محمد تفضلی شادپور

Objective- Investigate myocardial performance after autologous adipose-derived (ASCs) mesenchymal stem cell differentiated under equiaxial cyclic strain, transplantation in rabbits with acute myocardial infarction (AMI).
Design- Prospective, randomized experimental study
Animals- 20 New Zealand White rabbits (2-3 kg)
Procedure- ASCs were studied in four distinct groups of mechanical (ADM), chemical (ADC), undifferentiated (AD) and control (C) groups. According to this categorization, the cells were exposed to cyclic mechanical loading or 5-azacytidine as the chemical factor. 10 6 ASC cells were transplanted intramyocardially in rabbits with AMI (Acute Myocardial Infarction). Echocardiographic study was used to evaluate effects of cells on cardiac function.
Results- Left ventricle ejection fraction (LVEF) was significantly increased in the ADM (mechanically-differentiated adipose-derived mesenchymal stem cell) group at 2 months follow-up. Fractional shortening (FS) also showed a similar pattern as LVEF and increased in ADM group in compare to control and AD (undifferentiated adipose-derived mesenchymal stem cell) group.
Conclusion and clinical prevalence- The results indicate that intramyocardial transplantation of mechanically-differentiated ASCs improves cardiac function of ischemic myocardium. Transplantation of mechanically-differentiated ASCs for myocardial regeneration may become the future therapy for acute myocardial infarction.

Along with advancement in medical technologies, the academic field of Biomedical Engineering (BME) was developed. BME which was once considered as a subdivision of other disciplines, has gradually become an independent discipline with established departments. The extended medical and biological applications of the new discipline resulted in itsrapid progress. It is essential for academic centers to examine novel education and research areas of biomedical engineering every few years. In this paper we presented educational and research status of biomedical engineering among world's 50 top universities from different continents. We used three world university rankings (Time, QS, CWUR) to select top universities in 2016. Overally we studied 17 universities from America, 19 universities from Europe and 14 universities from Asia and Oceania. The undergraduate and postgraduate educational programs were presented and the independency status of biomedical engineering departments were studied using four models and results were compared among universities from different continents. The foundation year and number of academic staff of BME departmentswere further shown.Moreover, the BME researchfiledswere shown and compared among top universities from different contients and the most prevalent research areas were presented.

Cells and tissues are mainly exposed to different mechanical stimuli, which are essential for their function. Blood vessels are subjected to circumferential straining induced by pulse pressure. The phenotype regulation and function of vascular smooth muscle cells depend on both chemical factors and their mechanical environment. Chemical and mechanical stem cell stimulations can contribute to their differentiation to functional target cells, including smooth muscle cells. This makes a great potential subject for cell therapy and tissue engineering. Here, we evaluated effects of short term uniaxial cyclic strain on morphology of rabbit adipose derived mesenchymal stem cells. Using a custom made bioreactor, a 5% cyclic uniaxial strain with 1Hz frequency were applied on mesenchymal stem cells for 4, 8 and 24 hours. Smooth muscle specific gene expression was analyzed by Real Time PCR. Before and after experiments, cell images were taken and processed for morphological parameters evaluation. Cyclic strain caused cells to re-orient to the direction that cell body were experiencing minimal force. Two fold increases in smooth muscle gene expression was observed after 24 hour mechanical stimulation. Cyclic strain caused morphological alterations including reduction of cell shape index up to 41%, and elevation of aspect ratio up to 45% after 24 hours loading compared to control samples. Cyclic strain caused significant elongation of mesenchymal stem cells close to contractile smooth muscle phenotype. This method can be applied in cardiovascular tissue engineering to provide functional smooth muscle cells.

