Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Kumamaru Hiromi Last modified date:2023.11.27

Assistant Professor / Kyushu University Hospital


Papers
1. 1. Sinopoulou E, Rosenzweig ES, Conner JM, Gibbs D, Weinholtz CA, Weber JL, Brock JH, Nout-Lomas YS, Ovruchesky E, Takashima Y, Biane JS, Kumamaru H, Havton LA, Beattie MS, Bresnahan JC, Tuszynski MH, Rhesus macaque versus rat divergence in the corticospinal projectome, Neuron, 2022.09.
2. Kumamaru Hiromi, Nakashima Yasuharu, Harimaya Katsumi, L1 Radiculopathy Caused by L1-L2 Extraforaminal Disc Herniation., Spine Surg Relat Res, 2022.10.
3. Kumamaru H, Iida K, Saito T, Yoshizaki S, Nakashima Y, Harimaya K., The Posterolaterally Oriented and Laterally Downward Sloping Facet Joint Is a Risk Factor for Degenerative Cervical Spondylolisthesis and Myelopathy., Spine Surg Relat Res, 2022.05.
4. Harimaya K, Matsumoto Y, Kawaguchi K, Okada S, Saiwai H, Matsushita A, Iida K, Kumamaru H, Saito T, Nakashima Y., Clinical features of multiple spinal schwannomas without vestibular schwannomas, J Orthop Sci, 2021.04.
5. Hiromi Kumamaru, Ken Kadoya, Andrew F. Adler, Yoshio Takashima, Lori Graham, Giovanni Coppola, Mark H. Tuszynski, Generation and post-injury integration of human spinal cord neural stem cells, Nature Methods, 10.1038/s41592-018-0074-3, 15, 9, 723-731, 2018.09, Spinal cord neural stem cells (NSCs) have great potential to reconstitute damaged spinal neural circuitry, but they have yet to be generated in vitro. We now report the derivation of spinal cord NSCs from human pluripotent stem cells (hPSCs). Our observations show that these spinal cord NSCs differentiate into a diverse population of spinal cord neurons occupying multiple positions along the dorso-ventral axis, and can be maintained for prolonged time periods. Grafts into injured spinal cords were rich with excitatory neurons, extended large numbers of axons over long distances, innervated their target structures, and enabled robust corticospinal regeneration. The grafts synaptically integrated into multiple host intraspinal and supraspinal systems, including the corticospinal projection, and improved functional outcomes after injury. hPSC-derived spinal cord NSCs could enable a broad range of biomedical applications for in vitro disease modeling and constitute an improved clinically translatable cell source for ‘replacement’ strategies in several spinal cord disorders..
6. Hiromi Kumamaru, Paul Lu, Ephron S. Rosenzweig, Ken Kadoya, Mark H. Tuszynski, Regenerating Corticospinal Axons Innervate Phenotypically Appropriate Neurons within Neural Stem Cell Grafts, Cell Reports, 10.1016/j.celrep.2019.01.099, 26, 9, 2329-2339.e4, 2019.02, Neural progenitor cell grafts form new relays across sites of spinal cord injury (SCI). Using a panel of neuronal markers, we demonstrate that spinal neural progenitor grafts to sites of rodent SCI adopt diverse spinal motor and sensory interneuronal fates, representing most neuronal subtypes of the intact spinal cord, and spontaneously segregate into domains of distinct cell clusters. Host corticospinal motor axons regenerating into neural progenitor grafts innervate appropriate pre-motor interneurons, based on trans-synaptic tracing with herpes simplex virus. A human spinal neural progenitor cell graft to a non-human primate also received topographically appropriate corticospinal axon regeneration. Thus, grafted spinal neural progenitor cells give rise to a variety of neuronal progeny that are typical of the normal spinal cord; remarkably, regenerating injured adult corticospinal motor axons spontaneously locate appropriate motor domains in the heterogeneous, developing graft environment, without a need for additional exogenous guidance. Kumamaru et al. demonstrate that spinal cord neural progenitor cell grafts spontaneously segregate into motor and sensory domains when implanted into sites of spinal cord injury in rats and primates. Host corticospinal axons regenerating into grafts preferentially regenerate and synapse onto motor interneuron-rich domains, avoiding inappropriate sensory domains..
7. Iida K, Kumamaru H, Saito T, Harimaya K, Changes in magnetic resonance imaging signal intensity in predicting complications during acute phase osteoporotic vertebral fractures, J Orthop, 2020.06.
