Osteocalcin protects islet identity in low-density lipoprotein receptor knockout mice on high-fat diet

Metabolic syndrome (MetS) is an increasing global health threat and strong risk factor for type 2 diabetes (T2D). MetS causes both hyperinsulinemia and islet size overexpansion, and pancreatic β-cell failure impacts insulin and proinsulin secretion, mitochondrial density, and cellular identity loss. The low-density lipoprotein receptor knockout (LDLr-/-) model combined with high-fat diet (HFD) has been used to study alterations in multiple organs, but little is known about the changes to β-cell identity resulting from MetS. Osteocalcin (OC), an insulin-sensitizing protein secreted by bone, shows promising impact on β-cell identity and function. LDLr-/- mice at 12 months were fed chow or HFD for 3 months ± 4.5 ng/h OC. Islets were examined by immunofluorescence for alterations in nuclear Nkx6.1 and PDX1 presence, insulin-glucagon colocalization, islet size and %β-cell and islet area by insulin and synaptophysin, and mitochondria fluorescence intensity by Tomm20. Bone mineral density (BMD) and %fat changes were examined by Piximus Dexa scanning. HFD-fed mice showed fasting hyperglycemia by 15 months, increased weight gain, %fat, and fasting serum insulin and proinsulin; concurrent OC treatment mitigated weight increase and showed lower proinsulin-to-insulin ratio, and higher BMD. HFD increased %β and %islet area, while simultaneous OC-treatment with HFD was comparable to chow-fed mice. Significant reductions in nuclear PDX1 and Nkx6.1 expression, increased insulin-glucagon colocalization, and reduction in β-cell mitochondria fluorescence intensity were noted with HFD, but largely prevented with OC administration. OC supplementation here suggests a benefit to β-cell identity in LDLr-/- mice and offers intriguing clinical implications for countering metabolic syndrome.

High variability in short and long-term recovery kinetic of blood cell count and blood chemistry in a partial body irradiation mouse model

PURPOSE

In the aftermath of a nuclear disaster or accident, survivors will suffer from radiation-induced normal tissue damage. Recovery after radiation exposure is dictated by several factors, one of which is degree of shielding at time of exposure. This study aims to characterize the short and late term changes in kinetics and magnitude of pancytopenia and blood chemistry in a model of heterogeneous radiation exposure, or partial body irradiation (PBI), compared to whole body irradiation (WBI).

MATERIALS AND METHODS

Male C57BL/6 mice, 8-10 weeks of age, were WBI at 6 different doses (6, 6.1. 6.15, 6.2, 6.5, and 7.5 Gy) to establish the LD50. To determine the effect of shielding on blood cell counts and chemistry, animals were either WBI at 6 Gy (LD2230) or 6 Gy PBI with one leg shielding (LD030). Complete blood counts and chemistry were measured at 1, 5-, 10-, 20-, 30- and 120-days post-irradiation.

RESULTS AND CONCLUSIONS

Irradiated animals had significant depletion of white blood cells, red blood cells and platelets up to 10 days post-irradiation. Separation between PBI and WBI were observed at 10- and 20-days post-irradiation at which point PBI animals showed sign of recovery while overall cell count remains depleted in WBI animals up to 30 days post-irradiation. In addition, significant changes were found in parameters indicative of hematopoietic injury including hemoglobin count, hematocrit count and white blood cell population. Significant changes were observed in kidney function with changes to blood urea nitrogen and calcium concentration at 5-days post-irradiation. At 10-days post-irradiation. liver function changes differentiated WBI from PBI animals. Long-term, irradiated animal's chemistry values and many blood counts were not significantly different from Sham. In conclusion, partial shielding ensured complete survival and demonstrated a different recovery kinetics of blood and chemistry parameters after irradiation compared to survivors of whole body irradiation and no single hemopoietic parameter was able to consistently differentiate irradiated from Sham animals. This seems to indicate that there is no single robust hemopoietic parameter to differentiate those exposed from those who were not due to the inherent variability in individual responses. Furthermore, there were no significant long-term effects on these blood parameters between survivors of WBI and PBI except that shielding accelerated recovery.

Hyperoxia Disrupts Lung Lymphatic Homeostasis in Neonatal Mice

Inflammation causes bronchopulmonary dysplasia (BPD), a common lung disease of preterm infants. One reason this disease lacks specific therapies is the paucity of information on the mechanisms regulating inflammation in developing lungs. We address this gap by characterizing the lymphatic phenotype in an experimental BPD model because lymphatics are major regulators of immune homeostasis. We hypothesized that hyperoxia (HO), a major risk factor for experimental and human BPD, disrupts lymphatic endothelial homeostasis using neonatal mice and human dermal lymphatic endothelial cells (HDLECs). Exposure to 70% O2 for 24-72 h decreased the expression of prospero homeobox 1 (Prox1) and vascular endothelial growth factor c (Vegf-c) and increased the expression of heme oxygenase 1 and NAD(P)H dehydrogenase [quinone]1 in HDLECs, and reduced their tubule formation ability. Next, we determined Prox1 and Vegf-c mRNA levels on postnatal days (P) 7 and 14 in neonatal murine lungs. The mRNA levels of these genes increased from P7 to P14, and 70% O2 exposure for 14 d (HO) attenuated this physiological increase in pro-lymphatic factors. Further, HO exposure decreased VEGFR3+ and podoplanin+ lymphatic vessel density and lymphatic function in neonatal murine lungs. Collectively, our results validate the hypothesis that HO disrupts lymphatic endothelial homeostasis.

Targeting hippocampal neurogenesis to protect astronauts' cognition and mood from decline due to space radiation effects

Neurogenesis is an essential, lifelong process during which neural stem cells generate new neurons within the hippocampus, a center for learning, memory, and mood control. Neural stem cells are vulnerable to environmental insults spanning from chronic stress to radiation. These insults reduce their numbers and diminish neurogenesis, leading to memory decline, anxiety, and depression. Preserving neural stem cells could thus help prevent these neurogenesis-associated pathologies, an outcome particularly important for long-term space missions where environmental exposure to radiation is significantly higher than on Earth. Multiple developments, from mechanistic discoveries of radiation injury on hippocampal neurogenesis to new platforms for the development of selective, specific, effective, and safe small molecules as neurogenesis-protective agents hold great promise to minimize radiation damage on neurogenesis. In this review, we summarize the effects of space-like radiation on hippocampal neurogenesis. We then focus on current advances in drug discovery and development and discuss the nuclear receptor TLX/NR2E1 (oleic acid receptor) as an example of a neurogenic target that might rescue neurogenesis following radiation.

Looking on the horizon; potential and unique approaches to developing radiation countermeasures for deep space travel

Future lunar missions and beyond will require new and innovative approaches to radiation countermeasures. The Translational Research Institute for Space Health (TRISH) is focused on identifying and supporting unique approaches to reduce risks to human health and performance on future missions beyond low Earth orbit. This paper will describe three funded and complementary avenues for reducing the risk to humans from radiation exposure experienced in deep space. The first focus is on identifying new therapeutic targets to reduce the damaging effects of radiation by focusing on high throughput genetic screens in accessible, sometimes called lower, organism models. The second focus is to design innovative approaches for countermeasure development with special attention to nucleotide-based methodologies that may constitute a more agile way to design therapeutics. The final focus is to develop new and innovative ways to test radiation countermeasures in a human model system. While animal studies continue to be beneficial in the study of space radiation, they can have imperfect translation to humans. The use of three-dimensional (3D) complex in vitro models is a promising approach to aid the development of new countermeasures and personalized assessments of radiation risks. These three distinct and unique approaches complement traditional space radiation efforts and should provide future space explorers with more options to safeguard their short and long-term health.

LOX upregulates FAK phosphorylation to promote metastasis in osteosarcoma

Osteosarcoma is a malignant bone tumor that commonly occurs in the pediatric population. Despite the use of chemotherapy and surgery, metastasis remains to be the leading cause of death in patients with osteosarcoma. We have previously reported that cytoplasmic mislocalization of p27 is associated with a poor outcome in osteosarcoma. In this study, we further show that lysyl oxidase (LOX) expression was associated with p27 mislocalization. LOX is an enigmatic molecule that acts as a tumor suppressor or a metastatic promoter; however, its role in osteosarcoma is still unclear. Hence, we performed both in vitro and in vivo analyses to dissect the role of LOX in osteosarcoma. The result of our survival analysis indicated that LOX expression significantly correlated with a poor outcome in osteosarcoma with or without controlling for the initial metastasis status (P < 0.05). Functionally, we found that higher LOX expression promoted osteosarcoma cell proliferation, migration, and invasiveness in vitro and produced a higher number of mice with pulmonary metastases in an orthotopic xenograft mouse model. Mechanistically, phospho-FAK was increased in osteosarcoma cells with high LOX expression. Our results further showed that FAK inhibition significantly reduced tumor cell proliferation and migration in vitro as well as LOX-mediated metastasis in mice. Together, our findings suggest that there is a novel link between p27 mislocalization and LOX expression. LOX plays a pivotal role in osteosarcoma metastasis by upregulating FAK phosphorylation. FAK inhibition may constitute a promising therapeutic strategy to reduce the development of metastasis in osteosarcoma with LOX overexpression.

