[Show abstract][Hide abstract] ABSTRACT: Embryonic stem (ES) cell-derived astrocytes have several theoretical and practical advantages as gene therapy vectors in the treatment of malignant gliomas. The aim of this study was to test the proapoptotic effects of ES cell-derived astrocytes expressing transgenic tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in human malignant glioma cells.
Mouse ES cells containing a doxycycline-inducible transgene were engineered with human TRAIL (hTRAIL) and then directed to differentiate into astrocytes. The ES cell-derived-TRAIL-expressing astrocytes were cocultured with human malignant glioma cells. Reverse transcriptase polymerase chain reaction, immunocytochemistry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, and flow cytometry were used to quantify results. In vitro coculture of ES cell-derived astrocytes expressing hTRAIL with A172 human malignant glioma cells after doxycycline induction caused a significant decrease in cell viability from 85 +/- 2% at baseline to 8 +/- 2% posttreatment (p < 0.001). Labeling with apoptotic markers showed that cell death occurred by means of apoptosis. A significant increase in apoptotic rate (88 +/- 3%) from baseline (4 +/- 2%) was found in A172 cells after doxycycline induction (p < 0.005). This effect was superior to the apoptotic rate seen after treatment with recombinant TRAIL (57 +/- 2%). A decrease in cell viability and an increase in the apoptotic rate were not found in TRAIL-expressing-ES cell-derived astrocytes after induction with doxycycline or in A172 cells exposed to doxycycline alone.
Engineering of transgenic hTRAIL by using ES cell-derived astrocytes induced apoptosis in human malignant glioma cells while sparing nontumor astrocytes. The apoptotic effects of transgenic hTRAIL are greater than those of recombinant hTRAIL. Analysis of these results suggests that hTRAIL-expressing-ES cell-derived astrocytes should be considered in the development of new in vivo strategies to treat malignant human gliomas.
Journal of Neurosurgery 07/2006; 105(1):88-95. · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pituicytomas are rare tumors. Previously reported pituicytomas all presented with signs and symptoms relating to mass effect or endocrinological dysfunction. We report a 47 year old man who presented with sudden, severe headache and was found to have a hemorrhagic suprasellar mass with hemorrhage into the third ventricle. A mass arising from the pituitary stalk was found at surgery, and thorough pathological analysis revealed a pituicytoma. Pituicytoma should be considered in the differential diagnosis of a hemorrhagic suprasellar mass.
[Show abstract][Hide abstract] ABSTRACT: For gene therapy strategies currently in clinical trials, viral vectors are used to deliver transgenes directly to normal and tumor cells within the central nervous system (CNS). The use of viral vectors is limited by several factors. The aim of this study was to assess whether embryonic stem cell (ESC)-derived astrocytes expressing a doxycyclineinducible transgene can be used as a vector for gene therapy.
The authors generated a pure population of ESC-derived astrocytes carrying a transgene, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), inserted in the chromosome under the control of a highly regulated doxycycline-inducible expression system. Fully differentiated ESC-derived astrocytes were stereotactically transplanted in the mouse brain, and then cell migration and transgene expression were studied.
The ESC-derived astrocytes started to migrate from the transplant site 48 hours after the procedure. They were found to have migrated throughout the brain tissue by 6 weeks. Transplanted ESC-derived astrocytes expressed the TRAIL transgene after doxycycline induction throughout the duration of the experiment. Teratoma formation was not observed in long-term experiments (12 weeks).
These data show that ESC-derived astrocytes can be used as delivery vectors for CNS tumors. This technique might have a major impact on the treatment of patients with malignant gliomas and a wide spectrum of other neurological diseases.
[Show abstract][Hide abstract] ABSTRACT: Embryonic stem cell (ESC)-derived astrocytes have many theoretical and practical advantages as vectors for delivery of gene therapy to the central nervous system (CNS). The aim of this study was to generate highly pure populations of ESC-derived astrocytes expressing drug-inducible transgenes, while minimizing contamination by undifferentiated ESCs
Embryonic stem cells carrying a doxycycline-inducible green fluorescent protein (GFP) transgene were induced to differentiate into astrocytes by using feeder cell-free conditions that are completely defined. More than 95% of these cells expressed the astrocyte markers glial fibrillary acidic protein and GLT-1 glutamate transporter, and the morphological characteristics of these cells were typical of astrocytes. The expression of additional astrocyte markers was detected using reverse transcription-polymerase chain reaction. Undifferentiated ESCs comprised fewer than 0.1% of the cells after 10 days in this culture. Positive and negative selection techniques based on fluorescence-activated cell sorting were successfully used to decrease further the numbers of undifferentiated ESCs. Fully differentiated astrocytes expressed a GFP transgene under the tight control of a doxycycline-responsive promoter, and maintained their astrocytic phenotype 24 hours after transplantation into the mouse brain.
