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International audience; Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is a powerful analytical technique for in situ quantitative analysis of solid samples. Nevertheless, the reduced availability of appropriate external and internal standards makes difficult its routine application in biological or medical sciences [1]. Additionally, the capability of sharing samples and standards between different imaging techniques would be desirable. The aim of this work is therefore to develop a sample / standard preparation methodology compatible with LA-ICP-MS and secondary ion mass spectrometry (SIMS) analysis to make these both techniques complementary for the study of uranium distribution in kidney. In case of internal contamination, uranium is eliminated through urine excretion and its excessive accumulation in kidney causes renal failure, characterized by reduced glomerular filtration [2-4]. It has heterogeneous tissue distribution, mostly accumulating and producing pathological lesions in the S2 and S3 segments of the proximal tubule located in the cortical zone [5-8]. Chronic exposure to low doses of uranium might be linked with renal dysfunction and an increased risk of cancer mortality [9-11]. A novel approach based on internal standard (IS) doped resin was carried out in order to incorporate a more feasible internal standard than 13C [12, 13]. Then, IS enriched resin was employed to embed dehydrated samples according to the chemical sample preparation protocol of biological samples for SIMS analysis [14, 15]. Then, serial thin and ultra-thin sections were cut with microtome and the homogeneity of internal standard was evaluated by randomly analysing small selected areas by LA-ICP-MS and SIMS. For quantification, uranium and IS doped resin was employed. The parallel analysis of consecutive tissue sections by LA-ICP-MS and SIMS allows to precisely locate and quantify uranium in the tissue. The advantages of this methodology are 1) the use of resin standards containing both uranium and IS, 2) a sample preparation compatible with several imaging techniques (SIMS, TEM, LA), 3) the ease of preparation and 4) the conservation of standards at room temperature.

Mass spectrometry imaging (MSI) using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been employed for the elemental bio-distribution and quantification of uranium (U) in histological tissue sections of rodent kidneys. Kidneys were immediately immersed into 4% paraformaldehyde (PFA) solution for 24 h, Tissue-Tek O.C.T. Compound embedded and stored at - 80 °C until cutting in a cryostat, and mounted in gel-covered glass slides. In order to assure complete ablation of sample, sample preparation and laser conditions were carefully optimized. In this work, a new analytical methodology is presented for performing quantitative laser ablation analyses based on internal standard (thulium, Tm)-spiked gelatine (10% m/v) for correction of matrix effects, lack of tissue homogeneity, and instrumental drift. In parallel, matrix-matched laboratory standards, dosed at different concentrations of U, were prepared from a pool of rat kidneys. The quantitative images of cryo-sections revealed heterogeneous distribution of uranium within the renal tissue, because the cortical concentration was up to 120-fold higher than the medullary concentration. Graphical abstract.

International audience; La spectrométrie de masse à plasma à couplage inductif par ablation laser a évolué pour devenir une technique analytique performante pour l'analyse quantitative in situ d'échantillons solides. Cependant, les progrès dans les applications des sciences biologiques sont toujours dépendants de la disponibilité d’étalons externes et internes appropriés. En outre, il serait intéressant que les échantillons et les étalons soient compatibles entre différentes techniques d'imagerie. Le but de ce travail est donc de trouver une méthodologie de préparation d’échantillons / étalons compatible avec les analyses par LA-ICP-MS et SIMS afin de rendre ces deux techniques complémentaires pour l’étude de la distribution de l’uranium dans les reins. D'une part, des étalons solides internes ont été préparés à partir d'homogénat de rein enrichi d'uranium. D’autre part, une nouvelle approche basée sur une résine dopée au nitrate d’uranyle (en poudre) a également été testée. De plus un standard interne (thulium) est incorporé directement dans la résine dopée. L'homogénéité de l'étalon interne et de l’uranium a été évaluée. Les avantages de cette méthodologie sont 1) pas besoin des homogénats, 2) une préparation d’échantillon compatible avec plusieurs techniques d’imagerie, 3) la facilité de préparation et 4) la conservation des étalons à température ambiante.