8. Hiromi Kumamaru, Paul Lu, Ephron S. Rosenzweig, Mark H. Tuszynski, Activation of Intrinsic Growth State Enhances Host Axonal Regeneration into Neural Progenitor Cell Grafts, Stem Cell Reports, 10.1016/j.stemcr.2018.08.009, 11, 4, 861-868, 2018.10, Axonal regeneration after spinal cord injury (SCI) can be enhanced by activation of the intrinsic neuronal growth state and, separately, by placement of growth-enabling neural progenitor cell (NPC) grafts into lesion sites. Indeed, NPC grafts support regeneration of all host axonal projections innervating the normal spinal cord. However, some host axons regenerate only short distances into grafts. We examined whether activation of the growth state of the host injured neuron would elicit greater regeneration into NPC grafts. Rats received NPC grafts into SCI lesions in combination with peripheral “conditioning” lesions. Six weeks later, conditioned host sensory axons exhibited a significant, 9.6-fold increase in regeneration into the lesion/graft site compared with unconditioned axons. Regeneration was further enhanced 1.6-fold by enriching NPC grafts with phenotypically appropriate sensory neuronal targets. Thus, activation of the intrinsic host neuronal growth state and manipulation of the graft environment enhance axonal regeneration after SCI. Kumamaru and colleagues demonstrate that activation of intrinsic growth state robustly enhances host sensory axonal regeneration into neural stem cell grafts. Regeneration of lesioned host sensory axons was further enhanced by enriching neural stem cell grafts with phenotypically appropriate sensory neuron targets..
9. Hiromi Kumamaru, Yasuyuki Ohkawa, Hirokazu Saiwai, Hisakata Yamada, Kensuke Kubota, Kazu Kobayakawa, Koichi Akashi, Hideyuki Okano, Yukihide Iwamoto, Seiji Okada, Direct isolation and RNA-seq reveal environment-dependent properties of engrafted neural stem/progenitor cells, Nature communications, 10.1038/ncomms2132, 3, 2012.11, Neural stem/progenitor cell (NSPC) transplantation is a promising treatment for various neurodegenerative disorders including spinal cord injury, however, no direct analysis has ever been performed on their in vivo profile after transplantation. Here we combined bioimaging, flow-cytometric isolation and ultra-high-throughput RNA sequencing to evaluate the cellular properties of engrafted NSPCs. The acutely transplanted NSPCs had beneficial effects on spinal cord injury, particularly neuroprotection and neurohumoral secretion, whereas their in situ secretory activity differed significantly from that predicted in vitro. The RNA-sequencing of engrafted NSPCs revealed dynamic expression/splicing changes in various genes involved in cellular functions and tumour development depending on graft environments. Notably, in the pathological environment, overall transcriptional activity, external signal transduction and neural differentiation of engrafted NSPCs were significantly suppressed. These results highlight the vulnerability of engrafted NSPCs to environmental force, while emphasizing the importance of in situ analysis in advancing the efficacy and safety of stem cell-based therapies..
10. Hiromi Kumamaru, Hirokazu Saiwai, Kensuke Kubota, Kazu Kobayakawa, Kazuya Yokota, Yasuyuki Ohkawa, Keiichiro Shiba, Yukihide Iwamoto, Seiji Okada, Therapeutic activities of engrafted neural stem/precursor cells are not dormant in the chronically injured spinal cord, STEM CELLS, 10.1002/stem.1404, 31, 8, 1535-1547, 2013.08, The transplantation of neural stem/precursor cells (NSPCs) is a promising therapeutic strategy for many neurodegenerative disorders including spinal cord injury (SCI) because it provides for neural replacement or trophic support. This strategy is now being extended to the treatment of chronic SCI patients. However, understanding of biological properties of chronically transplanted NSPCs and their surrounding environments is limited. Here, we performed temporal analysis of injured spinal cords and demonstrated their multiphasic cellular and molecular responses. In particular, chronically injured spinal cords were growth factorenriched environments, whereas acutely injured spinal cords were enriched by neurotrophic and inflammatory factors. To determine how these environmental differences affect engrafted cells, NSPCs transplanted into acutely, subacutely, and chronically injured spinal cords were selectively isolated by flow cytometry, and their whole transcriptomes were compared by RNA sequencing. This analysis revealed that NSPCs produced many regenerative/ neurotrophic molecules irrespective of transplantation timing, and these activities were prominent in chronically transplanted NSPCs. Furthermore, chronically injured spinal cords permitted engrafted NSPCs to differentiate into neurons/oligodendrocytes and provided more neurogenic environment for NSPCs than other environments. Despite these results demonstrate that transplanted NSPCs have adequate capacity in generating neurons/oligodendrocytes and producing therapeutic molecules in chronic SCI microenvironments, they did not improve locomotor function. Our results indicate that failure in chronic transplantation is not due to the lack of therapeutic activities of engrafted NSPCs but the refractory state of chronically injured spinal cords. Environmental modulation, rather modification of transplanting cells, will be significant for successful translation of stem cell-based therapies into chronic SCI patients..