Cross-Sectional Characterization of Local Brain Network Connectivity Pre and Post Breast Cancer Treatment and Distinct Association With Subjective Cognitive and Psychological Function

Objective: We aimed to characterize local brain network connectivity in long-term breast cancer survivors compared to newly diagnosed patients. Methods: Functional magnetic resonance imaging (fMRI) and subjective cognitive and psychological function data were obtained from a group of 76 newly diagnosed, pre-treatment female patients with breast cancer (mean age 57 ± 7 years) and a separate group of 80, post-treatment, female breast cancer survivors (mean age 58 ± 8; mean time since treatment 44 ± 43 months). The network-based statistic (NBS) was used to compare connectivity of local brain edges between groups. Hubs were defined as nodes with connectivity indices one standard deviation or more above network mean and were further classified as provincial (higher intra-subnetwork connectivity) or connector (higher inter-subnetwork connectivity) using the participation coefficient. We determined the hub status of nodes encompassing significantly different edges and correlated the centralities of edges with behavioral measures. Results: The post-treatment group demonstrated significantly lower subjective cognitive function (W = 3,856, p = 0.004) but there were no group differences in psychological distress (W = 2,866, p = 0.627). NBS indicated significantly altered connectivity (p < 0.042, corrected) in the post-treatment group compared to the pre-treatment group largely in temporal, frontal-temporal and temporal-parietal areas. The majority of the regions projecting these connections (78%) met criteria for hub status and significantly less of these hubs were connectors in the post-treatment group (z = 1.85, p = 0.031). Subjective cognitive function and psychological distress were correlated with largely non-overlapping edges in the post-treatment group (p < 0.05). Conclusion: Widespread functional network alterations are evident in long-term survivors of breast cancer compared to newly diagnosed patients. We also demonstrated that there are both overlapping and unique brain network signatures for subjective cognitive function vs. psychological distress.

The bone microenvironment increases phenotypic plasticity of ER+ breast cancer cells

Estrogen receptor-positive (ER+) breast cancer exhibits a strong bone tropism in metastasis. How the bone microenvironment (BME) impacts ER signaling and endocrine therapy remains poorly understood. Here, we discover that the osteogenic niche transiently and reversibly reduces ER expression and activities specifically in bone micrometastases (BMMs), leading to endocrine resistance. As BMMs progress, the ER reduction and endocrine resistance may partially recover in cancer cells away from the osteogenic niche, creating phenotypic heterogeneity in macrometastases. Using multiple approaches, including an evolving barcoding strategy, we demonstrated that this process is independent of clonal selection, and represents an EZH2-mediated epigenomic reprogramming. EZH2 drives ER+ BMMs toward a basal and stem-like state. EZH2 inhibition reverses endocrine resistance. These data exemplify how epigenomic adaptation to BME promotes phenotypic plasticity of metastatic seeds, fosters intra-metastatic heterogeneity, and alters therapeutic responses. Our study provides insights into the clinical enigma of ER+ metastatic recurrences despite endocrine therapies.

NF-κB Blockade by NEMO Binding Domain Peptide Ameliorates Inflammation and Neurobehavioral Sequelae After Cranial Radiation Therapy in Juvenile Mice

PURPOSE

Cranial radiation therapy (CRT) is a common treatment for pediatric brain tumor patients. However, side effects include significant neurobehavioral dysfunction in survivors. This dysfunction may in part be caused by inflammation, including increased production of tumor necrosis factor alpha (TNFα) and its receptor TNFR1, which can activate the nuclear factor kappa light-chain enhancer of activated B cells (NF-κB). The TNFα blockade abrogates this inflammatory response, although it presents immunologic risks. Thus, modulation of pathway subsets may be preferable. Here, we test whether inhibition of NF-κB activation using an NF-κB essential modulator binding domain (NBD) peptide mitigates CRT-induced neuroinflammation and improves behavioral outcomes.

METHODS AND MATERIALS

Male C57BL/6J 28-day old mice were randomized to saline (sham), 5 Gy whole-brain CRT, or CRT + NBD-peptide. Brain tissue was collected after 4 hours or 3 months for Western blot or immunohistochemistry. The cortex, corpus callosum (CC), and dentate gyrus were variably imaged for NF-κB-p65, IκBα, proliferation, apoptosis, necroptosis, TNFα, TNFR1, IBA-1, doublecortin, CD11c, and GFAP. Neurobehavioral changes were assessed by open field and elevated plus maze tests 3 months post-CRT.

RESULTS

NF-κB expression increased in whole and nuclear fractions 4 hours after CRT and was abrogated by NBD treatment. Cell death increased and proliferation decreased after CRT, including within neuronal progenitors, with some loss mitigated by NBD. Increased levels of TNFα, IBA-1, and GFAP were found in the CC and cortex months after CRT and were limited by NBD. The anti-NF-κB peptide also improved neurobehavioral assessments, yielding improvements in anxiety and exploration.

CONCLUSIONS

Results suggest a role for NF-κB modulation by NBD peptide in the reduction of neuroinflammation and mitigation of behavioral complications after pediatric radiation therapy.

Adaptive thermogenesis enhances the life-threatening response to heat in mice with an Ryr1 mutation

Mutations in the skeletal muscle Ca2+ release channel, the type 1 ryanodine receptor (RYR1), cause malignant hyperthermia susceptibility (MHS) and a life-threatening sensitivity to heat, which is most severe in children. Mice with an MHS-associated mutation in Ryr1 (Y524S, YS) display lethal muscle contractures in response to heat. Here we show that the heat response in the YS mice is exacerbated by brown fat adaptive thermogenesis. In addition, the YS mice have more brown adipose tissue thermogenic capacity than their littermate controls. Blood lactate levels are elevated in both heat-sensitive MHS patients with RYR1 mutations and YS mice due to Ca2+ driven increases in muscle metabolism. Lactate increases brown adipogenesis in both mouse and human brown preadipocytes. This study suggests that simple lifestyle modifications such as avoiding extreme temperatures and maintaining thermoneutrality could decrease the risk of life-threatening responses to heat and exercise in individuals with RYR1 pathogenic variants.

Differentiation of Heterogeneous Radiation Exposure Using Hematology and Blood Chemistry

In the aftermath of a nuclear incident, survivors will suffer the deleterious effects from acute radiation exposure. The majority of those affected would have received heterogeneous radiation exposure, reflected in hematological metrics and blood chemistry. Here, we investigated the acute and long-term changes in kinetics and magnitude of pancytopenia and blood chemistry in rats irradiated using varying degrees of body shielding. We hypothesized that, although a single blood count may not be able to differentiate the degree of radiation exposure, a combination of measurements from complete blood cell counts (CBCs) and blood chemistry tests is able to do so. Male Sprague Dawley rats, 8-10 weeks of age, received single-dose 7.5 Gy (160 kVp, 25 mA, 1.16 Gy/min) whole-body irradiation (WBI, LD_100/30) or partial-body irradiation (PBI), as follows: one leg shielded (1LS, LD_0/30), two legs shielded (2LS, LD_0/30) or the upper half of the body shielded (UHS, LD_0/30). Animal morbidity and weights were measured. Blood was drawn at 1, 5, 10, 20 and 30 days postirradiation (n = 4-11). For kidney and liver function measurements, CBC and blood chemistry analyses were performed. WBI animals on average survived 9 ± 0.4 days postirradiation. In contrast, all PBI animals survived the 30-day study period. CBC analysis revealed that both white blood cell (WBC) and platelet counts were most affected after irradiation. While WBC counts were significantly lower in all irradiated groups on days 1, 5 and 10, platelets were only significantly lower on days 5 and 10 postirradiation. In addition, on day 5 postirradiation both WBC and platelet counts were able to differentiate WBI (non-survivors) from PBI 2LS and UHS animals (survivors). Using four blood parameters (platelets, percentage lymphocytes, percentage neutrophils and percentage monocytes) on day 5 after 7.5 Gy irradiation and a linear discrimination analysis (LDA), we were able to predict the degree of body exposure in animals with a 95.8% accuracy. Alkaline phosphatase (ALP) was significantly lower in all groups on days 5 and 10 postirradiation compared to baseline. Furthermore, ALP was significantly higher in the UHS than WBI animals. The AST:ALT ratio was significantly higher than baseline in all irradiated groups on day 1 postirradiation. In conclusion, four CBC parameters, on day 5 after receiving a 7.5 Gy dose of radiation, can be employed in a LDA to differentiate various degrees of exposure (shielding). The characterization presented in this work paves the way for further studies in differences caused by heterogeneous body exposure to radiation and a new metric for biodosimetry.

