Ji Hoon Phi

Pediatric moyamoya disease: An analysis of 410 consecutive cases

Moyamoya disease (MMD) is a cerebrovascular occlusive disease of the bilateral internal carotid arteries that causes a compensatory abnormal vascular network at the base of brain. The rare incidence and various surgical techniques applied have limited the clinical research on MMD.

Targeting Rat Brainstem Glioma Using Human Neural Stem Cells and Human Mesenchymal Stem Cells

Purpose: Brainstem gliomas are usually inoperable and have a dismal prognosis. Based on the robust tropisms of neural stem cells (NSC) and mesenchymal stem cells (MSC) to brain tumors, we compared the tumor-tropic migratory capacities of these stem cells and evaluated the therapeutic potential of genetically engineered human NSCs encoding cytosine deaminase (CD) and IFNβ against brainstem gliomas. Experimental Design: The directed migratory capacities of NSCs and MSCs to brainstem glioma (F98) were evaluated both in vitro and in vivo. The human NSCs (HB1.F3) and various human MSCs, such as bone marrow–derived MSCs (HM3.B10), adipose tissue–derived MSCs, and umbilical cord blood–derived MSCs, were tested. Human fibroblast cells (HFF-1) were used as the negative control. As a proof of concept, the bioactivity of HB1.F3-CD-IFNβ was analyzed with a cell viability assay, and animals with brainstem gliomas were injected with HB1.F3-CD-IFNβ cells followed by systemic 5-fluorocytosine treatment. Results: In an in vitro modified Transwell migration assay and in vivo stem cell injection into established brainstem gliomas in rats, all the stem cells showed a significant migratory capacity compared with that of the control (P < 0.01). Histologic analysis showed a 59% reduction in tumor volume in the HB1.F3-CD-IFNβ–treated group (P < 0.05). Apoptotic cells were increased 2.33-fold in animals treated with HB1.F3-CD-IFNβ compared with the respective control groups (P < 0.01). Conclusion: The brainstem glioma-tropic migratory capacities of MSCs from various sources were similar to those of NSCs. Genetically engineered NSCs show therapeutic efficacy against brainstem gliomas.

Sox2 Expression in Brain Tumors : A Reflection of the Neuroglial Differentiation Pathway

Sox2 is a key transcription factor that maintains the proliferation of neuroglial stem cells and inhibits neuronal fate commitment. Moreover, it was recently found that brain tumors contain stem cells that resemble normal neuroglial stem cells in many respects. This study was undertaken to describe Sox2 expression in various brain tumors, and to determine whether Sox2 expression is a universal feature of brain tumors, or whether its expression is limited to a specific lineage of brain tumors. Sox2 immunohistochemistry was performed on 194 brain tumor tissues of various kinds. Fetal and adult normal brain tissues obtained by autopsy and brain tissues of epilepsy patients with cortical dysplasia were used as controls. Semiquantitative reverse transcription polymerase chain reaction was used to confirm the immunohistochemical results. Double immunofluorescence was performed to characterize the lineage of Sox2-positive cells. Sox2 was found to be expressed in various glial tumors, including those with astroglial, oligodendroglial, and ependymal lineages, and in the glial components of mixed neuroglial tumors, regardless of pathologic grade. In brain tumors of embryonal origin, supratentorial primitive neuroectodermal tumors showed robust Sox2 expression, whereas medulloblastomas and pineoblastomas did not. The majority of Sox2-positive tumor cells coexpressed glial fibrillary acidic protein, and most Sox2-negative cells in medulloblastomas and pineoblastomas showed neuronal differentiation. This study suggest that Sox2 may be a tumor marker of glial lineages rather than a universal brain tumor stem cell marker, because its expression pattern was found to correspond to differentiation pathways. On the other hand, the aberrant coexpressions of Sox2 and of a neuronal marker were widely observed in glioblastomas, which reflects a disorganized differentiation pattern that characterizes highly malignant tumors.

