The implantation of biventricular assist device (BiVAD) is more challenging than that of left ventricular assist device for the interaction in the process of multiple input and output. Besides, ventricular assist device (VAD) often runs in constant speed (CS) mode in clinical use and thus BiVAD also faces the problems of low pulsation and imbalance of blood volume between systemic circulation and pulmonary circulation. In this paper, a delay assist mode for a VAD by shortening the support time of VAD was put forward. Then, the effect of the delay mode on cardiac output, pulsation and the function of the aortic valve was observed by numerical method and the rules of hemodynamics were revealed. The research showed that compared with VAD supported in CS mode, the VAD using delay mode in systolic and diastolic period proposed in this paper could meet the demand of cardiac output perfusion and restore the function of the arterial valves. The open ratio of aortic valve (AV) and pulmonary valve (PV) increased with the time set in delay mode, and the blood through the AV/PV helped to balance the left and the right cardiac volume. Besides, delay mode also improved the pulsation index of arterial blood flow, which is conducive to the recovery of the ventricular pulse function of patients.
Objective To investigate the protocols of combined culture of human placenta-derived mesenchymal stem cells (HPMSCs) and human umbilical vein endothelial cells (HUVECs) from the same and different individuals on collagen material, to provide the. Methods Under voluntary contributions, HPMSCs were isolated and purified from human full-term placenta using collagenase IV digestion and lymphocyte separation medium, and confirmed by morphology methods and flow cytometry, and then passage 2 cells were cultured under condition of osteogenic induction. HUVECs were isolated from fresh human umbilical vein by collagenase I digestion and subcultured to purification, and cells were confirmed by immunocytochemical staining of von Willebrand factor (vWF). There were 2 groups for experiment. Passage 3 osteoblastic induced HPMSCs were co-cultured with HUVECs (1 ∶ 1) from different individuals in group A and with HUVECs from the same individual in group B on collagen hydrogel. Confocal laser scanning microscope was used to observe the cellular behavior of the cell-collagen composites at 1, 3, 5, and 7 days after culturing. Results Flow cytometry showed that HPMSCs were bly positive for CD90 and CD29, but negative for CD31, CD45, and CD34. After induction, alizarin red, alkaline phosphatase, and collagenase I staining were positive. HUVECs displayed cobble-stone morphology and stained positively for endothelial cell marker vWF. The immunofluorescent staining of CD31 showed that HUVECs in the cell-collagen composite of group B had richer layers, adhered and extended faster and better in three-dimension space than that of group A. At 7 days, the class-like microvessel lengths and the network point numbers were (6.68 ± 0.35) mm/mm2 and (17.10 ± 1.10)/mm2 in group A, and were (8.11 ± 0.62) mm/mm2 and (21.30 ± 1.41)/mm2 in group B, showing significant differences between the 2 groups (t=0.894, P=0.000; t=0.732, P=0.000). Conclusion Composite implant HPMSCs and HUVECs from the same individual on collagen hydrogel is better than HPMSCs and HUVECs from different individuals in integrity and continuity of the network and angiogenesis.
Objective To explore the preparing methods in vitro and test the cl inical appl icabil ity of implantation in vivo of bone marrow stromal stem cells (BMSCs)-biphasic scaffold to repair defects of cartilage and subchondral bone and tocompare the differences in repaired outcomes of composite, single biphasic scaffold and rabbits themselves. Methods The upper chondral phase and the lower osseous phase of the plugs, using poly-lactic-co-glycol ic acid (PLGA), hydroxyapatite (HA), and other biomaterials, were fused into carrier scaffold, on which collagen type I (Col I) was coated. The surface and inner structure of bi phasic scaffold were observed under scanning electron microscope (SEM). BMSCs was isolated from the bone marrow of tibia and femurs of young New Zealand rabbits using centrifuging and washing, and their morphologies and adherences were observed everyday. Then BMSCs were inoculated on the surface of scaffold to form BMSCs-scaffold composites. Osteochondral defects were surgically created on articular surface of femoral intercondyles of 30 New Zealand rabbits, which were divided into groups A, B and C. In group A, a bi phasic osteochondral composite were implanted into defect, BMSCs and biphasic cyl indrical porous plug of PLGA-HA-Col I in group B, and group C was used as a control without implant. Specimens were harvested to make macroscopic and histological observations at the 1st, 3rd, 6th, and 9th months after operation respectively; meanwhile immunohistological and micro-computed tomography (micro CT) examinations were performed and graded at the 9th month after operation. Results SEM showed an excellent connection of holes in the biphasic scaffold infiltrated by Col I. Optical microscopy and SEM showed a good growth of BMSCs in scaffold without obvious cellular morphological changes and an accumulation in the holes. Macroscopic samples showed a resistant existence of defects of group C within 9 months; the scaffold completely degenerated and chondral-l ike tissue formed on articular surface with partly collapses and irregular defects in group A; and smoother surface without collapses and approach to normal with texture of new regeneration in group B. There were statistically significant differences in macroscopic results (P lt; 0.001), group B was superior to group A, and group C was the worst. The micro CT showed good repairs and reconstruction of subchondral bone, with a acceptable integration with newborn chondral-l ike tissue and host bone in group B. Quantificational analysis of relevantparameters showed no significant differences. Histological results showed inflammations located in defects at the 1st month, new tissue grew into scaffold at the 3rd month; new chondral-l ike tissue crept on the margin of defects and biphasic scaffold degenerated completely at the 6th month, and lots of collagen formed in subchondral bone with major fibrocartilage on chondralarea at the 9th month after surgery in groups A and B. In groups A and B, immunohistological observations were weak positive for Col II and positive for Col I. Conclusion Biphasic scaffold implanted in body can induce and accelerate repair of defects of articular cartilages which are mainly filled with fibrocartilage, especially for subchondral bone. Scaffold combined with BMSCs has the best repairing effects 9 months after implantation.
ObjectiveTo standardize the techniques for laparoscopic radical rectal resection and discuss its application prospect. MethodsThe clinical data of 433 patients who underwent laparoscopic radical rectal resections from July 2003 to December 2010 in our hospital were reviewed retrospectively, and the different surgery procedures and the development prospect were explored. ResultsFive cases (1.2%) underwent handassistant laparoscopic procedures, 412 cases (95.2%) were done by laparoscopic-assisted operation, and the specimens were taken out with transanal pull-through technique in 16 cases (3.7%). In all of them, conversion to open procedures occurred in 11 patients (2.5%), and 290 (67.0%) patients were followed-up in 1 to 6 years, average in 2.7 years. Local recurrence occurred in 7 (2.4%) patients, while distant metastasis were diagnosed in 22 （7.6%） cases, and the overall mortality was 15.9% (46/290). There was no port-site metastasis occurred. ConclusionsFour-port laparoscopic rectal resection technique is also the clinical mainstream. Standardized laparoscopic procedure for rectal resections enhances the transformation of laparoscopic skills, and makes the operation predictable. Single incision procedure and natural orifice transluminal endoscopic surgery are future direction to explore.