A comprehensive preclinical assessment of late-term imaging markers of radiation-induced brain injury

Background

Cranial radiotherapy (CRT) is an important part of brain tumor treatment, and although highly effective, survivors suffer from long-term cognitive side effects. In this study we aim to establish late-term imaging markers of CRT-induced brain injury and identify functional markers indicative of cognitive performance. Specifically, we aim to identify changes in executive function, brain metabolism, and neuronal organization.

Methods

Male Sprague Dawley rats were fractionally irradiated at 28 days of age to a total dose of 30 Gy to establish a radiation-induced brain injury model. Animals were trained at 3 months after CRT using the 5-choice serial reaction time task. At 12 months after CRT, animals were evaluated for cognitive and imaging changes, which included positron emission tomography (PET) and magnetic resonance imaging (MRI).

Results

Cognitive deficit with signs of neuroinflammation were found at 12 months after CRT in irradiated animals. CRT resulted in significant volumetric changes in 38% of brain regions as well as overall decrease in brain volume and reduced gray matter volume. PET imaging showed higher brain glucose uptake in CRT animals. Using MRI, irradiated brains had an overall decrease in fractional anisotropy, lower global efficiency, increased transitivity, and altered regional connectivity. Cognitive measurements were found to be significantly correlated with six image features that included myelin integrity and local organization of the neural network.

Conclusions

These results demonstrate that CRT leads to late-term morphological changes, reorganization of neural connections, and metabolic dysfunction. The correlation between imaging markers and cognitive deficits can be used to assess late-term side effects of brain tumor treatment and evaluate efficacy of new interventions.

Exercise ameliorates neurocognitive impairments in a translational model of pediatric radiotherapy

Background

While cranial radiation therapy (CRT) is an effective treatment, healthy areas surrounding irradiation sites are negatively affected. Frontal lobe functions involving attention, processing speed, and inhibition control are impaired. These deficits appear months to years after CRT and impair quality of life. Exercise has been shown to rejuvenate the brain and aid in recovery post-injury through its effects on neurogenesis and cognition.

Methods

We developed a juvenile rodent CRT model that reproduces neurocognitive deficits. Next, we utilized the model to test whether exercise ameliorates these deficits. Fischer rats (31 days old) were irradiated with a fractionated dose of 4 Gy × 5 days, trained and tested at 6, 9, and 12 months post-CRT using 5-choice serial reaction time task. After testing, fixed rat brains were imaged using diffusion tensor imaging and immunohistochemistry.

Results

CRT caused early and lasting impairments in task acquisition, accuracy, and latency to correct response, as well as causing stunting of growth and changes in brain volume and diffusion. Exercising after irradiation improved acquisition, behavioral control, and processing speed, mitigated the stunting of brain size, and increased brain fiber numbers compared with sedentary CRT values. Further, exercise partially restored global connectome organization, including assortativity and characteristic path length, and while it did not improve the specific regional connections that were lowered by CRT, it appeared to remodel these connections by increasing connectivity between alternate regional pairs.

Conclusions

Our data strongly suggest that exercise may be useful in combination with interventions aimed at improving cognitive outcome following pediatric CRT.

Echocardiography Differentiates Lethally Irradiated Whole-Body From Partial-Body Exposed Rats

Background: Acute radiation syndrome (ARS) affects morbidity and mortality dependent on the amount of body exposed. We propose the use of echocardiography (EC) to differentiate between survivors and non-survivors by measuring changes in cardiac function (CF) and pulmonary arterial function (PAF). We also investigate the role of rheology in our observed changes. Methods and Results: Rats were irradiated to the whole body (WB) or partial body with two-legs shielded (2LS) at a lethal dose of 7.5Gy. EC and magnetic resonance imaging were performed, and rheological measurements conducted. Only 2LS survived past 12-days post-exposure and their CF and PAR were not significantly different from baseline. WB was significantly different from both baseline and 2LS in stroke volume (P < 0.05), velocity time integral (VTI; P < 0.05) and pulmonary artery acceleration time (PAAT; P < 0.05). Differences were identified as early as six-days post-exposure, where VTI and PAAT were significantly (P < 0.05) decreased in WB versus baseline but only PAAT was different from 2LS. Blood viscosity was significantly lower in the WB versus baseline and 2LS (P < 0.0001). WB exhibited a significant rise in dense red blood cells versus baseline (P < 0.01) and 2LS (P < 0.01). Cell-free hemoglobin, a contributor to pulmonary artery hypertension and vasculopathy, was significantly elevated in WB vs. sham. Conclusions: Non-invasive and readily available imaging can be used to identify critically affected victims. Our findings point to heart failure as one possible cause of death in WB exposed animals, potentially exacerbated by rheological, hemolytic, and pulmonary factors, and the importance of developing radiomitigators against cardiac ARS mortality.

Particle Radiation Induced Neurotoxicity in the Central Nervous System

For patients with primary or metastatic brain tumors, radiation therapy plays a central role in treatment. However, despite its efficacy, cranial radiation is associated with a range of side effects ranging from mild cognitive impairment to overt brain necrosis. Given the negative effects on patient quality of life, radiation-induced neurotoxicities have been the subject of intense study for decades. Photon-based therapy has been and largely remains the standard of care for the treatment of brain tumors. This is particularly true for patients with metastatic tumors who may need treatment to the whole brain or those with very aggressive tumors and a limited life expectancy. Particle therapy is now becoming more widely available for clinical use with the two most common particles used being protons and carbon ions. For patients with favorable prognoses, particularly childhood brain tumors, proton therapy is increasingly used for treatment. This is, in part, driven by the desire to reduce the potential for radiation-induced side effects, including lasting cognitive impairment, which may potentially be achieved by reducing dose to normal tissues using the unique physical properties of particle therapy. There is also interest in using carbon ion therapy for the treatment of aggressive brain tumors, as this form of particle therapy not only spares normal tissues but may also improve tumor control. The biological effects of particle therapy, both proton and carbon, may differ substantially from those of photon radiation. In this review, we briefly describe the unique physical properties of particle therapy that produce differential biological effects. Focusing on the effects of various radiation types on brain parenchyma, we then describe biological effects and potential mechanisms underlying these, comparing to photon studies and highlighting potential clinical implications.

Olfactory Memory Impairment Differs by Sex in a Rodent Model of Pediatric Radiotherapy

Although an effective treatment for pediatric brain tumors, cranial radiation therapy (CRT) damages surrounding healthy tissue, thereby disrupting brain development. Animal models of pediatric CRT have primarily relied on visual tasks to assess cognitive impairment. Moreover, there has been a lack of sex comparisons as most research on the cognitive effects of pediatric CRT does not include females. Therefore, we utilized olfaction, an ethologically relevant sensory modality, to assess cognitive impairment in an animal model of CRT that included both male and female mice. Specifically, we used the novel odor recognition (NOdorR) task with social odors to test recognition memory, a cognitive parameter that has been associated with olfactory neurogenesis, a form of cellular plasticity damaged by CRT. In addition to odor recognition memory, olfactory ability or discrimination of non-social and social odors were assessed both acutely and 3 months after CRT. Magnetic resonance imaging (MRI) and histology were performed after behavioral testing to assess long-term damage by CRT. Long-term but not acute radiation-induced impairment in odor recognition memory was observed, consistent with delayed onset of cognitive impairment in human patients. Males showed greater exploration of social odors than females, but general exploration was not affected by irradiation. However, irradiated males had impaired odor recognition memory in adulthood, compared to non-irradiated males (or simply male controls). Female olfactory recognition memory, in contrast, was dependent on estrus stage. CRT damage was demonstrated by (1) histological evaluation of olfactory neurogenesis, which suggested a reduction in CRT versus control, and (2) imaging analyses which showed that the majority of brain regions were reduced in volume by CRT. Specifically, two regions involved in social odor processing (amygdala and piriform cortex) were damaged by cranial irradiation in males but not females, paralleling olfactory recognition findings.

Investigating the Abscopal Effects of Radioablation on Shielded Bone Marrow in Rodent Models Using Multimodality Imaging

The abscopal effect is the response to radiation at sites that are distant from the irradiated site of an organism, and it is thought to play a role in bone marrow (BM) recovery by initiating responses in the unirradiated bone marrow. Understanding the mechanism of this effect has applications in treating BM failure (BMF) and BM transplantation (BMT), and improving survival of nuclear disaster victims. Here, we investigated the use of multimodality imaging as a translational tool to longitudinally assess bone marrow recovery. We used positron emission tomography/computed tomography (PET/CT), magnetic resonance imaging (MRI) and optical imaging to quantify bone marrow activity, vascular response and marrow repopulation in fully and partially irradiated rodent models. We further measured the effects of radiation on serum cytokine levels, hematopoietic cell counts and histology. PET/CT imaging revealed a radiation-induced increase in proliferation in the shielded bone marrow (SBM) compared to exposed bone marrow (EBM) and sham controls. T₂-weighted MRI showed radiation-induced hemorrhaging in the EBM and unirradiated SBM. In the EBM and SBM groups, we found alterations in serum cytokine and hormone levels and in hematopoietic cell population proportions, and histological evidence of osteoblast activation at the bone marrow interface. Importantly, we generated a BMT mouse model using fluorescent-labeled bone marrow donor cells and performed fluorescent imaging to reveal the migration of bone marrow cells from shielded to radioablated sites. Our study validates the use of multimodality imaging to monitor bone marrow recovery and provides evidence for the abscopal response in promoting bone marrow recovery after irradiation.

