Journal of Artificial Organs最新文献

Kidney transplantation is the only curative option for patients with chronic renal failure, significantly improving their survival and quality of life. However, this treatment remains limited by the shortage of organ donors. The shortage of kidney donors remains a serious problem all over the world, and is particularly severe in Japan. While advancements in immunosuppressive therapies and histocompatibility testing have improved outcomes in allogeneic kidney transplantation, the rising number of dialysis patients has worsened the gap between the demand for and supply of suitable donor organs. In response to this pressing need, xenotransplantation has gained attention as a promising alternative solution. Recent progress driven by gene-editing technologies, including CRISPR-Cas9, has facilitated the development of genetically modified pigs suitable for potential human transplantation. This review provides an overview of the key differences in immune response and infection risks between xenogeneic and allogeneic kidney transplants. In addition, it comprehensively examines the challenges and potential of xenogeneic kidney transplantation from multiple perspectives, including differences in immunosuppressive therapies between allogeneic and xenogeneic transplantation. We also discuss the feasibility of xenogeneic kidney transplantation as a solution to the organ shortage in Japan and present directions for addressing challenges toward clinical application. We hope this review will provide valuable insights into the potential of xenogeneic kidney transplantation as a new treatment option for chronic renal failure and contribute to efforts to address the donor shortage problem in Japan.

A venous reservoir (VR) is crucial for safe blood volume regulation during cardiopulmonary bypass (CPB) procedures. Currently, blood volume measurement in VRs relies heavily on visual inspection, which limits its accuracy and responsiveness. In this paper, a method that leverages a laser displacement sensor for blood surface distance change detection in VRs with high accuracy and simplicity is proposed. It enables precise, non-contact, real-time measurements for displacement and position analysis of blood surface. Hard-shell VRs maintain a constant relationship between blood volume and blood surface height. Therefore, we measured the blood surface distance and the distance between the sensors. The findings of this study demonstrate that blood volume correlates with the distance measured from the blood surface to the sensor, showing clear "blood surface distance-volume characteristic" curves specific to each VR. Experimental results confirm excellent reproducibility and low variability, even under different conditions, such as blood dilution and varying ambient light. In addition, the blood volume dynamic behavior during CPB can be captured with measurements that are in good agreement with theoretical predictions. Our findings confirm the potential of blood volume estimation based on blood surface distance measurements, making it a promising alternative for real-time blood volume monitoring during CPB. Integrating this method into CPB systems could improve safety, prevent air embolisms, and improve fluid management, paving the way for more precise and automated circulating blood volume control.

During hemodialysis, proteins, such as albumin and globulin, are deposited on the dialysis membrane surface, causing fouling that affects solute removal and biocompatibility. This study aimed to measure the filtration coefficient as an index of dialysis membrane conditions in hemodialysis, pre-dilution online hemodiafiltration, and intermittent infusion hemodiafiltration modes using two different hemodiafiltration membranes ex vivo. The filtration coefficients of hemodiafiltration membranes in hemodialysis, pre-dilution online hemodiafiltration, and intermittent infusion hemodiafiltration modes were continuously measured for 123 min using 2 L bovine blood, which was adjusted with 32% hematocrit and 6.5 g/dL of total proteins. Polysulfone and cellulose triacetate were used as test membrane materials, and both membrane structures were asymmetric. The first fouling step was observed 20 s after filtration of both polysulfone and cellulose triacetate membranes in each mode. Thereafter, the filtration coefficient recovered in the pre-dilution online hemodiafiltration mode. However, it plateaued in the cellulose triacetate membrane and decreased in the polysulfone membrane. A flushing effect of the intermittent infusion hemodiafiltration mode was observed in both the cellulose triacetate and polysulfone membranes. The differences in fouling steps in each of the three modes-hemodialysis, pre-dilution online hemodiafiltration, and intermittent infusion hemodiafiltration-can be identified by continuously measuring filtration coefficient values.

