[Construction and evaluation of the property of decellular porcine aortic valve].

OBJECTIVE: To construct decellular porcine aortic valve (PAV) and to observe the existence of porcine endogenous retrovirus (PERV) and valve scaffold structure before and after implantation. METHODS: (1) Porcine aortic valve was obtained. The cellular components of PAV were completely removed by using detergent and nucleotidase solution combined with alteration of osmosis. (2) The decellular underwent HE staining and light microscopy and detection of its physical and chemical properties. (3) 20 pieces of decellular PAV were implanted into dogs. On e month later blood samples of the dogs were collected. PCR and RT-PCR were used to detect the PERV expression in 20 samples of pig's peripheral blood, 20 fresh PAVs, cultured pig kidney cells of the PK15 line (as positive control), decellular PAVs implanted into the dogs, and 10 samples of dogs' peripheral blood. (4) Small pieces of decellular PAVs were implanted into the subcutaneous tissues of 6 rabbits at the back, 6 pieces for one rabbit, and then extracted by the ends of the 4th, 6th, 8th and 10th week respectively after implantation to undergo HE staining and light microscopy. RESULTS: (1) Almost all cellular components in the PAVs had been removed after decellularization; the soluble protein contents lost markedly [(0.238 +/- 0.038)% vs. (0.484 +/- 0.116)%]; the water content of the decellular tissues increased significantly [(92.16 +/- 1.48)% vs. (89.2 +/- 1.55)%]; however, the decellular PAVs still maintained their excellent fibrous scaffold structure, and their shrinkage temperature and tension at fracture were not significantly changed [(72.0 +/- 0.7) degrees C vs. (71.2 +/- 0.8) degrees C, and (448.7 +/- 18.65)g/mm2 vs. (540.7 +/- 19.46)g/mm2 respectively]. (2) Agarose gel electrophoresis of all fresh PAVs and porcine peripheral blood samples showed a 219 bp band, which was 90% to 97% homologous with PERV-C gene, and the sequence of which is published in Medline. No 219 bp amplified band was found in all decellular PAVs and the peripheral blood samples of the dogs implanted with decellular PAV one month after the implantation. (3) The PAVs implanted in rabbit body showed very slight tissue reaction. Neutrophil, lymphocyte and plasmacyte infiltration were seen 4 weeks after; such inflammatory cell infiltration decreased markedly and the peripheral portions of the decellular PAVs began to be absorbed by the end of the 6th week after implantation. The decellular PAVs were completely absorbed without fibrosis or scar formation in the implantation area by the end of the 10th week. CONCLUSION: (1) The cellular components of PAV can be completely removed, the excellent fibrous scaffold structure and mechanical strength of aorta valve can be maintained, and the antigenicity is very weak. Subcutaneous implantation investigation shows that decellular PAV is an absorbable and degradable biological material. (2) There is PERV-C in PAV that can be removed after decellularization. PERV-C reaction is negative in the peripheral blood samples of the recipients implanted with decellular PAV.

[Construction of a tissue-engineered valve with decellular porcine aortic valve scaffold in the abdominal aorta of canine].

OBJECTIVE: To explore an experimental method for construction of tissue-engineered heart valve (TEHV) in canine abdominal aorta. METHODS: The decellular porcine aortic valve (PAV) leaflets seeded with canine vessel interstitial cells and endothelial cells (ECs) were implanted into 6 canine abdominal aortas. Valve specimens were obtained respectively at the end of 4, 6, 8 and 10 weeks after implantation were studied for morphology, histology and immunohistochemistry. RESULTS: (1) After 4 weeks implantation, multiple layers of cells grew into peripheral portion of valve scaffold, while new extracellular matrix appeared, and original scaffold tissue was partially absorbed. (2) At the end of 10th week after implantation, the decellular PAV scaffold disappeared completely and was substituted by recipient cells and new extracellular matrix. The interstitial cells in matrix was mainly consisted of fibroblasts and myofibroblast. The matrix was mainly composed by type I, III collagen, some elastic fibers with neutral and acid mucopolysaccharide. (3) Surface of valve leaflets were covered with endothelial cells. CONCLUSIONS: (1) TEHV is primarily constructed with recellularized PAV after implantation into canine abdominal aorta for 10 weeks. (2) Heterotopic implantation into the abdominal aorta is an alternative experimental procedure to study the TEHV.

Tissue-engineered heart valve on acellular aortic valve scaffold: in-vivo study.

The feasibility of constructing a tissue-engineered heart valve on an acellular porcine aortic valve leaflet was evaluated. A detergent and enzymatic extraction process was developed to remove the cellular components from porcine aortic valves. The acellular valve leaflets were seeded for 7 days in vitro with cells from canine arterial wall and endothelial cells. The constructs were implanted into the lumens of 6 canine abdominal aortas to assess the reconstruction of the valve leaflets. It was found that all cellular components had been removed from the porcine aortic valves. The valve leaflets were completely reconstructed at the end of the 10th week in vivo. Scanning electron microscopy showed that the valve leaflets were partially covered with endothelial cells. It was concluded that porcine aortic valves can be decellularized by the detergent and enzymatic extraction process and it is feasible to construct a tissue-engineered heart valve in vivo on an acellular valve scaffold.