A review of state-of-the-art stereology for better quantitative 3D morphology in cardiac research

Calafiore cardioplegia offers better myocardial protection in adult and senescent rat hearts than Del Nido cardioplegia

OBJECTIVES

We compared the cardioprotective capacity of Del Nido cardioplegia and warm Calafiore blood cardioplegia in an experimental setting during 90 min of ischaemia.

METHODS

20 adult and 20 senescent rat hearts were isolated and mounted on a blood-perfused, pressure-controlled Langendorff apparatus. After a stabilization period, cardiac arrest (90 min) was induced by the administration of either Calafiore (Cala) or Del Nido solution (DNS). While Cala was given warm and intermittently, DNS was given as a cold single shot. During 90 min of reperfusion, cardiac function and metabolism were evaluated and biomarker levels were measured. After the end of the experiment, hearts were prepared for electronmicroscopic investigation.

RESULTS

Hearts exposed to Cala recovered faster during reperfusion compared with hearts administered DNS (Cala vs DNS at 30 min reperfusion: left ventricular developed pressure 72, SD: 22% of baseline (BL) versus 40, SD: 32% of BL, p < .001, and positive derived left ventricular pressure over time was better in both adult and senescent Cala groups (96, SD: 31% of BL) than in the DNS groups (39, SD: 27% of BL, p < .001). Ischaemic contractures were seen in the DNS groups starting after 30 min of ischaemia, whereas no rise in diastolic pressure was observed for the Cala groups. Accordingly, lactate production was higher after DNS (1.23 mg/dl (SD 0.87) than after Cala (0.33 mg/dl (SD 0.68), p = .015) at the beginning of reperfusion. Troponin I levels at the end of reperfusion were higher after DNS treatment in adult hearts (DNS: 287.9 SD: 147.7 ng/mL vs Cala 91.2: SD: 94.7 ng/mL, p = .02) and in senescent hearts (DNS: 376.5 (SD: 162.8) ng/ml versus Cala 104.7 (SD: 150.2) ng/ml, p = .025). Electron microscopy showed that the cellular oedema index was higher in adult DNS hearts (1.2 ± 0.2) than in adult Cala hearts (0.8 ± 0.1, p = .012), whereas the VS ratio was similar (0.18 ± 0.01 vs 0.17 ± 0.03).

CONCLUSION

Calafiore cardioplegia offers better myocardial protection from ischaemia/reperfusion-related damage in isolated perfused adult and senescent rat hearts than Del Nido cardioplegia.

Biochemical and morphological responses to post-hepatectomy liver failure in rats

The upper limit for partial hepatectomy (PH) in rats is 90%, which is associated with an increased risk of post-hepatectomy liver failure (PHLF), correlating with high mortality. Sixty-eight rats were randomized to 90% PH, sham operation, or no surgery. Further block randomization was performed to determine the time of euthanasia, whether 12, 24, or 48 h after surgery. A general distress score (GDS) was calculated to distinguish between rats with reversible (GDS < 10) and irreversible PHLF (GDS ≥ 10). At euthanasia, the liver remnant and blood were collected. Liver-specific biochemistry and regeneration ratio were measured. Hepatocyte proliferation and volume were estimated using stereological methods. All rats subjected to 90% experienced biochemical PHLF. The biochemical and morphological liver responses did not differ between the groups until 48 h after surgery. At 48 h, liver regeneration and function were significantly improved in survivors. The peak mean regeneration ratio was 15% for rats with irreversible PHLF compared to 26% for rats with reversible PHLF. The 90% PH rat model was associated with PHLF and high mortality. Irreversible PHLF was characterized by impaired liver regeneration capacity and an insufficient ability to metabolize ammonia.

Myocardial Recovery, Metabolism, and Structure after Cardiac Arrest with Cardioplexol

OBJECTIVES

 Clinical studies indicate encouraging cardioprotective potential for Cardioplexol. Its cardioprotective capacities during 45 minutes of ischemia compared with pure no-flow ischemia or during 90 minutes of ischemia compared with Calafiore cardioplegia were investigated experimentally.

METHODS

 Forty-four rat hearts were isolated and inserted into a blood-perfused pressure-controlled Langendorff apparatus. In a first step, cardiac arrest was induced by Cardioplexol or pure no-flow ischemia lasting 45 minutes. In a second step, cardiac arrest was induced by Cardioplexol or Calafiore cardioplegia lasting 90 minutes. For both experimental steps, cardiac function, metabolic parameters, and troponin I levels were evaluated during 90 minutes of reperfusion. At the end of reperfusion, hearts were fixed, and ultrastructural integrity was examined by electron microscopy.

