Goki Matsumura

Late-term results of tissue-engineered vascular grafts in humans

OBJECTIVE The development of a tissue-engineered vascular graft with the ability to grow and remodel holds promise for advancing cardiac surgery. In 2001, we began a human trial evaluating these grafts in patients with single ventricle physiology. We report the late clinical and radiologic surveillance of a patient cohort that underwent implantation of tissue-engineered vascular grafts as extracardiac cavopulmonary conduits. METHODS Autologous bone marrow was obtained and the mononuclear cell component was collected. Mononuclear cells were seeded onto a biodegradable scaffold composed of polyglycolic acid and epsilon-caprolactone/L-lactide and implanted as extracardiac cavopulmonary conduits in patients with single ventricle physiology. Patients were followed up by postoperative clinic visits and by telephone. Additionally, ultrasonography, angiography, computed tomography, and magnetic resonance imaging were used for postoperative graft surveillance. RESULTS Twenty-five grafts were implanted (median patient age, 5.5 years). There was no graft-related mortality (mean follow-up, 5.8 years). There was no evidence of aneurysm formation, graft rupture, graft infection, or ectopic calcification. One patient had a partial mural thrombosis that was successfully treated with warfarin. Four patients had graft stenosis and underwent successful percutaneous angioplasty. CONCLUSION Tissue-engineered vascular grafts can be used as conduits in patients with single ventricle physiology. Graft stenosis is the primary mode of graft failure. Further follow-up and investigation for the mechanism of stenosis are warranted.

First Evidence That Bone Marrow Cells Contribute to the Construction of Tissue-Engineered Vascular Autografts In Vivo

Background—Materials commonly used to repair complex cardiac defects lack growth potential and have other unwanted side effects. We designed and tested a bone marrow cell (BMC)–seeded biodegradable scaffold that avoids these problems. Methods and Results—To demonstrate the contribution of the BMCs to histogenesis, we labeled them with green fluorescence, seeded them onto scaffolds, and implanted them in the inferior vena cava of dogs. The implanted grafts were analyzed immunohistochemically at 3 hours and subsequently at 2, 4, and 8 weeks after implantation using antibodies against endothelial cell lineage markers, endothelium, and smooth muscle cells. There was no stenosis or obstruction caused by the tissue-engineered vascular autografts (TEVAs) implanted into the dogs. Immunohistochemically, the seeded BMCs expressing endothelial cell lineage markers, such as CD34, CD31, Flk-1, and Tie-2, adhered to the scaffold. This was followed by proliferation and differentiation, resulting in expression of endothelial cells markers, such as CD146, factor VIII, and CD31, and smooth muscle cell markers, such as &agr;-smooth muscle cell actin, SMemb, SM1, and SM2. Vascular endothelial growth factor and angiopoietin-1 were also produced by cells in TEVAs. Conclusions—These results provide direct evidence that the use of BMCs enables the establishment of TEVAs. These TEVAs are useful for cardiovascular surgery in humans and especially in children, who require biocompatible materials with growth potential, which might reduce the instance of complications caused by incompatible materials and lead to a reduced likelihood of further surgery.

Successful application of tissue engineered vascular autografts: clinical experience.

Foreign materials often used in cardiovascular surgery may cause unwanted side effects and reduced growth potential. To resolve these problems, we have designed a tissue-engineering technique that utilizes bone marrow cells (BMCs) in clinical treatments. To obtain tissue-engineered material, we harvested saphenous vein samples from patients, which were then minced, cultured and seeded onto a biodegradable scaffold. The first operation was performed in May 1999 as previously described (N. Engl. J. Med. 344 (7) (2001) 532) and this method was repeated on two other patients. From November 2001, we used aspirated BMCs as the cell source, which were seeded onto the scaffold on the day of surgery. This method was applied in 22 patients. There was no morbidity such as thrombogenic complications, stenosis or obstruction of tissue-engineered autografts, and no mortality due to these techniques. These results indicate that BMCs seeded onto a biodegradable scaffold to establish tissue-engineered vascular autografts (TEVAs) is an ideal strategy, and present strong evidence for the justification and validity of our protocol in clinical trials of tissue engineering.

