[Characteristics of porcine thoracic arteries fixed with polyepoxy compound].

OBJECTIVE: To investigate the characteristics of porcine thoracic arteries fixed with ethylene glycol diglycidyl ether (EX-810) and to provide the proper scaffold materials for tissue-engineered blood vessel. METHODS: The porcine thoracic arteries were respectively treated with 40 ml/L EX-810 and 6.25 g/L glutaraldehyde, and then they were examined with naked-eye, light microscope and scanning electron microscope. The fixation index determination, the amino acid analysis and the biomechanics test were also performed. RESULTS: The antigenicity of vascular tissues can be diminished by EX-810 through getting rid of cell in the vascular tissues or reducing the level of free amino groups in the vascular tissues. The structural integrity of vascular tissues can be preserved after treatment with EX-810. It was also found that the EX-810-fixed porcine vascular tissues appeared more similar to the natural vascular tissues in color and mechanical properties, and were more pliable than the glutaraldehyde-fixed tissues. CONCLUSION: The EX-810-fixed porcine thoracic arteries with low cytotoxicity and low antigenicity showed favorable characteristic similar to those of natural vessel, and it should be a promising material for fabricating scaffold of tissue-engineered blood vessel.

Coculture of peripheral blood-derived mesenchymal stem cells and endothelial progenitor cells on strontium-doped calcium polyphosphate scaffolds to generate vascularized engineered bone.

Vascularization of engineered bone tissue is critical for ensuring its survival after implantation and it is the primary factor limiting its clinical use. A promising approach is to prevascularize bone grafts in vitro using endothelial progenitor cells (EPC) derived from peripheral blood. Typically, EPC are added together with mesenchymal stem cells (MSC) that differentiate into osteoblasts. One problem with this approach is how to promote traditional tissue engineering bone survival with a minimally invasive method. In this study, we examined the effectiveness of administering to stimulate the release of peripheral blood stem cells and their co-culturing system for generating prevascularized engineered bone. Cells were isolated by Ficoll density gradient centrifugation and identified as EPC and MSC based on morphology, surface markers, and functional analysis. EPC and MSC were cocultured in several different ratios, and cell morphology and tube formation were assessed by microscopy. Expression of osteogenesis and vascularization markers was quantified by enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction, and histochemical and immunofluorescence staining. Increasing the proportion of EPC in the coculture system led to greater tube formation and greater expression of the endothelial cell marker CD31. An EPC:MSC ratio of 75:25 gave the highest expression of osteogenesis and angiogenesis markers. Cocultures adhered to a three-dimensional scaffold of strontium-doped calcium polyphosphate and proliferated well. Our findings show that coculturing peripheral blood-derived EPC and MSC may prove useful for generating prevascularized bone tissue for clinical use.

Preparation and endothelialization of decellularised vascular scaffold for tissue-engineered blood vessel.

The proliferation of cells on the decellularised tissues fixed by chemical crosslinking agent is retarded for cytotoxicity of crosslinked tissues. To overcome this disadvantage, we prepared the decellularised vascular scaffold through fixing the porcine thoracic arteries with 40 mL/L ethylene glycol diglycidyl ether (EGDE), and reduced the cytotoxicity of this scaffold by treating it with lysine and coating it with type I collagen, finally endothelialized it in vitro. The EGDE-fixed porcine thoracic arteries were examined morphologically. The fixation index determination and the biomechanics test were also performed. Human umbilical vein endothelial cells (HUVECs) were seeded on the type I collagen-coated surface of different modified vascular tissues (fixed with glutaraldehyde or EGDE or EGDE + lysine), and the growths of HUVECs on the specimens were demonstrated by means of MTT test. Finally, HUVECs were seeded on the luminal surface of the modified porcine vascular scaffolds which were respectively treated in the same manner described above, and then cultured for 7 days. On the seventh day, the HUVECs on the specimens were examined by means of light microscopy, scanning electron microscopy and transmission electron microscopy (TEM). The antigenicity of the vascular tissues can be diminished by EGDE through getting rid of cell in the vascular tissues or reducing the level of free amino groups in the vascular tissues. In this study, it was also found that the EGDE-fixed porcine vascular tissues appeared similar to the native porcine vascular tissues in color and mechanical properties. After treated by 2% lysine and coated with type I collagen, the EGDE-fixed porcine vascular tissues were characterized by low cytotoxicity and good cytocompatible. The HUVECs can proliferate well on the modified vascular tissues, and easily make it endothelialized. The results showed that the modified porcine vascular scaffolds should be a promising material for fabricating scaffold of tissue-engineered blood vessel.

Effect of polymerization degree of calcium polyphosphate on its microstructure and in vitro degradation performance.

Preparation, characterization and in vitro study of a series of calcium polyphosphate (CPP) with different polymerization degree were reported. A series of CPP with different polymerization degree were prepared by controlling calcining time. Average polymerization degree was analyzed by liquid state 31P nuclear magnetic resonance (NMR). The microstructure was observed by scanning electric microscope (SEM). X-ray diffraction (XRD) analysis was used to demonstrate that polymerization degree would not affect the crystal system and space group of CPP. The results showed that polymerization degree increased with the increase of calcining time. Degradation studies were performed during 32 days in physiological saline solution (aqueous solution, 0.9 wt.%NaCl) to assess the effect of polymerization degree on the degradation velocity of the samples. It was also shown that the degradation velocity of CPP (polymerization degree=13) doubles than another two samples (polymerization degree=9,19). The results in the present study may be able to provide some fundamental data for controlling CPP degradation.