RESULTS

 Step 1: after 90 minutes of reperfusion, hearts exposed to Cardioplexol had significantly higher left ventricular developed pressure (CP-45': 74%BL vs. no-flow-45': 45%BL; p = 0.046) and significantly better maximal left ventricular relaxation (CP-45': 84%BL vs. no-flow-45': 51%BL; p = 0.012). Oxygen consumption, lactate production, and troponin levels were similar in both groups. Step 2: left ventricular developed pressure was lower (22 vs. 48% of BL; p = 0.001) and coronary flow was lower (24 vs. 53% of BL; p = 0.002) when Cardioplexol was used compared with Calafiore cardioplegia. Troponin I levels were significantly higher under Cardioplexol (358.9 vs. 106.1 ng/mL; p = 0.016).

CONCLUSION

 Cardioplexol significantly improves functional recovery after 45 minutes of ischemia compared with pure ischemia. However, Cardioplexol protects the myocardium from ischemia/reperfusion-related damage after 90 minutes of ischemia worse than Calafiore cardioplegia.

Decreased left heart flow in fetal lambs causes left heart hypoplasia and pro-fibrotic tissue remodeling

Low blood flow through the fetal left heart is often conjectured as an etiology for hypoplastic left heart syndrome (HLHS). To investigate if a decrease in left heart flow results in growth failure, we generate left ventricular inflow obstruction (LVIO) in mid-gestation fetal lambs by implanting coils in their left atrium using an ultrasound-guided percutaneous technique. Significant LVIO recapitulates important clinical features of HLHS: decreased antegrade aortic valve flow, compensatory retrograde perfusion of the brain and ascending aorta (AAo) from the arterial duct, severe left heart hypoplasia, a non-apex forming LV, and a thickened endocardial layer. The hypoplastic AAo have miRNA-gene pairs annotating to cell proliferation that are inversely differentially expressed by bulk RNA-seq. Single-nucleus RNA-seq of the hypoplastic LV myocardium shows an increase in fibroblasts with a reciprocal decrease in cardiomyocyte nuclei proportions. Fibroblasts, cardiomyocytes and endothelial cells from hypoplastic myocardium have increased expression of extracellular matrix component or fibrosis genes with dysregulated fibroblast growth factor signaling. Hence, a severe sustained ( ~ 1/3 gestation) reduction in fetal left heart flow is sufficient to cause left heart hypoplasia. This is accompanied by changes in cellular composition and gene expression consistent with a pro-fibrotic environment and aberrant induction of mesenchymal programs.

QUANTITATIVE ASSESSMENT OF MYOCARDIAL FIBROSIS BY DIGITAL IMAGE ANALYSIS: an adjunctive tool for pathologist "ground truth": original article

AIMS

Myocardial fibrosis (MF) is a common pathological process in a wide range of cardiovascular diseases. Its quantity has diagnostic and prognostic relevance. We aimed to assess if the complementary use of an automated artificial intelligence software might improve the precision of the pathologist´s quantification of MF on endomyocardial biopsies (EMB).

METHODS AND RESULTS

Intraoperative EMB samples from 30 patients with severe aortic stenosis submitted to surgical aortic valve replacement were analysed. Tissue sections were stained with Masson´s trichrome for collagen/fibrosis and whole slide images (WSI) from the experimental glass slides were obtained at a resolution of 0.5μm using a digital microscopic scanner. Three experienced pathologists made a first quantification of MF excluding the subendocardium. After two weeks, an algorithm for Masson´s trichrome brightfield WSI (at QuPath software) was applied and the automatic quantification was revealed to the pathologists, who were asked to reassess MF, blinded to their first evaluation. The impact of the automatic algorithm on the inter-observer agreement was evaluated using Bland-Altman type methodology. Median values of MF on EMB were 8.33% [IQR 5.00-12.08%] and 13.60% [IQR 7.32-21.2%], respectively for the first pathologist´s and automatic algorithm quantification, being highly correlated (R²: 0.79; p<0.001). Inter-observer discordance was relevant, particularly for higher percentages of MF. The knowledge of the automatic quantification significantly improved the overall pathologist´s agreement, which became unaffected by the degree of MF severity.