Human mesenchymal stem cells (hMSCs) have shown a great potential in the field of regenerative medicine as well as vascular tissue engineering. Mechanical properties of the cell substrate provides an environment that influences physiological activity of cells such as proliferation, differentiation and cell cytoskeleton developments and consequently modulates functionality of in vitro engineered cells. hMSCs were cultured under two groups of control and growth factor-induced differentiation within two types of substrates with different stiffness. We used Micropipette aspiration technique to evaluate mechanical behavior of cultured cells (effective Young’s modulus (E) and creep compliance value) during their differentiation into smooth muscle cells phenotype. hMSC with growth factor-induced differentiation showed significant decrease in E value in relation to both substrates in compare to control group, within 2 days of cell culture, whereas the creep compliance of these cells sharply increased. Consequently, by increasing the cultivation time to 4 to 6 days, the E values of induced-differentiation cells significantly increased in compare to control samples, with a decrease in the creep compliance of these cells. Furthermore, the state of increase or decrease in creep compliance was depended on substrate stiffness in which the cells were seeded on. Cells cultured on soft substrates showed high tendency for preserving their viscoelastic properties. Our results provides groundwork for stem cell-based tissue engineering in order to optimize culture conditions due to effective usage of external physical cues as well as substrate properties as the regulatory mechanisms of differentiation to functional target cells.

Since explosive blasts continue to cause casualties in both civil and military environments، there is a need for an understanding of the mechanisms of blast trauma at the human organ level، plus a more detailed predictive methodology. The primary goal of this research was to develop a finite element model capable of predicting primary blast injury to the lung so as to assist in the development of personal protective equipment. Numerical simulation of thorax blast loading consisted of the following components: 3D thorax modeling reconstruction، meshing and assembly of various thorax parts، blast and boundary loading، numerical solution، result extraction and data analysis. By comparing the models to published experimental data، local extent of injury in the lung was correlated to the peak pressure measured in each finite element، categorized as no injury (< 60 kPa)، trace (60-100 kPa)، slight (100-140 kPa)، moderate (140-240 kPa) and severe (> 240 kPa). It seemed that orienting the body at an angle of 45 degrees provides the lowest injury. The level and type of trauma inflicted on a human organ by a blast overpressure is related to many factors including: blast characteristics، body orientation، equipment worn and the number of exposures to blast loading.

Stress analysis is a proper tool in evaluation of vulnerable regions of dental tissues exposed to cyclic loading due to mastication and other physiological functions. In this study, effects of visco-elastic property of dental components on the distribution of stress are investigated in finite element models of upper central tooth prone to dynamic loading. Sensitivity of stress pulse to the visco-elastic property is studied. Results indicate reduction of stress pulse amplitude by elevation of visco-elastic parameter with highest effect in enamel-cementum junction and then in enamel-dentin junction. The visco-elastic property causes smoothening of the stress distribution in dental tissues. Such effect is due to reduction of stress wave amplitude and elevation of the ratio of minimum to maximum stress values. Increased visco-elasticity of components results in elevated phase shift between load and stress waves and higher attenuation of stress wave. This causes slow propagation of attenuated wave leading to lower maximum stress after reflection of stress wave in boundaries and junctions.

Cell vital function has correlation with mechanical loadings that cell experiences. Here, effects of in-vitro combined cyclic-static stretch on proliferation of human mesenchymal stem cell (HMSC) were evaluated. HMSCs were cultured on gelatin coated elastic membranes, and exposed to stretch loading. Four different regimes of cyclic, static, combined cyclic-static, and cyclic with a period of unloading were exerted on the elastic membrane. Duration of cyclic loading and static loading was 5 and 12 hours respectively. The results illustrate that 10% cyclic stretch causes cell alignment but there were no significant proliferation differences between control and test group. Combined cyclic-static stretch reduced proliferation significantly while cyclic stretch with an unloading period increased cell proliferation significantly. At last, static stretch did not affect cell proliferation significantly. Cell stretching regimes and post-loading duration are effective factors on cell proliferation.

Introduction & Fractals are complex geometric structures, which was introduced in 1975, and gained special place in medicine. Fractals are used in diagnosis of bone disease and structural of bone malignancies and heart arrhythmia diseases and it seems that fractals can be brought in any structural anarshaes, like cancers, for diagnosis and prognosis evaluation by quantifying it and expressing it in terms of fractal geometry. In this study we evaluate pathologic grades or breast carcinomas by fractal analysis. In this cross-sectional study 60 women with breast ductal carcinoma, of pathology grades 2 and 3, were recruited. They were randomly selected among 1000 women in Booali Hospital, Tehran, Iran, during the years 2008 to 2010. From all the patients some photographs from the smears with pathological standard and with Digital Sony Camera (700 Mega-pixel) were taken to analyze them by MATLAB software (version 7.0.1.246 [R14] Service Pack 3, Tehran, Iran) via Box-Counting method. The used analytical methods were ANOVA and T tests. The mean age of the women were 52.48±10.83 of these, 38(63.3%) had grade 2 and 22 (36.7%) had grade 3. The average size of tumor was 2.8±1.48. The mean fractal count was 1.95±0.03. There was a significant association between fractal count and pathological grade and the mean fractal count was 1.94±0.03 in grade 2 and 1.98±0.004 in grade 3 patients (P < 0.001). According to our results, it may be concluded that fractal count is a prognostic indicator in breast cancer patients. However, it is recommended to perform further studies with higher sample volume and also in other caners to obtain more definitive results.