Long-term results of cell-free biodegradable scaffolds for in situ tissue-engineering vasculature: in a canine inferior vena cava model.

We have developed a new biodegradable scaffold that does not require any cell seeding to create an in-situ tissue-engineering vasculature (iTEV). Animal experiments were conducted to test its characteristics and long-term efficacy. An 8-mm tubular biodegradable scaffold, consisting of polyglycolide knitted fibers and an L-lactide and ε-caprolactone copolymer sponge with outer glycolide and ε-caprolactone copolymer monofilament reinforcement, was implanted into the inferior vena cava (IVC) of 13 canines. All the animals remained alive without any major complications until euthanasia. The utility of the iTEV was evaluated from 1 to 24 months postoperatively. The elastic modulus of the iTEV determined by an intravascular ultrasound imaging system was about 90% of the native IVC after 1 month. Angiography of the iTEV after 2 years showed a well-formed vasculature without marked stenosis or thrombosis with a mean pressure gradient of 0.51±0.19 mmHg. The length of the iTEV at 2 years had increased by 0.48±0.15 cm compared with the length of the original scaffold (2–3 cm). Histological examinations revealed a well-formed vessel-like vasculature without calcification. Biochemical analyses showed no significant differences in the hydroxyproline, elastin, and calcium contents compared with the native IVC. We concluded that the findings shown above provide direct evidence that the new scaffold can be useful for cell-free tissue-engineering of vasculature. The long-term results revealed that the iTEV was of good quality and had adapted its shape to the needs of the living body. Therefore, this scaffold would be applicable for pediatric cardiovascular surgery involving biocompatible materials.

Local Tenomodulin Absence, Angiogenesis, and Matrix Metalloproteinase Activation Are Associated With the Rupture of the Chordae Tendineae Cordis

Background— Rupture of the chordae tendineae cordis (CTC) is a well-known cause of mitral regurgitation. Despite its importance, the mechanisms by which the CTC is protected and the cause of its rupture remain unknown. CTC is an avascular tissue. We investigated the molecular mechanisms underlying the avascularity of CTC and the correlation between avascularity and CTC rupture. Methods and Results— We found that tenomodulin, which is a recently isolated antiangiogenic factor, was expressed abundantly in the elastin-rich subendothelial outer layer of normal rodent, porcine, canine, and human CTC. Conditioned medium from cultured CTC interstitial cells strongly inhibited tube formation and mobilization of endothelial cells; these effects were partially inhibited by small-interfering RNA against tenomodulin. The immunohistochemical analysis was performed on 12 normal and 16 ruptured CTC obtained from the autopsy or surgical specimen. Interestingly, tenomodulin was locally absent in the ruptured areas of CTC, where abnormal vessel formation, strong expression of vascular endothelial growth factor-A and matrix metalloproteinases, and infiltration of inflammatory cells were observed, but not in the normal or nonruptured area. In anesthetized open-chest dogs, the tenomodulin layer of tricuspid CTC was surgically filed, and immunohistological analysis was performed after several months. This intervention gradually caused angiogenesis and expression of vascular endothelial growth factor-A and matrix metalloproteinases in the core collagen layer in a time-dependent manner. Conclusions— These findings provide evidence that tenomodulin is expressed universally in normal CTC in a concentric pattern and that local absence of tenomodulin, angiogenesis, and matrix metalloproteinase activation are associated with CTC rupture.