Abstract A59: A rodent in situ glioma allograft model to study bone marrow-derived cell migration

Radiotherapy (RT) induced hypoxia recruits bone marrow-derived cells (BMDCs) to tumors through the upregulation of Stromal Derived Factor-1, a chemokine that binds to receptor CXCR4 present on BMDCs. The infiltration of BMDCs, which includes endothelial progenitors, pericyte progenitors, tumor-associated macrophages, immature monocytes, VEGFR+ hemangiocytes, and CD11b+ myeloid cells has been implicated in supporting tumor establishment by contributing to tumor growth, angiogenesis, vasculogenesis, inflammation, and immune suppression. In this work, we have used a rodent glioma in situ allograft model to study the recruitment/migration of BMDCs post RT. Female albino C57 (8-10 weeks old, Jackson Laboratories) animals underwent +DsRed bone marrow transplant (B6.Cg-Tg(CAG-DsRed*MST)1Nagy/J donor mouse). Following engraftment, glioma cells were cranially implanted with 1x105 glioma cells (GL261-Luc, Perkin Elmer), at an average size of 26.4mm3 indicated by a bioluminescence signal of 5.28x108 photons/sec/cm2/sr, animals underwent 6Gy (RadSource 2000, 250kVp, 25mA) of irradiation limited to a 1cm wide slit centered on the tumor. Bioluminescence (tumor size) and fluorescence imaging (+DsRed BMDCs) was performed prior to and at 1- and 2-weeks post-RT to assess tumor growth and measure the influx of +DsRed BMDCs. In addition, flow cytometry was used to measure the number of +DsRed BMDCs in the tumor and brain. To study the effect of BMDCs in tumor regression, tumors were irradiated at a smaller size (9.3mm3) with 10Gy irradiation. At 1-week post-RT, flow cytometry was used to measure the number of BMDCs (CD45+) in the tumor. In our model 6Gy radiation was able to stall the growth of the tumor. Irradiated tumors did not significantly change in tumor size at either 1- or 2-weeks post irradiation compared to pre-RT size. In addition, irradiated tumors were significantly smaller than untreated tumors (p=0.0008) 1-week post-RT. Using flow cytometry 1-week post irradiation, we observed a significant increase in the number of +DsRed BMDCs in the irradiated tumor (23.5% of cells +DsRed BMDCs) compared to the irradiated brain (6.17% cells +DsRed BMDCs, p=0.03) as well as a significant increase in the tumors (16.6% cells +DsRed BMDCs) compared to the brain (11.1% cells +DsRed BMDCs p=0.02). There was no difference in the number of +DsRed BMDCS in tumors ± irradiation or brains ± irradiation. We found similar results in our tumor regression model using flow cytometry 1-week post-RT; we observed an increase in the number of BMDCs CD45+ in the tumor (~20% of cells CD45+) compared to control tumors (~6% of cells CD45+). Indicating that tumor size at the onset of RT did not effect the migration of BMDCs. Fluorescence imaging did not measure any significant change in the DsRed signal at 1- or 2-weeks post-irradiation. We have successfully shown that post-RT there is an increase in BMDCs migration at 1-week post RT regardless of tumor size at RT. Further experimentation is needed to better elucidate the role of BMDCs in tumor inflammation and immune suppression as well as angiogenesis and vasculogenesis. Our next step is to perform immunohistochemistry on our collected tumor tissue to map out the spatial location of migrated BMDCs within the tumor.

Citation Format: Janice A. Zawaski, Tien T. Tang, M Waleed Gaber. A rodent in situ glioma allograft model to study bone marrow-derived cell migration. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A59.

Imaging Radiation-Induced Gastrointestinal, Bone Marrow Injury and Recovery Kinetics Using 18F-FDG PET

Positron emission tomography using 18F-Fluro-deoxy-glucose (18F-FDG) is a useful tool to detect regions of inflammation in patients. We utilized this imaging technique to investigate the kinetics of gastrointestinal recovery after radiation exposure and the role of bone marrow in the recovery process. Male Sprague-Dawley rats were either sham irradiated, irradiated with their upper half body shielded (UHBS) at a dose of 7.5 Gy, or whole body irradiated (WBI) with 4 or 7.5 Gy. Animals were imaged using 18F-FDG PET/CT at 5, 10 and 35 days post-radiation exposure. The gastrointestinal tract and bone marrow were analyzed for 18F-FDG uptake. Tissue was collected at all-time points for histological analysis. Following 7.5 Gy irradiation, there was a significant increase in inflammation in the gastrointestinal tract as indicated by the significantly higher 18F-FDG uptake compared to sham. UHBS animals had a significantly higher activity compared to 7.5 Gy WBI at 5 days post-exposure. Animals that received 4 Gy WBI did not show any significant increase in uptake compared to sham. Analysis of the bone marrow showed a significant decrease of uptake in the 7.5 Gy animals 5 days post-irradiation, albeit not observed in the 4 Gy group. Interestingly, as the metabolic activity of the gastrointestinal tract returned to sham levels in UHBS animals it was accompanied by an increase in metabolic activity in the bone marrow. At 35 days post-exposure both gastrointestinal tract and bone marrow 18F-FDG uptake returned to sham levels. 18F-FDG imaging is a tool that can be used to study the inflammatory response of the gastrointestinal tract and changes in bone marrow metabolism caused by radiation exposure. The recovery of the gastrointestinal tract coincides with an increase in bone marrow metabolism in partially shielded animals. These findings further demonstrate the relationship between the gastrointestinal syndrome and bone marrow recovery, and that this interaction can be studied using non-invasive imaging modalities.

Novel patient-derived xenograft and cell line models for therapeutic testing of pediatric liver cancer

BACKGROUND & AIMS

Pediatric liver cancer is a rare but serious disease whose incidence is rising, and for which the therapeutic options are limited. Development of more targeted, less toxic therapies is hindered by the lack of an experimental animal model that captures the heterogeneity and metastatic capability of these tumors.

METHODS

Here we established an orthotopic engraftment technique to model a series of patient-derived tumor xenograft (PDTX) from pediatric liver cancers of all major histologic subtypes: hepatoblastoma, hepatocellular cancer and hepatocellular malignant neoplasm. We utilized standard (immuno) staining methods for histological characterization, RNA sequencing for gene expression profiling and genome sequencing for identification of druggable targets. We also adapted stem cell culturing techniques to derive two new pediatric cancer cell lines from the xenografted mice.

RESULTS

The patient-derived tumor xenografts recapitulated the histologic, genetic, and biological characteristics-including the metastatic behavior-of the corresponding primary tumors. Furthermore, the gene expression profiles of the two new liver cancer cell lines closely resemble those of the primary tumors. Targeted therapy of PDTX from an aggressive hepatocellular malignant neoplasm with the MEK1 inhibitor trametinib and pan-class I PI3 kinase inhibitor NVP-BKM120 resulted in significant growth inhibition, thus confirming this PDTX model as a valuable tool to study tumor biology and patient-specific therapeutic responses.

CONCLUSIONS

The novel metastatic xenograft model and the isogenic xenograft-derived cell lines described in this study provide reliable tools for developing mutation- and patient-specific therapies for pediatric liver cancer.

LAY SUMMARY

Pediatric liver cancer is a rare but serious disease and no experimental animal model currently captures the complexity and metastatic capability of these tumors. We have established a novel animal model using human tumor tissue that recapitulates the genetic and biological characteristics of this cancer. We demonstrate that our patient-derived animal model, as well as two new cell lines, are useful tools for experimental therapies.

Asprosin, a Fasting-Induced Glucogenic Protein Hormone

Hepatic glucose release into the circulation is vital for brain function and survival during periods of fasting and is modulated by an array of hormones that precisely regulate plasma glucose levels. We have identified a fasting-induced protein hormone that modulates hepatic glucose release. It is the C-terminal cleavage product of profibrillin, and we name it Asprosin. Asprosin is secreted by white adipose, circulates at nanomolar levels, and is recruited to the liver, where it activates the G protein-cAMP-PKA pathway, resulting in rapid glucose release into the circulation. Humans and mice with insulin resistance show pathologically elevated plasma asprosin, and its loss of function via immunologic or genetic means has a profound glucose- and insulin-lowering effect secondary to reduced hepatic glucose release. Asprosin represents a glucogenic protein hormone, and therapeutically targeting it may be beneficial in type II diabetes and metabolic syndrome.

Mapping Radiation Injury and Recovery in Bone Marrow Using 18F-FLT PET/CT and USPIO MRI in a Rat Model

We present and test the use of multimodality imaging as a topological tool to map the amount of the body exposed to ionizing radiation and the location of exposure, which are important indicators of survival and recovery. To achieve our goal, PET/CT imaging with 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) was used to measure cellular proliferation in bone marrow (BM), whereas MRI using ultra-small superparamagnetic iron oxide (USPIO) particles provided noninvasive information on radiation-induced vascular damage.