Human adipose tissue-derived mesenchymal stem cells: Characteristics and therapeutic potential as cellular vehicles for prodrug gene therapy against brainstem gliomas

Human mesenchymal stem cells (hMSCs) have emerged as attractive cellular vehicles for gene therapy against brain malignancy because of their targeted tropism for cancer and the intrinsic attribute of autologous transplantation. We evaluated the characteristics and therapeutic potential of human adipose tissue-derived MSCs (hAT-MSCs) and prodrug gene therapy against diffuse pontine gliomas. The hAT-MSCs were isolated from human adipose tissue and characterised for morphology, surface markers and potential to differentiate into mesenchymal and neuronal lineages. We genetically modified hAT-MSCs to express rabbit carboxylesterase (rCE) enzyme, which can efficiently convert the prodrug CPT-11 (irinotecan-7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin), into the active drug SN-38 (7-ethyl-10-hydroxycamptothecin). The migratory capacity of hAT-MSCs expressing rCE (hAT-MSC.rCE), their ability to convert CPT-11 to SN-38 and cytotoxic effect on F98 cells were evaluated in vitro. The therapeutic potential of hAT-MSC.rCE was confirmed using a rat brainstem glioma model. The hAT-MSCs showed fibroblast-like morphology and expressed hMSC-specific markers including CD73, CD90 and CD105. The hAT-MSCs could differentiate into a mesenchymal lineage and transdifferentiate into a neuronal lineage under optimum culture conditions. The hAT-MSC.rCE converted CPT-11 to SN-38 and preserved the tumour tropism of hAT-MSCs. Brainstem glioma-bearing rats treated with hAT-MSC.rCE and CPT-11 survived 5d more than rats treated with CPT-11 only (p=0.0018). Our study demonstrates that hAT-MSCs can be easily prepared and genetically modified as cellular vehicles for prodrug gene therapy and that they have therapeutic potential against brainstem gliomas.

Therapeutic efficacy and safety of TRAIL- producing human adipose tissue-derived mesenchymal stem cells against experimental brainstem glioma

Mesenchymal stem cells (MSCs) have an extensive migratory capacity for gliomas, which is comparable to that of neural stem cells. Among the various types of MSCs, human adipose tissue-derived MSCs (hAT-MSC) emerge as one of the most attractive vehicles for gene therapy because of their high throughput, lack of ethical concerns, and availability and ease of isolation. We evaluated the therapeutic potential and safety of genetically engineered hAT-MSCs encoding the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) against brainstem gliomas. Human AT-MSCs were isolated from human fat tissue, characterized, and transfected with TRAIL using nucleofector. The therapeutic potential of TRAIL-producing hAT-MSCs (hAT-MSC.TRAIL) was confirmed using in vitro and in vivo studies. The final fate of injected hAT-MSCs was traced in long-survival animals. The characterization of hAT-MSCs revealed the expression of MSC-specific cell-type markers and their differentiation potential into mesenchymal lineage. Short-term outcomes included a 56.3% reduction of tumor volume (P < .001) with increased apoptosis (3.03-fold, P < .05) in animals treated with hAT-MSC.TRAIL compared with the control groups. Long-term outcomes included a significant survival benefit in the hAT-MSC.TRAIL-treated group (26 days of median survival in the control group vs 84 days in the hAT-MSC.TRAIL-treated group, P < .0001), without any evidence of mesenchymal differentiation in vivo. Our study demonstrated the therapeutic efficacy and safety of nonvirally engineered hAT-MSCs against brainstem gliomas and showed the possibility of stem-cell-based targeted gene therapy for clinical application.

Plasma Matrix Metalloproteinases, Cytokines, and Angiogenic Factors in Moyamoya Disease

Objective To document the expression patterns of various matrixins, cytokines and angiogenic factors in plasma to assess their involvement in the pathogenesis of moyamoya disease (MMD). Methods This study included plasma samples from 20 MMD patients and nine healthy individuals. The plasma concentration of five matrix metalloproteinases (MMP-1, MMP-2, MMP-3, MMP-9, MMP-12), monocyte chemoattractant protein-1 (MCP-1), resistin, three interleukins (IL-1β, IL-6, IL-8), tumour necrosis factor-α, vascular endothelial growth factor (VEGF), platelet-derived growth factor BB (PDGF-BB) and basic fibroblast growth factor was determined using multianalyte profiling systems. The concentration of the tissue inhibitors of metalloproteinase (TIMP-1 and TIMP-2) was measured using ELISA. Gelatin zymography for MMP-2 and MMP-9 was also performed. Results MMD patients exhibited significantly higher plasma concentrations of MMP-9, MCP-1, IL-1β, VEGF and PDGF-BB, and lower plasma concentrations of MMP-3, TIMP-1 and TIMP-2 compared with healthy controls. Significant correlations were found among MMP-9, MCP-1, VEGF, PDGF-BB and TIMP-2 in MMD patients. Conclusion There were distinctive expression patterns of matrixins, cytokines and angiogenic factors in MMD patients, which seemed to correlate with disease pathogenesis. The balance between MMPs and TIMPs was disrupted in MMD and correlated with disease pathogenesis. Increased plasma levels of MCP-1 and VEGF in MMD patients may play a role in the recruitment of vascular progenitor cells and in the formation of collateral vessels.