CONCLUSIONS

The use of an automated artificial intelligence software for MF quantification on EMB samples improves the reproducibility of measurements by experienced pathologists. By improving the reliability of the quantification of myocardial tissue components, this adjunctive tool may facilitate the implementation of imaging-pathology correlation studies.

Hypercontractile Cardiac Phenotype in Mice with Migraine-Associated Mutation in the Na+,K+-ATPase α2-Isoform

Two α-isoforms of the Na⁺,K⁺-ATPase (α₁ and α₂) are expressed in the cardiovascular system, and it is unclear which isoform is the preferential regulator of contractility. Mice heterozygous for the familial hemiplegic migraine type 2 (FHM2) associated mutation in the α₂-isoform (G301R; α₂^+/G301R mice) have decreased expression of cardiac α₂-isoform but elevated expression of the α₁-isoform. We aimed to investigate the contribution of the α₂-isoform function to the cardiac phenotype of α₂^+/G301R hearts. We hypothesized that α₂^+/G301R hearts exhibit greater contractility due to reduced expression of cardiac α₂-isoform. Variables for contractility and relaxation of isolated hearts were assessed in the Langendorff system without and in the presence of ouabain (1 µM). Atrial pacing was performed to investigate rate-dependent changes. The α₂^+/G301R hearts displayed greater contractility than WT hearts during sinus rhythm, which was rate-dependent. The inotropic effect of ouabain was more augmented in α₂^+/G301R hearts than in WT hearts during sinus rhythm and atrial pacing. In conclusion, cardiac contractility was greater in α₂^+/G301R hearts than in WT hearts under resting conditions. The inotropic effect of ouabain was rate-independent and enhanced in α₂^+/G301R hearts, which was associated with increased systolic work.

Reproducing extracellular matrix adverse remodelling of non-ST myocardial infarction in a large animal model

The rising incidence of non-ST-segment elevation myocardial infarction (NSTEMI) and associated long-term high mortality constitutes an urgent clinical issue. Unfortunately, the study of possible interventions to treat this pathology lacks a reproducible pre-clinical model. Indeed, currently adopted small and large animal models of MI mimic only full-thickness, ST-segment-elevation (STEMI) infarcts, and hence cater only for an investigation into therapeutics and interventions directed at this subset of MI. Thus, we develop an ovine model of NSTEMI by ligating the myocardial muscle at precise intervals parallel to the left anterior descending coronary artery. Upon histological and functional investigation to validate the proposed model and comparison with STEMI full ligation model, RNA-seq and proteomics show the distinctive features of post-NSTEMI tissue remodelling. Transcriptome and proteome-derived pathway analyses at acute (7 days) and late (28 days) post-NSTEMI pinpoint specific alterations in cardiac post-ischaemic extracellular matrix. Together with the rise of well-known markers of inflammation and fibrosis, NSTEMI ischaemic regions show distinctive patterns of complex galactosylated and sialylated N-glycans in cellular membranes and extracellular matrix. Identifying such changes in molecular moieties accessible to infusible and intra-myocardial injectable drugs sheds light on developing targeted pharmacological solutions to contrast adverse fibrotic remodelling.

Opportunities and short-comings of the axolotl salamander heart as a model system of human single ventricle and excessive trabeculation

Few experimental model systems are available for the rare congenital heart diseases of double inlet left ventricle (DILV), a subgroup of univentricular hearts, and excessive trabeculation (ET), or noncompaction. Here, we explore the heart of the axolotl salamander (Ambystoma mexicanum, Shaw 1789) as model system of these diseases. Using micro-echocardiography, we assessed the form and function of the heart of the axolotl, an amphibian, and compared this to human DILV (n = 3). The main finding was that both in the axolotl and DILV, blood flows of disparate oxygen saturation can stay separated in a single ventricle. In the axolotl there is a solitary ventricular inlet and outlet, whereas in DILV there are two separate inlets and outlets. Axolotls had a lower resting heart rate compared to DILV (22 vs. 72 beats per minute), lower ejection fraction (47 vs. 58%), and their oxygen consumption at rest was higher than peak oxygen consumption in DILV (30 vs. 17 ml min^-1 kg^-1). Concerning the ventricular myocardial organization, histology showed trabeculations in ET (n = 5) are much closer to the normal human setting than to the axolotl setting. We conclude that the axolotl heart resembles some aspects of DILV and ET albeit substantial species differences exist.

