Kazuma Okamoto

The Significant Cardiomyogenic Potential of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells In Vitro

We tested the cardiomyogenic potential of the human umbilical cord blood‐derived mesenchymal stem cells (UCBMSCs). Both the number and function of stem cells may be depressed in senile patients with severe coronary risk factors. Therefore, stem cells obtained from such patients may not function well. For this reason, UCBMSCs are potentially a new cell source for stem cell‐based therapy, since such cells can be obtained from younger populations and are being routinely utilized for clinical patients. The human UCBMSCs (5 × 103 per cm2) were cocultured with fetal murine cardiomyocytes ([CM] 1 × 105 per cm2). On day 5 of cocultivation, approximately half of the green fluorescent protein (GFP)‐labeled UCBMSCs contracted rhythmically and synchronously, suggesting the presence of electrical communication between the UCBMSCs. The fractional shortening of the contracted UCBMSCs was 6.5% ± 0.7% (n = 20). The UCBMSC‐derived cardiomyocytes stained positive for cardiac troponin‐I (clear striation +) and connexin 43 (diffuse dot‐like staining at the margin of the cell) by the immunocytochemical method. Cardiac troponin‐I positive cardiomyocytes accounted for 45% ± 3% of GFP‐labeled UCBMSCs. The cardiomyocyte‐specific long action potential duration (186 ± 12 milliseconds) was recorded with a glass microelectrode from the GFP‐labeled UCBMSCs. CM were observed in UCBMSCs, which were cocultivated in the same dish with mouse cardiomyocytes separated by a collagen membrane. Cell fusion, therefore, was not a major cause of CM in the UCBMSCs. Approximately half of the human UCBMSCs were successfully transdifferentiated into cardiomyocytes in vitro. UCBMSCs can be a promising cellular source for cardiac stem cell‐based therapy.

Heterotopic transplantation of a decellularized and recellularized whole porcine heart

OBJECTIVES One of the final treatments for end-stage heart failure is heart transplantation. However, a shortage of donor hearts has created a long waiting list and limited benefits. Our ultimate goal is to create a whole beating heart fabricated on an organ scaffold for human heart transplantation. Here, we successfully performed the first transplantation using a decellularized whole porcine heart with mesenchymal stem cells. METHODS A porcine heart was harvested following cardiac arrest induced by a high-potassium solution and stored at -80°C for 24 h. The porcine heart was completely decellularized with 1% sodium dodecyl sulphate and 1% Triton X-100 under the control of perfusion pressure (100 mmHg) and maintained at 37°C. A decellularized whole-heart scaffold was sterilized with gamma irradiation. Cultured mesenchymal stem cells were collected and either infused into the ascending aorta or injected directly into the left ventricular wall. Finally, recellularized whole-heart scaffolds were transplanted into pigs under systemic anticoagulation treatment with heparin. Coronary artery angiography of the transplanted heart graft was performed. RESULTS In our decellularization method, all cellular components were removed, preserving the heart extracellular matrix. Heterotopic transplantations were successfully performed using a decellularized heart and a recellularized heart. The scaffolds were well perfused, without bleeding from the surface or anastomosis site. Coronary angiography revealed a patent coronary artery in both scaffolds. The transplanted decellularized heart was harvested on Day 3. Haematoxylin and eosin staining showed thrombosis in the coronary arteries and migrated inflammatory cells. Haematoxylin and eosin staining of the transplanted recellularized heart showed similar findings, with the exception of injected mesenchymal stem cells. CONCLUSIONS To the best of our knowledge, this is the first report of heterotopic transplantation of a decellularized whole porcine heart with mesenchymal stem cells. The scaffolds endured surgical procedures. We detected short-term coronary artery perfusion in the transplanted scaffolds by angiography. Future studies should analyse the histological features of transplanted decellularized scaffolds and optimize the system for recellularization to apply this unique technology clinically.

Serum‐independent Cardiomyogenic Transdifferentiation in Human Endometrium‐derived Mesenchymal Cells

Media with high concentrations of serum are commonly used to induce cardiomyogenic transdifferentiation in mesenchymal stem cells; however, serum contains numerous unknown growth factors and interferes with definition of specific cardiomyogenic transdifferentiation factors secreted from feeder cells. In the present study, we determined whether the transdifferentiation of human mesenchymal cells can be observed in a FBS-free medium. The efficiency of transdifferentiation was observed in 10% FBS-containing standard medium (10%FBS) and in FBS-free medium containing insulin and thyroxin (FBS-free). In the present study, we used human uterine endometrium-derived mesenchymal cells (EMC100, EMC214) and menstrual blood-derived mesenchymal cells (MMCs). After cardiomyogenic transdifferentiation, the efficiency and physiological properties of cardiomyogenesis (fractional shortening of the cell [%FS] and action potential [AP]) were evaluated. The efficiency of transdifferentiation in EMC100 and in MMCs increased 36%* and 163%* (*P < 0.05), respectively. The %FS in EMCs increased to 103%*. AP-duration more than 250 ms with a marked plateau was only observed in FBS-free (3/19), and not in 10% FBS (0/41). The cardiomyogenic transdifferentiation of human mesenchymal cells can be observed in the FBS-free medium. Phenotypes of generated cardiomyocytes were significantly more physiological in FBS-free than in 10% FBS.

