsiang YN, Breemen CV. Cellular Mechanisms of Bypass Vein Graft Arterialization and Approaches to Attenuate Graft Remodeling. ACTA ACUST UNITED AC 2008. [DOI: 10.2174/1567270000805010006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Okon EB, Golbabaie A, Breemen CV. Paracrine effects of endothelial cells in a diabetic mouse model: capacitative calcium entry stimulated thromboxane release. Horm Metab Res 2008; 40:645-50. [PMID: 18792877 DOI: 10.1055/s-0028-1083812] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Augmented vasoconstriction contributes to arterial stiffness associated with diabetes. It has been shown that capacitative calcium entry induced by sarcoplasmic-endoplasmic reticulum calcium ATPase blocker cyclopiazonic acid (CPA) in endothelial cells stimulates production of constrictor prostaglandins, which causes contractions of vascular smooth muscle cells. The aim of the work was to study the effect of diabetes on the vasoconstrictor response induced by calcium entry into endothelial and smooth muscle cells. Force was measured in isolated aortae of diabetic ob/ob and control C57BL/6J mice under isometric conditions. Contractions caused by 10 micromol/l CPA in diabetic mouse aortae featured higher amplitudes and longer durations in comparison with nondiabetic aortae. These contractions were abolished by a COX inhibitor indomethacin (10 micromol/l) or a specific thromboxane A2 receptor blocker SQ 29548 (1 micromol/l) and were not observed in denuded aortae. The contractions were sensitive to extracellular Ca (2+) and store-operated channel blockers. All together this suggests that vasoconstriction was caused by thromboxane A2 synthesis in endothelial cells induced by Ca (2+) entry through store-operated channels. Higher concentrations of CPA (30 micromol/l) or thapsigargin (1 micromol/l) elicited indomethacin-resistant tonic contractions of aortae with 2-fold amplitude in diabetic mice compared to their nondiabetic littermates, which were sensitive to store-operated channel blockers, but not to indomethacin, SQ 29548, or denudation. In conclusions, increases in intracellular Ca (2+) cause augmented vasoconstriction in diabetic vasculature through endothelial synthesis of contractile prostaglandins. In addition capacitative Ca (2+) entry is enhanced in diabetic vascular smooth muscle. These mechanisms indicate possible targets for clinical applications.
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Okon EB, Hranislavljevic J, Marjanovic V, Gopcevic K, Pavlovic N, Mitic B, Strahinjic D, Vucelic D, Kaminski IG. [Diurnal fluctuations of protein contents and the pH dependence of beta2-microglobulin stability in urine]. IZVESTIIA AKADEMII NAUK. SERIIA BIOLOGICHESKAIA 2008:46-52. [PMID: 18491561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Diurnal fluctuations of protein excretion into urine and the effect of urinary pH on the urinary protein concentrations were studied in patients with various kidney diseases. The diurnal kinetics of gamma-immunoglobulin, transferrin, albumin, alpha1-microglobulin, gamma-immunoglobulin light chains, and the retinol-binding protein proved to positively correlate with the diurnal fluctuations of proteinuria and to negatively correlate with urinary pH. Diurnal changes in urinary beta2-microglobulin content did not correlate with those of any other protein. Oral bicarbonate intake alkalinized the urine, increased the urinary beta2-microglobulin content, and led to a direct correlation between beta2-microglobulin excretion and excretion of other low-molecular proteins. Thus, proteinuria, single protein excretion, and urinary pH displayed diurnal rhythmicity in the patients; beta2-microglobulin was unstable in acid urine and its urinary level depended on the urinary pH.
