A comparison of the cutaneous microvascular properties of the spontaneously hypertensive rat and the Wistar-Kyoto rat

Exosomes Derived From Pericytes Improve Microcirculation and Protect Blood-Spinal Cord Barrier After Spinal Cord Injury in Mice

Spinal cord injury (SCI) often leads to severe and permanent paralysis and places a heavy burden on individuals, families, and society. Until now, the therapy of SCI is still a big challenge for the researchers. Transplantation of mesenchymal stem cells (MSCs) is a hot spot for the treatment of SCI, but many problems and risks have not been resolved. Some studies have reported that the therapeutic effect of MSCs on SCI is related to the paracrine secretion of cells. The exosomes secreted by MSCs have therapeutic potential for many diseases. There are abundant pericytes which possess the characteristics of stem cells in the neurovascular unit. Due to the close relationship between pericytes and endothelial cells, the exosomes of pericytes can be taken up by endothelial cells more easily. There are fewer studies about the therapeutic potential of the exosomes derived from pericytes on SCI now. In this study, exosomes of pericytes were transplanted into the mice with SCI to study the restoration of motor function and explore the underlying mechanism. We found that the exosomes derived from pericytes could reduce pathological changes, improve the motor function, the blood flow and oxygen deficiency after SCI. In addition, the exosomes could improve the endothelial ability to regulate blood flow, protect the blood-spinal cord barrier, reduce edema, decrease the expression of HIF-1α, Bax, Aquaporin-4, and MMP2, increase the expression of Claudin-5, bcl-2 and inhibit apoptosis. The experiments in vitro proved that exosomes derived from pericytes could protect the barrier of spinal cord microvascular endothelial cells under hypoxia condition, which was related to PTEN/AKT pathway. In summary, our study showed that exosomes of pericytes had therapeutic prospects for SCI.

A comparison of the cutaneous microvascular properties of the Spontaneously Hypertensive and the Wistar-Kyoto rats by Spectral analysis of Laser Doppler

This work was aimed to study skin blood perfusion, vasomotion and vascular responses of the Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) in different stages of age using spectral. Laser-Doppler flowmetry (LDF) was used to examine the ears and limbs of WKY (12 and 48 weeks old) and SHR (12 and 48 weeks old). The skin blood flow oscillations (SBFOs) were studied by wavelet spectral analysis of LDF tracings. Then, we observed that old groups showed decreased perfusion and SBFO in the ears of both SHR and WKY. The SHR showed obviously lower postocclusive reactive hypera (PORH) ratio at the same age. A decreased peak-time occurred in the SHR of old age group. After PORH test, a statistically significant increase was observed within all subintervals in the absolute amplitude of 12-week WKY and only within IV and III subintervals in the absolute amplitude of 12-week SHR. But, the absolute amplitude of 48-week WKY and SHR showed no statistically significant increase within all subintervals. Results indicated that local regulating function of peripheral vascular was impaired in rat with hypertension and aging. Abbreviations LDF: Laser-Doppler flowmetry; SBF: Skin blood flow; SBFO: Skin blood flow oscillation; PORH: Postocclusive reactive hyperemia; SHR: Spontaneously hypertensive rats; WKY: Wistar-Kyoto rats; LDF: Laser-Doppler flowmetry; LDI: Laser Doppler Imaging; BP: Blood pressure.

Cardioprotective activity of placental growth factor combined with oral supplementation of l-arginine in a rat model of acute myocardial infarction

OBJECTIVE

Exogenous administration of placental growth factor (PlGF) stimulates angiogenesis and improves ventricular remodeling after acute myocardial infarction (AMI), and supplementation with l-arginine ameliorates endothelial function. The objective of the present study was to compare the cardioprotective effects of combination therapy of PlGF and l-arginine with those of direct administration of PlGF alone in a rat model of AMI.

MATERIALS AND METHODS

Fifty male Sprague Dawley rats were randomly divided into five groups: sham group, normal saline group, l-arginine group, PlGF group, and combination group (PlGF + l-arginine). An AMI rat model was established by ligation of the left anterior descending of coronary arteries. After 4 weeks of postligation treatment, cardiac function, scar area, angiogenesis and arteriogenesis, myocardial endothelial nitric oxide synthase (eNOS) and collagen I protein content, and plasma concentration of brain natriuretic peptide (BNP) were studied. Echocardiography, Masson's staining, immunohistochemical analyses, Western blot, and enzyme-linked immunosorbent assay were performed.

