Artificial devices that are widely used in cardiac surgery. (A) Gore-tex patch, (B) various sizes of synthetic vascular grafts made of Gore-tex, and (C) prosthetic valves.

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... in children, particularly in newborns, could be more effective than regenerative therapy in adults. 10 Importantly, growth is something that cannot be ig- nored in pediatric patients. Children with CHDs who undergo blood vessel replacement or heart valve replace- ment often require an increase in the size of the implanted devices as they grow (Fig. 2). Unfortunately, they have to suffer from repeated interventions, including multiple redo surgeries, that are a major burden and a cause of pain. If, thanks to progress in regenerative medicine, a device that increases in size in accordance with a pa- tient's growth could be developed, such a device would be of great value to children ...

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... utilized devic- es in congenital cardiac surgeries. The ideal cardiovas- cular patch is non-thrombogenic, has good compliance and strength, and has the potential to grow. The patches used for congenital cardiac surgeries are made of vari- ous materials, such as Dacron (polyethylene terephthal- ate), Gore-tex (expanded-polytetrafluoroethylene) ( Fig. 2A), autologous pericardium, or bovine pericardium [36][37][38] ; however, none of these patches has the capacity to grow. CorMatrix (CorMatrix Cardiovascular, Inc., Atlanta, GA, USA) is decellularized extracellular matrix (ECM) made from porcine small intestine submucosa (SIS) and is commercially available in the USA for repairing ...

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... vascular grafts are commonly used in pedi- atric cardiac surgeries such as the Fontan operation for SV patients and the Rastelli operation. In many cases, surgeons use synthetic vascular grafts made of Gore-tex or Dacron (Fig. 2B). However, if new vascular grafts that are resistant to thrombus and infection and have poten- tial for growth could be developed from native tissue, these grafts would be of great benefit. Such small vas- cular grafts placed during childhood would grow larger with the growth of the body and would not need to be replaced. 46,47 ...

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... with CHD who need valve surgeries, such as mitral or tricuspid valve repairs, sometimes require re- peated interventions including multiple redo surgeries as they grow because of the unavailability of suitable devic- es that accommodate growth (Fig. 2C). A novel growth- accommodating device could improve the durability of pediatric heart valve repairs while also accommodating children's growth, leading to a decrease in the number of repeated interventions. Many research results on regener- ated heart valve using a tissue engineering approach have been reported, although only a few are ...

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... patch is one of the most utilized devic- es in congenital cardiac surgeries. The ideal cardiovas- cular patch is non-thrombogenic, has good compliance and strength, and has the potential to grow. The patches used for congenital cardiac surgeries are made of vari- ous materials, such as Dacron (polyethylene terephthal- ate), Gore-tex (expanded-polytetrafluoroethylene) ( Fig. 2A), autologous pericardium, or bovine pericardium [36][37][38] ; however, none of these patches has the capacity to grow. CorMatrix (CorMatrix Cardiovascular, Inc., Atlanta, GA, USA) is decellularized extracellular matrix (ECM) made from porcine small intestine submucosa (SIS) and is commercially available in the USA for repairing cardiac defects, although it is not yet approved in Japan. Small intestine submucosa-extracellular matrix (SIS-ECM) is thought to act as a bioscaffold in the repaired lesion and allows the ingrowth of site-specific native cells (Fig. 4). SIS-ECM may be transformed into native tissue, i.e., re- generated native ...

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... with CHD who need valve surgeries, such as mitral or tricuspid valve repairs, sometimes require re- peated interventions including multiple redo surgeries as they grow because of the unavailability of suitable devic- es that accommodate growth (Fig. 2C). A novel growth- accommodating device could improve the durability of pediatric heart valve repairs while also accommodating children's growth, leading to a decrease in the number of repeated interventions. Many research results on regener- ated heart valve using a tissue engineering approach have been reported, although only a few are in the pediatric ...

