Polarization smoothing based on full Poincaré beams modulated by stress-engineered optics.

In laser-driven inertial confinement fusion (ICF) facilities, nonuniform laser irradiation can cause significant challenges, such as hydrodynamics instability and laser plasma instability, which hinder the success of fusion. This article presents a new idea for improving the uniformity of far-field laser irradiation through a method of single-beam polarization smoothing. The method involves modulating full Poincaré beams using stress-engineered optics made from fused silica. We designed a stress birefringence system and conducted opto-mechanical modeling and analysis on it. The article elaborates on the mechanism and principles of generating large-aperture full Poincaré beams by stress birefringence, as well as the mechanism of polarization smoothing by full Poincaré beams. Near-field polarization measurements were conducted to verify these mechanisms, and the effectiveness of this method in improving the uniformity of laser irradiation in the target area was evaluated through far-field optical tests.

Divergent beam-based method for measuring the detuning angles of a laser frequency converter.

We propose a method to obtain the detuning angles of a frequency converter by tripling the frequency of a divergent Gaussian beam. The frequency tripling process of the divergent beam was first simulated. It is found that the detuning angles of the frequency converter are linearly related to the position of the maximum light intensity point of the third harmonic laser. The corresponding experiment was conducted, and the results agreed well with the theoretical analysis. This method measures the detuning angles of the frequency converter in only one measurement and within 1 min. The detuning angle measurement errors of KDP and KD*P crystals are less than 10 µrad and 36.5-61.9 µrad, respectively.

Combination of BMP-2 and 5-AZA is advantageous in rat bone marrow-derived mesenchymal stem cells differentiation into cardiomyocytes.

Bone morphogenetic protein-2 (BMP-2) has a crucial role in the development of cardiogenesis, and is used in inducing bone marrow mesenchymal stem cells (BMMSCs) to differentiate into cardiomyocytes. We have examined a combination of BMP-2 and 5-azacytidine (5-AZA) in inducing these differentiation effects. BMMSCs were collected and purified from bone marrow of 4-week-old Sprague-Dawley (SD) rats by density-gradient centrifugation and differential attachment. The fourth passage subculture of BMMSCs, selected by cytometry for purity and identification, was divided into four groups: a control group, BMP-2 treated, 5-AZA treated, and a combination of BMP-2 and 5-AZA treatment. Expression of cardiac Troponin I (cTnI) and Connexin 43 (CX-43) in BMMSCs after induction were detected by immunofluorescence and Western blot. Flow cytometry analysis was used for differentiation rates and apoptosis of induced BMMSCs, through the expression of cardiac Troponin T (cTnT) and Annexin V-FITC & PI kit, respectively. BMP-2 can ameliorate apoptosis of BMMSCs caused by 5-AZA and promote the differentiation of BMMSCs into cardiomyocyte-like cells. Thus a combination of BMP-2 and 5-AZA can significantly improve the cardiac differentiation with fewer cell damage effects, making it a safe and effective method of induction in vitro.

Inhibition of p53-p21 pathway promotes the differentiation of rat bone marrow mesenchymal stem cells into cardiomyocytes.

P53 is shown recently to play an important role in the proliferation and differentiation of bone marrow mesenchymal stem cells (BMMSCs). In this study, by inhibiting p53-p21 pathway with p53 inhibitor (p-fifty three inhibitor-alpha, PFT-α), we investigated the resulting effects on the differentiation of rat BMMSCs into cardiomyocyte-like cells. BMMSCs were isolated from bone marrow of SD rats by density gradient centrifugation. The fourth passage cells were divided into four groups: control group, PFT-α group, 5-AZA group, and PFT-α + 5-AZA group. The purified BMMSCs were identified by surface antigens and the proliferation and apoptosis of BMMSCs were examined by MTT and flow cytometry analysis. The expression of cTnI and CX-43 in BMMSCs after induction was detected by immunofluorescence and that of cTnI, p53, and p21 was detected by western blot. Our results demonstrated that PFT-α at 20 µmol/l significantly reduced the apoptosis and promoted the proliferation of BMMSCs, and induced BMMSCs to differentiate into cardiomyocyte-like cells. In conclusion, these data open up new possibility of modulating p53-p21 pathway for directed differentiation of BMMSCs into cardiomyocytes, which will be valuable for cardiovascular regenerative medicine.

Electrophysiological characteristics of cardiomyocyte-like cells from rat bone marrow derived mesenchymal stem cells by four inductors.

