Development of hematopoietic syndrome mice model for localized radiation exposure

Natural-history Characterization of a Murine Partial-body Irradiation Model System: Establishment of a Multiple-Parameter Based GI-ARS Severity-Scoring System

The purpose of this investigation was to characterize the natural history of a murine total-abdominal-irradiation exposure model to measure gastrointestinal acute radiation injury. Male CD2F1 mice at 12 to 15 weeks old received total-abdominal irradiation using 4-MV linear accelerator X-rays doses of 0, 11, 13.5, 15, 15.75 and 16.5 Gy (2.75 Gy/min). Daily cage-side (i.e., in the animal housing room) observations of clinical signs and symptoms including body weights on all animals were measured up to 10 days after exposure. Jejunum tissues from cohorts of mice were collected at 1, 3, 7 and 10 days after exposure and radiation injury was assessed by histopathological analyses. Results showed time- and dose-dependent loss of body weight [for example at 7 days: 0.66 (±0.80) % loss for 0 Gy, 6.40 (±0.76) % loss at 11 Gy, 9.43 (±2.06) % loss at 13.5 Gy, 23.53 (± 1.91) % loss at 15 Gy, 29.97 (±1.16) % loss at 15.75 Gy, and 31.79 (±0.76) % loss at 16.5 Gy]. Negligible clinical signs and symptoms, except body weight changes, of radiation injury were observed up to 10 days after irradiation with doses of 11 to 15 Gy. Progressive increases in the severity of clinical signs and symptoms were found after irradiation with doses >15 Gy. Jejunum histology showed a progressive dose-dependent increase in injury. For example, at 7 days postirradiation, the percent of crypts, compared to controls, decreased to 82.3 (±9.5), 69.2 (±12.3), 45.4 (±11.9), 18.0 (±3.4), and 11.5 (± 1.8) with increases in doses from 11 to 16.5 Gy. A mucosal injury scoring system was used that mainly focused on changes in villus morphology damage (i.e., subepithelial spaces near the tips of the villi with capillary congestion, significant epithelial lifting along the length of the villi with a few denuded villus tips). Peak levels of total-abdominal irradiation induced effects on the mucosal injury score were seen 7 days after irradiation for doses ≥15 Gy, with a trend to show a decline after 7 days. A murine multiple-parameter gastrointestinal acute-radiation syndrome severity-scoring system was established based on clinical signs and symptoms that included measures of appearance (i.e., hunched and/or fluffed fur), respiratory rate, general (i.e., decreased mobility) and provoked behavior (i.e., subdued response to stimulation), weight loss, and feces/diarrhea score combined with jejunum mucosal-injury grade score. In summary, the natural-history radio-response for murine partial-body irradiation exposures is important for establishing a well-characterized radiation model system; here we established a multiple-parameter gastrointestinal acute-radiation syndrome severity-scoring system that provides a radiation injury gastrointestinal tissue-based assessment utility.

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.

Ascorbate formulation improves healing efficacy in excisional wound mice model through interplay between pro and anti-inflammatory cytokines and angiogenic markers

BACKGROUND AND OBJECTIVE

Biomedical research in regenerative medicine prompts researchers to formulate cost-effective therapeutics for wound healing. The present study was conducted to characterize the ascorbate based formulation vis-a-vis investigating the molecular dynamics of the formulation.

MATERIALS AND METHODS

To characterize the formulation, particle size, zeta potential, thermal stability, compatibility, anti-oxidant, and permeation prospective were measured using standard protocols. The in-vitro healing potential and safety formulae were evaluated using the L929 cell line. For molecular unravelling of the pharmacodynamics of formulation, an excision wound model was used, and 54 mice were randomly and equally divided into three groups, i.e., untreated, betadine-treated, and formulation-treated, to ascertain the interplay between cytokines and chemokines and their culminative role in the release of growth factors.

RESULTS

The ascorbate formulae were found to be amorphous, biocompatible, safe, and long-lasting, with particle sizes and zeta potentials of 389.7 ± 0.69 nm and -38.1 ± 0.65 mV, respectively, and anti-oxidative potential. An in-vitro study revealed that the formulation has a significant (p<0.05) migration potential and is non-toxic. Expression profiling of TGF-β, FGF-2, VEGF, and collagen III & I showed significant (p<0.05) up-regulation, whereas significant (p<0.05) down-regulation of pro-inflammatory genes like IL-1α, IL-1β, TNF-α, IL-6, and temporal change in CCR-5 was observed in formulae-treated animals as compared to other groups.

CONCLUSION

By up-regulating angiogenic and collagen-promoting growth factor gene expression while down-regulating pro-inflammatory gene expression, ascorbate formulation promotes wound healing via extracellular matrix and granulation tissue deposition with significant improvement in tensile strength.