Cytokine and Growth Factor Response in a Rat Model of Radiation Induced Injury to the Submental Muscles

Submental muscles (i.e., mylohyoid and geniohyoid) play a vital role during swallowing, protecting the airway from ingested material. To design therapies to reduce the functional deficits associated with radiation treatment relies in part on our understanding of the changes in the cytokine and growth factor response that can impact muscle function. The purpose of this study is to quantify changes in the inflammatory, pro-fibrotic, and pro-angiogenic factors following 48 Gy of fractionated radiation to the mylohyoid muscle. We hypothesized that (1) irradiation will provoke increases in TGF-1β and MMP-2 mRNA in the mylohyoid muscle; and (2) muscles surrounding the target location (i.e., geniohyoid and digastric muscles) will exhibit similar alterations in their gene expression profiles. Rats were exposed to 6 fractions of 8 Gy using a 6 MeV electron beam on a clinical linear accelerator. The highest dose curve was focused at the mylohyoid muscle. After 2- and 4-weeks post-radiation, the mylohyoid, geniohyoid, and digastric muscles were harvested. Expression of TNF-α, IFNγ, IL-1β, IL-6, TGF-1β, VEGF, MMP-2, and MMP-9 mRNA was analyzed via PCR and/or RT-PCR. TGF-1β, MMP-2, and IL-6 expression was upregulated in the irradiated mylohyoid compared to non-irradiated controls. No notable changes in TNF-α, IFNγ, and IL-1β mRNA expression were observed in irradiated muscles. Differing expression profiles were found in the surrounding muscles post-radiation. Results demonstrated that irradiation provokes molecular signals involved in the regulation of wound healing, which could lead to fibrosis or atrophy in the swallowing muscle after radiation.

Emerging strategies for enhancing the homing of hematopoietic stem cells to the bone marrow after transplantation

Bone marrow failure is the primary cause of death after nuclear accidents or intentional exposure to high or low doses of ionizing radiation. Hematopoietic stem cell transplantation is the most potent treatment procedure for patients suffering from several hematopoietic malignancies arising after radiation injuries. Successful hematopoietic recovery after transplantation depends on efficient homing and subsequent engraftment of hematopoietic stem cells in specific niches within the bone marrow. It is a rapid and coordinated process in which circulating cells actively enter the bone marrow through the process known as transvascular migration, which involves the tightly regulated relay of events that finally leads to homing of cells in the bone marrow. Various adhesion molecules, chemokines, glycoproteins, integrins, present both on the surface of stem cells and sinusoidal endothelium plays a critical role in transvascular migration. But despite having an in-depth knowledge of homing and engraftment and the key events that regulate it, we are still not completely able to avoid graft failures and post-transplant mortalities. This deems it necessary to design a flawless plan for successful transplantation. Here, in this review, we will discuss the current clinical methods used to overcome graft failures and their flaws. We will also discuss, what are the new approaches developed in the past 10-12 years to selectively deliver the hematopoietic stem cells in the bone marrow by adopting proper targeting strategies that can help revolutionize the field of regenerative and translational medicine.

[High urinary diversion after irradiation to the lesser pelvis]

As useful and necessary as radiotherapy may be, it is associated with irreversible long-term adverse effects including loss of bladder function. In the majority of cases the small bowel, sigmoid rectum and ureter are also affected. The extent of injury depends on the irradiated area, the applied dose and the quality of application. Three factors are essential when choosing a urinary diversion: the length of functional ureter, the position of the bowel outside of the irradiated area and the type of diversion. A continent diversion is best performed through a ascending-transverse or transverse-descending colon pouch. The efferent segment is diverted through the umbilicus. The simplest technique for an incontinent diversion is a conduit using the ascending colon or the right colon flexure. If the length of the ureter does not suffice for such a conduit, the ideal solution is a transverse conduit, as this conduit can be attached to both renal pelves, while simultaneously allowing free choice of the lateral location of the stoma. In case of an exenteration, a double stoma on one side of the body should be avoided in order to prevent maintenance issues.

Bevacizumab in the treatment of radiation injury for children with central nervous system tumors

PURPOSE

Radiation-induced injury is a well-described toxicity in children receiving radiation therapy for tumors of the central nervous system. Standard therapy has historically consisted primarily of high-dose corticosteroids, which carry significant side effects. Preclinical models suggest that radiation necrosis may be mediated in part through vascular endothelial growth factor (VEGF) overexpression, providing the rationale for use of VEGF inhibitors in the treatment of CNS radiation necrosis. We present the first prospective experience examining the safety, feasibility, neurologic outcomes, and imaging characteristics of bevacizumab therapy for CNS radiation necrosis in children.