11. Hiromi Kumamaru, Hirokazu Saiwai, Kazu Kobayakawa, Kensuke Kubota, Nico van Rooijen, Kazuhide Inoue, Yukihide Iwamoto, Seiji Okada, Liposomal clodronate selectively eliminates microglia from primary astrocyte cultures, Journal of Neuroinflammation, 10.1186/1742-2094-9-116, 9, 2012.05, Background: There is increasing interest in astrocyte biology because astrocytes have been demonstrated to play prominent roles in physiological and pathological conditions of the central nervous system, including neuroinflammation. To understand astrocyte biology, primary astrocyte cultures are most commonly used because of the direct accessibility of astrocytes in this system. However, this advantage can be hindered by microglial contamination. Although several authors have warned regarding microglial contamination in this system, complete microglial elimination has never been achieved.Methods: The number and proliferative potential of contaminating microglia in primary astrocyte cultures were quantitatively assessed by immunocytologic and flow cytometric analyses. To examine the utility of clodronate for microglial elimination, primary astrocyte cultures or MG-5 cells were exposed to liposomal or free clodronate, and then immunocytologic, flow cytometric, and gene expression analyses were performed. The gene expression profiles of microglia-eliminated and microglia-contaminated cultures were compared after interleukin-6 (IL-6) stimulation.Results: The percentage of contaminating microglia exceeded 15% and continued to increase because of their high proliferative activity in conventional primary astrocyte cultures. These contaminating microglia were selectively eliminated low concentration of liposomal clodronate. Although primary microglia and MG-5 cells were killed by both liposomal and free clodronate, free clodronate significantly affected the viability of astrocytes. In contrast, liposomal clodronate selectively eliminated microglia without affecting the viability, proliferation or activation of astrocytes. The efficacy of liposomal clodronate was much higher than that of previously reported methods used for decreasing microglial contamination. Furthermore, we observed rapid tumor necrosis factor-α and IL-1b gene induction in conventional primary astrocyte cultures after IL-6 stimulation, which was due to the activation of the Janus kinase/signal transducer and activator of the transcription pathway in contaminating microglia.Conclusions: Because contaminating microglia could result in erroneous data regarding the pro-inflammatory properties of astrocytes, astrocyte biology should be studied in the absence of microglial contamination. Our simple method will be widely applicable to experimental studies of astrocyte biology and provide clues for understanding the role of astrocytes in neural development, function and disease..
12. Hiromi Kumamaru, Hirokazu Saiwai, Yasuyuki Ohkawa, Hisakata Yamada, Yukihide Iwamoto, Seiji Okada, Age-related differences in cellular and molecular profiles of inflammatory responses after spinal cord injury, Journal of Cellular Physiology, 10.1002/jcp.22845, 227, 4, 1335-1346, 2012.04, Previous experimental and clinical studies have suggested that the behavioral and pathological outcomes of spinal cord injury (SCI) are affected by the individual's age at the time of injury. However, the underlying mechanism responsible for these differences remains elusive because it is difficult to match injuries of similar severities between young and adult animals due to differences in the sizes of their respective spinal cords. In this study, the spinal cord size-matched young (4-week-old) and adult (10-week-old) mice were compared to evaluate their locomotor functions and inflammatory cellular/molecular responses after standardized contusion SCI. During the acute phase of SCI, young mice showed better functional recovery and lower pro-inflammatory cytokines/chemokines compared to adult mice. Flow-cytometric analysis revealed that the time courses of leukocyte infiltration were comparable between both groups, while the number of infiltrating neutrophils significantly decreased from 6h after SCI in young mice. By combining flow-cytometric isolation and gene expression analysis of each inflammatory cell fraction, we found that microglial cells immediately initiate the production of several cytokines in response to SCI, which serve as major sources of IL-6, TNFa, and CXCL1 in injured spinal cord. Interestingly, the secretion of pro-inflammatory cytokines/chemokines but not anti-inflammatory cytokines by microglia was significantly lower in young mice compared to that in adult mice at 3h after SCI, which will be attributed to the attenuation of the subsequent neutrophil infiltration. These results highlight age-related differences in pro-inflammatory properties of microglial cells that contribute to the amplification of detrimental inflammatory responses after SCI..
13. Masamitsu Hara, Kazu Kobayakawa, Yasuyuki Ohkawa, Hiromi Kumamaru, Kazuya Yokota, Takeyuki Saito, Ken Kijima, Shingo Yoshizaki, Katsumi Harimaya, Yasuharu Nakashima, Seiji Okada, Interaction of reactive astrocytes with type i collagen induces astrocytic scar formation through the integrin-N-cadherin pathway after spinal cord injury, Nature Medicine, 10.1038/nm.4354, 23, 7, 818-828, 2017.07.
14. Ken Kadoya, Paul Lu, Kenny Nguyen, Corinne Lee-Kubli, Hiromi Kumamaru, Lin Yao, Joshua Knackert, Gunnar Poplawski, Jennifer N. Dulin, Hans Strobl, Yoshio Takashima, Jeremy Biane, James Conner, Su Chun Zhang, Mark H. Tuszynski, Spinal cord reconstitution with homologous neural grafts enables robust corticospinal regeneration, Nature medicine, 10.1038/nm.4066, 22, 5, 479-487, 2016.05, The corticospinal tract (CST) is the most important motor system in humans, yet robust regeneration of this projection after spinal cord injury (SCI) has not been accomplished. In murine models of SCI, we report robust corticospinal axon regeneration, functional synapse formation and improved skilled forelimb function after grafting multipotent neural progenitor cells into sites of SCI. Corticospinal regeneration requires grafts to be driven toward caudalized (spinal cord), rather than rostralized, fates. Fully mature caudalized neural grafts also support corticospinal regeneration. Moreover, corticospinal axons can emerge from neural grafts and regenerate beyond the lesion, a process that is potentially related to the attenuation of the glial scar. Rat corticospinal axons also regenerate into human donor grafts of caudal spinal cord identity. Collectively, these findings indicate that spinal cord 'replacement' with homologous neural stem cells enables robust regeneration of the corticospinal projection within and beyond spinal cord lesion sites, achieving a major unmet goal of SCI research and offering new possibilities for clinical translation..