Ameliorate effects of resveratrol and l-carnitine on the testicular tissue and sex hormones level in busulfan induced azoospermia rats

Busulfan (Bus), is an alkylating agent widely used in chemotherapy which has been proven to possess toxic side effects on testicles. This study was carried out to compare the probable treatment effects of resveratrol (Res) or/and l-carnitine (Lca), as strong antioxidants, on the testicular tissue as well as on the level of sex hormones in busulfan-induced azoospermic rat models. A total of 78 adult male rats, were divided into six different experimental groups including: 1) Control; 2) Lca + Res; 3) BUS; 4) Bus + Lca; 5) BUS + Res and 6) Bus + Lca + Res. Busulfan was intraperitoneally administered in a single dose (10 mg/kg b.w), while resveratrol (20 mg/kg b.w/day) and l-carnitine (200 mg/kg b.w/day) were orally administered by gavage during 48 consecutive days to the rats. At the end of the experiment in all groups the level of LH, FSH, and testosterone were biochemically analyzed by ELISA and the testicular tissue evaluated histologically using stereological technique. Results showed that Lca or/and Res, increased the body and testis weight, the volume of the testis, interstitial tissue, germinal epithelium, and seminiferous tubule, the number of the different cells of germinal epithelium and the level of testosterone. On the other hand, Lca, Res and their combination decreased the concentration of LH and FSH compared to the group treated with Bus. In conclusion, these results suggested that l-carnitine or/and resveratrol treatment significantly attenuated busulfan -induced changes of the rat reproductive system led to the recovery of both testis and sperm parameters. However, co-administration of L-ca and Res was more effective than their individual treatment. This combination may alleviate the side effects of alkylating drugs, such as busulfan and may be beneficial for spermatogenesis.

A parasite outbreak in notothenioid fish in an Antarctic fjord

Climate changes can promote disease outbreaks, but their nature and potential impacts in remote areas have received little attention. In a hot spot of biodiversity on the West Antarctic Peninsula, which faces among the fastest changing climates on Earth, we captured specimens of two notothenioid fish species affected by large skin tumors at an incidence never before observed in the Southern Ocean. Molecular and histopathological analyses revealed that X-cell parasitic alveolates, members of a genus we call Notoxcellia, are the etiological agent of these tumors. Parasite-specific molecular probes showed that xenomas remained within the skin but largely outgrew host cells in the dermis. We further observed that tumors induced neovascularization in underlying tissue and detrimentally affected host growth and condition. Although many knowledge gaps persist about X-cell disease, including its mode of transmission and life cycle, these findings reveal potentially active biotic threats to vulnerable Antarctic ecosystems.

Methodological Progress of Stereology in Cardiac Research and Its Application to Normal and Pathological Heart Development

Design-based stereology is the gold standard for obtaining unbiased quantitative morphological data on volume, surface area, and length, as well as the number of tissues, cells or organelles. In cardiac research, the introduction of a stereological method to unbiasedly estimate the number of cardiomyocytes has considerably increased the use of stereology. Since its original description, various modifications to this method have been described. A particular field in which this method has been employed is the normal developmental life cycle of cardiomyocytes after birth, and particularly the question of when, during postnatal development, cardiomyocytes lose their capacity to divide and proliferate, and thus their inherent regenerative ability. This field is directly related to a second major application of stereology in recent years, addressing the question of what consequences intrauterine growth restriction has on the development of the heart, particularly of cardiomyocytes. Advances have also been made regarding the quantification of nerve fibers and collagen deposition as measures of heart innervation and fibrosis. In the present review article, we highlight the methodological progress made in the last 20 years and demonstrate how stereology has helped to gain insight into the process of normal cardiac development, and how it is affected by intrauterine growth restriction.