Mesenchymal stem cells (MSCs) can be expanded and differentiated into many mature cell types including smooth muscle cells (SMCs). In addition to growth factor, cyclic stretch contributes to differentiation of stem cells. Mechanical stimuli are critical to morphological changes, development, regeneration, differentiation and pathology of mesenchymal tissues. The aim of this study is to investigate effects of cyclic stretch with differing amplitudes on morphology and differentiation of mesenchymal stem cells. Mesenchymal stem cells are extracted from human bone marrow. Cells are cultured on silicone membrane and exposed to cyclic stretch by a custom made device. Cellular images are captured before and after tests. Effects of 5% and 15% uniaxial strain with 1Hz frequency and 1-8 hour durations on morphology of human mesenchymal stem cells are investigated. It is assumed that environmental factors such as mechanical loading regulate MSCs differentiation to SMCs. Fractal analysis is used to quantify alterations in cellular morphology. An image processing method with a designed code is used for evaluation of fractal dimension parameter. Results demonstrate statistically significant change in cell morphology due to mechanical stretch. By elevation of strain amplitude and number of load cycles, fractal dimensions of cell images decrease. Such decrease is equivalent to alignment of cells by mechanical stimulus. Cells are differentiated to SMCs purely by cyclic stretch. The initiation and rate of differentiation depend on mechanical conditions. To produce functional SMCs for engineered tissues, MSCs can be exposed to uniaxial cyclic stretch. The functionality of differentiated SMCs depends on loading conditions.

Vital function of the cell is correlated with the mechanical loads that the cell experiences. The cell shape and morphology are also related to its mechanical environments. Different methods have been proposed to obtain cell groups with the same morphology and alignment which considered desirable features in tissue engineering applications. For instance, applying cyclic loading makes cells elongated and aligned as bundles in a specific direction to the tension axis. Applying static stretches also affect the cells morphology, extra-cellular matrix, enzymes secretion and genes expression. The effect of applying in vivo static stretch on cellular alignment was evaluated in this study. Human mesenchymal stem cells (hMSCs) were cultured on the elastic membrane, and then subjected to static stretch. The results demonstrated that applying a 10% static stretch for 24 hours aligns intra-structure actin filaments and applying a 20% static stretch had a significant effect on the arrangement of the oriented fibers.

In this paper, we studied the effect of mechanical loading on remodeling process with aging in muscular arteries. Based on the gathered experimental data, the brachial artery was selected for simulation. In this simulation, pulsatile pressure and flow waves were considered as boundary conditions to study the effect of circumferential stress and wall shear stress on the remodeling process. FSI based transient numerical simulation was used to solve the fluid and solid equations. The results of three remodeling schemes showed that inward eutrophic scheme is an optimum algorithm for brachia! Artery remodeling with aging. Such remodeling scheme causes the most optimized outcome to keep circumferential stress with minimal alteration.

Arterial stenosis and the consequent cardiovascular diseases such as atherosclerosis remain the major cause of mortality in the world. In this study, blood flow was analyzed in a three-dimensional model of stenosed carotid artery with asymmetric stenosis utilizing fluid-structure interaction method. The modeling was performed by ANSYS finite element software. To overcome the software inconsistency in FSI mode, a new code was designed in ANSYS multi-physics environment for coupling of solid and fluid domains via incremental boundary iteration method. The results indicated a considerable variation of local blood pressure, velocity and shear stress in stenosed artery, high pressure drop along stenosis, compressive stress and larger flow separation zone in the post-stenotic region as the result of increased eccentricity of stenosis. The results might be applied in evaluation of plaque severity, progression of disease, plaque growth and vulnerable regions of plaque to fracture.