15. Ephron S. Rosenzweig, John H. Brock, Paul Lu, Hiromi Kumamaru, Ernesto A. Salegio, Ken Kadoya, Janet L. Weber, Justine J. Liang, Rod Moseanko, Stephanie Hawbecker, J. Russell Huie, Leif A. Havton, Yvette S. Nout-Lomas, Adam R. Ferguson, Michael S. Beattie, Jacqueline C. Bresnahan, Mark H. Tuszynski, Restorative effects of human neural stem cell grafts on the primate spinal cord, Nature medicine, 10.1038/nm.4502, 24, 4, 484-490, 2018.05, We grafted human spinal cord-derived neural progenitor cells (NPCs) into sites of cervical spinal cord injury in rhesus monkeys (Macaca mulatta). Under three-drug immunosuppression, grafts survived at least 9 months postinjury and expressed both neuronal and glial markers. Monkey axons regenerated into grafts and formed synapses. Hundreds of thousands of human axons extended out from grafts through monkey white matter and synapsed in distal gray matter. Grafts gradually matured over 9 months and improved forelimb function beginning several months after grafting. These findings in a 'preclinical trial' support translation of NPC graft therapy to humans with the objective of reconstituting both a neuronal and glial milieu in the site of spinal cord injury..
16. Kazu Kobayakawa, Hiromi Kumamaru, Hirokazu Saiwai, Kensuke Kubota, Yasuyuki Ohkawa, Junji Kishimoto, Kazuya Yokota, Ryosuke Ideta, Keiichiro Shiba, Hidetoshi Saitoh, Kazuhide Inoue, Yukihide Iwamoto, Seiji Okada, Acute hyperglycemia impairs functional improvement after spinal cord injury in mice and humans, Science Translational Medicine, 10.1126/scitranslmed.3009430, 6, 256, 2014.01, Spinal cord injury (SCI) is a devastating disorder for which the identification of exacerbating factors is urgently needed. We demonstrate that transient hyperglycemia during acute SCI is a detrimental factor that impairs functional improvement in mice and human patients after acute SCI. Under hyperglycemic conditions, both in vivo and in vitro, inflammation was enhanced through promotion of the nuclear translocation of the nuclear factor κB (NF-κB) transcription factor in microglial cells. During acute SCI, hyperglycemic mice exhibited progressive neural damage, with more severe motor deficits than those observed in normoglycemic mice. Consistent with the animal study findings, a Pearson χ2 analysis of data for 528 patients with SCI indicated that hyperglycemia on admission (glucose concentration ≥126 mg/dl) was a significant risk predictor of poor functional outcome. Moreover, a multiple linear regression analysis showed hyperglycemia at admission to be a powerful independent risk factor for a poor motor outcome, even after excluding patients with diabetes mellitus with chronic hyperglycemia (regression coefficient, -1.37; 95% confidence interval, -2.65 to -0.10; P
17. Gunnar H.D. Poplawski, Richard Lie, Matt Hunt, Hiromi Kumamaru, Riki Kawaguchi, Paul Lu, Michael K.E. Schäfer, Grace Woodruff, Jacob Robinson, Philip Canete, Jennifer N. Dulin, Cedric G. Geoffroy, Lutz Menzel, Binhai Zheng, Giovanni Coppola, Mark H. Tuszynski, Adult rat myelin enhances axonal outgrowth from neural stem cells, Science Translational Medicine, 10.1126/scitranslmed.aal2563, 10, 442, 2018.05, Axon regeneration after spinal cord injury (SCI) is attenuated by growth inhibitory molecules associated with myelin. We report that rat myelin stimulated the growth of axons emerging from rat neural progenitor cells (NPCs) transplanted into sites of SCI in adult rat recipients. When plated on a myelin substrate, neurite outgrowth from rat NPCs and from human induced pluripotent stem cell (iPSC)–derived neural stem cells (NSCs) was enhanced threefold. In vivo, rat NPCs and human iPSC–derived NSCs extended greater numbers of axons through adult central nervous system white matter than through gray matter and preferentially associated with rat host myelin. Mechanistic investigations excluded Nogo receptor signaling as a mediator of stem cell–derived axon growth in response to myelin. Transcriptomic screens of rodent NPCs identified the cell adhesion molecule neuronal growth regulator 1 (Negr1) as one mediator of permissive axon-myelin interactions. The stimulatory effect of myelin-associated proteins on rodent NPCs was developmentally regulated and involved direct activation of the extracellular signal–regulated kinase (ERK). The stimulatory effects of myelin on NPC/NSC axon outgrowth should be investigated further and could potentially be exploited for neural repair after SCI..