BACKGROUND: Bone marrow derived mesenchymal stem cells (BMdMSCs) can differentiate into cardiomyocyte-like cells induced by different inductors individually or collectively. In this study, by inducing BMdMSCs with p53 inhibitor (p-fifty three inhibitor-alpha, PFT-α), 5-azacytidine (5-AZA), angiotensin-II (Ang-II) and bone morphogenic protein-2 (BMP-2) we compared the influences of four inductors on the differentiation of rat BMdMSCs into caridomyocyte like-cells. METHODS: BMdMSCs were collected from the bone marrow of Sprague Dawley rats and after the fourth generation, the purified cells were divided into five groups: 5-AZA (10 µmol/L), Ang-II (0.1 µmol/L), PFT-α (20 µmol/L), BMP-2 (10 µg/L) and control. The purity of the BMdMSCs and the cardiac differentiation rates were obtained by flow cytometry. The expressions of cTnT in the BMdMSCs after four weeks of induction were detected by immunofluorescence and the expressions of cTnI and Cx43 detected by Western blotting. The green fluorescent levels reflecting intracellular calcium transient function were determined by laser scanning confocal microscopy. The total potassium current levels of cells were measured on patch clamp. RESULTS: All inductors affected to a different degree the differentiation of BMdMSCs into cardiomyocyte-like cells and the expressions of cTnT, cTnI and Cx43 suggesting that the combination of inductors could be an improved method for cardiac regenerative medicine. In addition, the total potassium current level and calcium transient in PFT-α cardiomyocyte-like cells were higher than other groups. CONCLUSIONS: The cardiac differentiation of BMdMSCs induced by PFT-α, 5-AZA, Ang-II and BMP-2 has been improved at different levels. PFT-α has an advantage of differentiation rate and electrophysiological function over other inductors.

Stress-induced growth-differentiation factor 15 plays an intriguing role in cardiovascular diseases.

OBJECTIVE: To provide an overview of the current knowledge of growth-differentiation factor 15 (GDF-15) in heart disease. DATA SOURCES: To identify relevant publications, we searched PubMED database combining the textual terms of heart, cardiac, cardiovascular disease with GDF-15. STUDY SELECTION: Well-controlled, relatively large-scale, retrospective studies as well as meaningful individual cases were all selected as materials. RESULTS: GDF-15 is a distant member of the transforming growth factor-ß cytokine superfamily. In myocardium, GDF-15 is weakly expressed under physiological conditions. However, its expression level is increased in response to pathological stress. Growing evidence indicate that elevated levels of GDF-15 is a promising prognostic biomarker in cardiovascular diseases. Moreover, GDF-15 exhibits the properties of endogenous anti-hypertrophy of cardiomyocytes and protecting the heart suffering from ischemia and reperfusion insult. CONCLUSION: Ve GDF-15 may be a promising biomarker for evaluation and management of patient with cardiovascular diseases, and have potential protective properties on myocardium.

Cardiac differentiation and electrophysiology characteristics of bone marrow mesenchymal stem cells.

OBJECTIVE: To review the progress of cardiac differentiation and electrophysiological characteristics of bone marrow mesenchymal stem cells. DATA SOURCES: The databases of PubMed, Springer Link, Science Direct and CNKI were retrieved for papers published from January 2000 to January 2012 with the key words of "bone marrow mesenchymal stem cells, cardiac or heart, electrophysiology or electrophysiological characteristics". STUDY SELECTION: The articles concerned cardiac differentiation and electrophysiological characteristics of bone marrow mesenchymal stem cells were collected. After excluding papers that study purposes are not coincident with this review or contents duplicated, 56 papers were internalized at last. RESULTS: For the treatment of myocardial infarction and myocardiac disease, the therapeutic effects of transplantation of bone marrow mesenchymal stem cells which have the ability to develop into functional myocardial cells by lots of methods have been proved by many researches. But the arrhythmogenic effect on ventricles after transplantation of bone marrow mesenchymal stem cells derived myocardial cells is still controversial in animal models. Certainly, the low differentiation efficiency and heterogeneous development of electrical function could be the most important risk for proarrhythmia. CONCLUSION: Many studies of cardiac differentiation of bone marrow mesenchymal stem cells have paid attention to improve the cardiac differentiation rate, and the electrophysiology characteristics of the differentiated cells should be concerned for the risk for proarrhythmia as well.