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Chung AWY, Luo H, Tejerina T, van Breemen C, Okon EB. Enhanced cell cycle entry and mitogen-activated protein kinase-signaling and downregulation of matrix metalloproteinase-1 and -3 in human diabetic arterial vasculature. Atherosclerosis 2007; 195:e1-8. [PMID: 17316652 DOI: 10.1016/j.atherosclerosis.2007.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2006] [Revised: 01/02/2007] [Accepted: 01/12/2007] [Indexed: 01/12/2023]
Abstract
Diabetic patients have a strong predilection for atherosclerosis and postangioplasty restenosis. Accelerated cell proliferation and excessive extracellular matrix deposition are believed to contribute to the development of atherosclerotic plaques and neointima. We investigated the effect of diabetes on cell cycle, proliferation signaling, and the activation of matrix metalloproteinases (MMPs). Segments of internal mammary arteries from 26 type 2 diabetic and 26 non-diabetic patients undergoing coronary artery bypass grafting surgery were compared. Increased levels of cyclin D1 mRNA (by 135+/-14%) and protein expression (by 93.8+/-7.0%), retinoblastoma protein phosphorylation (by 45.9+/-4.8%), and beta-catenin nuclear localization (by 176+/-16%) indicated the enhanced cell cycle entry in the diabetic arteries. Diabetes increased phosphorylation of extracellular signal-regulated kinase-1/2 and p-38-mitogen-activated protein kinase (MAPK) by 76.0+/-6.8 and 62.3+/-4.3%. Increased collagen deposition was evidenced in the diabetic arteries. mRNA levels of MMP-1 and MMP-3 were decreased in the diabetic tissue to 55 and 82%, respectively, compared to the non-diabetic group; protein levels were also decreased accompanied with decreased enzymatic activities by 21 and 50%, respectively. In conclusion, enhanced cell cycle entry, increased MAPK signaling, and downregulated MMP-1 and MMP-3 were characteristic of diabetic arterial vasculature, and could contribute to the progressive atherosclerosis and postangioplasty restenosis in diabetic patients.
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Okon EB, Chung AWY, Zhang H, Laher I, van Breemen C. Hyperglycemia and hyperlipidemia are associated with endothelial dysfunction during the development of type 2 diabetes. Can J Physiol Pharmacol 2007; 85:562-7. [PMID: 17632592 DOI: 10.1139/y07-026] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Diabetes mellitus impairs endothelial function, which can be considered as the hallmark in the development of cardiovascular diseases. Hyperglycemia, hyperinsulinemia, and hyperlipidemia are believed to contribute to endothelial dysfunction. In the present study, we investigated the possible links among these plasma metabolic markers and endothelial function in a mouse model during the development of type 2 diabetes. C57BL/6J-Lepob/ob mice at 8, 12, and 16 weeks were used to study endothelial function during the establishment of type 2 diabetes. Endothelial function was accessed in vitro in the thoracic aorta by measuring acetylcholine (ACh)-stimulated vasodilatation. Blood plasma was obtained for the measurements of glucose, insulin, triglycerides, and cholesterol levels. Correlation and multiple regression analysis revealed strong negative associations between the ACh responsiveness and the plasma levels of glucose, insulin, and lipid profiles at the age of 8 weeks. Associations were observed at neither older age nor in C57BL/6J mice. In conclusion, the increase in plasma levels of glucose, insulin, and lipids is associated with the impairment of the endothelial function during the early stage of the development of type 2 diabetes. The loss of correlation at an older age suggests multifactorial regulation of endothelial function and cardiovascular complications at later stages of the disease.
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Chung AWY, Rauniyar P, Luo H, Hsiang YN, van Breemen C, Okon EB. Pharmacologic relaxation of vein grafts is beneficial compared with pressure distention caused by upregulation of endothelial nitric oxide synthase and nitric oxide production. J Thorac Cardiovasc Surg 2006; 132:925-32. [PMID: 17000306 DOI: 10.1016/j.jtcvs.2006.04.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 03/30/2006] [Accepted: 04/24/2006] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Pressure distention of veins during preparation for bypass surgery is believed to impair vascular integrity and reduce graft patency. We previously suggested a combination of pharmacologic vasodilatators as an alternative to distention. Vascular homeostasis is largely regulated by nitric oxide. We investigated the role of distention in comparison with pharmacologic vasorelaxation in the regulation of nitric oxide synthases, nitric oxide bioavailability, and vascular reactivity in vein grafts. METHODS In a porcine model the internal jugular vein from either side received pressure distention or the combination of vasodilators (alpha-adrenergic antagonist, phenoxybenzamine, 10 micromol/L; Rho-kinase inhibitor, HA-1077 [fasudil], 50 mumol/L; calcium blocker, nicardipine, 1 micromol/L) and then was grafted into the carotid artery. Regulation of nitric oxide synthase, as well as nitrate and nitrite levels, were examined in vein grafts after 2 weeks of implantation. RESULTS Distention of jugular veins resulted in reduction of vasoconstriction in response to depolarization and agonist stimulation. Arterial grafting doubled inducible nitric oxide synthase expression in both grafts but caused a pronounced upregulation of endothelial nitric oxide synthase protein (by 57.3% +/- 5%) only in drug-treated grafts, whereas in distended grafts the endothelial nitric oxide synthase level was decreased by 27.5% +/- 2.7%. The downregulated endothelial nitric oxide synthase level in the distended grafts was accompanied by a 45.2% +/- 3.1% reduction of phospho-endothelial nitric oxide synthase Ser1177 levels and by a significant reduction in nitric oxide synthase activity (12.1% +/- 1.2%) and nitrate production (48.9% +/- 5.6%) in comparison with that seen in drug-treated grafts. CONCLUSIONS Pharmacologic preparation of the vein grafts results in upregulation of endothelial nitric oxide synthase and increased nitric oxide production in the vein grafts after arterial implantation. This might provide greater clinical benefit than conventional pressure-distention methods.