Loop-in-Loop Technique in Mitral Valve Repair via Minithoracotomy

Although multiple neochordae creations with premeasured loops by polytetrafluoroethylene (PTFE) sutures is a feasible and effective technique for mitral valve repair by an endoscopic-assisted minithoracotomy approach, measuring the correct length of premeasured loops is difficult because of diversity of the distance between the papillary muscle and the prolapsed mitral leaflet. A new technique consisted of a premade primary loop set and a secondary loop to adjust the length of the neochordae was devised as a loop-in-loop technique. Facilitating tying a slippery PTFE suture as the secondary loop in a correct position, a knot fixation using a neurosurgical titanium clip was applied.

New innovative instruments facilitate both direct-vision and endoscopic-assisted mini-mitral valve surgery

OBJECTIVE The efficacy of new, innovative, original instruments, including a left atrial retractor, silicon annuloplasty ring sizer, modified Cosgrove aortic clamp, and reusable clip for fixing knots of polytetrafluoroethylene (Gore-Tex; WL Gore & Associates, Inc, Flagstaff, Ariz) suture, to allow surgical exposure in an ideal operative setting of mini-mitral valve repair surgery was verified. METHODS Since 1998, a great deal of innovation has contributed to establishing mitral valve repair via right minithoracotomy as a routine surgical approach for mitral valve insufficiency in 252 cases. During the last 2 years, a newly launched left atrial retractor system attachable to the minithoracotomy spreader has been used. An additional retractor for the posterior wall of the left atrium was attached to the minithoracotomy spreader. The retractor moves flexibly and can be fixed in any favorable position to realize optimal exposure of the mitral valve. A 5 blade size was available depending on the left atrial size and target legion. By using the smallest size, even papillary muscles were exposed easily and clearly. Furthermore, a flexible silicon ring sizer, which could easily pass thorough a narrow working port without tissue damage, was used for sizing the annuloplasty ring. For the surgical technique, multiple chordal reconstructions by the loop technique with polytetrafluoroethylene (Gore-Tex CV-5 sutures) were applied. A reusable clip for fixing knots made it easy to tie the Gore-Tex suture in the correct position without slipping. RESULTS No operative mortality occurred. There were 2 conversions to sternotomy for correction of aortic dissection (1) and for coronary artery bypass grafting (1). There were 2 early reoperations for failure of mitral valve repair. The mean aortic crossclamp time was 163.5 ± 41.6 minutes. Annuloplasty with a ring or band was performed in all cases except one. The loop technique was used in 173 cases. Among them, a combination of the loop technique and resection and suture technique was used in 56 cases. CONCLUSIONS Newly innovated mini-mitral valve surgical instruments and techniques facilitate both direct-vision and endoscopic-assisted approaches and accomplish a favorable surgical outcome even in the complex pathology of mitral valve insufficiency.

Giant left coronary ostial aneurysm after modified Bentall procedure in a Marfan patient.

We performed surgical repair of a giant left coronary ostial aneurysm after aortic root replacement using composite valve graft (modified Bentall procedure) in a patient with Marfan syndrome. Aneurysmal formation in the left main stem itself is very rare. In order to avoid mobilizing the coronary ostium from severe adhesions after previous surgery and to reduce the tension on the anastomosis, the left main trunk was reconstructed using an interposition Dacron graft. In aortic root surgeries in Marfan patients, the size of the side hole on the composite graft should be kept relatively small to fit the diameter of the native coronary arteries for prevention of coronary buttons from forming aneurysms at the level of the coronary button anastomosis. In addition, close observation to the coronary button anastomosis is indispensable in postoperative check-up.