METHODS

Seven patients between 1 and 25 years of age with neurologic deterioration and MRI findings consistent with radiation injury or necrosis were enrolled on an IRB-approved pilot feasibility study. Patients received bevacizumab at a dose of 10 mg/kg intravenously every 2 weeks for up to 6 total doses.

RESULTS

Five patients (83%) were able to wean off corticosteroid therapy during the study period and 4 patients (57%) demonstrated improvement in serial neurologic exams. All patients demonstrated a decrease in T1-weighted post-gadolinium enhancement on MRI, while 5 (71%) showed a decrease in FLAIR signal. Four patients developed a progressive disease of their underlying tumor during bevacizumab therapy.

CONCLUSIONS

Our experience lends support to the safety and feasibility of bevacizumab administration for the treatment of radiation necrosis for appropriately selected patients within the pediatric population.

Graphite Furnace Atomic Absorption Spectrometric Evaluation of Iron Excretion in Mouse Urine Caused by Whole-Body Gamma Irradiation

A procedure for the determination of iron in mice urine using graphite furnace atomic absorption spectrometry was developed. The mice urinary samples contain many organic compounds in the matrix, whose concentrations are approximately 20%, and the value is 30-fold higher compared to those found in human urine. Moreover, only 0.2 mL or less of urine was obtained as a sample volume per urination event. It was difficult to decompose the organic materials in the samples by wet digestion using mineral acids and oxidising agents, because of the tiny volumes. In this experiment, raw urinary samples were placed directly into the graphite tube furnace for analysis. The organic contents were simply ashed during the preheating stages. To facilitate ashing in the furnace, air was invaded from the surroundings by interrupting the stream of argon gas. Atomic absorption was measured at 248.3270 nm (wavelength for atomic absorption), with the background monitored at 247.0658 nm (wavelength for background correction). The optimised instrument operating conditions precluded the use of chemical modification technique. The analytical procedures used are quite simple, i.e. an aliquot of raw urine sample was injected directly into the graphite tube furnace and was followed by a suitable heating programme with no chemical modifier. Therefore, this method is useful for scientists who are not familiar with delicate chemical experiments. The proposed analytical method was applied as a kind of biomarker by determining iron concentrations in urinary samples of mice, which were irradiated with 4 Gy of gamma irradiation to their whole body. The time dependence of the iron concentration was determined, and the iron concentrations increased within 1 day of irradiation exposure, then decreased to ordinal values after several days.

Critical role of toll-like receptor 4 (TLR4) in dextran sulfate sodium (DSS)-Induced intestinal injury and repair

Ulcerative colitis² (UC) is an inflammatory bowel disease³ (IBD) that causes long-lasting inflammation and ulcers in the human digestive tract. The repair function of TLR4 in the intestinal epithelium is still unknown. Here, wild-type⁴ (WT) mice, TLR4-knockout mice⁵ (KO; TLR4^-/-) and commensal-depleted mice were used as dextran sulfate sodium⁶ (DSS)-induced or radiation-induced colitis and injury models to explore the role of TLR4 signaling in intestinal injury. Exogenous lipopolysaccharide⁷ (LPS) promoted DSS-induced inflammatory cytokines and aggravated intestinal damage. TLR4 deficiency and commensal bacterial depletion inhibited the toxic effects of LPS, but these mice were more susceptible to DSS-induced and radiation-induced intestinal damage. Compared with WT mice, neither DSS nor radiation promoted production of more inflammatory cytokines in the guts of TLR4-KO and commensal-depleted mice. Introducing the cytokine repair factors, PGE2 and GM-CSF, increased the cytokine levels in the guts of DSS-induced colitis mice. We hypothesized that TLR4 and its ligands repaired the epithelium after DSS-induced and radiation-induced intestinal damage by upregulating PGE₂ and GM-CSF. Transwell migration assays suggested that LPS, IL6, TNF, PGE₂ and GM-CSF promoted intestinal cell migration, and cell viability analysis suggested that these factors protected against radiation-induced intestinal damage. Our data underscore the importance of the balancing role of TLR4 in intestinal injury and repair.