METHODS

Animals were x-ray-irradiated at a dose of 7.5 Gy with 1 of 3 radiation schemes-whole-body irradiation, half-body shielding (HBS), or 1-leg shielding (1LS)-and imaged repeatedly. The spatial information from the CT scan was used to segment the region corresponding to BM from the PET scan using algorithms developed in-house, allowing for quantification of proliferating cells, and BM blood volume was estimated by measuring the changes in the T2 relaxation rates (ΔR2) collected from MR scans.

RESULTS

(18)F-FLT PET/CT imaging differentiated irradiated from unirradiated BM regions. Two days after irradiation, proliferation of 1LS animals was significantly lower than sham (P = 0.0001, femurs; P < 0.0001, tibias) and returned to sham levels by day 10 (P = 0.6344, femurs; P = 0.3962, tibias). The degree of shielding affected proliferation recovery, showing an increase in the irradiated BM of the femurs, but not the tibias, of HBS animals when compared with 1LS (P = 0.0310, femurs; P = 0.5832, tibias). MRI of irradiated spines detected radiation-induced BM vascular damage, measured by the significant increase in ΔR2 2 d after whole-body irradiation (P = 0.0022) and HBS (P = 0.0003) with a decreasing trend of values, returning to levels close to baseline over 10 d. Our data were corroborated using γ-counting and histopathology.

CONCLUSION

We demonstrated that (18)F-FLT PET/CT and USPIO MRI are valuable tools in mapping regional radiation exposure and the effects of radiation on BM. Analysis of the (18)F-FLT signal allowed for a clear demarcation of exposed BM regions and elucidated the kinetics of BM recovery, whereas USPIO MRI was used to assess vascular damage and recovery.

Abstract 3321: Effects of glioma presence during radiotherapy on tissue damage

Animal models have been used to quantify the genomic and functional changes post-radiotherapy in brain tissue. However, in these models the effects of tumor presence during radiotherapy is not taken into account. We have recently measured significant genomic changes in the rat brain tissue that was occupied by the tumor post-radiotherapy compared to normal irradiated tissue. In our current work we are characterizing the long term functional changes caused by the presence of the tumor during radiotherapy.

Sprague Dawley male rats (7wks) were divided between three experimental groups: Sham implant, RT+sham implant, and RT+Tumor (C6-GFP tumor implant glioma). Hypofractionated irradiation (8-6Gy/day for 5 days) was localized to a 1cm strip of the cranium starting 5 days post implant, which resulted in a complete regression of the tumor and prolonged survival. The former tumor area was imaged 65 days post implant using a 9.4T Biospec MRI scanner (Bruker) with a 20cm bore using a quadrature rat brain array. 1H magnetic resonance spectroscopy (1H-MRS) was performed in the former tumor/implant region using a STEAM sequence with the following parameters: TR = 2s/TE = 2.22ms/ # of averages = 512/ voxel size 56mm3. Diffusion tensor imaging (DTI) was performed using a spin echo EPI sequence with a TR = 500ms, TE = 33.2ms, 2 repetitions, slice thickness = 12.8mm, b value = 800 s/mm2, 30 of directions, matrix size 128×256×16 giving a spatial resolution of 150×150×800mm. 1H MRS data was analyzed using LC Model and DTI was analyzed using Medinria. Intravital microscopy was also used to quantify blood brain-barrier (BBB) permeability and leukocyte activity.

1H-MRS revealed that both RT+sham implant and RT+C6-GFP tumor groups had a significant reduction in taurine levels (p &lt;0.04) in the former tumor/implant area. However, the RT+C6-GFP tumor group had a significant increase in GABA levels (p = 0.02), which may indicate an effect on synaptic neurotransmission. Interestingly, myo-inositol levels ,which is associated with RT-induced brain damage, did not decrease significantly in either RT+sham implant or RT+tumor groups (p = 0.056 and p = 0.061, respectively). Fractional anisotropy (FA), which measures neuronal fiber density showed no significant changes when comparing RT+sham implant and RT+Tumor to sham. Using intravital imaging we also measured a significant increase in BBB permeability (p&lt;0.05) in the RT+tumor implant compared to sham and an elevated level of leukocyte-endothelial adhesion.

In conclusion, using our tumor implant model to study the effect of radiation alone versus radiation combined with the presence of tumor, we have measured several functional changes post-radiotherapy. Our results indicate that radiation might be the most significant influence on neuronal fiber disruption and damage while tumor presence might play an important role in disrupting synaptic transmission as well as exasperating the inflammatory side effects of radiation.

Citation Format: Janice A. Zawaski, Omaima M. Sabek, Kelvin Wong, M. Waleed Gaber. Effects of glioma presence during radiotherapy on tissue damage. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3321. doi:10.1158/1538-7445.AM2015-3321

Vascular-targeted photothermal therapy of an orthotopic murine glioma model

AIM

To develop nanoshells for vascular-targeted photothermal therapy of glioma.

MATERIALS & METHODS

The ability of nanoshells conjugated to VEGF and/or poly(ethylene glycol) (PEG) to thermally ablate VEGF receptor-2-positive endothelial cells upon near-infrared laser irradiation was evaluated in vitro. Subsequent in vivo studies evaluated therapy in mice bearing intracerebral glioma tumors by exposing tumors to near-infrared light after systemically delivering saline, PEG-coated nanoshells, or VEGF-coated nanoshells. The treatment effect was monitored with intravital microscopy and histology.

RESULTS

VEGF-coated but not PEG-coated nanoshells bound VEGF receptor-2-positive cells in vitro to enable targeted photothermal ablation. In vivo, VEGF targeting doubled the proportion of nanoshells bound to tumor vessels and vasculature was disrupted following laser exposure. Vessels were not disrupted in mice that received saline. The normal brain was unharmed in all treatment and control mice.

CONCLUSION

Nanoshell therapy can induce vascular disruption in glioma.

Effects of irradiation on brain vasculature using an in situ tumor model

PURPOSE

Damage to normal tissue is a limiting factor in clinical radiotherapy (RT). We tested the hypothesis that the presence of tumor alters the response of normal tissues to irradiation using a rat in situ brain tumor model.

METHODS AND MATERIALS

Intravital microscopy was used with a rat cranial window to assess the in situ effect of rat C6 glioma on peritumoral tissue with and without RT. The RT regimen included 40 Gy at 8 Gy/day starting Day 5 after tumor implant. Endpoints included blood-brain barrier permeability, clearance index, leukocyte-endothelial interactions and staining for vascular endothelial growth factor (VEGF) glial fibrillary acidic protein, and apoptosis. To characterize the system response to RT, animal survival and tumor surface area and volume were measured. Sham experiments were performed on similar animals implanted with basement membrane matrix absent of tumor cells.

RESULTS

The presence of tumor alone increases permeability but has little effect on leukocyte-endothelial interactions and astrogliosis. Radiation alone increases tissue permeability, leukocyte-endothelial interactions, and astrogliosis. The highest levels of permeability and cell adhesion were seen in the model that combined tumor and irradiation; however, the presence of tumor appeared to reduce the volume of rolling leukocytes. Unirradiated tumor and peritumoral tissue had poor clearance. Irradiated tumor and peritumoral tissue had a similar clearance index to irradiated and unirradiated sham-implanted animals. Radiation reduces the presence of VEGF in peritumoral normal tissues but did not affect the amount of apoptosis in the normal tissue. Apoptosis was identified in the tumor tissue with and without radiation.

CONCLUSIONS

We developed a novel approach to demonstrate that the presence of the tumor in a rat intracranial model alters the response of normal tissues to irradiation.

Modulation of collagen-induced arthritis by adenovirus-mediated intra-articular expression of modified collagen type II

INTRODUCTION

Rheumatoid arthritis (RA) is a systemic disease manifested by chronic inflammation in multiple articular joints, including the knees and small joints of the hands and feet. We have developed a unique modification to a clinically accepted method for delivering therapies directly to the synovium. Our therapy is based on our previous discovery of an analog peptide (A9) with amino acid substitutions made at positions 260 (I to A), 261 (A to B), and 263 (F to N) that could profoundly suppress immunity to type II collagen (CII) and arthritis in the collagen-induced arthritis model (CIA).

METHODS

We engineered an adenoviral vector to contain the CB11 portion of recombinant type II collagen and used PCR to introduce point mutations at three sites within (CII124-402, 260A, 261B, 263D), (rCB11-A9) so that the resulting molecule contained the A9 sequence at the exact site of the wild-type sequence.

RESULTS

We used this construct to target intra-articular tissues of mice and utilized the collagen-induced arthritis model to show that this treatment strategy provided a sustained, local therapy for individual arthritic joints, effective whether given to prevent arthritis or as a treatment. We also developed a novel system for in vivo bioimaging, using the firefly luciferase reporter gene to allow serial bioluminescence imaging to show that luciferase can be detected as late as 18 days post injection into the joint.