This study shows that transgenic ESCs can be induced to differentiate into highly pure populations of astrocytes. The astrocytes continue to express the transgene under the tight control of a drug-inducible promoter and are suitable for transplantation into the mouse brain. The number of potentially hazardous ESCs can be minimized using cell-sorting techniques. This strategy may be used to generate cellular vectors for delivering gene therapy to the CNS.
Journal of Neurosurgery 08/2005; 103(1):115-23. · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper the authors describe the indications for and the results and complications of repeated transsphenoidal surgery (RTSS) to treat recurrent or residual pituitary adenoma.
A retrospective review was conducted of 96 consecutive patients who underwent RTSS to treat recurrent or residual pituitary adenoma. Ninety-six patients underwent RTSS: 42 to treat a recurrent or residual pituitary mass and 54 to treat a recurrent or persistent hormone hypersecretion. There was no case of perioperative death and there was a 1% incidence of major complications. Postoperative endocrinological deficiencies were uncommon unless planned total hypophysectomy was performed to treat Cushing disease. Clinical remission occurred in 93% of patients undergoing RTSS to treat a tumor mass, and 15% of patients initially experienced remission only to face a relapse after a mean of 32 months. Endocrinological remission occurred in 57% of patients undergoing RTSS to treat hormone hypersecretion; most of these patients had Cushing disease. Thirty-five percent of patients with an initial endocrinological remission experienced a relapse of their symptoms after a mean of 31 months (thus, 37% of patients achieved sustained endocrinological remission). We failed to identify factors that accurately predicted initial symptom remission or delayed relapse following RTSS. Ten patients in our series eventually underwent a third transsphenoidal surgery without major complications.
Repeated transsphenoidal surgery is a more effective treatment for recurrent or residual mass than it is for hormone hypersecretion and has acceptable rates of morbidity and mortality. If hypophysectomy is not performed, endocrinological deficiencies are unlikely following RTSS.
Journal of Neurosurgery 07/2005; 102(6):1004-12. · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Intraoperative brain shift may cause inaccuracy of stereotactic image guidance on the basis of preoperatively acquired imaging data. The purpose of our study was to determine whether factors predicting brain shift affect the success of image-guided resection of malignant brain tumors.
We retrospectively studied 54 patients who underwent image-guided resections of histopathologically confirmed malignant brain tumors (9 metastases, 45 high-grade gliomas). Precautions were taken during surgery to minimize brain shift, but intraoperative imaging was not performed. The following factors predictive of intraoperative brain shift were assessed: tumor size, periventricular location, patient age, prior surgery or radiation therapy, patient positioning, use of mannitol, and length of operative time. Postoperative magnetic resonance imaging was obtained in all cases within 48 hours of surgery to assess extent of resection.
Perioperative mortality was 0% in our series; perioperative morbidity was 3 of 54 patients (5.5%); 1 patient required reoperation for a hematoma, and 2 had transient neurological deficits. Successful resection was accomplished in 93% of tumors less than 30 cm(3) compared with 63.6% of tumors greater than 30 cm(3) (P = .026, Fisher exact test). This difference was more pronounced for patients with malignant gliomas. However, other factors predictive of intraoperative brain shift were not associated with unsuccessful resection.
Intraoperative brain shift does not significantly affect the likelihood of successful resection of malignant brain tumors smaller than 30 cm(3). Larger tumors are less likely to be successfully resected, although factors other than brain shift can contribute to unsuccessful resection.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to identify the optimal surgical goals and techniques for managing symptomatic Rathke cleft cysts (RCCs).