Cutaneous radiation syndrome has severe long‐term health consequences. Because it causes an unpredictable course of inflammatory waves, conventional surgical treatment is ineffective and often leads to a fibronecrotic process. Data about the long‐term stability of healed wounds, with neither inflammation nor resumption of fibrosis, are lacking. In this study, we investigated the effect of injections of local autologous bone marrow‐derived mesenchymal stromal cells (BM‐MSCs), combined with plastic surgery for skin necrosis, in a large‐animal model. Three months after irradiation overexposure to the rump, minipigs were divided into three groups: one group treated by simple excision of the necrotic tissue, the second by vascularized‐flap surgery, and the third by vascularized‐flap surgery and local autologous BM‐MSC injections. Three additional injections of the BM‐MSCs were performed weekly for 3 weeks. The quality of cutaneous wound healing was examined 1 year post‐treatment. The necrotic tissue excision induced a pathologic scar characterized by myofibroblasts, excessive collagen‐1 deposits, and inadequate vascular density. The vascularized‐flap surgery alone was accompanied by inadequate production of extracellular matrix (ECM) proteins (decorin, fibronectin); the low col1/col3 ratio, associated with persistent inflammatory nodules, and the loss of vascularization both attested to continued immaturity of the ECM. BM‐MSC therapy combined with vascularized‐flap surgery provided mature wound healing characterized by a col1/col3 ratio and decorin and fibronectin expression that were all similar to that of nonirradiated skin, with no inflammation, and vascular stability. In this preclinical model, vascularized flap surgery successfully and lastingly remodeled irradiated skin only when combined with BM‐MSC therapy. Stem Cells Translational Medicine 2018:569–582

International audience; Endothelial progenitor cell (EPC) transplantation has beneficial effects for therapeutic neovascularization. We therefore assessed the effect of a therapeutic strategy based on EPC administration in the healing of radiation-induced damage. To improve cell therapy for clinical use, we used pretreatment with ephrin B2-Fc (Eph-B2-Fc) and/or coadministration with smooth muscle progenitor cells. At day 3, EPCs promoted dermal wound healing in both nonirradiated and irradiated mice by 1.2- and 1.15-fold, respectively, compared with animals injected with phosphate-buffered saline. In addition, EPCs also improved skin-blood perfusion and capillary density in both irradiated and nonirradiated mice compared with PBS-injected animals. We also demonstrated that activation with Eph-B2-Fc increased wound closure by 1.6-fold compared with unstimulated EPCs in nonirradiated mice. Interestingly, the beneficial effect of Eph-B2-Fc was abolished in irradiated animals. In addition, we found that Eph-B2-Fc stimulation did not improve EPC-induced vascular permeability or adhesiveness compared to unstimulated EPCs. We hypothesized that this effect was due to high oxidative stress during irradiation, leading to inhibition of EPCs' beneficial effect on vascular function. In this line, we demonstrated that, in irradiated conditions, N-acetyl-L-cysteine treatment restored the beneficial effect of EPC stimulation with Eph-B2-Fc in the wound healing process. In conclusion, stimulation by Eph-B2-Fc improved the beneficial effect of EPCs in physiological conditions and irradiated conditions only in association with antioxidant treatment. Additionally, cotherapy was beneficial in pathological conditions. © 2015 Cognizant Comm. Corp.

International audience; Each year, millions of people worldwide are treated for primary or recurrent pelvic malignancies, involving radiotherapy in almost 50% of cases. Delayed development of visceral complications after radiotherapy is recognized in cancer survivors. Therapeutic doses of radiation may lead to the damage of healthy tissue around the tumor and abdominal pain. Because of the lack of experimental models, the underlying mechanisms of radiation-induced long-lasting visceral pain are still unknown. This makes managing radiation-induced pain difficult, and the therapeutic strategies proposed are mostly inefficient. The aim of our study was to develop an animal model of radiation-induced visceral hypersensitivity to (1) analyze some cellular and molecular mechanisms involved and (2) to test a therapeutic strategy using mesenchymal stromal cells (MSCs). Using a single 27-Grays colorectal irradiation in rats, we showed that such exposure induces a persistent visceral allodynia that is associated with an increased spinal sensitization (enhanced p-ERK neurons), colonic neuroplasticity (as increased density of substance P+ nerve fibers), and colonic mast cell hyperplasia and hypertrophy. Mast cell stabilization by ketotifen provided evidence of their functional involvement in radiation induced allodynia. Finally, intravenous injection of 1.5 million MSCs, 4 weeks after irradiation, induced a time-dependent reversion of the visceral allodynia and a reduction of the number of anatomical interactions between mast cells and PGP9.51 nerve fibers. Moreover, unlike ketotifen, MSC treatment has the key advantage to limit radiation-induced colonic ulceration. This work provides new insights into the potential use of MSCs as cellular therapy in the treatment of pelvic radiation disease.

