Microstructural alterations owing to handling of bovine pericardium to manufacture bioprosthetic heart valves: A potential risk for cusp dehiscence

Promotion of right ventricular outflow tract reconstruction using a novel cardiac patch incorporated with hypoxia-pretreated urine-derived stem cells

Approximately 25% of patients with congenital heart disease require implantation of patches to repair. However, most of the currently available patches are made of inert materials with unmatched electrical conductivity and mechanical properties, which may lead to an increased risk for arrhythmia and heart failure. In this study, we have developed a novel Polyurethane/Small intestinal submucosa patch (PSP) with mechanical and electrical properties similar to those of the native myocardial tissue, and assessed its feasibility for the reconstruction of right ventricular outflow tract. A right ventricular outflow tract reconstruction model was constructed in 40 rabbits. Compared with commercially available bovine pericardium patch, the PSP patch has shown better histocompatibility and biodegradability, in addition with significantly improved cardiac function. To tackle the significant fibrosis and relatively poor vascularization during tissue remodeling, we have further developed a bioactive patch by incorporating the PSP composites with urine-derived stem cells (USCs) which were pretreated with hypoxia. The results showed that the hypoxia-pretreated bioactive patch could significantly inhibit fibrosis and promote vascularization and muscularization, resulting in better right heart function. Our findings suggested that the PSP patch combined with hypoxia-pretreated USCs may provide a better strategy for the treatment of congenital heart disease.

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A novel cardiac patch (PSP) with mechanical and electrical properties similar to native myocardium.

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PSP patch improved cardiac function in right ventricular outflow tract reconstruction model.

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Hypoxia pretreated USCs combined PSP patch promoted vascularization and inhibited fibrosis.

Is cell regeneration and infiltration a double edged sword for porcine aortic valve deterioration? A large cohort of histopathological analysis

BACKGROUND AND OBJECTIVE

Bioprostheses are the most common prostheses used for valve replacement in the Western medicine. The major flaw of bioprostheses is the occurrence of structural valve deterioration (SVD). This study aimed to assess the pathological features of porcine aortic valve (PAV)-SVD based on histomorphological and immunopathological characteristics of a large cohort of patients.

METHODS

Histopathological data of 109 cases with resected PAV were collected. The type and amount of infiltrated cells were evaluated in the different types of bioprosthetic SVD by immunohistochemical staining.

RESULTS

The most common cause of SVD was calcification, leaflet tear, and dehiscence (23.9%, 19.3%, and 18.3%, respectively). Immunohistochemical staining demonstrated that macrophages were infiltrated in the calcified, lacerated and dehiscence PAV, in which both M1 and M2 macrophages were existed in the calcified PAV. Importantly, the higher content of M1 macrophages and less content of M2 macrophages were found in the lacerated and dehiscence PAV, and MMP-1 expression was mainly found in the lacerated PAV. The endothelialization rate of leaflet dehiscence was higher than that of calcified and lacerated leaflets. A large number of CD31+/CD11b+ cells was aggregated in the spongy layer in the lacerated and dehiscence PAV.

CONCLUSION

Cell regeneration and infiltration is a double edged sword for the PAV deterioration. Macrophage infiltration is involved in the different types of SVD, while only MMP-1 expression is involved in lacerated leaflets. The macrophage subtype of circulating angiogenic cells in dehiscence and tear PAV could be identified, which could reserve macrophages in the PAV-SVD.

Coronary artery bypass graft combined with liver transplantation in patients with advanced alcoholic liver cirrhosis: A case report

Performing cardiothoracic surgery on patients with advanced liver failure and liver cirrhosis is high-risk for patients. Coronary artery bypass grafting is the most effective treatment for patients with liver failure that is complicated with severe coronary heart disease, and who cannot be treated using coronary stent intervention. In the current study, one case of coronary artery bypass grafting combined with liver transplantation was assessed, with the patient exhibiting advanced alcoholic liver cirrhosis. A coronary artery bypass graft was performed to relieve angina pectoris. Following surgery, wound exudation, secondary infection, liver failure, pleuroperitoneal fluid leakage, hypoproteinemia and other adverse treatment results occurred, and the chest wound did not heal. Allograft liver transplantation was subsequently performed and, following surgery, the chest wound healed gradually after debridement, and the patient recovered.

