Tissue engineering of heart valves by recellularization of glutaraldehyde-fixed porcine valves using bone marrow-derived cells.

To increase the biocompatibility and durability of glutaraldehyde (GA)-fixed valves, a biological coating with viable endothelial cells (ECs) has been proposed. However, stable EC layers have not been formed successfully on GA-fixed valves due to their inability to repopulate. In this study, to improve cellular adhesion and proliferation, the GA-fixed prostheses were detoxified by treatment with citric acid to remove free aldehyde groups. Canine bone marrow mononuclear cells (MNCs) were differentiated into EC-like cells and myofibroblast-like cells in vitro. Detoxified prostheses were seeded and recellularized with differentiated bone marrow- derived cells (BMCs) for seven days. Untreated GA-fixed prostheses were used as controls. Cell attachment, proliferation, metabolic activity, and viability were investigated and cell-seeded leaflets were histologically analyzed. On detoxified GA-fixed prostheses, BMC seeding resulted in uninhibited cell proliferation after seven days. In contrast, on untreated GA-fixed prostheses, cell attachment was poor and no viable cells were observed. Positive staining for smooth muscle a-actin, CD31, and proliferating cell nuclear antigen was observed on the luminal side of the detoxified valve leaflets, indicating differentiation and proliferation of the seeded BMCs. These results demonstrate that the treatment of GA-fixed valves with citric acid established a surface more suitable for cellular attachment and proliferation. Engineering heart valves by seeding detoxified GA-fixed biological valve prostheses with BMCs may increase biocompatibility and durability of the prostheses. This method could be utilized as a new approach for the restoration of heart valve structure and function in the treatment of end-stage heart valve disease.

Tissue engineering of heart valves in vivo using bone marrow-derived cells.

In this study, we tissue-engineered heart valves in vivo using autologous bone marrow-derived cells (BMCs). Canine BMCs were differentiated into endothelial cell (EC)-like cells and myofibroblast (MF)-like cells. Decellularized porcine pulmonary valves were seeded with BMCs and implanted to abdominal aorta and pulmonary valve of bone marrow donor dogs. Histological examination of the explants identified the regeneration of valvular structures expressing CD31 and smooth muscle alpha-actin, indicating the presence of EC-like and MF-like cells in the grafts at 3 and 1 week, respectively, after implantation. Fluorescent microscopic examinations identified the presence of fluorescently labeled cells in the explants, indicating that the implanted BMCs survived and participated in the heart valve reconstitution. This study reports, for the first time, on tissue engineering of heart valve in vivo using BMCs.

Small-diameter blood vessels engineered with bone marrow-derived cells.

OBJECTIVE: The objective of this study is to investigate if bone marrow-derived cells (BMCs) regenerate vascular tissues and improve patency in tissue-engineered small-diameter (internal diameter = 3 mm) vascular grafts. SUMMARY BACKGROUND DATA: BMCs have demonstrated the ability to differentiate into endothelial-like cells and vascular smooth muscle-like cells and may offer an alternative cell source for vascular tissue engineering. Thus, we tissue-engineered small-diameter vascular grafts with BMCs and decellularized arteries. METHODS: Canine BMCs were differentiated in vitro into smooth muscle alpha-actin/smooth muscle myosin heavy-chain-positive cells and von Willebrand factor/CD31-positive cells and seeded onto decellularized canine carotid arteries (internal diameter = 3 mm). The seeded grafts were implanted in cell donor dogs. The vascular-tissue regeneration and graft patency were investigated with immunohistochemistry and angiography, respectively. RESULTS: The vascular grafts seeded with BMCs remained patent for up to 8 weeks in the canine carotid artery interposition model, whereas nonseeded grafts occluded within 2 weeks. Within 8 weeks after implantation, the vascular grafts showed regeneration of the 3 elements of artery (endothelium, media, and adventitia). BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular grafts, indicating that the BMCs participated in the vascular tissue regeneration. CONCLUSIONS: Here we show that BMCs have the potential to regenerate vascular tissues and improve patency in tissue-engineered small-diameter vascular grafts. This is the first report of a small-diameter neovessel engineered with BMCs as a cell source.

Implantation of bone marrow mononuclear cells using injectable fibrin matrix enhances neovascularization in infarcted myocardium.