Effects of N-acetylcysteine and metformin treatment on the stereopathological characteristics of uterus and ovary

In this study, the stereo-pathological effect of metformin and N-acetyl cysteine is evaluated on the uterus and ovary of polycystic ovary syndrome (PCOS) mice. 96 mature females (8-weekold, weight of 20–30 gr) BALB/c mice were classified into 6 groups including the control group (n= 16), letrozole-induced PCOS group (n=16), PCOS + metformin (n=16), PCOS+NAC (n=16) and a separate control group for NAC (n=16). Another PCOS group was maintained for a month to make sure that features remain till the end of the study. Testosterone level, vaginal cytology and stereological evaluations were assessed. Vaginal cytology in letrozole-receiving mice showed a diestrus phase continuity. Testosterone level, body weight, uterine weight, endometrial volume, myometrial volume, gland volume, stromal volume, epithelial volume, vessel volume, daughter and conglomerate glands, endometrial thickness, and myometrial thickness exhibited an increasing trend in the uterus of PCOS mice. While normal gland and vessel length decreased in the PCOS group. Ovarian volume, corticomedullary volume, primary follicles, secondary follicles, and ovarian cysts were increased in PCOS ovaries. While corpus luteum, primordial, graafian, and atretic follicles showed a decline in the PCOS group. NAC and metformin, however, managed to restore the condition to normal. Given the prevalence of PCOS and its impact on fertility, the use of noninvasive methods is of crucial significance. NAC can control and treat pathological parameters and help as a harmless drug in the treatment of women with PCOS.

Feline hypertrophic cardiomyopathy: reduced microvascular density and involvement of CD34+ interstitial cells

The sequence of pathological events in feline hypertrophic cardiomyopathy (fHCM) is still largely unknown, although we know that fHCM is characterized by interstitial remodeling in a macrophage-driven pro-inflammatory environment and that myocardial ischemia might contribute to its progression. This study aimed to gain further insights into the structural changes associated with interstitial remodeling in fHCM with special focus on the myocardial microvasculature and the phenotype of the interstitial cells. Twenty-eight hearts (16 hearts with fHCM and 12 without cardiac disease) were evaluated in the current study, with immunohistochemistry, RNA-in situ hybridization, and transmission electron microscopy. Morphometrical evaluations revealed a statistically significant lower microvascular density in fHCM. This was associated with structural alterations in capillaries that go along with a widening of the interstitium due to the accumulation of edema fluid, collagen fibers, and mononuclear cells that also proliferated locally. The interstitial cells were mainly of fibroblastic or vascular phenotype, with a substantial contribution of predominantly resident macrophages. A large proportion expressed CD34 mRNA, which suggests a progenitor cell potential. Our results indicate that microvascular alterations are key events in the pathogenesis of fHCM and that myocardial interstitial cell populations with CD34+ phenotype play a role in the pathogenesis of the disease.

Spermidine supplementation influences mitochondrial number and morphology in the heart of aged mice

Aging is associated with cardiac hypertrophy and progressive decline in heart function. One of the hallmarks of cellular aging is the dysfunction of mitochondria. These organelles occupy around 1/4 to 1/3 of the cardiomyocyte volume. During cardiac aging, the removal of defective or dysfunctional mitochondria by mitophagy as well as the dynamic equilibrium between mitochondrial fusion and fission is distorted. Here, we hypothesized that these changes affect the number of mitochondria and alter their three-dimensional (3D) characteristics in aged mouse hearts. The polyamine spermidine stimulates both mitophagy and mitochondrial biogenesis, and these are associated with improved cardiac function and prolonged lifespan. Therefore, we speculated that oral spermidine administration normalizes the number of mitochondria and their 3D morphology in aged myocardium. Young (4-months old) and old (24-months old) mice, treated or not treated with spermidine, were used in this study (n = 10 each). The number of mitochondria in the left ventricles was estimated by design-based stereology using the Euler-Poincaré characteristic based on a disector at the transmission electron microscopic level. The 3D morphology of mitochondria was investigated by 3D reconstruction (using manual contour drawing) from electron microscopic z-stacks obtained by focused ion beam scanning electron microscopy. The volume of the left ventricle and cardiomyocytes were significantly increased in aged mice with or without spermidine treatment. Although the number of mitochondria was similar in young and old control mice, it was significantly increased in aged mice treated with spermidine. The interfibrillar mitochondria from old mice exhibited a lower degree of organization and a greater variation in shape and size compared to young animals. The mitochondrial alignment along the myofibrils in the spermidine-treated mice appeared more regular than in control aged mice, however, old mitochondria from animals fed spermidine also showed a greater diversity of shape and size than young mitochondria. In conclusion, mitochondria of the aged mouse left ventricle exhibited changes in number and 3D ultrastructure that is likely the structural correlate of dysfunctional mitochondrial dynamics. Spermidine treatment reduced, at least in part, these morphological changes, indicating a beneficial effect on cardiac mitochondrial alterations associated with aging.