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... vascular grafts are commonly used in pedi- atric cardiac surgeries such as the Fontan operation for SV patients and the Rastelli operation. In many cases, surgeons use synthetic vascular grafts made of Gore-tex or Dacron (Fig. 2B). However, if new vascular grafts that are resistant to thrombus and infection and have poten- tial for growth could be developed from native tissue, these grafts would be of great benefit. Such small vas- cular grafts placed during childhood would grow larger with the growth of the body and would not need to be replaced. 46,47 Tissue-engineered vascular grafts (TEVGs) have been reported since the 1980s. 48 Shinoka's group published ex- cellent results of their human clinical trial of TEVG im- plantation in 2001, the first such trial in the world. 49 They explanted the patient's peripheral vein, from which they isolated mononuclear cells. These cells were cultured and expanded, and then cultured with a biodegradable poly- mer conduit composed of a polycaprolactone-polylactic acid copolymer reinforced with woven polyglycolic acid. The tissue-engineered graft was transplanted to a 4-year- old girl with right pulmonary artery occlusion. The ar- tery was successfully replaced with no evidence of graft occlusion 7 months later. They implanted a total of 25 tissue-engineered grafts as extracardiac cavopulmonary conduits in patients with SV physiology. The long-term results were suboptimal because of the stenosis of four grafts that required intervention. 50,51 Instead of using a biodegradable polymer conduit as a scaffold, a tissue-engineered vascular graft made of de- cellularized conduit was clinically implanted in a child with portal vein obstruction. 52 A 9-cm segment of an allogeneic donor iliac vein was decellularized and then recellularized with endothelial and smooth muscle cells differentiated from bone marrow-derived MSCs of the recipient. Although this graft had to be extended by a second TEVG at 1 year because of stenosis caused by mechanical obstruction, the patient benefitted from im- proved exercise tolerance, improved mental function, and growth without receiving immunosuppressive drugs. It was not reported whether this TEVG had grown; howev- er, a major advantage of this procedure is that the immu- nogenicity of the graft appeared to be very low, despite donor tissue being ...

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... are diagnosed in approximately 1 in 100 births and are the most frequent pathological congenital condi- tion. The anatomical and pathological conditions of pa- tients may vary greatly. Among CHDs, single-ventricle (SV) physiologies, such as hypoplastic left heart syn- drome (HLHS) and tricuspid atresia, were previously considered to be severe and often lethal conditions (Fig. 1). In 1984, it was reported that only 30% of SV patients not undergoing surgical treatment were alive by the age of 16 years. 4 To survive and grow, a baby born with SV usually requires three stages of palliations (i.e., systemic to pulmonary shunt/pulmonary artery banding, the Glenn procedure, and the Fontan procedure). As the manage- ment strategies for these kinds of patients have improved gradually and significantly, many SV patients survive using the Fontan procedure. However, the prevalence of ventricular dysfunction continues to increase over time after the Fontan procedure, and ventricular dysfunction has been reported as an independent risk factor for an adverse outcome after the Fontan procedure. 5 A patient with SV, particularly the right-ventricle dominant type, may suffer from ventricular dysfunction at any time be- cause of volume overload, atrioventricular valve regur- gitation, or arrhythmia, among others. 6 At present, the final treatment for SV patients who develop heart fail- ure is heart transplantation. The revised organ transplant law enabling pediatric heart transplantation in Japan was implemented in July 2010; however, only 17 pediatric pa- tients had undergone heart transplantation by the end of June 2016 after the law came into effect. 7 For problems such as those mentioned above, the clini- cal application of various forms of regenerative medicine, such as stem cell therapy and patch therapy, for CHD patients (particularly SV patients) with heart failure is highly anticipated and desired as the ultimate therapy or "bridge to transplantation" therapy. Although it is thought that cardiomyocytes in normal hearts hardly regenerate, 8 basic research using mice has shown that cardiomyocytes have regenerative ability, particularly during the neona- tal period immediately after birth, but not in adulthood. 9 Therefore, regenerative therapy in children, particularly in newborns, could be more effective than regenerative therapy in adults. 10 Importantly, growth is something that cannot be ig- nored in pediatric patients. Children with CHDs who undergo blood vessel replacement or heart valve replace- ment often require an increase in the size of the implanted devices as they grow (Fig. 2). Unfortunately, they have to suffer from repeated interventions, including multiple redo surgeries, that are a major burden and a cause of pain. If, thanks to progress in regenerative medicine, a device that increases in size in accordance with a pa- tient's growth could be developed, such a device would be of great value to children with ...