Extracardiac total cavopulmonary connection using a tissue-engineered graft

OBJECTIVE Extracardiac and lateral tunnel total cavopulmonary connection are currently 2 major options for patients with a single ventricle physiology. However, each procedure has some disadvantages over the other. We developed a new technique of extracardiac total cavopulmonary connection using a tissue-engineered graft to overcome some of the disadvantages previously associated with both the extracardiac and lateral tunnel procedures. METHODS Between February 2001 and October 2002, 8 patients underwent an extracardiac total cavopulmonary connection using a tissue-engineered graft in our institution. Collected bone marrow cells (1 x 10(8) mononucleocytes) from a patient (approximately 1-4 mL/kg body weight) were seeded onto a biodegradable scaffold composed of polycaprolactone-polylactic acid copolymer reinforced with woven polylactic acid. After a 2- to 4-hour cultivation, the seeded scaffold was implanted as an extracardiac conduit during the total cavopulmonary connection operation. RESULTS There were no hospital or late deaths. At a mean follow-up of 13.4 months (range 4-25 months), all patients are alive and asymptomatic with no need for repeat surgery. A postoperative catheter examination or computed tomography showed all tissue-engineered grafts to be patent and revealed no stenosis, obstruction, or aneurysmal change in the 8 patients. CONCLUSION We believe that extracardiac total cavopulmonary connection using a tissue-engineered graft has the potential to overcome some of the disadvantages previously associated with extracardiac or lateral tunnel total cavopulmonary connection. However, an extended follow-up period is required to clarify the long-term clinical outcome for the tissue-engineered graft.

A novel method to reduce pericardial adhesion: a combination technique with hyaluronic acid biocompatible membrane.

OBJECTIVE This study was to evaluate the efficacy of the hyaluronic acid (HA) bioabsorbable membrane combined use with both expanded-polytetrafluoroethylene (ePTFE) and autologous pericardium for preventing postoperative pericardial adhesions. METHODS The HA bioresorbable surgical membrane (Seprafilm, Genzyme, Cambridge, Mass) was used with either ePTFE or autologous pericardium in an experimental pericardial adhesion model. Twenty-four beagle dogs were classified as follows; Group A (n = 6): ePTFE only, Group B (n = 6): Seprafilm + ePTFE, Group C (n = 6): autologous pericardium only, Group D (n = 6): Seprafilm + autologous pericardium. Pericardial adhesions were evaluated at necropsy at 4, 8, and 12 weeks. The tenacity of adhesion was graded by macroscopic examination, and the adhesion tissue thickness was analyzed microscopically with an image processing program. The regeneration of mesothelial cells on neo-tissue fibrils were immunohistochemically studied. RESULTS In groups B and D, the adhesions were significant lower compared with those of control groups in the tenacity (Group A vs B: 2.5 +/- 0.55 vs 1.5 +/- 0.55, P < 0.05; Group C vs D: 3.2 +/- 0.75 vs 0.33 +/- 0.52, P < 0.01) and the tissue thickness (Group A vs B: 30.4 +/- 12.9 vs 10.3 +/- 4.42, P < 0.01; Group C vs D: 22.6 +/- 11.5 vs 4.96 +/- 4.87, P < 0.01). Immunohistochemically, a single layer of mesothelial cells were regenerated on the surface of neo-tissue fibrils in HA treated groups. CONCLUSION The combined use of Seprafilm with either ePTFE or autologous pericardium effectively reduced the formation of pericardial adhesion.

Long-term results of cell-free biodegradable scaffolds for in situ tissue engineering of pulmonary artery in a canine model.

We previously developed a cell-free, biodegradable scaffold for in-situ tissue-engineering vasculature (iTEV) in a canine inferior vena cava (IVC) model. In this study, we investigated application of this scaffold for iTEV of the pulmonary artery (iTEV-PA) in a canine model. In vivo experiments were conducted to determine scaffold characteristics and long-term efficacy. Biodegradable scaffolds comprised polyglycolide knitted fibers and an l-lactide and ε-caprolactone copolymer sponge, with an outer glycolide and ε-caprolactone copolymer monofilament reinforcement. Tubular scaffolds (8 mm diameter) were implanted into the left pulmonary artery of experimental animals (n = 7) and evaluated up to 12 months postoperatively. Angiography of iTEV-PA after 12 months showed a well-formed vasculature without marked stenosis, aneurysmal change or thrombosis of iTEV-PA. Histological analysis revealed a vessel-like vasculature without calcification. However, vascular smooth muscle cells were not well-developed 12 months post-implantation. Biochemical analyses showed no significant difference in hydroxyproline and elastin content compared with native PA. Our long-term results of cell-free tissue-engineering of PAs have revealed the acceptable qualities and characteristics of iTEV-PAs. The strategy of using this cell-free biodegradable scaffold to create relatively small PAs could be applicable in pediatric cardiovascular surgery requiring materials.

