Objective To provide a ventricular assist device for patients with heart failure, Fu Wai （FW） axial blood pump was developed for partly or totally to assist the left ventricular function. Vitro hemolysis and animals tests were also employed to test the hydromechanics and hemocompatibility of the FW left ventricular assist devices developed in Fu Wai hospital. Methods Using vitro test loop, FW axial blood pump has been used to evaluate the performance of hemolysis， the pump has also been tested for hemolysis characteristic through five sheep experiments. Results At 8 400 r/min, the pump generates 5 L/min flow against 100 mm Hg, the normalized index of hemolysis (NIH) was0.17±0.06 mg/L. The plasma free hemoglobin of in vivo tests was around 30 mg/dl. Conclusion The results obtained in vitro and in vivo testing indicate an acceptable design for the blood pump, further in vivo tests will be performed before clinical use.
Objective Engineer heart tissue (EHT) was constructed with mesenchymal stem cells (MSCs) and poly lacticacidCOglycolic acid (PLGA), and grafted onto the surface of myocardial infarction rats. We hypothesized that great omentum wrapping would increase EHT blood supply and ameliorate EHT microenvironment which is in favor of cardiac collagen remodling and heart function. We hope that omentun wrapped EHT could provide a valuable strategy for surgically myocardial infarction therapy. Methods MSCs were isolated from SD rats.Eight weeks after SD rats were subjected to left anterior descending (LAD) ligation, 18 rats were enrolled and divided into three groups, group A(n=6): great omentum wrapped MSCsPLGA EHT implantation; group B (n=6):MSCsPLGA EHT implantation; control group (n=6): the myocardial infarction; the sham group (n=6): only opened and closed chest, underwent LAD ligation, but no EHT implantation. Four weeks after transplantation, the following variables were evaluated: specimen stained with picrosirius red, left ventricle function evaluated by echocardiography, infarction ventricular wall motion by color kinesis (CK). Results Hearts of group A showed significantly less fibrosis than group B and control group (Plt;0.05). Infarction ventricular wall motion assessed by CK indicated significantly improvement in group A compared with group B and control group (Plt;0.05). Four weeks after transplantation, cardiac echocardiography showed left ventricle ejection fraction was lower in control group and group B compared with group A (Plt;0.05). Conclusion Transplantation of MSCsPLGA EHT with great omentum wrapping ameliorated infarction ventricular collagen remodeling, ameliorated infarction ventricular wall motion and preserved left ventricular function.
ObjectiveTo evaluate the feasibility of using acellular bovine pericardium as a viable tissue engineering vascular patch.MethodsFresh bovine pericardium was treated by enzyme detergent cell extraction, then they were used as vascular patches, ovine jugular vein segments were harvested, separated into endothelial and myofibroblast cells, expanded in cell culture, sequentially seeded onto acellular bovine pericardium patches (3cm×3cm). After 7 days of in vitro culture, the autologous cell/patches as experimental group ( n =5) were used to replace partial pulmonary artery wall. Animals were sacrificed at 4, 6, 8, 12 and 24 weeks. The acellular bovine pericardium patches without autologous cells were used as control group ( n =3). Animals were sacrificed at intervals of 4, 12 and 24 weeks. Explanted patches were evaluated by macroscopic and histologic examinations, assayed for calcium, elastin and collagen content.ResultsAll animals were survived without complications of thrombosis and aneurysm before sacrificed; there was no significant difference in calcium content in two groups; elastin ratio assay showed progressive increase over 4 to 24 weeks, similar to normal pulmonary artery wall, suggesting an ongoing tissue remodeling.ConclusionThe acellular bovine pericardium patch with or without autologous cell seeded to a certain extent can be changed into viable vascular wall tissue after being used to replace partial ovine pulmonary artery wall.
Objective To evaluate the effect of Schwann cell (SC) on the proliferation of marrow mesenchymal stem cells (MSCs) and provide evidence for application of SC in construction of the tissue engineered vessels.Methods SC and MSCs were harvested from SD rats(weight 40 g). SC were verified immunohstochemically by the S-100 staining, and MSCs were verified by CD 44, CD 105, CD 34 and CD 45. The 3rd passages of both the cells were cocultured in the Transwell system and were amounted by the 3H-TDR integration technique at 1, 3, 5 and 7 days,respectively. The results were expressed by the CPM(counts per minute, CPM) values. However, MSCs on both the layers were served as the controls. The Westernblot was performed to assess the expression of the vascular endothelial growth factor (VEGF), its receptor Flk-1, and the associated receptor neuropilin 1(NRP-1) in SC, the trial cells, and the controls. Results SC had a spindle shape in the flasks, and more than 90% of SC had a positive reaction for the S-100 staining.MSCs expressed CD44 and CD105, and had a negativesignal in CD 34 and CD 45. The CPM values of MSCs in the trial groups were 2 411.00±270.84，3 016.17±241.57，6 570.83±2 848.27 and 6 375.8±1 431.28at 1, 3, 5 and 7 days, respectively. They were significantly higher in their values than the control group (2 142.17±531.63，2 603.33±389.64，2 707.50±328.55，2 389.00±908.01), especially at 5 days （P＜0.05）. The Western blot indicated that VEGF was expressedobviously in both the SC group and the cocultured MSCs grou,p and was less visible in the control cells. The expressions of Flk-1 and NRP-1 inthe cocultured MSCs were much ber than in the controls. Conclusion SC can significantly promote the proliferation of MSCs when they are cocultured. The peak time of the proliferation effect appeared at 5 days. This effect may be triggered by the up-regulation of VEGF in MSCs, which also leads to the upregulation of Flk-1 and NRP-1 .
An implantable axial blood pump was designed according to the circulation assist requirement of severe heart failure patients of China. The design point was chosen at 3 L/min flow rate with 100 mm Hg pressure rise when the blood pump can provide flow rates of 2-7 L/min. The blood pump with good hemolytic and anti-thrombogenic property at widely operating range was designed by developing a structure that including the spindly rotor impeller structure and the diffuser with splitter blades and cantilevered main blades. Numerical simulation and particle image velocimetry (PIV) experiment were conducted to analyze the hydraulic, flow fields and hemolytic performance of the blood pump. The results showed that the blood pump could provide flow rates of 2-7 L/min with pressure rise of 60.0-151.3 mm Hg when the blood pump rotating from 7 000 to 11 000 r/min. After adding the splitter blades, the separation flow at the suction surface of the diffuser has been reduced efficiently. The cantilever structure changed the blade gap from shroud to hub that reduced the tangential velocity from 6.2 m/s to 4.3-1.1 m/s in blade gap. Moreover, the maximum scalar shear stress of the blood pump was 897.3 Pa, and the averaged scalar shear stress was 37.7 Pa. The hemolysis index of the blood pump was 0.168% calculated with Heuser’s hemolysis model. The PIV and simulated results showed the overall agreement of flow field distribution in diffuser region. The blood damage caused by higher shear stress would be reduced by adopting the spindle rotor impeller and diffuser with splitter blades and cantilevered main blades. The blood could flow smoothly through the axial blood pump with satisfactory hydraulics performance and without separation flow.