18. Jennifer N. Dulin, Andrew F. Adler, Hiromi Kumamaru, Gunnar H.D. Poplawski, Corinne Lee-Kubli, Hans Strobl, Daniel Gibbs, Ken Kadoya, James W. Fawcett, Paul Lu, Mark H. Tuszynski, Injured adult motor and sensory axons regenerate into appropriate organotypic domains of neural progenitor grafts, Nature communications, 10.1038/s41467-017-02613-x, 9, 1, 2018.12, Neural progenitor cell (NPC) transplantation has high therapeutic potential in neurological disorders. Functional restoration may depend on the formation of reciprocal connections between host and graft. While it has been reported that axons extending out of neural grafts in the brain form contacts onto phenotypically appropriate host target regions, it is not known whether adult, injured host axons regenerating into NPC grafts also form appropriate connections. We report that spinal cord NPCs grafted into the injured adult rat spinal cord self-Assemble organotypic, dorsal horn-like domains. These clusters are extensively innervated by regenerating adult host sensory axons and are avoided by corticospinal axons. Moreover, host axon regeneration into grafts increases significantly after enrichment with appropriate neuronal targets. Together, these findings demonstrate that injured adult axons retain the ability to recognize appropriate targets and avoid inappropriate targets within neural progenitor grafts, suggesting that restoration of complex circuitry after SCI may be achievable..
19. Andrew F. Adler, Corinne Lee-Kubli, Hiromi Kumamaru, Ken Kadoya, Mark H. Tuszynski, Comprehensive Monosynaptic Rabies Virus Mapping of Host Connectivity with Neural Progenitor Grafts after Spinal Cord Injury, Stem Cell Reports, 10.1016/j.stemcr.2017.04.004, 8, 6, 1525-1533, 2017.06, Neural progenitor cells grafted to sites of spinal cord injury have supported electrophysiological and functional recovery in several studies. Mechanisms associated with graft-related improvements in outcome appear dependent on functional synaptic integration of graft and host systems, although the extent and diversity of synaptic integration of grafts with hosts are unknown. Using transgenic mouse spinal neural progenitor cell grafts expressing the TVA and G-protein components of the modified rabies virus system, we initiated monosynaptic tracing strictly from graft neurons placed in sites of cervical spinal cord injury. We find that graft neurons receive synaptic inputs from virtually every known host system that normally innervates the spinal cord, including numerous cortical, brainstem, spinal cord, and dorsal root ganglia inputs. Thus, implanted neural progenitor cells receive an extensive range of host neural inputs to the injury site, potentially enabling functional restoration across multiple systems..
20. Paul Lu, Steven Ceto, Yaozhi Wang, Lori Graham, Di Wu, Hiromi Kumamaru, Eileen Staufenberg, Mark H. Tuszynski, Prolonged human neural stem cell maturation supports recovery in injured rodent CNS, Journal of Clinical Investigation, 10.1172/JCI92955, 127, 9, 3287-3299, 2017.09, Neural stem cells (NSCs) differentiate into both neurons and glia, and strategies using human NSCs have the potential to restore function following spinal cord injury (SCI). However, the time period of maturation for human NSCs in adult injured CNS is not well defined, posing fundamental questions about the design and implementation of NSC-based therapies. This work assessed human H9 NSCs that were implanted into sites of SCI in immunodeficient rats over a period of 1.5 years. Notably, grafts showed evidence of continued maturation over the entire assessment period. Markers of neuronal maturity were first expressed 3 months after grafting. However, neurogenesis, neuronal pruning, and neuronal enlargement continued over the next year, while total graft size remained stable over time. Axons emerged early from grafts in very high numbers, and half of these projections persisted by 1.5 years. Mature astrocyte markers first appeared after 6 months, while more mature oligodendrocyte markers were not present until 1 year after grafting. Astrocytes slowly migrated from grafts. Notably, functional recovery began more than 1 year after grafting. Thus, human NSCs retain an intrinsic human rate of maturation, despite implantation into the injured rodent spinal cord, yet they support delayed functional recovery, a finding of great importance in planning human clinical trials. ENGL..
21. Francois Renault-Mihara, Masahiko Mukaino, Munehisa Shinozaki, Hiromi Kumamaru, Satoshi Kawase, Matthieu Baudoux, Toshiki Ishibashi, Soya Kawabata, Yuichiro Nishiyama, Keiko Sugai, Kaori Yasutake, Seiji Okada, Masaya Nakamura, Hideyuki Okano, Regulation of RhoA by STAT3 coordinates glial scar formation, Journal of Cell Biology, 10.1083/jcb.201610102, 216, 8, 2533-2550, 2017.01, Understanding how the transcription factor signal transducer and activator of transcription-3 (STAT3) controls glial scar formation may have important clinical implications. We show that astrocytic STAT3 is associated with greater amounts of secreted MMP2, a crucial protease in scar formation. Moreover, we report that STAT3 inhibits the small GTPase RhoA and thereby controls actomyosin tonus, adhesion turnover, and migration of reactive astrocytes, as well as corralling of leukocytes in vitro. The inhibition of RhoA by STAT3 involves ezrin, the phosphorylation of which is reduced in STAT3-CKO astrocytes. Reduction of phosphatase and tensin homologue (PTEN) levels in STAT3-CKO rescues reactive astrocytes dynamics in vitro. By specific targeting of lesion-proximal, reactive astrocytes in Nestin-Cre mice, we show that reduction of PTEN rescues glial scar formation in Nestin-Stat3+/- mice. These findings reveal novel intracellular signaling mechanisms underlying the contribution of reactive astrocyte dynamics to glial scar formation..