CONCLUSIONS

Our therapy is unique in that we target synovial cells to ultimately shut down T cell-mediated inflammation. Its effectiveness is based on its ability to transform potential inflammatory T cells and/or bystander T cells into therapeutic (regulatory-like) T cells which secrete interleukin (IL)-4. We believe this approach has potential to effectively suppress RA with minimal side effects.

Studies of biaxial mechanical properties and nonlinear finite element modeling of skin

The objective of this research is to conduct mechanical property studies of skin from two individual but potentially connected aspects. One is to determine the mechanical properties of the skin experimentally by biaxial tests, and the other is to use the finite element method to model the skin properties. Dynamic biaxial tests were performed on 16 pieces of abdominal skin specimen from rats. Typical biaxial stress-strain responses show that skin possesses anisotropy, nonlinearity and hysteresis. To describe the stress-strain relationship in forms of strain energy function, the material constants of each specimen were obtained and the results show a high correlation between theory and experiments. Based on the experimental results, a finite element model of skin was built to model the skin's special properties including anisotropy and nonlinearity. This model was based on Arruda and Boyce's eight-chain model and Bischoff et al.'s finite element model of skin. The simulation results show that the isotropic, nonlinear eight-chain model could predict the skin's anisotropic and nonlinear responses to biaxial loading by the presence of an anisotropic prestress state.

Improved intratumoral oxygenation through vascular normalization increases glioma sensitivity to ionizing radiation

PURPOSE

Ionizing radiation, an important component of glioma therapy, is critically dependent on tumor oxygenation. However, gliomas are notable for areas of necrosis and hypoxia, which foster radioresistance. We hypothesized that pharmacologic manipulation of the typically dysfunctional tumor vasculature would improve intratumoral oxygenation and, thus, the antiglioma efficacy of ionizing radiation.

METHODS AND MATERIALS

Orthotopic U87 xenografts were treated with either continuous interferon-beta (IFN-beta) or bevacizumab, alone, or combined with cranial irradiation (RT). Tumor growth was assessed by quantitative bioluminescence imaging; the tumor vasculature using immunohistochemical staining, and tumor oxygenation using hypoxyprobe staining.

RESULTS

Both IFN-beta and bevaziumab profoundly affected the tumor vasculature, albeit with different cellular phenotypes. IFN-beta caused a doubling in the percentage of area of perivascular cell staining, and bevacizumab caused a rapid decrease in the percentage of area of endothelial cell staining. However, both agents increased intratumoral oxygenation, although with bevacizumab, the effect was transient, being lost by 5 days. Administration of IFN-beta or bevacizumab before RT was significantly more effective than any of the three modalities as monotherapy or when RT was administered concomitantly with IFN-beta or bevacizumab or 5 days after bevacizumab.

CONCLUSION

Bevacizumab and continuous delivery of IFN-beta each induced significant changes in glioma vascular physiology, improving intratumoral oxygenation and enhancing the antitumor activity of ionizing radiation. Additional investigation into the use and timing of these and other agents that modify the vascular phenotype, combined with RT, is warranted to optimize cytotoxic activity.

IFN-beta restricts tumor growth and sensitizes alveolar rhabdomyosarcoma to ionizing radiation

Ionizing radiation is an important component of multimodal therapy for alveolar rhabdomyosarcoma (ARMS). We sought to evaluate the ability of IFN-beta to enhance the activity of ionizing radiation. Rh-30 and Rh-41 ARMS cells were treated with IFN-beta and ionizing radiation to assess synergistic effects in vitro and as orthotopic xenografts in CB17 severe combined immunodeficient mice. In addition to effects on tumor cell proliferation and xenograft growth, changes in the tumor microenvironment including interstitial fluid pressure, perfusion, oxygenation, and cellular histology were assessed. A nonlinear regression model and isobologram analysis indicated that IFN-beta and ionizing radiation affected antitumor synergy in vitro in the Rh-30 cell line; the activity was additive in the Rh-41 cell line. In vivo continuous delivery of IFN-beta affected normalization of the dysfunctional tumor vasculature of both Rh-30 and Rh-41 ARMS xenografts, decreasing tumor interstitial fluid pressure, increasing tumor perfusion (as assessed by contrast-enhanced ultrasonography), and increasing oxygenation. Tumors treated with both IFN-beta and radiation were smaller than control tumors and those treated with radiation or IFN-beta alone. Additionally, treatment with high-dose IFN-beta followed by radiation significantly reduced tumor size compared with radiation treatment followed by IFN-beta. The combination of IFN-beta and ionizing radiation showed synergy against ARMS by sensitizing tumor cells to the cytotoxic effects of ionizing radiation and by altering tumor vasculature, thereby improving oxygenation. Therefore, IFN-beta and ionizing radiation may be an effective combination for treatment of ARMS.

A chitosan/beta-glycerophosphate thermo-sensitive gel for the delivery of ellagic acid for the treatment of brain cancer

We report here the development of a chitosan/beta-glycerophosphate(Ch/beta-GP) thermo-sensitive gel to deliver ellagic acid (EA) for cancer treatment. The properties of the Ch/beta-GP gels were characterized regarding chemical structure, surface morphology, and viscoelasticity. In vitro EA release rate from the EA loaded Ch/beta-GP gel and chitosan degradation rate were investigated. The anti-tumor effect of the EA loaded Ch/beta-GP gel on brain cancer cells (human U87 glioblastomas and rat C6 glioma cells) was evaluated by examining cell viability. Cell number and activity were monitored by the MTS assay. The Ch/beta-GP solution formed a heat-induced gel at body temperature, and the gelation temperature and time were affected by the final pH of the Ch/beta-GP solution. The lysozyme increased the EA release rate by 2.5 times higher than that in the absence of lysozyme. Dialyzed chitosan solution with final pH 6.3 greatly reduced the beta-GP needed for gelation, thereby significantly improving the biocompatibility of gel (p < 0.001). The chitosan gels containing 1% (w/v) of ellagic acid significantly reduced viability of U87 cells and C6 cells compared with the chitosan gels at 3 days incubation (p < 0.01, and p < 0.001, respectively).

Development of chitosan-ellagic acid films as a local drug delivery system to induce apoptotic death of human melanoma cells

This study was designed to develop a local chemotherapy device using chitosan as a local drug carrier and ellagic acid (EA) as an anticancer drug. We fabricated chitosan-ellagic acid (Ch-EA) films with concentrations of 0, 0.05, 0.1, 0.5, and 1% (w/v) of EA and examined the films using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and contact angle measurement. The WM115 human melanoma cell line as a skin cancer model was used to evaluate cell response to the films with the MTS assay and apoptosis assay, and HS68 human newborn fibroblast cell line as a control. With the increase in the concentration of the EA, the composite films exhibit increasing amide and ester groups and diffraction peaks of the crystallized EA and greater surface roughness and hydrophilicity. The chitosan films with 0.5 and 1% (w/v) of EA were found to have a potent antiproliferative effect on the melanoma cells by inducing apoptotic cell death. Localized effect of composites on cell behaviors has been clearly demonstrated. Our study demonstrated that the novel Ch-EA film can be potentially used in local chemotherapy.

Radiation-induced astrogliosis and blood-brain barrier damage can be abrogated using anti-TNF treatment

PURPOSE

In this article, we investigate the role of tumor necrosis factor-alpha (TNF) in the initiation of acute damage to the blood-brain barrier (BBB) and brain tissue following radiotherapy (RT) for CNS tumors.

METHODS AND MATERIALS

Intravital microscopy and a closed cranial window technique were used to measure quantitatively BBB permeability to FITC-dextran 4.4-kDa molecules, leukocyte adhesion (Rhodamine-6G) and vessel diameters before and after 20-Gy cranial radiation with and without treatment with anti-TNF. Immunohistochemistry was used to quantify astrogliosis post-RT and immunofluorescence was used to visualize protein expression of TNF and ICAM-1 post-RT. Recombinant TNF (rTNF) was used to elucidate the role of TNF in leukocyte adhesion and vessel diameter.

RESULTS

Mice treated with anti-TNF showed significantly lower permeability and leukocyte adhesion at 24 and 48 h post-RT vs. RT-only animals. We observed a significant decrease in arteriole diameters at 48 h post-RT that was inhibited in TNF-treated animals. We also saw a significant increase in activated astrocytes following RT that was significantly lower in the anti-TNF-treated group. In addition, immunofluorescence showed protein expression of TNF and ICAM-1 in the cerebral cortex that was inhibited with anti-TNF treatment. Finally, administration of rTNF induced a decrease in arteriole diameter and a significant increase in leukocyte adhesion in venules and arterioles.

CONCLUSIONS

TNF plays a significant role in acute changes in BBB permeability, leukocyte adhesion, arteriole diameter, and astrocyte activation following cranial radiation. Treatment with anti-TNF protects the brain's microvascular network from the acute damage following RT.