Long-term prognosis of double-switch operation for congenitally corrected transposition of the great arteries

OBJECTIVES Recently, the double-switch operation for congenitally corrected transposition of the great arteries has become the procedure of choice in our institute; however, the long-term follow-up is uncertain. METHODS From 1983 to 2010, 90 patients with congenitally corrected transposition of the great arteries underwent the double-switch operation, which comprised of an atrial switch plus intraventricular rerouting (with or without extracardiac conduits) in 72 patients (group I), and an atrial switch plus arterial switch in 18 patients (group II). The mean age at operation was 7.4 years old in group I vs. 4.3 years old in group II. The mean follow-up period was 12.9 years in group I vs. 10.9 years in group II. Hospital and late mortality, reoperation, arrhythmia and NYHA status were analysed retrospectively. RESULTS The Kaplan-Meier survival, including hospital and late mortality at 20 years, was similar (75.7% in group I vs. 83.3% in group II). The freedom from reoperation was 77.6% in group I (redo-Rastelli in five patients, subaortic stenosis resection in three, tricuspid valve replacement in one and mitral valve plasty in one) vs. 94.1% in group II (P < 0.05 vs. group I; aortic valve replacement in one). The freedom from arrhythmia was 57.1% in group I vs. 78.6% in group II (P < 0.05 vs. group I). The ratio of NYHA class I to II at outpatient clinic was similar (86% in group I vs. 86% in group II). CONCLUSIONS The long-term prognosis of the double-switch operation for congenitally corrected transposition of the great arteries was acceptable. In particular, an atrial switch plus arterial switch could be performed with low morbidity, and it should be considered as the optimal procedure.

Surgical Results for Functional Univentricular Heart With Total Anomalous Pulmonary Venous Connection Over a 25-Year Experience

BACKGROUND Surgical results for functional univentricular heart with total anomalous pulmonary venous connection (TAPVC) have been unsatisfactory to date. METHODS During a 25-year period until December 2009, 207 TAPVC patients underwent surgical repair at our institute, including 56 with a univentricular heart. The 10-year survival rate was 51.1% with univentricular heart and 84.7% with biventricular heart (p<0.0001; log-rank, 27.6). Surgical outcomes and risk factors for early and late death after TAPVC repair in univentricular hearts were retrospectively analyzed. RESULTS Patients were aged 3.8±4.3 years and weighed 12.3±10.7 kg at operation. Preoperative diagnoses included heterotaxy syndrome in 55, asplenia in 48, preoperative pulmonary venous obstruction in 35, and pulmonary atresia in 20. TAPVC was classified as I in 22, II in 26, III in 5, and IV in 3. Concomitant procedures included Fontan procedure in 29, bidirectional Glenn procedure in 5, systemic-pulmonary shunt in 11, and pulmonary artery banding in 5. There were 17 hospital deaths and 11 late deaths. Fontan completion was undertaken in 31 (55.3%). Postoperative pulmonary venous obstruction was found in 15. Multivariate analysis identified TAPVC III and IV and pulmonary atresia as risk factors for hospital death. Univariate analysis identified postoperative pulmonary venous obstruction and concomitant systemic-pulmonary shunt as risk factors for hospital and late death. CONCLUSIONS TAPVC III, IV, and pulmonary atresia are risk factors for early postoperative death. Intensive intervention, including perioperative management and operation, is required in these complex patients.