Tamotsu Kanbara

Role of Hypoxia-Inducible Factor 1α in T Cells as a Negative Regulator in Development of Vascular Remodeling

Background and Purpose—Recent studies have shown that the cellular immune response in the development of vascular remodeling modulates the resulting pathological alterations. We show that hypoxia-inducible factor 1 (Hif-1) (specifically expressed in T cells) is involved in the immune response to vascular remodeling that accompanies arteriosclerosis. Methods and Results—To study the role of T cells in the development of vascular remodeling, femoral arterial injury induced by an external vascular polyethylene cuff was examined in mice lacking Hif-1 (specifically in T cells). We found that cuff placement caused prominent neointimal hyperplasia of the femoral artery in Hif-1– (T-cell)–deficient mice compared with that in control mice and that infiltration of inflammatory cells at the adventitia was markedly increased in the mutant mice. Studies to clarify the mechanism of augmented vascular remodeling in the mutant mice showed enhanced production of cytokines by activated T cells and augmented antibody production in response to a T-dependent antigen in the mutant mice. Conclusions—The results of this study revealed that Hif-1&agr; in T cells plays a crucial role in vascular inflammation and remodeling in response to cuff injury as a negative regulator of T cell–mediated immune response. Potential new therapeutic strategies that target Hif-1&agr; are described.

Syngeneic Bone Marrow Mononuclear Cells Improve Pulmonary Arterial Hypertension Through Vascular Endothelial Growth Factor Upregulation

BACKGROUND We investigated the effects and possible mechanism of syngeneic bone marrow mononuclear cell (BM-MNC) transplantation on pulmonary arterial hypertension induced by monocrotaline. METHODS Monocrotaline (80 mg/kg body weight) was administrated to C57BL/6 mice, and pulmonary arterial hypertension was induced 4 weeks later. Bone marrow mononuclear cells harvested from syngeneic donor mice were injected intravenously into those mice 4 weeks after monocrotaline administration. The ratio of right ventricular to septum plus left ventricular weight, the number of small pulmonary arteries, and medial thickness of pulmonary arteries were measured. Western immunoblotting of the lung tissue was performed to observe vascular endothelial growth factor and its receptor expression 1 week after BM-MNC transplantation. Vascular endothelial growth factor receptor-2 inhibitor was administered to pulmonary arterial hypertension mice simultaneously with BM-MNC transplantation. RESULTS The ratio of right ventricular to septum plus left ventricular weight increased, the number of pulmonary arteries decreased, and medial thickness increased significantly 4 weeks after monocrotaline injection compared with those of vehicle-injected mice. These indices of monocrotaline-injected mice improved significantly 4 weeks after BM-MNC transplantation compared with those of mice at 8 weeks after monocrotaline injection (0.22 +/- 0.02 versus 0.31 +/- 0.02; 17.1 +/- 2.6 versus 8.2 +/- 1.7; 7.7% +/- 2.2% versus 20% +/- 2.1%, respectively; p < 0.01). However, BM-MNCs were not incorporated into the lung at 1 week after transplantation, and significant vascular endothelial growth factor upregulation and without receptor expression was observed in lung tissue 1 week after transplantation. Improvement of pulmonary arterial hypertension was inhibited by simultaneous administration of vascular endothelial growth factor receptor-2 inhibitor with BM-MNC transplantation. CONCLUSIONS These results indicate that syngeneic BM-MNC transplantation improves monocrotaline-induced pulmonary arterial hypertension by favorable pulmonary artery remodeling through vascular endothelial growth factor upregulation.

Successful early resection of cardiac papillary fibroelastomas

Two adult patients with previous transient cerebral ischemic attacks (TIAs) or chest oppression were referred for further investigation. A swaying pedicled tumor was detected in the left atrium of the former patient and in the left coronary cusp of the latter by echocardiography. The TIA, or angina-like attack, was anticipated to be caused by thromboembolism of the tumor. Both patients underwent tumor extirpation. The histological findings demonstrated that both tumors were benign papillary fibroelastoma limited to the endocardium/endothelium layer. In conclusion, early surgical resection of a cardiac papillary fibroelastoma should be performed.

Autologous peripheral blood-derived mononuclear cells induced by erythropoietin improve critical ischemic limbs.

PURPOSE Efficient and secure collection of CD34+ cells are crucial for the angiogenic therapies. We have developed autologous peripheral blood-mononuclear cell (MNC) transplantation induced by erythropoietin (rhEPO) for critical ischemic limbs. METHODS Seven patients, including five with arteriosclerosis obliterans, one with Buergers disease and one with progressive systemic sclerosis, underwent ten cell therapies. The first administration of rhEPO was performed two weeks before apheresis, and the second administration and blood donation were performed one week before apheresis to activate bone marrow. MNCs including CD34+ cells, isolated from peripheral blood by apheresis, were immediately injected intramuscularly into ischemic limbs. RESULTS The number of peripheral blood-CD34 + cells had significantly increased from 1.32 ± 0.83/microL, before the rhEPO induction, to 1.86 ± 0.94/microL, before the apheresis. The number of transplanted MNCs ranged between 0.5 × 10(9) and 16.5 × 10(9), and that of CD34+ cells, between 0.1 × 10(6) and 12.7 × 10(6), accounting for 0.02%-0.1% of MNCs. There were no serious complications. Finger ulcers with Buergers disease were significantly improved one month after the transplantations, but the same or other ulcer(s) appeared 2-6 months later. Three patients had an improvement in rest pain, and one patient extended maximum pain-free walking distance. CONCLUSIONS Erythropoietin-induced autologous peripheral blood-MNC transplantation is a useful and safe alternative for ischemic limbs.

Functional restoration of endothelial cells of the cryopreserved heart valve.

PurposeAlthough several approaches have been tried to improve the durability of cryopreserved valves, cellular restoration after thawing remains to be investigated. The aim of our study was to assess the functional restoration of endothelial cells of cryopreserved heart valves by in vitro culture for an alternative step to improving longevity.MethodsCryopreserved human umbilical vein endothelial cells (HUVECs) and porcine aortic cusps were cultivated for 14 days after thawing. Then the cellular activity of the enzymes cytosolic esterase and mitochondrial dehydrogenase was measured. The cellular viability of cryopreserved cusps was also assessed using confocal laser scanning microscopy.ResultsThe number of viable HUVECs decreased markedly after cryopreservation and thawing but recovered to pre-cryopreservation level after 14 days of culture. In contrast, the enzyme activity of the cryopreserved porcine aortic cusps showed recovery at 7 days of in vitro tissue culture after thawing. Confocal laser scanning microscopy findings showed that the cellular cytosolic esterase activity of cryopreserved cusps deteriorated after thawing but displayed considerable recovery by day 14 of culture.ConclusionThe functional recovery of endothelial cells in cryopreserved heart valves seems to require tissue culture of at least 14 days. Ex vivo endothelial restoration of cryopreserved heart valves may add to heart valve durability.