Using virtual microscopy for the development of sampling strategies in quantitative histology and design-based stereology

Only a fraction of specimens under study are usually selected for quantification in histology. Multilevel sampling or tissue probes, slides and fields of view (FOVs) in the regions of interest (ROIs) are required. In general, all parts of the organs under study should be given the same probability to be taken into account; that is, the sampling should be unbiased on all levels. The objective of our study was to provide an overview of the use of virtual microscopy in the context of developing sampling strategies of FOVs for stereological quantification. We elaborated this idea on 18 examples from multiple fields of histology, including quantification of extracellular matrix and muscle tissue, quantification of organ and tumour microvessels and tumour-infiltrating lymphocytes, assessing osseointegration of bone implants, healing of intestine anastomoses and osteochondral defects, counting brain neurons, counting nuclei in vitro cell cultures and others. We provided practical implications for the most common situations, such as exhaustive sampling of ROIs, sampling ROIs of different sizes, sampling the same ROIs for multiple histological methods, sampling more ROIs with variable intensities or using various objectives, multistage sampling and virtual sampling. Recommendations were provided for pilot studies on systematic uniform random sampling of FOVs as a part of optimizing the efficiency of histological quantification to prevent over- or undersampling. We critically discussed the pros and cons of using virtual sections for sampling FOVs from whole scanned sections. Our review demonstrated that whole slide scans of histological sections facilitate the design of sampling strategies for quantitative histology.

The Protective Effects of Coenzyme Q10 and Lisinopril Against Doxorubicin-Induced Cardiotoxicity in Rats: A Stereological and Electrocardiogram Study

Doxorubicin (DOX) is used as an anticancer drug despite its several side effects, especially its irreversible impacts on cardiotoxicity. Coenzyme Q10 (Q10) as a powerful antioxidant and lisinopril (LIS) as an angiotensin-converting enzyme inhibitor seem to provide protection against DOX-induced cardiotoxicity. Therefore, this study aimed to assess the cardioprotective effects of Q10 and LIS against DOX-induced cardiotoxicity in rats. Adult male Sprague-Dawley rats were randomly assigned into the control, LIS, Q10, DOX, DOX + LIS, and DOX + Q10 groups. On day 21, ECG was recorded and the right ventricle was dissected for evaluation of catalase activity and malondialdehyde (MDA) concentration. Additionally, the left ventricle and the sinoatrial (SA) node were dissected to assess the stereological parameters. The results of ECG indicated bradycardia and increase in QRS duration and QT interval in the DOX group compared to the control group. Meanwhile, the total volumes of the left ventricle, myocytes, and microvessels and the number of cardiomyocyte nuclei decreased, whereas the total volume of the connective tissue and the mean volume of cardiomyocytes increased in the DOX group. On the other hand, the SA node and the connective tissue were enlarged, while the volume of the SA node nuclei was reduced in the DOX group. Besides, catalase activity was lower and MDA concentration was higher in the DOX-treated group. Q10 could recover most stereological parameters, catalase activity, and MDA concentration. LIS also prevented some stereological parameters and ECG changes and improved catalase activity and MDA concentration in the DOX group. The findings suggested that Q10 and LIS exerted cardioprotective effects against DOX-induced cardiac toxicity.

A New Automated Histomorphometric MATLAB Algorithm for Immunohistochemistry Analysis Using Whole Slide Imaging

The use of animal models along with the employment of advanced and sophisticated stereological methods for assessing bone quality combined with the use of statistical methods to evaluate the effectiveness of bone therapies has made it possible to investigate the pathways that regulate bone responses to medical devices. Image analysis of histomorphometric measurements remains a time-consuming task, as the image analysis software currently available does not allow for automated image segmentation. Such a feature is usually obtained by machine learning and with software platforms that provide image-processing tools such as MATLAB. In this study, we introduce a new MATLAB algorithm to quantify immunohistochemically stained critical-sized bone defect samples and compare the results with the commonly available Aperio Image Scope Positive Pixel Count (PPC) algorithm. Bland and Altman analysis and Pearson correlation showed that the measurements acquired with the new MATLAB algorithm were in excellent agreement with the measurements obtained with the Aperio PPC algorithm, and no significant differences were found within the histomorphometric measurements. The ability to segment whole slide images, as well as defining the size and the number of regions of interest to be quantified, makes this MATLAB algorithm a potential histomorphometric tool for obtaining more objective, precise, and reproducible quantitative assessments of entire critical-sized bone defect image data sets in an efficient and manageable workflow.

