Evaluations for surrounding tissue incorporation after implantation of synthetic vascular prostheses in animal models.

Incorporation of surrounding tissues after implantation of synthetic vascular prostheses potentially varies in accordance with implanted prostheses. To evaluate post-implant tissue incorporation, we examined surgical, histological and ultrastructural findings after implantation in animal models. Three types of commercially available prostheses were tested (Gelweave™; Group G, J Graft SHIELD NEO®; Group J and Triplex®; Group T). Prostheses were implanted into Sprague-Dawley rats subcutaneously or sutured on abdominal aorta of Japanese white rabbits. The tissues were surgically examined for adhesion and were subjected to histological evaluations for cellular and tissue infiltration and ultrastructural observations by scanning electron microscopy (SEM). Group G exhibited less tendency in adhesion formation in early phase (rat: G vs J, P < 0.0001; G vs T, P < 0.0001/rabbit: G vs J, P < 0.0001; G vs T, P = 0.059). In late phase, Group J showed highest adhesion (rat: G vs J, P = 0.0004; J vs T, P = 0.015/rabbit: G vs J, P = 0.0015; J vs T, P = 0.0044). In group G, a gap was observed between implants and surrounding tissues forming capsulation, whereas other groups exhibited tissue infiltration inside of the implants wall which were also confirmed by SEM. The tissue permeation toward the implants and adhesion was positively correlated (P < 0.0001). Surrounding tissue conformation varied in accordance with the type of prostheses. It is desirable to elucidate characteristics of each prosthesis to select suitable grafts for each patient to achieve a better surgical outcome.

Open thoracoabdominal aortic aneurysm repair in a patient with myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disorder and rarely coexists with aortic aneurysms requiring open repair. A 66-year-old patient with MG underwent extended thoraco-abdominal aortic aneurysm (TAAA) repair 16 years after onset of type-B acute aortic dissection. At 62 years, the patient was diagnosed with MG (MGFA class IIIa) from positive anti-acetylcholine receptor antibody without thymoma. Preoperatively, MG was well-controlled by prednisolone, cyclosporin and pyridostigmine. Extent II TAAA repair was performed under general anaesthesia maintained by total intravenous anaesthesia. Transcranial motor-evoked potential and somatosensory-evoked potential were applied to monitor intraoperative spinal cord ischaemia and muscle weakness. Amplitudes of motor-evoked potential and somatosensory-evoked potential attenuated intraoperatively but normalized after reperfusion from the reconstructed tube graft. Perioperative steroid coverage was given against surgical stress. The patient was weaned from mechanical ventilatory support on postoperative day 7. No signs of spinal cord ischaemia or muscle weakness were seen.

Establishment of a heart-on-a-chip microdevice based on human iPS cells for the evaluation of human heart tissue function.

Human iPS cell (iPSC)-derived cardiomyocytes (CMs) hold promise for drug discovery for heart diseases and cardiac toxicity tests. To utilize human iPSC-derived CMs, the establishment of three-dimensional (3D) heart tissues from iPSC-derived CMs and other heart cells, and a sensitive bioassay system to depict physiological heart function are anticipated. We have developed a heart-on-a-chip microdevice (HMD) as a novel system consisting of dynamic culture-based 3D cardiac microtissues derived from human iPSCs and microelectromechanical system (MEMS)-based microfluidic chips. The HMDs could visualize the kinetics of cardiac microtissue pulsations by monitoring particle displacement, which enabled us to quantify the physiological parameters, including fluidic output, pressure, and force. The HMDs demonstrated a strong correlation between particle displacement and the frequency of external electrical stimulation. The transition patterns were validated by a previously reported versatile video-based system to evaluate contractile function. The patterns are also consistent with oscillations of intracellular calcium ion concentration of CMs, which is a fundamental biological component of CM contraction. The HMDs showed a pharmacological response to isoproterenol, a ß-adrenoceptor agonist, that resulted in a strong correlation between beating rate and particle displacement. Thus, we have validated the basic performance of HMDs as a resource for human iPSC-based pharmacological investigations.

[Annuloaortic ectasia associated with antithrombin III deficiency; report of a case].

A 33-year-old male with hereditary deficiency of antithrombin III (AT III) was diagnosed with annuloaortic ectasia and scheduled for the aortic root replacement. As perioperative anticoagulation, AT III was administered to have its activity≥70% in addition to heparin. During the operation with cardiopulmonary bypass, 3,000 IU of AT III concentrate was infused, and there was no hemorrhagic complication. After the operation low-molecular-weight heparin was used instead of unfractionated heparin to avoid bleeding. However, renal infarction occurred on postoperative day 11. Heparin was continuously given in combination with 1,500 IU/day of AT III concentrate until oral warfarin reached within therapeutic range. The patient recovered without further sequelae. Cardiac surgery might be safely performed in patients with AT III deficiency by replenishing AT III concentrate to keep its activity higher than 80%.