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Chung AWY, Hsiang YN, Matzke LA, McManus BM, van Breemen C, Okon EB. Reduced expression of vascular endothelial growth factor paralleled with the increased angiostatin expression resulting from the upregulated activities of matrix metalloproteinase-2 and -9 in human type 2 diabetic arterial vasculature. Circ Res 2006; 99:140-8. [PMID: 16778129 DOI: 10.1161/01.res.0000232352.90786.fa] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Impaired angiogenesis could contribute to the increased incidence of coronary and peripheral artery disease in diabetic patients. Angiogenesis is initiated by vascular endothelial growth factor (VEGF), a potent angiogenic cytokine, and suppressed by angiostatin, which is generated by matrix metalloproteinase (MMP)-2 and -9 through proteolytic cleavage of plasminogen. We hypothesized that MMP-2 and -9 were upregulated in the diabetic vasculature, resulting in increased angiostatin production and reduced blood vessel formation. In diabetic internal mammary artery samples (n=32) collected from patients undergoing coronary artery bypass grafting surgery, capillary density was only 30% of that in the nondiabetic vessels (n=32), whereas VEGF expression was reduced by 48%. Diabetes upregulated the expression and the gelatinolytic activity of MMP-2 and -9. Active MMP-2 and -9 were released from diabetic arteries, but not from nondiabetic vessels, during phenylephrine-induced vasoconstriction. Diabetes enhanced transcription and protein expression of tissue inhibitor of MMP (TIMP)-1 but had an opposite effect on TIMP-2. In diabetic vessels angiostatin was increased by 62% and was positively correlated with the activities of MMP-2 and -9 (r2=0.806 and 0.742, respectively). This report indicated a strong correlation between the upregulation of MMP-2 and MMP-9 and the increased angiostatin expression in the human diabetic arterial vasculature. The enhanced angiostatin production with a reduced VEGF formation may explain the pathogenesis of impaired angiogenesis in diabetes mellitus.
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Good BM, Tranfield EM, Tan PC, Shehata M, Singhera GK, Gosselink J, Okon EB, Wilkinson MD. Fast, cheap and out of control: a zero curation model for ontology development. PACIFIC SYMPOSIUM ON BIOCOMPUTING. PACIFIC SYMPOSIUM ON BIOCOMPUTING 2006:128-39. [PMID: 17094234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
During two days at a conference focused on circulatory and respiratory health, 68 volunteers untrained in knowledge engineering participated in an experimental knowledge capture exercise. These volunteers created a shared vocabulary of 661 terms, linking these terms to each other and to a pre-existing upper ontology by adding 245 hyponym relationships and 340 synonym relationships. While ontology-building has proved to be an expensive and labor-intensive process using most existing methodologies, the rudimentary ontology constructed in this study was composed in only two days at a cost of only 3 t-shirts, 4 coffee mugs, and one chocolate moose. The protocol used to create and evaluate this ontology involved a targeted, web-based interface. The design and implementation of this protocol is discussed along with quantitative and qualitative assessments of the constructed ontology.
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