Silk-elastin is an artificial protein that helps promote wound healing. The present study was performed to examine the effect of silk-elastin on burns using an animal model. Partial- and full-thickness burns were applied to the back of rats using a metal device. And the necrotic tissue was excised via surgical debridement and dressing materials were applied. Two groups, namely, the silk-elastin sponge and control groups, were established in the case of deep partial-thickness burns and full-thickness burns, respectively. Tissue samples from the partial-thickness burn model obtained at the 5th day and the 7th day after debridement were analyzed. The length of epithelization in the tissue sample and wound healing rate were evaluated on macro-photographs. And tissue samples from the full-thickness burn model obtained at the 7th day and 14th day after debridement were analyzed. The area of granulation, length of epithelization, and number of vessels in the tissue sample and wound healing rate were evaluated on macro-photographs. The silk-elastin group showed a better wound healing rate and superior epithelization and granulation and angiogenesis in comparison to control group. And our findings on day 14 in full-thickness burn suggest a potential difference in the quality of scars. Silk-elastin sponge can help promote burn wound healing after debridement. This new material can accelerate epithelization, granulation, and neoangiogenesis at the early stage after application with less dressing change. We believe that silk-elastin is a good material for use in topical burn therapy. And the new material may reduce scar forming after healed.

The mechanical circulatory support (MCS) for pediatric patients with severe acute heart failure and poor pulmonary conditions is challenging. Herein, we report the first pediatric case of successfully treated by central Y-Y extra-corporeal membrane oxygenation (ECMO). A 10-year-old boy weighing 35 kg with a body surface area of 1.11 m² was transferred to our institution in cardiac arrest with ongoing cardiopulmonary resuscitation using intra-aortic balloon pump and peripheral ECMO inserted at the previous hospital. Then, MCS system was converted to central ECMO with left heart drainage due to severe pulmonary congestion and the anticipation of long-term MCS. After 3 days, we converted it to central Y-Y ECMO because of concern about intracavitary thrombus formation due to poor pulmonary conditions. After four more days, the pulmonary conditions were improved, and we converted the MCS system into left ventricular assist device (LVAD) system. He is awaiting the heart transplantation eligibility review in a stable condition. Central Y-Y ECMO system can be used as a bridge to decision also for a pediatric patient with acute severe heart failure and poor pulmonary conditions.

Brain-dead donor (DBD) is the basis for most organ transplants and has been the exclusive method of choice for heart transplantation (HTx). However, the severe shortage of donors has been the common problem worldwide, especially in Japan. Meanwhile, the number of donors after cardiac (circulatory) death (DCD) has increased rapidly in the last 10 years, especially in Europe, thus expanding the donor pool. This strategy has been introduced in HTx since 2014, starting in Australia and the United Kingdom, with acceptable results. In most DCD, organs are removed under withdrawal of life support (WLST), which is called controlled DCD (cDCD). In Japan, we should consider introducing cDCD to supplement DBD, which is compromised by the shortage of donors. In this setting of cDCD, ethical and regulatory arguments arise as to the definition of human death and how to deal with WLST in organ donation. From a regulatory point of view, cDCD has been misunderstood as requiring a separate legislative development, and to dispel this misconception is the important message of this report. The development of an ex vivo machine perfusion system is another issue to start cDCD HTx as well as other organs. This paper outlines the issues involved in the introduction of cDCD for heart transplantation in Japan.

This study aimed to investigate whether the efficacy of proximal landing zones (LZs) 0, 1, and 2 in hybrid thoracic endovascular aortic repair (TEVAR) without cardiopulmonary bypass (CPB) in elderly patients can broaden aortic arch surgical eligibility from the perspective of a lifetime loss. From April 2008 to March 2020, 254 patients who underwent LZs 0, 1, and 2 hybrid TEVAR without CPB were enrolled (zone 0 in 41, zone 1 in 82, and zone 2 in 131 patients). The patients had a median age of 73 years, with a median follow-up period of 5.8 years. The median operative time was 172 min, the median postoperative hospital stay was 11 days, and the discharge rate to home was 95.3%. The survival rate, aorta-related death-free rate, and aortic events-free rate at 10 years were 72.8%, 97.0%, and 88.5%. A multivariable Cox proportional hazard regression analysis showed that age (p < 0.001), preoperative stroke (p = 0.042), and an occurrence of 30-day aortic events (p = 0.022) were significant risk factors for all-cause death. The lifetime loss for 75, 80, 85, and ≥ 90-year-old patients at the time of surgery was 0.2, 0.1, 0, and 0 years. Despite the high risk of surgical management of aortic arch diseases, this study revealed that LZs 0, 1, and 2 hybrid TEVAR without CPB in ≥ 75-year-old patients can be expected to result in a life expectancy similar to the standard life expectancy. Advanced age alone should not exclude surgical treatment for patients with arch diseases.

