Mesenchymal stem cell therapy for acute radiation syndrome: innovative medical approaches in military medicine

After a radiological or nuclear event, acute radiation syndrome (ARS) will present complex medical challenges that could involve the treatment of hundreds to thousands of patients. Current medical doctrine is based on limited clinical data and remains inadequate. Efforts to develop medical innovations that address ARS complications are unlikely to be generated by industry because of market uncertainties specific to this type of injury. A prospective strategy could be the integration of cellular therapy to meet the medical demands of ARS. The most clinically advanced cellular therapy to date is the administration of mesenchymal stem cells (MSCs). Results of currently published investigations describing MSC safety and efficacy in a variety of injury and disease models demonstrate the unique qualities of this reparative cell population in adapting to the specific requirements of the damaged tissue in which the cells integrate. This report puts forward a rationale for the further evaluation of MSC therapy to address the current unmet medical needs of ARS. We propose that the exploration of this novel therapy for the treatment of the multivariate complications of ARS could be of invaluable benefit to military medicine.

Emergency arterio-venous loop for free-flap defect reconstruction of the lower thigh with a post-irradiated and heavily infected wound

Although being a safe and standardised procedure, free-flap reconstruction can be harmful if unpredictable situations occur intraoperatively. The case presented reveals a situation in which an unscheduled interdisciplinary approach allowed to complete our reconstructive aim. An extensive defect at the thigh was planned for reconstruction by means of a free rectus abdominis flap. As the distant part of the flap showed a compromised perfusion during operation and had to be partially discarded, our colleagues from the vascular surgery department created an arterio-venous loop for anastomosis. This allowed a more distant positioning of the flap and ensured a complete defect reconstruction.

Heparin-binding EGF-like growth factor (HB-EGF) protects the intestines from radiation therapy-induced intestinal injury

PURPOSE

Radiation therapy (RT) often induces enteritis by inhibiting proliferation and inducing apoptosis. Heparin-binding EGF-like growth factor (HB-EGF) has been shown to protect the intestine in several animal injury models. The objective of this study was to examine whether HB-EGF affects RT-induced intestinal injury.

METHODS

HB-EGF or PBS was administered intraperitoneally to mice daily for 3 days, followed by total body irradiation (TBI). Three days after TBI, intestinal segments were harvested, and BrdU immunohistochemistry was performed to identify proliferating crypts (n=25). Four days after TBI, intestinal segments were harvested and assessed for histologic injury (n=34), and FITC-dextran was administered via gavage with serum FITC-dextran levels quantified to determine gut barrier function (n=18).

RESULTS

Compared to non-HB-EGF-treated irradiated mice, administration of HB-EGF to irradiated mice led to a significantly increased percentage of proliferative crypts (72.6% vs. 50.5%, p=0.001), a significantly decreased percent of histologic sections with severe histologic injury (13.7% vs. 20.3%, p=0.005), and significantly reduced intestinal permeability (18.8 μg/mL vs. 22.6 μg/mL, p=0.02).

CONCLUSIONS

These results suggest that administration of HB-EGF protects the intestines from injury after exposure to radiation therapy. Administration of HB-EGF may represent a novel therapy for the prevention of radiation enteritis in the future.

Evaluation of Genomic Evidence for Oxidative Stress in Experimental Radiation Nephropathy

BACKGROUND

Chronic persistent oxidative stress has been proposed as a mechanism for late radiation injury to normal tissue. Using biochemical, histological, and pharmacological techniques, we have not been able to confirm this hypothesis for late renal radiation injury. Gene expression may be more revealing, especially since the initial effects of radiation are to damage DNA.

METHODS

Gene array studies were done using kidney tissue from irradiated rats, with particular attention to genes pertinent to oxidative stress. The time points were from 1 to 49 days after irradiation. Cellular RNA and mitochondrial DNA were isolated, for gene expression analysis and common deletion testing, respectively.

RESULTS

For the gene expression studies, and from over 30,000 transcripts, only nine related to oxidative stress had 1.4 fold or greater changes in expression. Mitochondrial DNA showed no changes in the common deletion.

CONCLUSION

These studies do not support the hypothesis of chronic oxidative stress as a mechanism for radiation nephropathy.

Radiation-induced brain injury: retrospective analysis of twelve pathologically proven cases

Purpose

This study was designed to determine the influencing factors and clinical course of pathologically proven cases of radiation-induced brain injury (RIBI).

Materials and Methods

The pathologic records of twelve patients were reviewed; these patients underwent surgery following radiotherapy due to disease progression found by follow-up imaging. However, they were finally diagnosed with RIBI. All patients had been treated with 3-dimensional conventional fractionated radiotherapy and/or radiosurgery for primary or metastatic brain tumors with or without chemotherapy. The histological distribution was as follows: two falx meningioma, six glioblastoma multiform (GBM), two anaplastic oligodendroglioma, one low grade oligodendroglioma, and one small cell lung cancer with brain metastasis.

Results

Radiation necrosis was noted in eight patients and the remaining four were diagnosed with radiation change. Gender (p = 0.061) and biologically equivalent dose (BED)₃ (p = 0.084) were the only marginally influencing factors of radiation necrosis. Median time to RIBI was 7.3 months (range, 0.5 to 61 months). Three prolonged survivors with GBM were observed. In the subgroup analysis of high grade gliomas, RIBI that developed <6 months after radiotherapy was associated with inferior overall survival rates compared to cases of RIBI that occurred ≥6 months (p = 0.085).

