Effects of oscillatory flow on shear stress distributions in perfusion bioreactor for bone tissue engineering / 医用生物力学

Objective To study the effects of oscillatory flow, as well as pore size and porosity of the 3D scaffold on distributions of flow rate and shear stress in perfusion bioreactor, and to propose optimization methods for preparing the 3D decellularized bone scaffold and perfusion bioreactor based on theoretical results. Methods Based on the previously established 3D decelluarized scaffold and perfusion bioreactor for bone tissue engineering in the laboratory, the decelluarized scaffold was simplified as an isotropic porous media. The velocity and shear stress distributions in the bioreactor were further simulated theoretically. Results Under the oscillatory flow, the Darcy shear stress and velocity in the 3D porous scaffold presented a consistently regular pattern. Compared with the unidirectional flow, the difference of velocity and Darcy shear stress decreased at different radius, which could contribute to the homogeneous 3D culture of seed cells in bone tissue engineering. Increasing the inlet perfusion velocity could improve the average Darcy shear stress. Increasing the pore diameter or porosity of the scaffold had no obvious effects on the peak value of velocity, but sharply reduced the average Darcy shear stress. Increasing inlet oscillation frequency could decrease the peak value of velocity and obviously decrease the difference of velocity at different radius. Conclusions Appropriate oscillatory flow was beneficial for generating required shear stress for stem cells in bone tissue engineering. The research findings in this study are expected to provide theoretical guidance to optimize the 3D culture method of seed cells for bone tissue engineering.

Effect of different substrate static loading on α-SMA expression of rabbit myofibroblasts（protomyofibroblasts） / 医用生物力学

Objective To exert different substrate strain stimulation on rabbit myofibroblasts (MFs) (proto-) at different differentiation stages so as to study the variation of α-SMA expression. MethodsBy implanting heterologous protein into rabbits’ peritoneal cavity, 5 d and 7 d MFs (proto-) were obtained and cultured on the elastic substrates. Strain of 0%-3% and 3%-6% as well as strain of 0%-6% were applied by substrate static stretch. Results α-SMA expression was not found in 3 d MFs (proto-), while α-SMA expression could be detected in 5-7 d MFs (proto-), and α-SMA expression was significantly enhanced in 10-15 d MFs (proto-) (P<0.01). Under the two loading modes, α-SMA expression was both significantly improved, and higher α-SMA expression was presented under sectioned loading. Conclusionsα-SMA expression of MFs（proto-） is increased after the substrate static stretch in response to different loading modes, which suggests that mechanical factors can play an important role in the process of MFs differentiation and wound healing response.

Renal protective effect of Shenkang pill on diabetic rats / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the effects of Shenkang pill on renal function and extracellular matrix secretion on the diabetic rats.</p><p><b>METHOD</b>The diabetic rat models were induced by intraperitoneal injection of streptozotocin (STZ) and randomly divided into 3 groups' model control group; Capoten group and Shenkangwan group. Some normal other rats were used as normal control group. All rats were treated with corresponding drugs for 8 weeks. During and after the treatment, the general state, blood and urine glucose levels, excretion rate of the 24 hour urine protein and albumin, serum creatinine and blood urea nitrogen contents, kidney weight and relative kidney weight were measured. The mRNA of fibronectin(FN) in the kidney also detected by semi-quantitative reverse transcription polymerase chain reaction(RT-PCR).</p><p><b>RESULT</b>Diabetes mellitus and renal lesions occurred in the three model groups. The expression of FN mRNA of the kidney in diabetic rats increased obviously. Shenkang pill could improve the general state and renal function of the diabetic rats, decrease the blood glucose levels and the excretion rate of the 24 hour urine protein and albumin, reduce the expression of FN mRNA in kidney.</p><p><b>CONCLUSION</b>Shenkang pill has a certain protective effect on the diabetic kidney.</p>

Effect of Shenkangwan on mesangial cell NO and TGF-beta1 excretion in rats with early diabetic nephropathy / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the mechanism of Shenkangwan (SKW) in treating early diabetic nephropathy (DN).</p><p><b>METHODS</b>The effect of SKW on NO and transforming growth factor (TGF)-beta(1) production by the mesangial cells (MCs) of rats with early diabetic nephropathy was evaluated with serum pharmacological method.</p><p><b>RESULTS</b>Compared with normal serum, the SKW-containing serum dose- and time-dependently inhibited TGF-beta(1) excretion and increased NO production in the MCs of rats with early DN (P<0.05 and P<0.01, respectively).</p><p><b>CONCLUSION</b>The therapeutic effect of SKW on early DN may rely on the balance modulation of cytokine network by increasing NO production and decreasing TGF-beta(1) excretion to prevent cytokine-induced damage of the MCs.</p>

Activation of phosphorylating-p38 mitogen-activated protein kinase and its relationship with localization of intestinal stem cells in rats after ischemia-reperfusion injury.

AIM: To investigate the expression of phosphorylating p38 mitogen-activated protein kinase (MAPK) in rat small intestine after ischemia-reperfusion (I/R) insult and its relationship with the localization of intestinal stem cells. METHODS: Forty-eight Wistar rats were divided randomly into three groups, namely intestinal ischemia-reperfusion group (R), intestinal ischemia group (I) and sham-operated control group (C). In group I, the animals were killed 45 minutes after superior mesenteric artery (SMA) occlusion, while in group R the rats sustained SMA occlusion for 45 minutes and reperfusion for 2, 6, 12 or 24 hours respectively. In sham-operated control group, SMA was separated, but without occlusion. The activity of plasma diamine oxidase (DAO) was determined. Intestinal tissue samples were also taken for histological analysis and immunohistochemical analysis of MAPK p38 detection and intestinal stem cell localization. RESULTS: The changes in histological structure and plasma DAO levels indicated that the intestinal barrier was damaged after intestinal I/R injury. In group C and I, each crypt contained 5-6 p38 MAPK positive cells, which were mainly located in the lower region of the crypts. This was consistent with the distribution of intestinal stem cells. The presence of positive cells in crypts increased with the time of reperfusion and reached its peak at 12 hours after reperfusion (35.6 %). CONCLUSION: After intestinal I/R injury, the expression of phosphorylating-p38 MAPK in small intestine increased with the duration of reperfusion, and its distribution coincided with that of intestinal stem cells and their daughter cells, indicating that phosphorylating-p38 might be a possible marker of intestinal stem cells.