RESULTS

Left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), and capillary and arteriole densities were higher in the PlGF group than in the normal saline group (P<0.01). Scar area, collagen I protein content, and plasma concentration of BNP were decreased in the PlGF group (P<0.01). Myocardial eNOS protein level was elevated in the l-arginine group and PlGF + l-arginine group (P<0.01). Compared with the PlGF group, LVEF, LVFS, myocardial eNOS, and capillary and arteriole densities were higher in the combination group (P<0.01). Scar area, content of collagen I protein, and plasma concentration of BNP were reduced in the combination group (P<0.01).

CONCLUSION

Exogenous administration of PlGF stimulates angiogenesis and improves cardiac function. l-arginine increases the expression of the eNOS protein. PlGF and l-arginine have a more pronounced, synergistic protective effect on myocardial protection compared with that of exogenous PlGF therapy alone.

Effects of Hypertension on Abdominal Wall Healing: Experimental Study in Rats

PURPOSE

The aim of this study was to investigate the effects of untreated and treated hypertension on abdominal wall healing.

METHODS

Thirty-two spontaneously hypertensive rats (SHR) were randomly allocated into two groups: H (n = 16), untreated and E (n = 16), treated with enalapril (40 mg/kg per day). Group C (n = 16) was a nonhypertensive control group. The animals of each group were submitted to a midline laparotomy and randomly divided, according to the day on which they were killed (7th or 14th postoperative day), into subgroups of 8 animals, as follows: H-7, H-14, E-7, E-14, C-7 and C-14. On the day of their deaths, two strips of the anterior abdominal wall were collected. One strip was submitted to breaking strength measurement and the other to hydroxyproline determination.

RESULTS

No mortalities or complications were observed in the six subgroups. The breaking strength in E-7 subgroup was significantly lower than in C-7 (P < 0.05). The tissue hydroxyproline levels were similar in all six subgroups (P > 0.05).

CONCLUSIONS

Untreated hypertension had no effect on the abdominal wall healing of rats. Hypertensive animals treated with enalapril showed a significant decrease in abdominal wound-breaking strength on the 7th postoperative day.

Dermal capillary clearance: physiology and modeling

Substances applied to the skin surface may permeate deeper tissue layers and pass into the body's systemic circulation by entering blood or lymphatic vessels in the dermis. The purpose of this review is an in-depth analysis of the dermal clearance/exchange process and its constituents: transport through the interstitium, permeability of the microvascular barrier and removal via the circulation. We adapt an 'engineering' viewpoint with emphasis on quantifying the dermal microcirculatory physiology, providing the theoretical framework for the physics of key transport processes and reviewing the available computational clearance models in a comparative manner. Selected experimental data which may serve as valuable input to modeling attempts are also reported.

Decrease in heart rates by artificial CO2 hot spring bathing is inhibited by beta1-adrenoceptor blockade in anesthetized rats

To investigate the effects of carbon dioxide (CO2) hot spring baths on physiological functions, head-out immersion of urethane-anesthetized, fursheared male Wistar rats was performed. Animals were immersed in water (30 or 35 degrees C) with high-CO2 content ( approximately 1,000 parts/million; CO2-water). CO2-water for bathing was made by using an artificial spa maker with normal tap water and high-pressure CO2 from a gas cylinder. When a human foot was immersed for 10 min in the CO2-water at 35 degrees C, the immersed skin reddened, whereas skin color did not change in normal tap water at the same temperature. Arterial blood pressure, heart rate (HR), underwater skin tissue blood flow, and temperatures of the colon and immersed skin were continuously measured while animals were immersed in a bathtub of water for approximately 30 min at room temperature (26 degrees C). Immersed skin vascular resistance, computed from blood pressure and tissue blood flow, was significantly lower in the CO2-water bath than in tap water at 30 degrees C, but no differences were apparent at 35 degrees C. HR of rats in CO2-water was significantly slower than in tap water at 35 degrees C. Decreased HR in CO2-water was inhibited by infusion of atenolol (beta1-adrenoceptor blocker), but it was unaffected by atropine (muscarinic cholinoceptor blocker). Theses results suggest that bradycardia in CO2 hot spring bathing is caused by inhibition of the cardiac sympathetic innervation. This CO2-water maker should prove a useful device for acquiring physiological evidence of balneotherapy.