Conclusion

Our study demonstrated that RIBI could occur in early periods after conventional fractionated brain radiotherapy within normal tolerable dose ranges. Studies with a larger number of patients are required to identify the strong influencing factors for RIBI development.

Medical management of the acute radiation syndrome

The acute radiation syndrome (ARS) occurs after whole-body or significant partial-body irradiation (typically at a dose of >1 Gy). ARS can involve the hematopoietic, cutaneous, gastrointestinal and the neurovascular organ systems either individually or in combination. There is a correlation between the severity of clinical signs and symptoms of ARS and radiation dose. Radiation induced multi-organ failure (MOF) describes the progressive dysfunction of two or more organ systems over time. Radiation combined injury (RCI) is defined as radiation injury combined with blunt or penetrating trauma, burns, blast, or infection. The classic syndromes are: hematopoietic (doses >2-3 Gy), gastrointestinal (doses 5-12 Gy) and cerebrovascular syndrome (doses 10-20 Gy). There is no possibility to survive after doses >10-12 Gy. The Phases of ARS are-prodromal: 0-2 days from exposure, latent: 2-20 days, and manifest illness: 21-60 days from exposure. Granulocyte-colony stimulating factor (G-CSF) at a dose of 5 μg/kg body weight per day subcutaneously has been recommended as treatment of neutropenia, and antibiotics, antiviral and antifungal agents for prevention or treatment of infections. If taken within the first hours of contamination, stable iodine in the form of nonradioactive potassium iodide (KI) saturates iodine binding sites within the thyroid and inhibits incorporation of radioiodines into the gland. Finally, if severe aplasia persists under cytokines for more than 14 days, the possibility of a hematopoietic stem cell (HSC) transplantation should be evaluated. This review will focus on the clinical aspects of the ARS, using the European triage system (METREPOL) to evaluate the severity of radiation injury, and scoring groups of patients for the general and specific management of the syndrome.

Hyperbaric oxygen therapy

Hyperbaric oxygen is a treatment in which a patient breathes 100% oxygen intermittently while inside a treatment chamber at a pressure higher than at sea level pressure (ie, >1 atm). In certain circumstances, it represents the primary treatment modality, whereas in others it is an adjunct to surgical or pharmacologic interventions. After reviewing all the scientific evidence available to date, the Undersea and Hyperbaric Medical Society, in its latest publication, Hyperbaric Oxygen Therapy Indications (12th ed.), recommends 13 indications for hyperbaric oxygen therapy. Several of these indications are related to our practice of wound care. The article discusses these indications in detail.

The effect of whole-body radiation on blood levels of gastrointestinal peptides in the rat

Radiation-induced injury may occur in various incidents as well as the terrorist radiation exposure scenario. The digestive tract is among the most radiosensitive organs in the body and its function, which is partly regulated by gastrointestinal (GI) peptides, can be affected by radiation exposure. However, very little is known about the effect of whole-body radiation on blood GI peptides. The aim of this study therefore was to determine the effect of whole-body radiation on circulating levels of GI peptides in the rat. To study this, rats were exposed to 5-Gy whole-body gamma radiation. They were then euthanized at 1, 2, 4, or 8 days after irradiation. Plasma levels of cholecystokinin (CCK), secretin, gastrin, and ghrelin were determined using specific enzyme immunoassays. Serum levels of alanine transaminase (ALT), alkaline phosphatase (ALP), total bilirubin, and lactate were also measured. Our results showed that whole-body irradiation significantly decreased plasma CCK levels by 57% and 54% at 1 and 2 days after irradiation (P<0.05), respectively. At 4 and 8 days after irradiation, plasma CCK levels returned to normal. Similarly, plasma levels of secretin decreased by 48% at 2 days after irradiation (P<0.05), and returned to normal at 8 days after irradiation. In contrast, there was no significant change in plasma levels of gastrin and ghrelin after irradiation. No significant differences were observed in ALT, ALP, total bilirubin, or lactate. In conclusion, whole-body radiation exposure alters blood GI peptides especially the ones that were produced in the small intestine, such as CCK and secretin. The diverse response of the GI peptides to irradiation could be due to a difference in radiosensitivity in different regions of the GI tract.

Ume (Japanese apricot)-induced small bowel obstruction with chronic radiation enteritis

Stricture formation is recognized as one of the complications of chronic radiation enteritis. Here, we present a case of a 73-year-old woman who presented with small bowel obstruction 16 years after pelvic irradiation for uterine cancer. Computed tomographic (CT) scan of the abdomen demonstrated a 1-cm foreign body in the terminal ileum. Laparotomy revealed a stone of ume (Japanese apricot) stuck in an ileal stricture, leading to complete impaction and perforation. She was successfully treated with ileocecal resection and ileocolic anastomosis without any complication. Pathological study revealed that the low compliance caused by fibrosis of the bowel wall prevented the small ume stone from passing through the irradiated ileum. Our case implies the specific risk of food-induced small bowel obstruction in patients with a history of pelvic irradiation.

Biomarkers for radiation-induced small bowel epithelial damage: An emerging role for plasma Citrulline

Reduction of cancer treatment-induced mucosal injury has been recognized as an important target for improving the therapeutic ratio as well as reducing the economic burden associated with these treatment related sequellae. Clinical studies addressing this issue are hampered by the fact that specific objective parameters, which enable monitoring of damage in routine clinical practice, are lacking. This review summarizes pros and cons of currently available endpoints for intestinal injury. The metabolic background and characteristics of plasma citrulline, a recently investigated biomarker specifically for small intestinal injury, are discussed in more detail.