Syngeneic bone marrow cell therapy prevents intimal proliferation in allogeneic vascular transplantation.

BACKGROUND: Transplant arteriosclerosis is characterized by intraluminal obstructive proliferation occurring in response to immune-mediated arterial wall injury. Cell therapy with vascular progenitor cells have been suggested to repair intimal lesions following endothelial injury. The aim of the current study was to assess the effects of autologous bone marrow cell direct transfer and of Fucan-mobilization bone marrow-derived progenitor cells on intimal thickening in vascular grafts. METHODS: Aortic allografts were performed in Brown Norway (BN) and Lewis (LEW) rats. Cell therapy was performed by injection of two doses of 10 million LEW bone marrow mononuclear cells to recipient LEW following aortic grafting. Fucan, a low molecular weight sulfated polysaccharide (LMWF) was used to mobilize bone marrow-derived progenitor cells. Five groups of 10 rats included: untreated isografts (BN to BN), untreated allografts, and three allografted groups, respectively, treated by fucan therapy, cell therapy, or cell and fucan therapy. Aorta were studied by morphometric analysis at 30 d. RESULTS: In the absence of treatment, intimal thickening was greater in allograft than in isograft groups (299±50 versus 3.5±1.7 µm, P<0.001). Cell therapy alone, fucan therapy alone, and the combined treatment were shown to prevent intimal thickening in allografts (5.1±1.7, 6.1±2.3, 4.1±2.5, versus 299±50 µm respectively, P<0.001). In the three treated groups, the intimal lining was a single layer of endothelial cells expressing CD34 positive, endothelial nitric oxide synthase (eNOS) positive, and Ox3 specific-recipient monoclonal antibody positive. CONCLUSION: These results provide the proof of concept of recipient syngenic bone-marrow cell therapy for the prevention of chronic vasculopathy.

Low molecular weight fucoidan prevents neointimal hyperplasia after aortic allografting.

BACKGROUND: Fucoidan, a new low molecular weight sulfated polysaccharide (LMWF), has previously been shown to mobilize bone marrow-derived progenitors cells via stimulation of stromal derived factor (SDF)-1 release. Mobilized progenitor cells have been suggested to repair intimal lesions after immune-mediated endothelial injury and thus prevent intimal proliferation. The aim of this study was to evaluate the effect of LMWF treatment in a rat aortic allograft model of transplant arteriosclerosis (TA). METHODS: Aortic grafts were performed in Brown Norway (BN, donor) and Lewis (Lew, recipient) rats. The recipient rats were treated with LMWF (5 mg/kg/day) and sacrificed at 30 days. To determine the role of SDF-1 in mediating the effects of LMWF, a specific inhibitor of the SDF-1 receptor CXCR4, AMD 3100 (20 microg/kg/day), was used. The grafted segments were evaluated by morphometric (histochemical) analyses. RESULTS: Untreated aortic allografts exhibited severe intimal proliferation, indicative of TA. In contrast, LMWF treatment significantly prevented allograft intimal proliferation as compared with controls (5.7+/-3 vs. 66.2+/-6 microm, P<0.01) and permitted a normalization of the intima/media ratio (0.1+/-0.1 vs. 1.7+/-0.3, P<0.01). Further, LMWF treatment stimulated allograft reendothelialization, as evidenced by strong intimal endothelial nitric oxide synthase antibody and CD31 signals. Unexpectedly, AMD treatment failed to prevent the protective effect of LMWF on intimal thickening and AMD treatment alone was found to reduced intimal proliferation in allografts. CONCLUSIONS: We found that LMWF treatment reduced intimal thickness and induced the presence of an endothelial cell lining in the vascular graft at 30 days. Our findings may suggest a novel therapeutic strategy in the prevention of TA.

Antidonor humoral transfer induces transplant arteriosclerosis in aortic and cardiac graft models in rats.

OBJECTIVE: The humoral pathway is suggested as playing a key role in transplant arteriosclerosis. The humoral immunity is demonstrated in the present study to induce direct vascular lesion. METHODS: Ten abdominal aortic grafts were performed on 4 groups of rats: Brown Norway (BN) isografts, BN to Lewis (LEW) allografts, and two BN to nude (RNU) grafted groups with and without any humoral transfer. The humoral sera were obtained by skin grafts performed in BN to LEW combination. Lewis anti-BN alloantisera was transferred in nude recipients through intraperitoneal injections. The aortic wall was histologically studied with morphometric analysis on the 21st day. Two additional BN to RNU aortic graft groups were evaluated by immunohistochemistry on days 3 (10 rats) and 10 (10 rats). RESULTS: In the absence of the humoral transfer, the BN aortic wall implanted in RNU remained intact. The humoral transfer induced a marked intimal proliferation (63 +/- 4 vs 4 +/- 1.1 microm; P < .001) and an adventitial cell infiltration (5.1 +/- 0.7 vs 2.8 +/- 0.6 x 10(3) c/mm2, P < .001). The medial thickness and the medial cell density were not modified. On day 3, the remaining endothelial cells were covered by immunoglobulin G deposits. On day 10 the endothelial cells disappeared completely and intimal proliferation occurred. In an additional cardiac graft group, transplant coronary arteriopathy was evidenced in 7 of the 9 nude recipients that had undergone the humoral transfer. CONCLUSION: The transplant arterial occlusive lesion is demonstrated here (1) to be induced by humoral antidonor immunity and (2) to be linked to an adventitial or perivascular inflammation.

Low molecular weight fucan prevents transplant coronaropathy in rat cardiac allograft model.

INTRODUCTION: Transplant arteriosclerosis is the main cause of long-term failure after cardiac transplantation. Vascular rejection is thought to be due to intimal proliferation occurring in response to arterial wall immune-mediated injury. A low molecular weight fucan (LMWF) compound, a sulfated polysaccharide, has been demonstrated to increase plasma levels of stromal cell-derived factor 1 (SDF-1) and consequently to mobilize bone marrow-derived vascular progenitor cells (BMVPC). The aim of this study was to evaluate the capacity of LMWF to prevent coronary intimal proliferation in a rat cardiac allograft model. METHODS: Heterotopic abdominal cardiac graftings were performed in Brown Norway (BN) and Lewis (LEW) rats. Animals were divided into 4 groups of 10 rats. Two groups were treated intramuscularly with LMWF (5 mg/kg/day) (one BN to BN isograft group, and one BN to LEW allograft group); and two control groups were LMWF-untreated (one BN to BN isograft group and one BN to LEW allograft group). All animals were treated by cyclosporin (15 mg/kg/day) sub-cutaneously and sacrificed at day 30. The cardiac grafts were assessed by morphometry of structural parameters and by histological and immunohistochemical analyses. RESULTS: All cardiac isografts were devoid of any coronary and parenchymal lesions. In contrast, the majority of untreated allografts developed coronary intimal proliferation in close association with intimal and adventitial inflammatory CD68(+) cell infiltration. Further, the parenchyma exhibited large areas of actin(+) cells (myofibroblasts) of recipient origin colocalized with the CD68(+) infiltrating cells. Interestingly, all LMWF-treated allografts were well protected against coronary and parenchymal lesions and the coronary arteries exhibited an intimal monolayer of flat cells, which however were CD34 negative. CONCLUSION: treatment with LMWF appeared very effective in this rat cardiac allograft model to prevent arterial and parenchymal lesions occurring in response to alloimmune injury. However this protective effect does not appear to depend on mobilization of bone marrow-derived cells.