The market for small-diameter vascular grafts (< 6 mm) used in cardiac and vascular surgery has not yet been fully established, as stable long-term patency has not been achieved. This paper focuses on the clinical development of tissue-engineered vascular grafts (TEVGs), especially those that have progressed to clinical trials, and introduces their current status with historical background and future directions. This review was created based on a translation of the Japanese review first reported in the Japanese Journal of Artificial Organs in 2023 (vol. 52, no. 3, pp. 161-166), with some modifications.

Transcatheter pulmonary valve implantation (TPVI) is a minimally invasive procedure used to treat pulmonary valve dysfunction in congenital heart disease. However, the limited durability of xenogeneic bioprosthetic valves is a significant concern. Tissue-engineered heart valves (TEHVs) have emerged as a promising alternative. We developed an autologous TEHV, Biovalve, using an in-body tissue architecture technology based on tissue encapsulation. In this study, we aimed to develop stent-integrated Biovalves (stent Biovalves) that can be applied to TPVI. We designed an asymmetric hourglass-shaped stent and a caged mold specifically for TPVI. The stent was fixed inside the mold by placing it on a core rod and covering it with an outer cage. After subcutaneous implantation of the molds with stents for 2 months, the molds with formed tissue were harvested and removed to obtain the stent Biovalve. The stent struts were completely covered with dense collagen. The stent Biovalve demonstrated intact insertion and deployment via the catheter and was successfully implanted in the goat pulmonary valve location. No complications such as stenosis, regurgitation, or translocation occurred post-implantation, with about 6 months of survival without anticoagulant therapy, excellent biocompatibility, and potential antithrombotic properties. There were no significant findings of thrombus or calcification in the excised Biovalve, and cell migration from the host tissue indicated ongoing tissue remodeling. Utilizing a novel mold with an outer cage ensures stent integration, enabling Biovalve production regardless of stent shape. This study presents a promising strategy to address the challenges of transcatheter heart valve implantation.

Destination therapy (DT) using an implantable left ventricular assist device (i-LVAD) in Japan has expanded treatment options for patients with out-of-hospital cardiac arrest (OHCA) receiving extracorporeal cardiopulmonary resuscitation (ECPR). However, achieving hemodynamic stabilization and improved peripheral organ perfusion is essential. In patients with OHCA, percutaneous mechanical circulatory support (MCS) devices may be inadequate in some cases, necessitating surgical MCS. Despite the growing importance of MCS upgrading, awareness among Japanese emergency physicians remains unclear. We aimed to assess awareness of advanced MCS upgrading strategies in refractory patients after ECPR. A nationwide survey of 293 emergency and critical care centers in Japan assessed awareness of i-LVAD therapy after ECPR. The questionnaire collected data on demographics, LVAD strategy recognition, MCS upgrade practices, and barriers. Of 90 facilities (31%) that responded, 87 (30%) consented to using their responses in the analysis. Awareness of DT was 59.8%. Notably, 66.7% and 70.1% of the respondents recognized that MCS upgrading could lead to i-LVAD treatment and heart transplantation, respectively. The major barrier to MCS upgrade therapy was the facility's inability to implement it. DT awareness was similar between IMPELLA-registered and non-registered facilities, but i-LVAD indication recognition was higher in IMPELLA-registered facilities (78.0% vs. 51.4%, P = 0.009). The low survey response rate suggests limited MCS upgrade awareness among Japanese emergency physicians. Although facilities recognize pathways to i-LVAD and transplantation, barriers to their implementation persist. IMPELLA-registered facilities showed higher i-LVAD indication recognition, reflecting their accessibility to LV unloading devices and connections with backup hospitals.