22. Akihito Harada, Seiji Okada, Daijiro Konno, Jun Odawara, Tomohiko Yoshimi, Saori Yoshimura, Hiromi Kumamaru, Hirokazu Saiwai, Toshiaki Tsubota, Hitoshi Kurumizaka, Koichi Akashi, Taro Tachibana, Anthony N. Imbalzano, Yasuyuki Ohkawa, Chd2 interacts with H3.3 to determine myogenic cell fate, EMBO Journal, 10.1038/emboj.2012.136, 31, 13, 2994-3007, 2012.07, Cell differentiation is mediated by lineage-determining transcription factors. We show that chromodomain helicase DNA-binding domain 2 (Chd2), a SNF2 chromatin remodelling enzyme family member, interacts with MyoD and myogenic gene regulatory sequences to specifically mark these loci via deposition of the histone variant H3.3 prior to cell differentiation. Directed and genome-wide analysis of endogenous H3.3 incorporation demonstrates that knockdown of Chd2 prevents H3.3 deposition at differentiation-dependent, but not housekeeping, genes and inhibits myogenic gene activation. The data indicate that MyoD determines cell fate and facilitates differentiation-dependent gene expression through Chd2-dependent deposition of H3.3 at myogenic loci prior to differentiation..
23. Katsumi Harimaya, Yoshihiro Matsumoto, Kenichi Kawaguchi, Seiji Okada, Hirokazu Saiwai, Akinobu Matsushita, Keiichiro Iida, Hiromi Kumamaru, Takeyuki Saito , Yasuharu Nakashima, Clinical features of multiple spinal schwannomas without vestibular schwannomas, Journal of Orthopaedic Science, 10.1016/j.jos.2021.02.014., 23, 21, S0949-2658, 2021.05.
24. Keiichiro Iida, Hiromi Kumamaru, Takeyuki Saito, Katsumi Harimaya, Overcorrection of fractured vertebrae increases the incidence of adjacent fractures after balloon kyphoplasty: A retrospective study, Journal of orthopaedics, 10.1016/j.jor.2021.02.035., 2, 24, 194-200, 2021.03.
25. Keiichiro Iida ,Hiromi Kumamaru ,Takeyuki Saito ,Katsumi Harimaya, Changes in magnetic resonance imaging signal intensity in predicting complications during acute phase osteoporotic vertebral fractures, Journal of orthopedics, 10.1016/j.jor.2020.05.021, 4, 21, 309-313, 2020.06.
26. Kensuke Kubota, Seiji Okada, Takeshi Maeda, Yoshihiro Matsumoto, Akio Sakamoto, Katsumi Harimaya, Hirokazu Saiwai, Hiromi Kumamaru, Yoshinao Oda, Yukihide Iwamoto, Extradural nodular fasciitis arising in the spinal canal, Spine, 10.1097/BRS.0b013e318224568a, 37, 2, 2012.01, STUDY DESIGN.: Case report. OBJECTIVE.: To describe a patient with nodular fasciitis arising in the lumbar extradural space. SUMMARY OF BACKGROUND DATA.: Nodular fasciitis is a benign proliferation of fibroblasts and myofibroblasts. It commonly occurs in the subcutaneous tissue of an upper extremity, trunk, head, and neck, but rarely arises in the spinal canal. METHODS.: A 7-year-old boy experienced gradually increasing intense radiating pain from the bilateral buttocks to the lower extremities after a bruise on his lower back. Computed tomography and magnetic resonance imaging demonstrated a relatively circumscribed mass in the dorsal epidural space from the first lumbar vertebra (L1) to L2. The presumptive diagnosis based on the radiologic findings included aggressive neoplasm such as extraskeletal Ewing sarcoma/primitive neuroectodermal tumor or malignant lymphoma. RESULTS.: The patient underwent L1-L2 laminectomy and resection of the tumor. Histologically, the tumor was mainly composed of a proliferation of spindle cells without atypia, positive for vimentin and smooth muscle actin, and myxoid areas with a loosely textured feathery pattern. These findings are the typical features of nodular fasciitis. Surgery relieved the patient's pain, with no evidence of recurrence at a recent 4-year follow-up. CONCLUSION.: This report presents a very rare case of extradural nodular fasciitis arising in the lumbar spinal canal, which could have been misinterpreted as a malignant tumor such as extraskeletal Ewing sarcoma/primitive neuroectodermal tumor because of its rapid growth and absence of distinguishing radiologic features. A detailed histopathologic examination including immunohistochemistry is important for the correct diagnosis..