International audience; Mesenchymal stem cell (MSC) therapy has recently been investigated as a potential treatment for cutaneous radiation burns. We tested the hypothesis that injection of local gingival fibroblasts (GFs) would promote healing of radiation burn lesions and compared results with those for MSC transplantation. Human clinical-grade GFs or bone marrow-derived MSCs were intradermally injected into mice 21 days after local leg irradiation. Immunostaining and real-time PCR analysis were used to assess the effects of each treatment on extracellular matrix remodeling and inflammation in skin on days 28 and 50 postirradiation. GFs induced the early development of thick, fully regenerated epidermis, skin appendages, and hair follicles, earlier than MSCs did. The acceleration of wound healing by GFs involved rearrangement of the deposited collagen, modification of the Col/MMP/TIMP balance, and modulation of the expression and localization of tenascin-C and of the expression of growth factors (VEGF, EGF, and FGF7). As MSC treatment did, GF injection decreased the irradiation-induced inflammatory response and switched the differentiation of macrophages toward an M2-like phenotype, characterized by CD163+ macrophage infiltration and strong expression of arginase-1. These findings indicate that GFs are an attractive target for regenerative medicine, for easier to collect, can grow in culture, and promote cutaneous wound healing in irradiation burn lesions. © 2015, Mary Ann Liebert, Inc.

The management of proctitis in patients who have undergone very-high-dose conformal radiotherapy is extremely challenging. The fibrosis-necrosis, fistulae, and hemorrhage induced by pelvic overirradiation have an impact on morbidity. Augmenting tissue repair by the use of mesenchymal stem cells (MSCs) may be an important advance in treating radiation-induced toxicity. Using a preclinical pig model, we investigated the effect of autologous bone marrow-derived MSCs on high-dose radiation-induced proctitis. Irradiated pigs received repeated intravenous administrations of autologous bone marrow-derived MSCs. Immunostaining and real-time polymerase chain reaction analysis were used to assess the MSCs' effect on inflammation, extracellular matrix remodeling, and angiogenesis, in radiation-induced anorectal and colon damages. In humans, as in pigs, rectal overexposure induces mucosal damage (crypt depletion, macrophage infiltration, and fibrosis). In a pig model, repeated administrations of MSCs controlled systemic inflammation, reduced in situ both expression of inflammatory cytokines and macrophage recruitment, and augmented interleukin-10 expression in rectal mucosa. MSC injections limited radiation-induced fibrosis by reducing collagen deposition and expression of col1a2/col3a1 and transforming growth factor-β/connective tissue growth factor, and by modifying the matrix metalloproteinase/TIMP balance. In a pig model of proctitis, repeated injections of MSCs effectively reduced inflammation and fibrosis. This treatment represents a promising therapy for radiation-induced severe rectal damage.

About half of people with cancer are treated with radiation therapy; however, normal tissue toxicity still remains a dose-limiting factor for this treatment. The skin response to ionizing radiation may involve multiple inflammatory outbreaks. The endothelium is known to play a critical role in radiation-induced vascular injury. Furthermore, endothelial dysfunction reflects a decreased availability of nitric oxide. Statins have been reported to preserve endothelial function through their antioxidant and anti-inflammatory activities. In this study, wild type and endothelial nitric oxide synthase (eNOS)(-/-) mice were subjected to dorsal skin irradiation and treated with pravastatin for 28 days. We demonstrated that pravastatin has a therapeutic effect on skin lesions and abolishes radiation-induced vascular functional activation by decreasing interactions between leukocytes and endothelium. Pravastatin limits the radiation-induced increase of blood CCL2 and CXCL1 production expression of inflammatory adhesion molecules such as E-selectin and intercellular adhesion molecule-1, and inflammatory cell migration in tissues. Pravastatin limits the in vivo and in vitro radiation-induced downregulation of eNOS. Moreover, pravastatin has no effect in eNOS(-/-) mice, demonstrating that eNOS plays a key role in the beneficial effect of pravastatin in radiation-induced skin lesions. In conclusion, pravastatin may be a good therapeutic approach to prevent or reduce radiation-induced skin damage.