Macrophages Educated with Exosomes from Primed Mesenchymal Stem Cells Treat Acute Radiation Syndrome by Promoting Hematopoietic Recovery

In the setting of radiation-induced trauma, exposure to high levels of radiation can cause an acute radiation syndrome (ARS) causing bone marrow (BM) failure, leading to life-threatening infections, anemia, and thrombocytopenia. We have previously shown that human macrophages educated with human mesenchymal stem cells (MSCs) by coculture can significantly enhance survival of mice exposed to lethal irradiation. In this study, we investigated whether exosomes isolated from MSCs could replace direct coculture with MSCs to generate exosome educated macrophages (EEMs). Functionally unique phenotypes were observed by educating macrophages with exosomes from MSCs (EEMs) primed with bacterial lipopolysaccharide (LPS) at different concentrations (LPS-low EEMs or LPS-high EEMs). LPS-high EEMs were significantly more effective than uneducated macrophages, MSCs, EEMs, or LPS-low EEMs in extending survival after lethal ARS in vivo. Moreover, LPS-high EEMs significantly reduced clinical signs of radiation injury and restored hematopoietic tissue in the BM and spleen as determined by complete blood counts and histology. LPS-high EEMs showed significant increases in gene expression of STAT3, secretion of cytokines like IL-10 and IL-15, and production of growth factors like FLT-3L. LPS-EEMs also showed increased phagocytic activity, which may aid with tissue remodeling. LPS-high EEMs have the potential to be an effective cellular therapy for the management of ARS.

Disasters Resulting from Radiologic and Nuclear Events

Radiation accidents are rare, but can produce large numbers of casualties with predictable patterns of injury. Casualties may suffer from a wide range of radiation exposures. Triage based on presence or absence of conventional injuries and an accurate assessment of radiation dose based on event history, symptoms, and laboratory testing, is critical. Treatment of acute radiation syndrome is supportive: including fluids, antibiotics, blood products, colony-stimulating factors, and stem cell or bone marrow transplantation. Care of radiation-injured patients with conventional trauma or burns needs to be modified to account for adverse effects of radiation on wound healing and susceptibility to infections.

Oncologic outcomes and radiation safety of nipple-sparing mastectomy with intraoperative radiotherapy for breast cancer

BACKGROUND

Nipple-sparing mastectomy combined with breast reconstruction helps to optimize the contour of the breast after mastectomy. However, the indications for nipple-sparing mastectomy are still controversial. Local radiation to the nipple-areola complex may play some roles in improving the oncological safety of this procedure.

METHODS

From January 2014 to December 2017, 41 consecutive patients who underwent nipple-sparing mastectomy combined with Intrabeam intraoperative radiotherapy to the nipple-areola complex flap and breast reconstruction were enrolled in this prospective study. The prescribed radiation dose at the surface of the spherical applicator was 16 Gy.

RESULTS

In eight cases, carcinomas were in the central portion of the breast. Partial necrosis of the nipple-areola complex occurred in three cases. Over 90% of patients reported "no or poor sensation" of the nipple-areola complex postoperatively. With a median follow-up time of 26 months, no recurrences or metastases were identified; however, breast-cancer mortality occurred in one patient. Pathologic evaluation of paraffin-embedded sections showed ductal carcinoma in situ in the remaining tissues deep to the nipple-areola complex flap in two patients. Although no further treatment was administered to the nipple-areola complexes postoperatively, no recurrences or metastases were identified 20 months and 24 months later, respectively. Optical microscopy and transmission electron microscopy revealed changes in some normal tissues immediately after Intrabeam intraoperative radiotherapy. Karyopyknosis were observed in gland tissues, and the collagenous fibers became sparse and arranged chaotically. As assessed by thermoluminescence, radiation doses at different sites in the nipple-areola complex flap varied considerably and were about 10 Gy at the areola surface. No Intrabeam intraoperative radiotherapy-related acute or chronic radiation injuries of the lung, heart or bone marrow were identified.

CONCLUSIONS

Our findings indicate that Intrabeam intraoperative radiotherapy during nipple-sparing mastectomy combined with breast reconstruction is safe and feasible.

TRIAL REGISTRATION

The current study was approved by the Ethics Committee of the First Affiliated Hospital of Guangzhou Medical University (registering order 201750). All participants gave their written informed consent.

Radiation: a poly-traumatic hit leading to multi-organ injury

The range of radiation threats we face today includes everything from individual radiation exposures to mass casualties resulting from a terrorist incident, and many of these exposure scenarios include the likelihood of additional traumatic injury as well. Radiation injury is defined as an ionizing radiation exposure inducing a series of organ injury within a specified time. Severity of organ injury depends on the radiation dose and the duration of radiation exposure. Organs and cells with high sensitivity to radiation injury are the skin, the hematopoietic system, the gastrointestinal (GI) tract, spermatogenic cells, and the vascular system. In general, acute radiation syndrome (ARS) includes DNA double strand breaks (DSB), hematopoietic syndrome (bone marrow cells and circulatory cells depletion), cutaneous injury, GI death, brain hemorrhage, and splenomegaly within 30 days after radiation exposure. Radiation injury sensitizes target organs and cells resulting in ARS. Among its many effects on tissue integrity at various levels, radiation exposure results in activation of the iNOS/NF-kB/NF-IL6 and p53/Bax pathways; and increases DNA single and double strand breaks, TLR signaling, cytokine concentrations, bacterial infection, cytochrome c release from mitochondria to cytoplasm, and possible PARP-dependent NAD and ATP-pool depletion. These alterations lead to apoptosis and autophagy and, as a result, increased mortality. In this review, we summarize what is known about how radiation exposure leads to the radiation response with time. We also describe current and prospective countermeasures relevant to the treatment and prevention of radiation injury.