27. Kensuke Kubota, Hirokazu Saiwai, Hiromi Kumamaru, Kazu Kobayakawa, Takeshi Maeda, Yoshihiro Matsumoto, Katsumi Harimaya, Yukihide Iwamoto, Seiji Okada, Neurological recovery is impaired by concurrent but not by asymptomatic pre-existing spinal cord compression after traumatic spinal cord injury, Spine, 10.1097/BRS.0b013e31824ffda5, 37, 17, 1448-1455, 2012.08, STUDY DESIGN. An in vivo animal study to examine the influence of pre-existing or concurrent spinal canal stenosis (SCS) on the functional recovery after spinal cord injury (SCI). OBJECTIVES. To clarify whether spinal cord compression before or after SCI results in less favorable neurological recovery. SUMMARY OF BACKGROUND DATA. The influence of spinal cord compression on the neurological recovery after SCI remains unclear. METHODS. We created mice with SCS using an extradural spacer before or after producing SCI and statistically analyzed the correlation between the extent of SCS and neurological outcomes. The extent of SCS was calculated by micro-computed tomography, and the spinal cord blood flow (SCBF) was measured serially with laser Doppler flowmetry. Molecular and immunohistochemical examinations were performed to evaluate the neovascularization at the site of cord compression. RESULTS. Spacer placement (
28. Seiji Okada, Takeshi Maeda, Yasuyuki Ohkawa, Katsumi Harimaya, Hirokazu Saiwai, Hiromi Kumamaru, Yoshihiro Matsumoto, Toshio Doi, Takayoshi Ueta, Keiichiro Shiba, Yukihide Iwamoto, Does ossification of the posterior longitudinal ligament affect the neurological outcome after traumatic cervical cord injury?, Spine, 10.1097/BRS.0b013e31819e3215, 34, 11, 1148-1152, 2009.05, STUDY DESIGN.: Retrospective outcome measurement study. OBJECTIVES.: The purpose of this study is to assess whether ossification of the posterior longitudinal ligament (OPLL) affects neurologic outcomes in patients with acute cervical spinal cord injury (SCI). SUMMARY OF BACKGROUND DATA.: There have so far been few reports examining the relationship between OPLL and SCI and there is controversy regarding the deteriorating effects of OPLL-induced canal stenosis on neurologic outcomes. METHODS.: To obtain a relatively uniform background, patients nonsurgically treated for an acute C3-C4 level SCI without any fractures or dislocations of the spinal column were selected, resulting in 129 patients. There were 110 men and 19 women (mean age was 61.1 years), having various neurologic conditions on admission (American Spinal Injury Association [ASIA] impairment scale A, 43; B, 16; C, 58; D, 12). The follow-up period was the duration of their hospital stay and ranged from 50 to 603 days (mean, 233 days). The presence of OPLL, the cause of injury, the degree of canal stenosis (both static and dynamic), and the neurologic outcomes in motor function, including improvement rate, were assessed. RESULTS.: Of the 129 patients investigated in this study, OPLL was identified at the site of the injury in 13 patients (10.1%). In this OPLL+ group, the static and dynamic canal diameters at C3 and C4 were significantly smaller than those of the remaining 116 patients (OPLL- group). However, no significant difference was observed between the 2 groups in terms of ASIA motor score both at the time of administration and discharge, and the mean improvement rate in ASIA motor score was 55.5 ± 9.0% in OPLL+ group, while it was 43.1 ± 2.8% in the OPLL-group. Furthermore, no significant correlation was observed between the static/dynamic canal diameters and neurologic outcome in all 129 patients. CONCLUSION.: No evidence was found for OPLL to have any effect on the initial neurologic status or recovery in motor function after traumatic cervical cord injury, suggesting that the neurologic outcome is not significantly dependent on canal space..
29. Kensuke Kubota, Hirokazu Saiwai, Hiromi Kumamaru, Takeshi Maeda, Yasuyuki Ohkawa, Yasuaki Aratani, Tetsuo Nagano, Yukihide Iwamoto, Seiji Okada, Myeloperoxidase exacerbates secondary injury by generating highly reactive oxygen species and mediating neutrophil recruitment in experimental spinal cord injury, Spine, 10.1097/BRS.0b013e31824b9e77, 37, 16, 1363-1369, 2012.07.
30. Takeyuki Saito, Masamitsu Hara, Hiromi Kumamaru, Kazu Kobayakawa, Kazuya Yokota, Ken Kijima, Shingo Yoshizaki, Katsumi Harimaya, Yoshihiro Matsumoto, Kenichi Kawaguchi, Mitsumasa Hayashida, Yutaka Inagaki, Keiichiro Shiba, Yasuharu Nakashima, Seiji Okada, Macrophage Infiltration Is a Causative Factor for Ligamentum Flavum Hypertrophy through the Activation of Collagen Production in Fibroblasts, American Journal of Pathology, 10.1016/j.ajpath.2017.08.020, 187, 12, 2831-2840, 2017.12.