Long-term outcomes in children with glioblastoma

OBJECT Glioblastoma is the most common primary malignant brain tumor; however, glioblastoma in children is less common than in adults, and little is known about its clinical outcome in children. The authors evaluated the long-term outcome of glioblastoma in children. METHODS Twenty-seven children were confirmed to have harbored a glioblastoma between 1985 and 2007. The clinical features and treatment outcomes were reviewed retrospectively. All patients underwent resection; complete resection was performed in 12 patients (44%), subtotal resection in 12 patients (44%), and biopsy in 3 patients (11%). Twenty-four patients (89%) had radiation therapy, and 14 (52%) patients received chemotherapy plus radiation therapy. Among the latter, 5 patients had radiation therapy concurrent with temozolomide chemotherapy. Four patients with small-size recurrent glioblastoma received stereotactic radiosurgery. RESULTS The median overall survival (OS) was 43 months, and the median progression-free survival was 12 months. The OS rate was 67% at 1 year, 52% at 2 years, and 40% at 5 years. The median OS was significantly associated with tumor location (52 months for superficially located tumors vs 7 months for deeply located tumors; p = 0.017) and extent of removal (106 months for completely resected tumors vs 11 months for incompletely resected tumors; p < 0.0001). CONCLUSIONS The prognosis of glioblastoma is better in children than in adults. Radical resection followed by concurrent chemoradiation therapy may be the initial treatment of choice.

Radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2: tumor control and hearing preservation.

The radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2 (NF2) is controversial. The authors investigated the radiologically proven tumor control rate after gamma knife radiosurgery. The factors that affect tumor control and serviceable hearing preservation were analyzed.

Long-term surgical outcomes of temporal lobe epilepsy associated with low-grade brain tumors

Tumor‐related temporal lobe epilepsy (TLE) has a high likelihood of medical intractability and requires surgical treatment. The aims of this study were to analyze the long‐term surgical outcomes of and to present appropriate surgical strategies for tumor‐related TLE.

Longitudinal analyses of the surgical outcomes of pediatric epilepsy patients with focal cortical dysplasia.

OBJECT The long-term surgical outcome of pediatric patients with epilepsy accompanied by focal cortical dysplasia (FCD) is not clear. The authors report on the long-term surgical outcomes of children with FCD, based on longitudinal analyses. METHODS The authors retrospectively analyzed the records of 41 children who underwent epilepsy surgery for pathologically proven FCD. Twenty of these patients were male and 21 were female. The median age at surgery was 9 years (range 1-17 years). RESULTS The actuarial seizure-free rates were 49, 44, and 33% in the 1st, 2nd, and 5th years after surgery, respectively. There was no seizure recurrence after 3 years. Three patients with initial failure of seizure control experienced late remission of seizures (the so-called running-down phenomenon). Eventually, 19 patients (46%) were seizure free at their last follow-up visit. Absence of a lesion on MR imaging and incomplete resection were significantly associated with seizure-control failure. Concordance of presurgical evaluation data was a marginally significant variable for seizure control in patients with lesional epilepsy. Three patients with seizure-control failure became seizure free as a result of the running-down phenomenon. The actuarial rate of antiepileptic drug discontinuation was 91% in the 5th year in the seizure-free patients. CONCLUSIONS The seizure-free rate after surgery in children with FCD was 49% in the 1st year; however, it declined thereafter. The running-down phenomenon could be an important mechanism of seizure alleviation for patients with FCD during long-term follow-up. Because a complete resection of FCD has a strong prognostic implication for seizure control, a better method to define the extent of FCD is required to assist with resection, especially in nonlesional epilepsy.