Neovascularization may improve cardiac function and prevent further scar tissue formation in infarcted myocardium. A number of studies have demonstrated that bone marrow-derived cells have the potential to induce neovascularization in ischemic tissues. In this study, we hypothesized that implantation of bone marrow mononuclear cells (BMMNCs) using injectable fibrin matrix further enhances neovascularization in infarcted myocardium compared to BMMNC implantation without matrix. To test this hypothesis, infarction was induced in rat myocardium by cryoinjury. Three weeks later, rat BMMNCs were mixed with fibrin matrix and injected into the infarcted myocardium. Injection of either BMMNCs or medium alone into infarcted myocardium served as controls. Eight weeks after the treatments, histological analyses indicated that implantation of BMMNCs using fibrin matrix resulted in more extensive tissue regeneration in the infarcted myocardium compared to BMMNC implantation without matrix. Examination with fluorescence microscopy revealed that cells labeled with a fluorescent dye prior to implantation survived in the infarcted myocardium at 8 weeks of implantation. Importantly, implantation of BMMNCs using fibrin matrix resulted in much more extensive neovascularization in infarcted myocardium than BMMNC implantation without matrix. The microvessel density in infarcted myocardium was significantly higher (p < 0.05) when BMMNCs were implanted using fibrin matrix (350 +/- 22 microvessels/mm2) compared to BMMNC implantation without matrix (262 +/- 13 microvessels/mm2) and medium injection (76 +/- 9 microvessels/mm2). In addition, average internal diameter of microvessels was significantly larger (p < 0.05) in BMMNC implantation with fibrin matrix group (14.6 +/- 1.2 microm) than BMMNC implantation without matrix group (10.2 +/- 0.7 microm) and medium injection group (7.3 +/- 0.5 microm). These results suggest that fibrin matrix could serve as a cell implantation matrix that enhances neovascularization efficacy for myocardial infarction treatment.

A case of pulmonary artery intimal sarcoma diagnosed with multislice CT scan with 3D reconstruction.

Pulmonary artery intimal sarcoma is a rare highly lethal disease, with additional retrograde extension to pulmonic valve and right ventricle being an extremely rare condition. It is frequently mistaken for pulmonary thromboembolism. We report a case of 64-year-old woman with progressive dyspnea initially suspected and treated for pulmonary thromboembolism. Her helical chest CT scan with 3 dimensional (3D) reconstruction combined with echocardiography revealed a compacting main pulmonary artery mass extending to the right ventricular outflow tract and the right pulmonary artery. After excision of the mass, the patient's condition improved dramatically, and the pathologic findings revealed pulmonary intimal sarcoma. This report emphasizes that helical chest CT with 3D reconstruction can be an important tool to differentiate the characteristics of pulmonary artery lesions, such as intimal sarcoma and thromboembolism.

Pelvic leiomyomatosis with intracaval and intracardiac extension: a case report and review of the literature.

BACKGROUND: Intravenous leiomyomatosis with intracaval and intracardiac extension has been rarely described in surgical, gynecological, and radiological literatures. Complete excision of the tumor is essential for a favorable outcome. Because of the uniqueness of this tumor having an absent or localized attachment site, its removal is feasible when assisted, prior to surgery, with appropriate imaging and planning. CASE: The case was a 46-year-old woman, with intravenous leiomyomatosis originating from the uterus and extending to the inferior vena cava and right atrium, with extensive intracaval attachment, diagnosed from the various preoperative studies and operated successfully through the single-stage approach using cardiopulmonary bypass. CONCLUSION: We present an unusual case of intravenous leiomyomatosis originating from the uterus and extending to the inferior vena cava and right atrium with extensive intracaval attachment. We include a brief review of the literatures.

Localized immunosuppression in the cardiac allograft induced by a new liposome-mediated IL-10 gene therapy.

BACKGROUND: Overexpression of interleukin 10 (IL-10) in the donor heart prolongs allograft survival in animals. Interleukin-10 has many immunosuppressive effects; however, the mechanism(s) of its protective effect on allograft rejection remains unknown. METHODS: Recently, we optimized an ex vivo, intracoronary infusion of the GAP:DLRIE, liposome-mediated, IL-10 gene method using a rabbit, cervical, heterotopic heart transplant model. RESULTS: The efficiency of this new-generation, liposome-mediated, IL-10 gene transfer to the donor hearts was 15% in hypothermic conditions, which represents a 30% increase from the efficiency of other liposomes, such as DOSPA/DOPE, DOGS/DOPE, and DMRIE/DOPE. Cardiac allograft survival was prolonged from 6.0 +/- 0.7 days to 14.3 +/- 1.8 days. Infiltrating lymphocyte sub-populations CD3+, CD4+, and CD8) decreased significantly in the gene therapy group compared with the control group. Local IL-10 overexpression correlated significantly with decreased CD4+ and CD8+ responsiveness and Type-1 helper (Th1) cytokine gene (IL-2, interferon-gamma, and tumor necrosis factor alpha) expression level and correlated inversely with the allograft rejection grade. In the gene therapy group, the cytotoxic activity of infiltrating T cells in the allograft decreased greatly, but the time course of this decrease did not parallel the rejection process. CONCLUSION: We conclude that GAP:DLRIE is the best cationic liposome for ex vivo gene transfection in hypothermic conditions. The effects of IL-10 gene therapy on antigen-specific T-lymphocyte proliferation and Th1-cytokine expression may play an important role in localized immunosuppression and tolerance induction.