The effectiveness of rigid pericardial endoscopy for minimally invasive minor surgeries: cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation

BackgroundThe efficacy and safety of rigid pericardial endoscopy as the promising minimally invasive approach to the pericardial space was evaluated. Techniques for cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation were developed.MethodsTwo swine and 5 canines were studied to evaluate the safety and efficacy of rigid pericardial endoscopy. After a double pericardiocentesis, a transurethral rigid endoscope was inserted into the pericardial space. The technique to obtain a clear visual field was examined, and acute complications such as hemodynamic changes and the effects on intra-pericardial pressure were evaluated. Using custom-made needles, pacemaker leads, and forceps, the applications for cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation were also evaluated.ResultsThe use of air, the detention of a stiff guide wire in the pericardial space, and the stretching of the pericardium with the rigid endoscope were all useful to obtain a clear visual field. A side-lying position also aided observation of the posterior side of the heart. As a cell transplantation methodology, we developed an ultrasonography-guided needle, which allows for the safe visualization of transplantation without major complications. Pacemaker leads were safely and properly implanted, which provides a better outcome for cardiac resynchronizing therapy. Furthermore, the success of clear visualization of the pulmonary veins enabled us to perform epicardial ablation.ConclusionsRigid pericardial endoscopy holds promise as a safe method for minimally invasive cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation by allowing clear visualization of the pericardial space.

Comparison of aortic arch repair using the endovascular technique, total arch replacement and staged surgery

OBJECTIVES We evaluated the operative and long-term outcomes of various approaches for aortic arch repair. METHODS A total of 436 consecutive patients who underwent aortic arch repair from January 2001 to March 2016 in our centre were evaluated. Of these, 276 underwent conventional total arch replacement (TAR), and 118 underwent thoracic endovascular repair (TEVAR). The remaining 42 patients underwent staged thoracic endovascular repair (STEVAR). A total of 72 patients in the TEVAR group were matched to 72 patients who underwent open surgery including TAR or STEVAR by using propensity score analysis. RESULTS Surgical outcomes showed shorter ICU and hospital stay in the TEVAR group ( P  < 0.001 and P  < 0.001, respectively). The 30-day mortality and neurologic dysfunction showed no significant difference among the three groups (2.8 and 5.4% in TAR group, 1.7 and 8.5% in TEVAR group and 0 and 2.4% in STEVAR group; P  = 0.500 and P  = 0.297, respectively). Long-term survival was not significantly different among the three groups (78% in TAR group, 67% in TEVAR group and 81% in STEVAR group at 5 years; P  = 0.123). Freedom from aortic reintervention was lower in the TEVAR group than in other groups (98% in TAR, 92% in TEVAR and 97% in STEVAR at 5 years, P  = 0.040). CONCLUSIONS Operative outcomes showed no significant differences between the groups except for early recovery after TEVAR. Long-term survival was similar between groups; however, TEVAR had inferior reintervention free rate.

Comparison of clinical outcomes after transcatheter vs. Minimally invasive cardiac surgery closure for atrial septal defect

BACKGROUND Percutaneous closure has replaced surgery for the majority of cases of secundum atrial septal defect (ASD). However, technological advances have made contemporary minimally invasive cardiac surgery (MICS) less invasive than conventional surgery. The aim of this study was to compare clinical outcomes of percutaneous closure of secundum ASD with those of contemporary MICS.Methods and Results:We conducted a single-center retrospective study of 354 patients with ASD treated either with the Amplatzer Septal Occluder (134 patients) or MICS (220 patients) between 2000 and 2013. Success rates and the incidence of complications were compared. The success rates were 98% for percutaneous closure and 100% for MICS. There were no deaths in either group. Major complications occurred in 2 patients (1.5%) who underwent percutaneous closure and in 8 patients (3.6%) treated with MICS (P=0.16). Minor complications occurred in 15 patients (11.2%) who underwent percutaneous closure and in 46 patients (20.9%) treated with MICS (P=0.02). On multivariate analysis, MICS (odds ratio [OR]: 2.91, 95% confidence interval [CI]: 1.46-5.81; P=0.002) and age >70 years (OR: 3.50, 95% CI: 1.40-8.75; P=0.008) were independent predictors of complications. CONCLUSIONS Percutaneous closure and MICS had high success rates without deaths. For ASD patients with a suitable anatomy, percutaneous closure can be considered as the first therapeutic option.

Designing innovative retractors and devices to facilitate mitral valve repair surgery

Various devices have been developed to facilitate mitral valve surgery, including those that improve mitral valve exposure and assist surgeons with associated procedures. Choosing appropriate supporting devices when performing minimally invasive mitral valve surgery (MIMVS) through a minithoracotomy with endoscopic assistance is critical. Depending on the surgeon’s preference, trans-thoracic or trans-working-port left atrial retractors can be utilized. Although the trans-thoracic retractors provide a simple and orderly working space around the minithoracotomy working port, the positioning of the shaft is difficult and there is an implicit risk of chest wall bleeding. On the other hand, the trans-working-port type provides excellent exposure, is easily handled and manipulated, and facilitates surgeries involving various anatomical structures without special training. A great deal of understanding and knowledge about retractors is necessary to achieve the optimal exposure required to facilitate surgical techniques, and to maintain a reproducible and safe surgical system during mitral valve surgery.