Improving hematopoietic recovery through modeling and modulation of the mesenchymal stromal cell secretome

BACKGROUND

Efficient and sustained hematopoietic recovery after hematopoietic stem cell or bone marrow transplantation is supported by paracrine signaling from specific subpopulations of mesenchymal stromal cells (MSCs). Here, we considered whether in vitro mechanopriming of human MSCs could be administered to predictively and significantly improve in vivo hematopoietic recovery after irradiation injury.

METHODS

First, we implemented regression modeling to identify eight MSC-secreted proteins that correlated strongly with improved rescue from radiation damage, including hematopoietic recovery, in a murine model of hematopoietic failure. Using these partial least squares regression (PLSR) model parameters, we then predicted recovery potential of MSC populations that were culture expanded on substrata of varying mechanical stiffness. Lastly, we experimentally validated these predictions using an in vitro co-culture model of hematopoiesis and using new in vivo experiments for the same irradiation injury model used to generate survival predictions.

RESULTS

MSCs grown on the least stiff (elastic moduli ~ 1 kPa) of these polydimethylsiloxane (PDMS) substrata secreted high concentrations of key proteins identified in regression modeling, at concentrations comparable to those secreted by minor subpopulations of MSCs shown previously to be effective in supporting such radiation rescue. We confirmed that these MSCs expanded on PDMS could promote hematopoiesis in an in vitro co-culture model with hematopoietic stem and progenitor cells (HSPCs). Further, MSCs cultured on PDMS of highest stiffness (elastic moduli ~ 100 kPa) promoted expression of CD123+ HSPCs, indicative of myeloid differentiation. Systemic administration of mechanoprimed MSCs resulted in improved mouse survival and weight recovery after bone marrow ablation, as compared with both standard MSC expansion on stiffer materials and with biophysically sorted MSC subpopulations. Additionally, we observed recovery of white blood cells, platelets, and red blood cells, indicative of complete recovery of all hematopoietic lineages.

CONCLUSIONS

These results demonstrate that computational techniques to identify MSC biomarkers can be leveraged to predict and engineer therapeutically effective MSC phenotypes defined by mechanoprimed secreted factors, for translational applications including hematopoietic recovery.

A retrospective dosimetry study of intensity-modulated radiotherapy for nasopharyngeal carcinoma: radiation-induced brainstem injury and dose-volume analysis

Background

Radiation therapy is the standard radical treatment for nasopharyngeal carcinoma (NPC) but also causes transient as well as long-term complications. Patients who develop severe radiation-induced brainstem injuries have a poor prognosis due to the lack of effective medical therapies. However, the relationship between brainstem injury and radiation volume dose is unknown. In this study, we found that radiation-induced brainstem injury was significantly associated with brainstem dose per unit volume.

Methods

A retrospective analysis was performed on a consecutive cohort of 327 patients with NPC receiving IMRT from May 2005 to December 2014. Dose-volume data and long-term outcome were analyzed.

Results

The median follow-up duration was 56 months (range, 3–141 months), and six with T₄ and two with T₃ patients had radiation-induced brainstem injuries. The 3-year and 5-year incidences were 2.2% and 2.8%, respectively. The latency period of brainstem injury ranged from 9 to 58 months, with a median period of 21 months. The Cox regression analysis showed that brainstem radiation toxicity was associated with the T₄ stage, D_2% of gross tumor volume of nasopharyngeal primary lesions and their direct extensions (GTVnx), D_max (the maximum point dose), D_1%, D_0.1cc (the top dose delivered to a 0.1-ml volume), and D_1cc (the top dose delivered to a 1-ml volume) of the brainstem (p < 0.05). Receiver operating characteristic (ROC) curves showed that GTVnx D_2% and the D_max, D_1%, D_0.1cc, and D_1cc of the brainstem were significant predictors of brainstem injury. The area under the ROC curve for these five parameters was 0.724, 0.813, 0.818, 0.818, and 0.798, respectively (p < 0.001), and the cutoff points 77.26 Gy, 67.85 Gy, 60.13 Gy, 60.75 Gy, and 54.58 Gy, respectively, were deemed as the radiation dose limit.