Characterization of angiogenesis and inflammation surrounding ePTFE implanted on the epicardium

The response of epicardial tissue to the implantation of expanded polytetrafluoroethylene (ePTFE) was evaluated and compared with identical material implanted within subcutaneous and adipose tissues. These two tissue environments were selected for comparison with epicardial implants because they represent tissue often involved in device implantation. Discs of ePTFE (6 mm) were implanted into three different tissue sites in Sprague-Dawley rats. At 5 weeks, polymers and surrounding tissues were harvested and processed for light microscopy. General histology and histochemistry data indicated all polymers to be well incorporated with new tissue. Subcutaneous implants were covered by a dense fibrous capsule (55-70 microm). Epicardial and adipose implants had no fibrous capsule and a significantly greater number of microvessels (arterioles, capillaries, and venules) within the surrounding tissues compared with subcutaneous implants. An increased level of inflammation was also observed around epicardial implants compared with the other implants. Additionally, the new vasculature surrounding epicardially implanted ePTFE revealed an altered microvessel density and vessel type distribution compared with normal (control) epicardium. These results suggest that epicardial tissue responds to implanted ePTFE with a robust inflammatory response that may support the formation of a new microvasculature that is uniquely different from the native epicardial microvasculature.

Scaffold-based three-dimensional human fibroblast culture provides a structural matrix that supports angiogenesis in infarcted heart tissue

BACKGROUND

We have developed techniques to implant angiogenic patches onto the epicardium over regions of infarcted cardiac tissue to stimulate revascularization of the damaged tissue. These experiments used a scaffold-based 3D human dermal fibroblast culture (3DFC) as an epicardial patch. The 3DFC contains viable cells that secrete angiogenic growth factors and has previously been shown to stimulate angiogenic activity. The hypothesis tested was that a viable 3DFC cardiac patch would stimulate an angiogenic response within an area of infarcted cardiac tissue.

METHODS AND RESULTS

A coronary occlusion of a branch of the left anterior descending coronary artery was performed by thermal ligation in severe combined immunodeficient mice. 3DFCs with or without viable cells were sized to the damaged area, implanted in replicate mice onto the epicardium at the site of tissue injury, and compared with animals that received infarct surgery but no implant. Fourteen and 30 days after surgery, hearts were exposed and photographed, and tissue samples were prepared for histology and cytochemistry. Fourteen and 30 days after surgery, the damaged myocardium receiving viable 3DFC exhibited a significantly greater angiogenic response (including arterioles, venules, and capillaries) than nonviable and untreated control groups.

CONCLUSIONS

In this animal model, viable 3DFC stimulates angiogenesis within a region of cardiac infarction and can augment a repair response in damaged tissue. Therefore, a potential use for 3DFC is the repair of myocardial tissue damaged by infarction.

A novel approach to the quantification of hepatic stellate cells in intravital fluorescence microscopy of the liver using a computerized image analysis system

Hepatic stellate cells (HSC) are nonparenchymal liver cells which reside in the space of Disse within the hepatic microcirculatory unit. HSC can be distinguished using intravital fluorescent microscopy (IVFM) due to the autofluorescence from their intracellular vitamin A. Herein we report on a novel approach for the quantification of video-recorded rat HSC images acquired by IVFM (excitation 360 nm/emission 420 nm) by the combined use of the "Cell counting macro" and the "Measurement macros" in the NIH image software. The approach involved two major steps using (i) the "Cell counting macro" for automatic detection, threshold-setting, and generation of a binary image of the vitamin A autofluorescence in the HSC images and (ii) the "Compute percent black and white" command in the "Measurement macros" to automatically determine the HSC density (%), which was then expressed as percentage of the total area of vitamin A autofluorescence-associated sites per observation area. Comparing the vitamin A autofluorescence areas in the original and the binary fashion HSC images revealed that the "Cell counting macro" was an optimal option for the analysis of the low-magnification (x10 objective) HSC images, whereas this macro was not suitable for the analysis of the higher magnification (40x objective) HSC images unless modifications were made. Our analysis revealed that HSC represent approximately 4-5% of the total area of the liver surface. In analyzing the higher magnification HSC microfluorographs, the use of the original "Cell counting macro" resulted in a significant underestimation of HSC density (60% reduction, P < 0.01) when compared with those analyzed using our modified macro. This study represents the first report of an automatic and reliable approach to the intravital fluorescent microscopic quantification of HSC using a computer-NIH image analysis system.