International audience; Intestinal radiation injury is a dose-limiting factor in radiation therapy for abdominal and pelvic cancers. Because transforming growth factor-β1 is a key mediator involved in radiation-induced damage, we hypothesized that its target gene, plasminogen activator inhibitor type 1 (PAI-1), is an essential mediator of intestinal radiation toxicity. In a model of radiation enteropathy, survival was monitored and intestinal radiation injury was assessed in both wild-type (Wt) and PAI-1 knockout mice. Immunohistochemical labeling of PAI-1 was also assessed in patients treated with preoperative radiotherapy for rectal adenocarcinoma. Finally, the molecular mechanisms involved in radiation-induced PAI-1 expression were investigated. We found that PAI-1 -/- mice exhibited increased survival and better intestinal function compared with Wt mice. Intestinal radiation injury was attenuated in irradiated PAI-1 -/- mice compared with irradiated Wt mice, and irradiation increased blood cell-endothelial cell interactions in Wt but not PAI-1 -/- mice. In vivo, radiation-induced intestinal damage in mice, as well as in patients treated with radiotherapy, was associated with the up-regulation of PAI-1 in the endothelium. In vitro, irradiation increased PAI-1 expression in endothelial cells by a p53/Smad3-dependent mechanism. Together, these data demonstrate that PAI-1 plays a critical role in radiation-induced intestinal damage, suggesting that PAI-1 is an attractive target for preventing or reducing the side effects of radiation therapy. Copyright © American Society for Investigative Pathology.

Radiation-induced lesion outcomes of normal tissues are difficult to predict. In particular, radiotherapy or local exposure to a radioactive source by accident can trigger strong injury to the skin. The finding of biomarkers is of fundamental relevance for the prediction of lesion apparition and its evolution, and for the settlement of therapeutic strategies. In order to study radiation-induced cutaneous lesions, we developed a mouse model in which the dorsal skin was selectively exposed to ionizing radiation (IR). 2-D difference gel electrophoresis (2-D DIGE) coupled with MS was used to investigate proteins altered in expression and/or PTM in serum. Proteome changes were monitored from 1 day to 1 month postirradiation, at a dose of 40 Gy, in this specific model developing reproducible clinical symptoms ranging from erythema to skin ulceration with wound healing. About 60 proteins (including some isoforms and likely post-translational variants), representing 20 different proteins, that exhibited significant and reproducible kinetic expression changes, were identified using MS and database searches. Several proteins, down- or up-regulated from day one, could prove to be good candidates to prognosticate the evolution of a skin lesion such as necrosis. In addition, we observed shifts in pI of several spot trains, revealing potential PTM changes, which could also serve as indicators of irradiation or as predictors of lesion severity.

International audience; La surexposition à l'uranium entraîne un dysfonctionnement rénal suite à son effet toxique par des actions chimique et radiologique. De plus, la distribution tissulaire de l’uranium est hétérogène, s'accumulant et induisant principalement des lésions pathologiques dans les segments S2 et S3 du tubule proximal situés dans la zone corticale (100 fois la concentration rénale moyenne). Ce travail présente le développement d'une méthodologie analytique basée sur la spectrométrie de masse à couplage inductif et la technique d’ablation laser (LA-ICP-MS) pour la cartographie et la quantification de l'uranium dans des coupes de tissus histologiques de reins de souris. À ce jour, une seule équipe a récemment publié une analyse de l’uranium dans les reins de souris qui reste semi-quantitative à cause de l’absence d’un étalon interne approprié. Afin de réaliser des analyses quantitatives de bio-imagerie LA-ICPMS, nous avons développé des standards de laboratoire adaptés à la matrice rénale et une stratégie de normalisation basée sur la gélatine dopée avec un standard interne. Les premiers résultats quantitatifs obtenus à partir d’images préliminaires de cryo-sections de rein ont mis en évidence une distribution hétérogène de l'uranium dans le tissu rénal, avec une concentration corticale 60 fois supérieure à la concentration médullaire.