Donkey pericardium compares favorably with commercial xenopericardia used in the manufacture of transcatheter heart valves

Transcatheter aortic valve implantation (TAVI) has gained considerable acceptance in the past decade due to its lower risks than conventional open-heart surgery. However, the deformation and delamination of the leaflets during the crimping procedure have raised questions about the durability and long-term serviceability of the pericardium tissue from which the leaflets are made. The collagen architecture, wall thickness and mechanical properties of donkey pericardium were investigated to assess its suitability as an alternative material for the manufacture of heart valves. Coupons sampled from different locations of donkey pericardium were investigated. Bovine, equine, and porcine pericardium specimens served as controls. The donkey pericardium had a similar surface morphology to that of the control pericardia except for the wavy topology on both the fibrous and serous sides. The average thickness of donkey pericardium (ca. 120 µm) was significantly lower than that from bovine (375 µm) and equine (410 µm), but slightly higher than that from porcine (99 µm) specimens. The interlaced wavy collagen bundles in the pericardium were composed of collagen fibers about 100 nm in diameter. This unique structure ensures that the donkey pericardium has a comparable ultimate tensile strength (UTS) and a much higher failure strain than the commercial pericardia used for the manufacture of heart valves. The donkey pericardium has an organized wavy collagen bundle architecture similar to that of bovine pericardium and has a satisfactory UTS and high failure strain. The thin and strong donkey pericardium might be a good candidate valve leaflet material for TAVI.

The Red Kangaroo pericardium as a material source for the manufacture of percutaneous heart valves

BACKGROUND

The kangaroo pericardium might be considered to be a good candidate material for use in the manufacture of the leaflets of percutaneous heart valves based upon the unique lifestyle. The diet consists of herbs, forbs and strubs. The kangaroo pericardium holds an undulated structure of collagen.

MATERIAL AND METHOD

A Red Kangaroo was obtained after a traffic fatality and the pericardium was dissected. Four compasses were cut from four different sites: auricular (AUR), atrial (ATR), sternoperitoneal (SPL) and phrenopericardial (PPL). They were investigated by means of scanning electron microscopy, light microscopy and transmission electron microscopy.

RESULTS

All the samples showed dense and wavy collagen bundles without vascularisation from both the epicardium and the parietal pericardium. The AUR and the ATR were 150±25μm thick whereas the SPL and the PPL were thinner at 120±20μm. The surface of the epicardium was smooth and glistening. The filaments of collagen were well individualized without any aggregation, but the banding was poorly defined and somewhat blurry.

CONCLUSION

This detailed morphological analysis of the kangaroo pericardium illustrated a surface resistant to thrombosis and physical characteristics resistant to fatigue. The morphological characteristics of the kangaroo pericardium indicate that it represents an outstanding alternative to the current sources e.g., bovine and porcine. However, procurement of tissues from the wild raises supply and sanitary issues. Health concerns based upon sanitary uncertainty and reliability of supply of wild animals remain real problems.

In vivo functional assessment of a novel degradable metal and elastomeric scaffold-based tissue engineered heart valve

OBJECTIVE

Ideal heart valve solutions aim to provide thrombosis-free durability. A scaffold-based polycarbonate urethane urea tissue-engineered heart valve designed to mimic native valve microstructure and function was used. This study examined the acute in vivo function of a stented tissue-engineered heart valve in a porcine model.

METHODS

Trileaflet valves were fabricated by electrospinning polycarbonate urethane urea using double component fiber deposition. The tissue-engineered heart valve was mounted on an AZ31 magnesium alloy biodegradable stent frame. Five 80-kg Yorkshire pigs underwent open tissue-engineered heart valve implantation on cardiopulmonary bypass in the pulmonary position. Tissue-engineered heart valve function was echocardiographically evaluated immediately postimplant and at planned study end points at 1, 4, 8, and 12 hours. Explanted valves underwent biaxial mechanical testing and scanning electron microscopy for ultrastructural analysis and thrombosis detection.

RESULTS

All 5 animals underwent successful valve implantation. All were weaned from cardiopulmonary bypass, closed, and recovered until harvest study end point except 1 animal that was found to have congenital tricuspid valve dysplasia and that was euthanized postimplant. All 5 cases revealed postcardiopulmonary bypass normal leaflet function, no regurgitation, and an average peak velocity of 2 m/s, unchanged at end point. All tissue-engineered heart valve leaflets retained microstructural architecture with no platelet activation or thrombosis by scanning electron microscopy. There was microscopic evidence of fibrin deposition on 2 of 5 stent frames, not on the tissue-engineered heart valve. Biaxial stress examination revealed retained postimplant mechanics of tissue-engineered heart valve fibers without functional or ultrastructural degradation.

CONCLUSIONS

A biodegradable elastomeric heart valve scaffold for in situ tissue-engineered leaflet replacement is acutely functional and devoid of leaflet microthrombosis.