31. Hirokazu Saiwai, Hiromi Kumamaru, Yasuyuki Ohkawa, Kensuke Kubota, Kazu Kobayakawa, Hisakata Yamada, Takehiko Yokomizo, Yukihide Iwamoto, Seiji Okada, Ly6C+Ly6G- Myeloid-derived suppressor cells play a critical role in the resolution of acute inflammation and the subsequent tissue repair process after spinal cord injury, Journal of Neurochemistry, 10.1111/jnc.12135, 125, 1, 74-88, 2013.04, Acute inflammation is a prominent feature of central nervous system (CNS) insult and is detrimental to the CNS tissue. Although this reaction spontaneously diminishes within a short period of time, the mechanism underlying this inflammatory resolution remains largely unknown. In this study, we demonstrated that an initial infiltration of Ly6C+Ly6G- immature monocyte fraction exhibited the same characteristics as myeloid-derived suppressor cells (MDSCs), and played a critical role in the resolution of acute inflammation and in the subsequent tissue repair by using mice spinal cord injury (SCI) model. Complete depletion of Ly6C+Ly6G- fraction prior to injury by anti-Gr-1 antibody (clone: RB6-8C5) treatment significantly exacerbated tissue edema, vessel permeability, and hemorrhage, causing impaired neurological outcomes. Functional recovery was barely impaired when infiltration was allowed for the initial 24 h after injury, suggesting that MDSC infiltration at an early phase is critical to improve the neurological outcome. Moreover, intraspinal transplantation of ex vivo-generated MDSCs at sites of SCI significantly reduced inflammation and promoted tissue regeneration, resulting in better functional recovery. Our findings reveal the crucial role of an Ly6C+Ly6G- fraction as MDSCs in regulating inflammation and tissue repair after SCI, and also suggests an MDSC-based strategy that can be applied to acute inflammatory diseases. Myeloid-derived suppressor cells (MDSCs) exert immunosuppressive effects in several inflammatory diseases, including cancer and autoimmune disease. We demonstrated that Ly6C+Ly6G- myeloid cells which infiltrated into injured spinal cord had a typical feature of MDSCs and played a critical role in the attenuation of acute inflammation and the subsequent tissue repair process after spinal cord injury (SCI). Our findings clarified the role of MDSCs after traumatic SCI, and suggested a potential MDSC-based therapeutic strategy for the acute phase of central nervous system injury..
32. Seiji Okada, Hirokazu Saiwai, Hiromi Kumamaru, Kensuke Kubota, Akihito Harada, Masahiro Yamaguchi, Yukihide Iwamoto, Yasuyuki Ohkawa, Flow cytometric sorting of neuronal and glial nuclei from central nervous system tissue, Journal of cellular physiology, 10.1002/jcp.22365, 226, 2, 552-558, 2011.02, Due to the complex cellular heterogeneity of the central nervous system (CNS), it is relatively difficult to reliably obtain molecular descriptions with cell-type specificity. In particular, comparative analysis of epigenetic regulation or molecular profiles is hampered by the lack of adequate methodology for selective purification of defined cell populations from CNS tissue. Here, we developed a direct purification strategy of neural nuclei from CNS tissue based on fluorescence-activated cell sorting (FACS). We successfully fractionated nuclei from complex tissues such as brain, spinal cord, liver, kidney, and skeletal muscle extruded mechanically or chemically, and fractionated nuclei were structurally maintained and contained nucleoproteins and nuclear DNA/RNA. We collected sufficient numbers of nuclei from neurons and oligodendrocytes using FACS with immunolabeling for nucleoproteins or from genetically labeled transgenic mice. In addition, the use of Fab fragments isolated from papain antibody digests, which effectively enriched the specialized cell populations, significantly enhanced the immunolabeling efficacy. This methodology can be applied to a wide variety of heterogeneous tissues and is crucial for understanding the cell-specific information about chromatin dynamics, nucleoproteins, protein-DNA/RNA interactions, and transcriptomes retained in the nucleus, such as non-coding RNAs..
33. Kazu Kobayakawa, Hiromi Kumamaru, Hirokazu Saiwai, Kensuke Kubota, Yasuyuki Ohkawa, Junji Kishimoto, Kazuya Yokota, Ryosuke Ideta, Keiichiro Shiba, Hidetoshi Tozaki-Saitoh, Kazuhide Inoue, Yukihide Iwamoto, Seiji Okada, Acute hyperglycemia impairs functional improvement after spinal cord injury in mice and humans, SCIENCE TRANSLATIONAL MEDICINE, 6, 256, 2014.10.
34. Akihito Harada, Seiji Okada, Jun Odawara, Hiromi Kumamaru, Hirokazu Saiwai, Mayumi Aoki, Mako Nakamura, Yuko Nishiyama, Yasuyuki Ohkawa, Production of a rat monoclonal antibody specific for Myf5, Hybridoma, 10.1089/hyb.2009.0066, 29, 1, 59-62, 2010.02, Myogenic regulatory factors (MRFs) are transcription factors that possess a characteristic basic helix-loop-helix domain. Myf5, MyoD, MRF4, and myogenin are well-known MRF family members that activate muscle-specific genes during differentiation. Myf5 is expressed first among MRFs at the very early phase and plays an important role in myoblast specificity and cell proliferation. Myf5 shares high homology with MyoD, and therefore some commercial Myf5 antibodies are cross-reactive for Myf5 and MyoD. To allow for detailed studies of the function of Myf5, we generated a monoclonal antibody specific for Myf5 utilizing a rat medial iliac lymph node method. Immunoblot analysis using our monoclonal antibody enabled us to identify Myf5 protein from rat myoblast L6E9 cell extract. Moreover, cell immunostaining revealed the nuclear localization of Myf5 in the L6E9 cells. This monoclonal antibody against Myf5 will allow us to perform further detailed studies of Myf5 and Myf5 function..