Conclusions

Radiotherapy-induced brainstem injury was uncommon in patients with NPC who received definitive IMRT. Multiple dose-volume data may be the dose tolerance of radiation-induced brainstem injury.

Macrophages in radiation injury: a new therapeutic target

Radiotherapy can induce toxicity in healthy tissues such as radiation-induced fibrosis (RIF), and macrophages are proposed as new profibrogenic cells. In this Point-of-View, we summarize the role of the immune response in ionizing radiation injury, and we focus on macrophages as a new therapeutic target in RIF.

Discriminating radiation injury from recurrent tumor with [18F]PARPi and amino acid PET in mouse models

Background

Radiation injury can be indistinguishable from recurrent tumor on standard imaging. Current protocols for this differential diagnosis require one or more follow-up imaging studies, long dynamic acquisitions, or complex image post-processing; despite much research, the inability to confidently distinguish between these two entities continues to pose a significant dilemma for the treating clinician. Using mouse models of both glioblastoma and radiation necrosis, we tested the potential of poly(ADP-ribose) polymerase (PARP)-targeted PET imaging with [¹⁸F]PARPi to better discriminate radiation injury from tumor.

Results

In mice with experimental radiation necrosis, lesion uptake on [¹⁸F]PARPi-PET was similar to contralateral uptake (1.02 ± 0.26 lesion/contralateral %IA/cc_max ratio), while [¹⁸F]FET-PET clearly delineated the contrast-enhancing region on MR (2.12 ± 0.16 lesion/contralateral %IA/cc_max ratio). In mice with focal intracranial U251 xenografts, tumor visualization on PARPi-PET was superior to FET-PET, and lesion-to-contralateral activity ratios (max/max, p = 0.034) were higher on PARPi-PET than on FET-PET.

Conclusions

A murine model of radiation necrosis does not demonstrate [¹⁸F]PARPi avidity, and [¹⁸F]PARPi-PET is better than [¹⁸F]FET-PET in distinguishing radiation injury from brain tumor. [¹⁸F]PARPi-PET can be used for discrimination between recurrent tumor and radiation injury within a single, static imaging session, which may be of value to resolve a common dilemma in neuro-oncology.

Electronic supplementary material

The online version of this article (10.1186/s13550-018-0399-z) contains supplementary material, which is available to authorized users.

18β-Glycyrrhetinic acid mitigates radiation-induced skin damage via NADPH oxidase/ROS/p38MAPK and NF-κB pathways

Radiation-induced inflammation plays an important role in radiation-induced tissue injury. 18β-glycyrrhetinic acid (18β-GA) has shown an anti-inflammatory activity. This study aimed to assess the activity of 18β-GA against radiation-induced skin damage, and explore the underlying mechanisms. In vitro assay revealed 18β-GA treatment decreased the production of IL-1β, IL-6, PGE2 and decreased p38MAPK phosphorylation, DNA-binding activity of AP-1, and NF-κB activation in irradiated RAW264.7 macrophages. Additionally, 18β-GA suppressed NF-κB activation by inhibiting NF-κB/p65 and IκB-α phosphorylation and alleviated ROS overproduction in irradiated RAW264.7 macrophages. In vivo assay showed 18β-GA alleviated severity of radiation-induced skin damage, reduced inflammatory cell infiltration and TNF-α, IL-1β and IL-6 levels in cutaneous tissues. Our findings demonstrate that 18β-GA exhibits anti-inflammatory actions against radiation-induced skin damage probably by inhibiting NADPH oxidase activity, ROS production, activation of p38MAPK and NF-κB signaling, and the DNA binding activities of NF-κB and AP-1, consequently suppressing pro-inflammatory cytokine production.

Prophylactic Bevacizumab May Mitigate Radiation Injury: An Experimental Study

BACKGROUND

Stereotactic radiosurgery (SRS) is widely used to treat brain pathologies alone or in concert with other treatment modalities. However, there are some side effects, such as radiation injury characterized by edema and necrosis in peripheral tissues, that must be managed. A new treatment agent against this side effect is bevacizumab, which targets increased vascular endothelial growth factor (VEGF) as a prominent etiologic factor in radiation injury. In this study, we created a rat experimental model to describe the effects of both radiation and the anti-VEGF monoclonal antibody bevacizumab following high-dose SRS, and to compare the effects of prophylactic and delayed-onset bevacizumab treatment.

METHODS

Fifty-four adult male Wistar rats were allocated into 9 groups based on differing Gamma-knife surgery (GKS) doses and bevacizumab treatment protocols. After 12 weeks, the rats' right frontal lobes were examined with hematoxylin and eosin staining and immunohistochemistry analysis via VEGF and CD31 antibodies.