The authors conducted a retrospective study of 62 consecutive patients who had undergone surgery for RCCs. Postoperative follow up was a mean of 28 months. Fifty-six patients underwent transsphenoidal cyst decompression and biopsy procedures, and six underwent cyst wall resection. Postoperatively, symptoms improved in 91% of patients with headaches and 92% of patients with visual deficits. Decompression and biopsy were associated with a 10% incidence of new anterior pituitary hormone deficiencies and a 6% incidence of new permanent diabetes insipidus; the incidence of new hormone deficiencies was significantly higher in the few patients who had undergone cyst wall resection. The incidence of relapse, defined as cyst regrowth with either recurrent symptoms or chiasmal compression, was 16%. Resection of the cyst wall was associated with a trend toward a decreased risk of relapse. Sellar packing, sellar floor reconstruction, and irrigation with absolute ethanol did not affect the likelihood of relapse. Squamous metaplasia and inflammation increased the risk of relapse. Residual cyst demonstrated on postoperative magnetic resonance imaging was associated with an increased risk of subsequent asymptomatic cyst regrowth. Seven patients (11%) underwent repeated operation with symptomatic improvement and minimal morbidity; only one patient relapsed following a second surgery.
Decompression and biopsy procedures in the treatment of RCCs lead to improvement in signs and symptoms, with low morbidity rates. Repeated operations will be required in as many as 16% of patients but are also associated with symptomatic improvement, low morbidity, and durable remission. Decompression and biopsy may represent the optimal surgical management of RCC.
Journal of Neurosurgery 11/2004; 101(4):577-84. · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neurosurgeons are often involved in the care of patients with cerebral venous sinus thrombosis (CVST). Medical management of CVST includes appropriate diagnostic imaging studies, evaluation for potentially treatable causes of thrombosis, and control of increased intracranial pressure with medications and cerebrospinal fluid drainage. Seizure prophylaxis is indicated in the acute phase of disease and should be continued indefinitely in selected patients. Systemic anticoagulation with heparin and warfarin is the mainstay of medical treatment of CVST; anticoagulation is safe and effective even in the presence of intracerebral hemorrhage. Patients who deteriorate neurologically despite appropriate medical treatment are candidates for endovascular treatment. Endovascular interventions include infusion of thrombolytic agents directly into the thrombosed sinus and mechanical thrombectomy with balloons or rheolytic catheters. These interventions are effective and generally safe, although local thrombolytic infusions increase the risk of new or worsened intracranial hemorrhages. Chronic CVST with stenosis of the venous sinuses may be treated with balloon angioplasty and stenting. Under rare circumstances, open surgical interventions may be considered, including open thrombectomy and decompressive craniectomy. Neurosurgeons should also be prepared to treat late complications of CVST, including pseudotumor cerebri and dural arteriovenous fistulas. In summary, CVST is a serious but treatable disease, and effective medical, endovascular, and open surgical therapies exist.
[Show abstract][Hide abstract] ABSTRACT: Frameless image-guided stereotaxy is often used in the resection of high-grade gliomas. The authors of several studies, however, have suggested that brain shift may occur intraoperatively and result in inaccurate resection. To determine the usefulness of frameless stereotactic image-guided surgery of high-grade gliomas, the authors correlated factors predictive of brain shift, such as tumor size, periventricular location, and patient age (as an indicator of brain atrophy) with the extent of resection.
Inclusion criteria included the following: 1) stereotactic volumetric craniotomy for resection of tumor; 2) histologically proven high-grade glioma; 3) preoperative magnetic resonance (MR) imaging demonstration of an enhancing portion of tumor; 4) postoperative MR imaging within 48 hours to assess the extent of resection; and 5) preoperative intention to perform gross-total resection of the enhancing tumor. Fifty-four patients met these criteria between September 1997 and November 2002. Accurate resection was considered to be indicated by a lack of nodular enhancement on postoperative Gd-enhanced MR images obtained within 48 hours of surgery. Frameless stereotactic image-guided surgery resulted in the successful resection of 46 (85%) of 54 high-grade gliomas. Accurate resection was significantly more likely with tumors less than 30 ml in volume than with those greater than 30 ml (93 and 58%, respectively [p < 0.05]). In addition, small periventricular tumors were associated with significant less successful resection compared with nonperiventricular tumor (77 and 96%, respectively [p = 0.5]). Patient age did not affect the likelihood of successful resection.
Frameless image-guided stereotactic techniques can be reliably used for accurate resection of high-grade gliomas when the tumor is less than 30 ml in volume and not adjacent to the ventricular system. In cases involving tumors larger in volume or located near the ventricles, intraoperative ultrasonography or MR imaging updates should be considered.