Continuous delivery of IFN-beta promotes sustained maturation of intratumoral vasculature

IFNs have pleiotropic antitumor mechanisms of action. The purpose of this study was to further investigate the effects of IFN-beta on the vasculature of human xenografts in immunodeficient mice. We found that continuous, systemic IFN-beta delivery, established with liver-targeted adeno-associated virus vectors, led to sustained morphologic and functional changes of the tumor vasculature that were consistent with vessel maturation. These changes included increased smooth muscle cell coverage of tumor vessels, improved intratumoral blood flow, and decreased vessel permeability, tumor interstitial pressure, and intratumoral hypoxia. Although these changes in the tumor vasculature resulted in more efficient tumor perfusion, further tumor growth was restricted, as the mature vasculature seemed to be unable to expand to support further tumor growth. In addition, maturation of the intratumoral vasculature resulted in increased intratumoral penetration of systemically administered chemotherapy. Finally, molecular analysis revealed increased expression by treated tumors of angiopoietin-1, a cytokine known to promote vessel stabilization. Induction of angiopoietin-1 expression in response to IFN-beta was broadly observed in different tumor lines but not in those with defects in IFN signaling. In addition, IFN-beta-mediated vascular changes were prevented when angiopoietin signaling was blocked with a decoy receptor. Thus, we have identified an alternative approach for achieving sustained vascular remodeling-continuous delivery of IFN-beta. In addition to restricting tumor growth by inhibiting further angiogenesis, maturation of the tumor vasculature also improved the efficiency of delivery of adjuvant therapy. These results have significant implications for the planning of combination anticancer therapy.

A recombinant protein and a chemically synthesized peptide containing the active peptides of the platelet collagen receptors inhibit ferric chloride-induced thrombosis in a rat model

We have previously reported that a recombinant protein (M(r) 47 kDa), which contains both active peptide of platelet receptors for types I and III collagen inhibits both types I and III collagen-induced platelet aggregation. In order to eliminate non-reactive portion of the protein, we have constructed a recombinant of rHyB (M r 6 kDa). In addition, we chemically synthesized a hybrid peptide with 30 amino acid residues (cHyB, M r 3 kDa) that contains each of the active peptide derived from platelet receptors for types I and III collagen and a linker of 12 amino acid residues. In the present investigation, we report that both rHyB and cHyB inhibit type I and type III collagen-induced platelet aggregation, and the adhesion of radiolabeled platelets onto rabbit aortic segments in a dose-dependent manner. We have used an animal model, which employs FeCl3 to induce thrombi formation to study the effectiveness of both rHyb and cHyB on preventing thrombi formation. We obtained results that show that both rHyB and cHyB can inhibit thrombi formation in a dose-dependent manner. These results suggest that either rHyB or cHyB may be a possible therapeutic agent in preventing thrombi formation.

Anti-TNFA (TNF-alpha) treatment abrogates radiation-induced changes in vacular density and tissue oxygenation

Ionizing radiation significantly alters the structure and function of microvasculature, which regulates delivery of oxygen to brain tissue. Previous experimental and modeling studies have shown that tissue oxygenation patterns are significantly different in irradiated normal tissue compared to age-matched controls, and the differences are apparent as early as 3 days postirradiation. However, oxygen delivery to irradiated tissue recovers within 6 months postirradiation. Changes in perfusion and oxygenation were studied in a bilaterally (both cerebral hemispheres) and unilaterally (only one hemisphere) irradiated mouse brain model at 6 and 24 h as well as 3, 7, 30, 60 and 120 days postirradiation. The results indicate that significant changes in the number of perfused vessels (as measured by fluorescent DiOC(7) staining) and anatomical vessels (as indicated by CD31 immunohistochemical staining) and tissue oxygenation (by immunohistochemical detection of a fluorescently conjugated monoclonal antibody to EF5) are most pronounced at 3 days postirradiation, while a degree of recovery is observed at later times. However, in the unilaterally irradiated animals, both irradiated and unirradiated (out-of-field) cerebral hemispheres showed similarly significant changes in oxygenation and/or perfusion compared to unirradiated controls. Anti-TNFA treatment inhibited radiation-induced local as well as abscopal effects in the brain tissue.

A perivascular niche for brain tumor stem cells

Cancers are believed to arise from cancer stem cells (CSCs), but it is not known if these cells remain dependent upon the niche microenvironments that regulate normal stem cells. We show that endothelial cells interact closely with self-renewing brain tumor cells and secrete factors that maintain these cells in a stem cell-like state. Increasing the number of endothelial cells or blood vessels in orthotopic brain tumor xenografts expanded the fraction of self-renewing cells and accelerated the initiation and growth of tumors. Conversely, depletion of blood vessels from xenografts ablated self-renewing cells from tumors and arrested tumor growth. We propose that brain CSCs are maintained within vascular niches that are important targets for therapeutic approaches.

Platelet-activating factor receptor and innate immunity: uptake of gram-positive bacterial cell wall into host cells and cell-specific pathophysiology

The current model of innate immune recognition of Gram-positive bacteria suggests that the bacterial cell wall interacts with host recognition proteins such as TLRs and Nod proteins. We describe an additional recognition system mediated by the platelet-activating factor receptor (PAFr) and directed to the pathogen-associated molecular pattern phosphorylcholine that results in the uptake of bacterial components into host cells. Intravascular choline-containing cell walls bound to endothelial cells and caused rapid lethality in wild-type, Tlr2(-/-), and Nod2(-/-) mice but not in Pafr(-/-) mice. The cell wall exited the vasculature into the heart and brain, accumulating within endothelial cells, cardiomyocytes, and neurons in a PAFr-dependent way. Physiological consequences of the cell wall/PAFr interaction were cell specific, being noninflammatory in endothelial cells and neurons but causing a rapid loss of cardiomyocyte contractility that contributed to death. Thus, PAFr shepherds phosphorylcholine-containing bacterial components such as the cell wall into host cells from where the response ranges from quiescence to severe pathophysiology.

Changes in Abdominal Wounds Following Treatment With Sirolimus and Steroids in a Rat Model

Wound healing complications have been observed in patients receiving sirolimus (SLR). This study examined the degree and duration of delayed healing in various protocols using SLR. Sprague-Dawley rats underwent a standard midline abdominal incision and wound closure. Groups of 6 rats each were randomized to receive different doses of SLR (2 and 5 mg/kg) with or without loading dose (10 mg/kg x3 days), and with or without steroids (20 mg/kg x3 days followed by 5 mg/kg for 2 weeks). Rats were humanely killed on postoperative days 5, 10, or 15. Wound breaking force was measured using the EHMI BIAX-II instrument and tensile strength was calculated. Wounds in control animals had gradual increase in tensile strength during the 15-day observation. In contrast, high and loading doses of SLR caused reduction in wound strength until day 10, but the wounds' tensile strength became equivalent to control by day 15. The addition of steroids prolonged wound recovery with low doses of SLR until day 15 and had very profound effects on healing in high-dose SLR-treated animals (>50% reduction) that continued beyond the 2 weeks of observation. Low doses of SLR in non-steroid-treated animals had a short-term (5-day) impact on wound healing; high dose and loading doses delayed healing for 10 to 15 days. The addition of steroids had a synergistic effect on delayed wound healing, particularly in animals receiving high-dose SLR, which demonstrated prolonged wound weakness. These results may provide practical guidelines for postoperative introduction of SLR in the context of various clinical protocols.

Effects of fractionated radiation on the brain vasculature in a murine model: Blood–brain barrier permeability, astrocyte proliferation, and ultrastructural changes

PURPOSE

Radiation therapy of CNS tumors damages the blood-brain barrier (BBB) and normal brain tissue. Our aims were to characterize the short- and long-term effects of fractionated radiotherapy (FRT) on cerebral microvasculature in mice and to investigate the mechanism of change in BBB permeability in mice.

METHODS AND MATERIALS

Intravital microscopy and a cranial window technique were used to measure BBB permeability to fluorescein isothiocyanate (FITC)-dextran and leukocyte endothelial interactions before and after cranial irradiation. Daily doses of 2 Gy were delivered 5 days/week (total, 40 Gy). We immunostained the molecules to detect the expression of glial fibrillary acidic protein and to demonstrate astrocyte activity in brain parenchyma. To relate the permeability changes to endothelial ultrastructural changes, we used electron microscopy.

RESULTS

Blood-brain barrier permeability did not increase significantly until 90 days after FRT, at which point it increased continuously until 180 days post-FRT. The number of adherent leukocytes did not increase during the study. The number of astrocytes in the cerebral cortex increased significantly; vesicular activity in endothelial cells increased beginning 90 days after irradiation, and most tight junctions stayed intact, although some were shorter and less dense at 120 and 180 days.

CONCLUSIONS

The cellular and microvasculature response of the brain to FRT is mediated through astrogliosis and ultrastructural changes, accompanied by an increase in BBB permeability. The response to FRT is delayed as compared with single-dose irradiation treatment, and does not involve leukocyte adhesion. However, FRT induces an increase in the BBB permeability, as in the case of single-dose irradiation.