RESULTS

Radiation necrosis occurred to varying degrees in all irradiated animals between 3 and 10 weeks post-SRS. Higher GKS dose (50% isodose of 100 Gy) led earlier necrosis and prophylaxis of bevacizumab at this dose was associated with delayed onset of necrosis. Moreover, prophylactic bevacizumab mitigated the effects of radiation necrosis following GKS at both doses, whereas this effect was not prominent with late initiation of bevacizumab (treatment protocol).

CONCLUSIONS

Our findings show that the onset and degree of radiation injury are affected by the GKS dose and protocol of bevacizumab administration.

Total body irradiation tremendously impair the proliferation, differentiation and chromosomal integrity of bone marrow-derived mesenchymal stromal stem cells

Total body irradiation (TBI) is frequently used in hematopoietic stem cell transplantation (HSCT) and is associated with many complications due to radiation injury to the normal cells, including normal stem cells. Nevertheless, the effects of TBI on the mesenchymal stromal stem cell (MSC) are not fully understood. Bone marrow-derived MSCs (BM-MSCs) isolated from normal adults were irradiated with 200 cGy twice daily for consecutive 3 days, a regimen identical to that used in TBI-conditioning HSCT. The characteristics, differentiation potential, cytogenetics, hematopoiesis-supporting function, and carcinogenicity of the irradiated BM-MSCs were then compared to the non-irradiated control. The irradiated and non-irradiated MSCs shared similar morphology, phenotype, and hematopoiesis-supporting function. However, irradiated MSCs showed much lower proliferative and differentiative potential. Irradiation also induced clonal cytogenetic abnormalities of MSCs. Nevertheless, the carcinogenicity of irradiated MSCs is low in vitro and in vivo. In parallel with the ex vivo irradiation experiments, decreased proliferative and differentiative abilities and clonal cytogenetic abnormalities can also be found in MSCs isolated from transplant recipients who had received TBI-based conditioning previously. Thus, TBI used in HSCT drastically injury MSCs and may contribute to the development of some long-term complications associated with clonal cytogenetic abnormality and poor adipogenesis and osteogenesis after TBI.

Radiation-induced pulmonary gene expression changes are attenuated by the CTGF antibody Pamrevlumab

BACKGROUND

Fibrosis is a delayed side effect of radiation therapy (RT). Connective tissue growth factor (CTGF) promotes the development of fibrosis in multiple settings, including pulmonary radiation injury.

METHODS

To better understand the cellular interactions involved in RT-induced lung injury and the role of CTGF in these responses, microarray expression profiling was performed on lungs of irradiated and non-irradiated mice, including mice treated with the anti-CTGF antibody pamrevlumab (FG-3019). Between group comparisons (Welch's t-tests) and principal components analyses were performed in Genespring.

RESULTS

At the mRNA level, the ability of pamrevlumab to prolong survival and ameliorate RT-induced radiologic, histologic and functional lung deficits was correlated with the reversal of a clear enrichment in mast cell, macrophage, dendritic cell and mesenchymal gene signatures. Cytokine, growth factor and matrix remodeling genes that are likely to contribute to RT pneumonitis and fibrosis were elevated by RT and attenuated by pamrevlumab, and likely contribute to the cross-talk between enriched cell-types in injured lung.

CONCLUSIONS

CTGF inhibition had a normalizing effect on select cell-types, including immune cells not typically regarded as being regulated by CTGF. These results suggest that interactions between RT-recruited cell-types are critical to maintaining the injured state; that CTGF plays a key role in this process; and that pamrevlumab can ameliorate RT-induced lung injury in mice and may provide therapeutic benefit in other immune and fibrotic disorders.

The neck burn scar contracture: a concept of effective treatment

A neck scar contracture can severely and negatively affect the function of mastication, phonic, or breathing and result in neck pain and issues with esthetics. The best way is of course to avoid such contracture by means of non-surgical treatment such as use of a growth factor. The basic fibroblastic growth factor is clinically well proven in decreasing scar formation and improving healing. There are numerous reconstructive methods for neck contracture, especially when the lesions are relatively limited in part of the neck. However, a very severe and full circumferential scar contracture requires extensive reconstruction. The thin groin flap is one of the answers and well matches with the tissue texture and maintains the flexibility. Even with extensive burns and delayed reconstructions due to resuscitation first, the groin area is well preserved and can be safely harvested by dual vasculature systems of the superficial circumflex iliac artery and superficial epigastric artery, which warrant more reliability compared to the perforator flaps in this area. More demanding and stringent forms of the neck burn scar contracture are the sequelae of radiation. A radiation burn or radiation injury can be progressing and hard to heal. Adipose-derived stem cells can reverse the scar contracture as the surrounding tissue is softened and can accelerate wound healing. In this review, different types of neck burn scar contracture and reconstructive methods are summarized, including innovative use of bFGF and ADSCs in the management of difficult wound healing and scar contracture.

