Experimental model for coadjuvant treatment with mesenchymal stem cells for aortic aneurysm.

UNLABELLED Many factors are possibly involved in the inflammatory process which causes the degeneration of the arterial wall in the formation of Abdominal Aortic Aneurysms. During the last years different experimental models have been published to treat this fault of the arterial walls. Parallel the clinical treatment has evolved. With this work we have tried to develop an animal model basing on the clinical current treatment. Finally, we propose a treatment based on mesenchymal cells to disable local immune response, preventing excessive fibrosis, apoptosis, and inducing intrinsic cellular progenitors. OBJECTIVE To present a reproducible superior animal model of experimentation, intending to show that mesenchymal stem cells inserted in the sac of an artificial aneurysm are able to survive, so that they can be made accountable for a subsequent beneficial effect upon this condition. METHODS Six Landrace-White pigs, weighing around 25Kg. We generate 2 aneurysms of abdominal aorta (2x1cm) with Dacron's patches. Later we treat the aneurysms endoscopic with a covered endograft. Finally, in one of the aneurysmal sac we introduce 1cc fibrin sealant and in another 1 cc of fibrin sealant with 10 million MSC. Animals were sacrificed at 24 hs and 1, 3, 5, 7 and 9 weeks. Samples of aneurysms were processed histologically (H&E and Masson). The injected cells were located by immunofluorescence (GFP market). RESULTS The surgical technique is reproducible and similar to those conducted in common clinical practice. Histological cross-section samples of cases treated with MSC and analyzed by a blind researcher present a lower inflammation reaction, or with longer evolution time than in controls. Immunofluorescence studies have detected cells marked with GFP up to three weeks after treatment. CONCLUSION This reproducible animal model is similar to common clinical treatment. MSC can stand alive at least for three weeks since their implantation within an aneurysm sac. This may improve the results of conventional endovascular treatment by the stabilization of the aneurysmal sac.