Radiation-induced up-regulation of adhesion molecules in brain microvasculature and their modulation by dexamethasone

Little is known about the time course and magnitude of the up-regulation of endothelial cell adhesion molecules (ECAMs) in irradiated brain vasculature and the mechanisms by which dexamethasone modulates this up-regulation. We used antibody-conjugated microspheres and a rat closed cranial window model to determine the time course of functional up-regulation of radiation (20 Gy)-induced ICAM1, E-selectin and P-selectin in the pial vasculature of the rat brain and to determine the relationship between suppression of inflammation by dexamethasone and the expression of these ECAMs. The results indicate that ICAM1, E-selectin and P-selectin were up-regulated to a functional level in the microvasculature with distinct time-course patterns. The number of adherent anti-E-selectin and anti-P-selectin microspheres was 5- 12 times greater than that of IgG microspheres 3-6 h postirradiation, and their expression returned to normal at 48 h. The number of adherent anti-ICAM1 microspheres was five and nine times greater than that of IgG at 24 and 48 h, respectively, and returned to baseline by 7 days. Dexamethasone significantly reduced the number of adhering leukocytes and the number of adhering anti-ICAM1, anti-E-selectin and anti-P-selectin microspheres to background levels. Our findings partially identify a key sequence in radiation-induced inflammatory response and provide a potential means to limit radiation-induced inflammatory responses and their potential side effects in the brain.

An intravital microscopy study of radiation-induced changes in permeability and leukocyte–endothelial cell interactions in the microvessels of the rat pia mater and cremaster muscle

Using intravital microscopy and a closed window method, we measured irradiation-induced changes in the vascular permeability and cell interactions in microcirculation networks of the rat pia mater; the same effects were monitored in the cremaster muscle as a control. The closed cranial window has many advantages, including long-term direct visualization of microcirculation. The method allows for repeated testing of the same vessel or network, thereby reducing variability. The method also allows for measurement of permeability changes and the accompanying leukocyte-endothelial cell interactions in the same network or vessel, which permits correlative studies of these phenomena. However, this method is not without challenges. The optical conditions are difficult, because the brain is three-dimensional and its parenchyma is more complex than the thinner, flatter peripheral tissues. To overcome this limitation, we performed a dynamic background subtraction. The background is dynamically related to vessel intensity, and changes in intensity were determined by eliminating the effects of neighboring and underlying vessels. We applied this method to studying the effects of ionizing radiation on the blood-brain barrier (BBB) permeability and cell interactions and the modulation of these effects by anti-ICAM-1 antibodies. Our results demonstrate that this method is sensitive to changes in these properties of the BBB.

Determination of calibration parameters of a VRX CT system using an "Amoeba" algorithm

Efforts to improve the spatial resolution of CT scanners have focused mainly on reducing the source and detector element sizes, ignoring losses from the size of the secondary-ionization charge "clouds" created by the detected x-ray photons, i.e., the "physics limit." This paper focuses on implementing a technique called "projective compression." which allows further reduction in effective cell size while overcoming the physics limit as well. Projective compression signifies detector geometries in which the apparent cell size is smaller than the physical cell size, allowing large resolution boosts. A realization of this technique has been developed with a dual-arm "variable-resolution x-ray" (VRX) detector. Accurate values of the geometrical parameters are needed to convert VRX outputs to formats ready for optimal image reconstruction by standard CT techniques. The required calibrating data are obtained by scanning a rotating pin and fitting a theoretical parametric curve (using a multi-parameter minimization algorithm) to the resulting pin sinogram. Excellent fits are obtained for both detector-arm sections with an average (maximum) fit deviation of ~0.05 (0.1) detector cell width. Fit convergence and sensitivity to starting conditions are considered. Pre- and post-optimization reconstructions of the alignment pin and a biological subject reconstruction after calibration are shown.

Differences in ICAM-1 and TNF-alpha expression between large single fraction and fractionated irradiation in mouse brain

PURPOSE

To elucidate the brain molecular response to irradiation. The expression of the intercellular adhesion molecule (ICAM-1) and tumour necrosis factor-alpha (TNF-alpha) in the mouse brain was compared after single-dose and fractionated whole-brain irradiation.

MATERIALS AND METHODS

Mice received a single dose of 2, 10 or 20 Gy or a fractionated dose (2 Gy day(-1)) of 10, 20 or 40 Gy. ICAM-1, and TNF-alpha mRNA expression were quantified by the highly sensitive real-time polymerase chain reaction technique. Expression of ICAM-1 protein was quantified by dual-labelled monoclonal antibody assay.

RESULTS

After a 20-Gy single dose, there was an increase in ICAM-1 and TNF-alpha mRNA levels (14- and 11-fold, respectively) as well as a significant increase in the level of ICAM-1 protein (p=0.0243). The expression of ICAM-1 and TNF-alpha mRNA increased at the end of the 40-Gy fractionated regimen (3.55- and 2.30-fold, respectively).

CONCLUSIONS

The molecular response of the brain to single-dose irradiation was rapid, while its response to fractionated irradiation was slow. This finding is consistent with clinical observations and could be of use when designing strategies to mitigate radiation sequelae.

Radiation-induced permeability and leukocyte adhesion in the rat blood-brain barrier: modulation with anti-ICAM-1 antibodies

We assessed the acute effects of radiation on the rat blood-brain barrier. A cranial window model and intravital microscopy were used to measure changes in permeability and leukocyte adhesion in pial vessels after a localized, single dose of 20 Gy. Permeability was assessed using five sizes of fluorescein isothiocyanate (FITC)-dextran molecules (4.4-, 10-, 38.2-, 70-, and 150-kDa) with measurements performed before and 2, 24, 48, 72 and 96 h after irradiation for the 4.4 and 38.2-kDa molecules and before and 24 h after irradiation for the other three molecules. To demonstrate the nature of blood-brain barrier permeability, we concurrently studied the permeability of microvessels in the cremaster muscle. In both tissues, permeability to FITC-dextran was significantly greater 24 h after irradiation than before (P<0.05). The exception was that radiation did not affect the permeability of pial vessels to the 150-kDa molecule. The particle-size dependence of the permeability changes in the brain were indicative of altered integrity of endothelial tight junctions and occurred concomitantly with an increase in cell adhesion which was determined by fluorescent labeling of leukocytes with rhodamine 6G. An early inflammatory response to irradiation was apparent in the brain 2 h after irradiation. The numbers of rolling and adherent leukocytes increased significantly and peaked at 24 h. Injection with the anti-ICAM-1 mAb significantly reduced leukocyte adhesion and permeability thereby linking the two processes. These findings provide a target to reduce radiation-related permeability and cell adhesion and potentially the side effects of radiation in the CNS.

Oxygen delivery in irradiated normal tissue

Ionizing radiation exposure significantly alters the structure and function of microvascular networks, which regulate delivery of oxygen to tissue. In this study we use a hamster cremaster muscle model to study changes in microvascular network parameters and use a mathematical model to study the effects of these observed structural and microhemodynamic changes in microvascular networks on oxygen delivery to the tissue. Our experimental observations indicate that in microvascular networks while some parameters are significantly affected by irradiation (e.g. RBC transit time), others remain at the control level (e.g. RBC path length) up to 180 days post-irradiation. The results from our mathematical model indicate that tissue oxygenation patterns are significantly different in irradiated normal tissue as compared to age-matched controls and the differences are apparent as early as 3 days post irradiation. However, oxygen delivery to irradiated tissue was not found to be significantly different from age matched controls at any time between 7 days to 6 months post-irradiation. These findings indicate that microvascular late effects in irradiated normal tissue may be due to factors other than compromised tissue oxygenation.

Targeting microparticles to select tissue via radiation-induced upregulation of endothelial cell adhesion molecules

PURPOSE

Certain endothelial cell adhesion molecules are up regulated in tissue that has been irradiated for therapeutic purposes. This up-regulation of adhesion molecules provides a potential avenue for targeting drugs to select tissues.

METHODS

Microspheres were coated with a mAb to ICAM-1 and the level of adhesion of the anti-ICAM-1 microspheres to irradiated tissue in vitro and in vivo was quantified.

RESULTS

Under in vitro flow conditions, the number of adherent microspheres on irradiated HUVEC was 4.8 +/- 0.9 times that of control; the adhesion of anti-ICAM-1 microspheres on irradiated HUVEC could be enhanced by more than 170% in the presence of RBC (20% hematocrit) in the medium. In vivo in a rat cranial window model, the number of adherent anti-ICAM-1 microspheres in locally irradiated cerebral tissue was 8 and 13 times that of IgG microspheres at 24 h and 48 h post-irradiation, respectively and returned to baseline 7 days post-irradiation. In locally irradiated animals, the number of adhering microspheres in unirradiated tissue remained at the basal level.

CONCLUSIONS

Radiation-induced up-regulation of endothelial cell adhesion molecules may be exploited to target drugs and/or genes to select segments of the endothelium.