Chemical, Electrical, and Radiation Injuries

This article reviews the unique challenges presented by chemical, electrical, and radiation injuries. The authors discuss pathophysiology and diagnosis of these injuries and provide recommendations for management.

Human Mesenchymal Stem Cell-Educated Macrophages Are a Distinct High IL-6-Producing Subset that Confer Protection in Graft-versus-Host-Disease and Radiation Injury Models

Mesenchymal stem cells (MSCs) have immunosuppressive and tissue repair properties, but clinical trials using MSCs to prevent or treat graft-versus-host disease (GVHD) have shown mixed results. Macrophages (MØs) are important regulators of immunity and can promote tissue regeneration and remodeling. We have previously shown that MSCs can educate MØs toward a unique anti-inflammatory immunophenotype (MSC-educated MØs [MEMs]); however, their implications for in vivo models of inflammation have not been studied yet. We now show that in comparison with MØs, MEMs have increased expression of the inhibitory molecules PD-L1, PD-L2, in addition to markers of alternatively activated MØs: CD206 and CD163. RNA-Seq analysis of MEMs, as compared with MØs, show a distinct gene expression profile that positively correlates with multiple pathways important in tissue repair. MEMs also show increased expression of IL-6, transforming growth factor-β, arginase-1, CD73, and decreased expression of IL-12 and tumor necrosis factor-α. We show that IL-6 secretion is controlled in part by the cyclo-oxygenase-2, arginase, and JAK1/STAT1 pathway. When tested in vivo, we show that human MEMs significantly enhance survival from lethal GVHD and improve survival of mice from radiation injury. We show these effects could be mediated in part through suppression of human T cell proliferation and may have attenuated host tissue injury in part by enhancing murine fibroblast proliferation. MEMs are a unique MØ subset with therapeutic potential for the management of GVHD and/or protection from radiation-induced injury.

Hyperbaric oxygen therapy for a refractory skin ulcer after radical mastectomy and radiation therapy: a case report

Background

Radiation therapy is performed as an adjuvant therapy when indicated following surgical resection of malignant tumors. However, radiation exposure induces acute or chronic dermatitis, depending on the radiation dose, interval, tissue volume, or irradiated area of the body. Radiation-induced skin ulcers and osteomyelitis of the underlying bone are intractable late-stage complications of radiation therapy, and often require reconstructive surgery to cover exposed tissue. Hyperbaric oxygen therapy has been suggested as a treatment for delayed radiation injury with soft tissue and bony necrosis.

Case presentation

A 74-year-old Japanese female underwent left radical mastectomy for breast cancer (T3N3M0, stage IIIB) in 1987. Radiation therapy was initiated 6 weeks after the surgery. She received telecobalt-60 in a total dose of 50 Gy with 25 fractions to the left supraclavicular, parasternal and left axillary regions, and electron treatment (9 MeV) in a total dose of 50 Gy in 25 fractions to the left chest wall. After irradiation, her skin became thinner and more fragile on the left chest wall, but no severe infections were observed. She noticed a small ulcer that repeatedly healed and recurred in 2000. She visited the hospital where she received radiation therapy and was treated for a skin ulcer on the left chest wall in December 2012. A fistula developed and then pus was discharged in January 2013. She was referred to the hyperbaric medical center in February 2013, and the fistula (1.5 × 3 cm) with pus discharge was observed. She was diagnosed with a late-onset radiation-induced skin ulcer that developed 25 years after radical mastectomy. HBO₂ (2.5 atmospheres absolute with 100% oxygen for 60 minutes) was indicated for the refractory ulcer and osteomyelitis of the ribs. The patient was treated with HBO₂ a total of 101 times over the course of 1 year and completely recovered.

Conclusions

Hyperbaric oxygen therapy can be performed safely for even more than 100 sessions in patients with radiation-induced skin ulcers and osteomyelitis. Hyperbaric oxygen therapy can be considered as an alternative, conservative treatment when surgical resection for late-onset, radiation-induced skin ulcers is not indicated because of fragile skin in the irradiated areas.

Post-WBRT cognitive impairment and hippocampal neuronal depletion measured by in vivo metabolic MR spectroscopy: Results of prospective investigational study

BACKGROUND AND PURPOSE

The aim of this prospective study is to evaluate post-whole brain radiotherapy (WBRT) changes in hippocampal concentration of N-acetylaspartate (h-tNAA) as a marker of neuronal loss and to correlate those changes to neurocognitive function.

