BACKGROUND:

1Department of Radiation Oncology, Albert Einstein College of Medicine and Montefiore Medical Center2Department of Pharmacology and Pathology, Stony Brook University Medical Center

Radiation exposure in a mass casualty setting represents a serious physiological threat

RIGS results from a combination of direct cytocidal effects of of irradiation on intestinal crypt cells and stromal cells with loss of mucosal barrier and symptoms ranging from electrolyte imbalance and diarrhea to death.

To date there are no approved radiomitigating agents for RIGS.

We have previously shown that rats exposed to intestinal irradiation developed RIGS consequently died within 14 days (Bhanja et al, 2009)

Previous Studies have shown that subcutanoeus adipose tissue derived stromal cells were able to facilitate intestinal repair in a TNBS induced colitis rat model

We hypothesize that adipose tissue contains stromal stem cells including mesenchymal (MSC), endothelial progenitors and myeloid cells that could provide the neccesary microenvironment to regenerate irradiated ISC’s and mitigate RIGS.

OBJECTIVES:

MATERIALS AND METHODS: RESULTS:

Mitigation of Radiation Induced Gastrointestinal SyndomeBy Adipose Derived Stromal Therapy

Sujith Baliga1, Subhrajit Saha1, Alan Alfieri1, Xin Yuan Dong1, Laibin Liu1, Emily Chen2 and Chandan Guha1

REFERENCES

1. Ando, Yugo,Inaba Muneo, Sakaguchi, Yataku, Tsdua Masanobu, Quan Ke Guo, Omae Mariko, Okazaki Kazuichi, and Susumu Ikehara. Subcutaneous Adipose Tissue-Derived Stem cell facilitate Colonic Mucosal recovery from 2, 4, 6 Trinitrobenzene Sulfonic Acid (TNBS) induced colitis in rats. Inflammat Bowel Disease.

2. Metzger, Marco, Contrad, Sabine, Bolado-Alvarez, Gonzalo, Skutella, Thomas, and Lothar Just Gene Expressionof the repulsive Guidance Molecules During develioment of the mouse intestine. Developmental dyanmics.

3. Tiaka K Elisavet Anastassios C Manolakis, Kapsoritakis N Andreas, Potamiianos P Spyros. Implication of adiponectin and resistin in gastrointestinal diseases.

4. Haydont V, Bourgier C, and Brotons Vozenin M-C. Rho-ROCK pathway as a molecular target for intestinal radiation toxicity . The British Journal of Radiology.

To determine whether intravenous transplantation of adherent and non-adherent fractions of adipose tissue-derived stromal cells (ADNASC or ADASC) would mitigate RIGS.

Donor cells were harvested from C57Bl/6 mice (n=10) subcutaneous and intraperitoneal fat using sterile techniques and cultured in in DMEM with 10% FBS and 1% P/S for 4d.

Adherent and non-adherent floating cells were collected by centrifugation and resuspended in PBS prior to transplantation.

C57Bl/6 mice received whole body Irradiation. Twenty-four hours after WBI animals received intravenous transplanation of either ADASC or ADNASC or cell culture supernatant and growth medium.

Flow cytometry analysis was performed to determine cell types.

Proteomics analysis was conducted on cell supernatant to determine protein targets for RIGS.

The data sets obtained were uploaded to Metacore, a pathway analysis tool.

Ontology enrichment analysis was performed using Gene-ontology and GeneGo processes which represent manually curated protein interactions assembled on the basis of proven literature evidence.

Statistical analysis uses a hypergeometric distribution to calculate the probability of overlap between protein targets to determine the likelihood of co—incidental overlap within ontology groups.

Funding This work was made possible through funding

from the National institute of Allergic and Infectious diseases with the U19 grant

Results and ConclusionTransplantation of ADNASC and Cell Culture supernatant

improved survival in irradiated mice (P<0.01)This is the first demonstration that transplantation of adipose

derived stromal cells could mitigate RIGS after Lethal doses of radiation.

Using Gene ontology and GeneGo databases we show that the majority of proteins identified via proteomics are involved in cytoskeletal remodeling and cell adhesion.

It has previously been shown that Rho/ROCK pathway is responsible for intestinal radiation induced fibrosis and inflammation( Haydont et al., 2007).

Proteins upregulated in this Rho/ROCK pathway include cofilin, profilin, actin, Arp2/3, PAK1, Myosin II, MyHC, and MELC (Fig. 7).

This data suggests that remodeling of the actin cytoskelton (RhoA/ROCK) may play a major role in cellular response to radiation induced injury and may represent a target for future therapy to mitigate RIGS.