MATERIAL AND METHODS

Thirty-five patients with brain metastases underwent baseline single slice multi-voxel MR spectroscopy (MRS) examination for measurement of hippocampal h-tNAA together with baseline battery of neurocognitive tests focused on memory (Auditory Verbal Learning Test and Brief Visuospatial Memory Test - Revised) as well as quality of life questionnaires (EORTC QLQ-C30 a EORTC QLQ-BN20). Eighteen patients completed follow-up evaluation four months after standard WBRT (2 laterolateral fields, 10×3.0Gy, 6MV photons) and were included in this analysis. MRS and cognitive examinations were repeated and compared to baseline measurements.

RESULTS

Statistically significant decreases in h-tNAA were observed in the right (8.52-7.42mM; -12.9%, 95%CI: -7.6 to -16.4%) as well as in the left hippocampus (8.64-7.60mM; -12%, 95%CI: -7.9 to -16.2%). Statistically significant decline was observed in all AVLT and BVMT-R subtests with exception of AVLT_Recognition. Quality of life declined after WBRT (mean Δ -14.1±20.3 points in transformed 0-100 point scale; p=0.018) with no correlation to changes in hippocampal metabolite concentrations. Moderate positive correlation was observed between left h-tNAA concentration decrease and AVLT_TR decline (r=+0.32; p=0.24) as well as with AVLT_DR (r=+0.33; p=0.22) decline. Changes in right h-tNAA/Cr negatively correlated with AVLT_DR (r=-0.48; p=0.061). No correlation between right hippocampus h-tNAA and memory decline (AVLT) was observed.

CONCLUSIONS

Our results suggest hippocampal NAA concentrations decline after WBRT and MRS may be a useful biomarker for monitoring neuronal loss after radiotherapy.

Radiation injury vs. recurrent brain metastasis: combining textural feature radiomics analysis and standard parameters may increase 18F-FET PET accuracy without dynamic scans

OBJECTIVES

We investigated the potential of textural feature analysis of O-(2-[¹⁸F]fluoroethyl)-L-tyrosine (¹⁸F-FET) PET to differentiate radiation injury from brain metastasis recurrence.

METHODS

Forty-seven patients with contrast-enhancing brain lesions (n = 54) on MRI after radiotherapy of brain metastases underwent dynamic ¹⁸F-FET PET. Tumour-to-brain ratios (TBRs) of ¹⁸F-FET uptake and 62 textural parameters were determined on summed images 20-40 min post-injection. Tracer uptake kinetics, i.e., time-to-peak (TTP) and patterns of time-activity curves (TAC) were evaluated on dynamic PET data from 0-50 min post-injection. Diagnostic accuracy of investigated parameters and combinations thereof to discriminate between brain metastasis recurrence and radiation injury was compared.

RESULTS

Diagnostic accuracy increased from 81 % for TBR_mean alone to 85 % when combined with the textural parameter Coarseness or Short-zone emphasis. The accuracy of TBR_max alone was 83 % and increased to 85 % after combination with the textural parameters Coarseness, Short-zone emphasis, or Correlation. Analysis of TACs resulted in an accuracy of 70 % for kinetic pattern alone and increased to 83 % when combined with TBR_max.

CONCLUSIONS

Textural feature analysis in combination with TBRs may have the potential to increase diagnostic accuracy for discrimination between brain metastasis recurrence and radiation injury, without the need for dynamic ¹⁸F-FET PET scans.

KEY POINTS

• Textural feature analysis provides quantitative information about tumour heterogeneity • Textural features help improve discrimination between brain metastasis recurrence and radiation injury • Textural features might be helpful to further understand tumour heterogeneity • Analysis does not require a more time consuming dynamic PET acquisition.

Should future interventional neuroradiologists be screened for mutations that impair radiation-induced DNA repair?

In our current medical practice, an increasing number of specialists now have access to radiology technical platforms in order to perform imaging-guided procedures. Although knowledge about the current guidelines and radiation protection devices is a pre-requisite for the use of radiation, the preventive measures are often more or less strictly followed, leading to chronic daily exposure to significant doses of radiation and large accumulated lifetime exposures. Aortic intervention, electrophysiology, and neuro intervention in particular can result in large doses to the operators. Interventionalists might try to rationalize their dismissal of the exposure risks with various excuses: they don't know where they left their badges (even though, guiltily, they would readily admit it is good practice to always wear them), the estimated short duration of the procedure, significant muscular strain and spasm caused by the heaviness of lead aprons, decreased dexterity with lead gloves, or discomfort in wearing lead protective glasses. But their dismissive attitude is most likely due to the inherent inability to feel threatened by something they cannot see or feel, a commitment to the patient at all cost, and a culture of bravado that reinforces their behavior.