Elastin-like recombinamers-based hydrogel modulates post-ischemic remodeling in a non-transmural myocardial infarction in sheep

Ischemic heart disease is a leading cause of mortality due to irreversible damage to cardiac muscle. Inspired by the post-ischemic microenvironment, we devised an extracellular matrix (ECM)-mimicking hydrogel using catalyst-free click chemistry covalent bonding between two elastin-like recombinamers (ELRs). The resulting customized hydrogel included functional domains for cell adhesion and protease cleavage sites, sensitive to cleavage by matrix metalloproteases overexpressed after myocardial infarction (MI). The scaffold permitted stromal cell invasion and endothelial cell sprouting in vitro. The incidence of non-transmural infarcts has increased clinically over the past decade, and there is currently no treatment preventing further functional deterioration in the infarcted areas. Here, we have developed a clinically relevant ovine model of non-transmural infarcts induced by multiple suture ligations. Intramyocardial injections of the degradable ELRs-hydrogel led to complete functional recovery of ejection fraction 21 days after the intervention. We observed less fibrosis and more angiogenesis in the ELRs-hydrogel-treated ischemic core region compared to the untreated animals, as validated by the expression, proteomic, glycomic, and histological analyses. These findings were accompanied by enhanced preservation of GATA4⁺ cardiomyocytes in the border zone of the infarct. We propose that our customized ECM favors cardiomyocyte preservation in the border zone by modulating the ischemic core and a marked functional recovery. The functional benefits obtained by the timely injection of the ELRs-hydrogel in a clinically relevant MI model support the potential utility of this treatment for further clinical translation.

Chronic scrotal hyperthermia induces azoospermia and severe damage to testicular tissue in mice

Scrotal hyperthermia leads to altered spermatogenesis due to heat-related oxidative stress. One of the main causes of infertility in men is oxidative stress, which refers to an imbalance in the levels of reactive oxygen species (ROS) and antioxidants. Therefore, this study aimed to evaluate the effects of chronic scrotal hyperthermia on testicular tissue structure, sperm parameters, and oxidative stress in adult mice. Thirty adult NMRI male mice were divided into three groups: Control (n = 10), Sham (n = 10), and Hyperthermia (n = 10). At the end of the study animals were sacrificed for evaluations of biochemical, cellular and histological analysis. The Hyperthermia group revealed a significant reduction in sperm count and weight of testis when compared to the control and sham groups. Also, succinate dehydrogenase (SDH) activity, ROS, ATP production, glutathione disulfide (GSH), tiols metabolism and stereological parameters in the hyperthermia group showed a significant reduction compared to the control and sham groups. Our results also revealed that scrotal hyperthermia significantly increases ROS production, mitochondrial membrane permeability (MMP), malondialdehyde (MDA), oxidized glutathione (GSSG) and apoptotic cells in testicular tissue in the hyperthermia groups in comparison with the control and sham groups. Overall, our result indicated that chronic scrotal hyperthermia causes complete spermatogenic arrest, probably mainly throughout the induction of oxidative stress.

Cardiac regeneration in the axolotl is unaffected by alterations in leukocyte numbers induced by lipopolysaccharide and prednisolone

Objective

Cardiac regeneration in the axolotl has been found to rely on the innate immune system, and especially macrophages have been demonstrated to play a vital role in regulating the regenerative process. In this study we wanted to induce a pro- and anti-inflammatory milieu in the axolotl during heart regeneration to test the resilience of the regenerative response.

Results

This was induced via repeated intrapericardial injections of lipopolysaccharide or prednisolone during a 40-day regeneration period in order to challenge the presumably fine-tuned inflammatory response that normally facilitates regeneration. We observed a local and systemic leucocyte response to pro- and anti-inflammatory stimulation, but we found cardiac regeneration to be structurally and functionally unaffected.

Changes in gill and air-breathing organ characteristics during the transition from water- to air-breathing in juvenile Arapaima gigas

The obligate air-breathing Amazonian fish, Arapaima gigas, hatch as water-breathing larvae but with development, they modify their swim bladder to an air-breathing organ (ABO) while reducing their gill filaments to avoid oxygen loss. Here, we show that significant changes already take place between 4 weeks (1.6 g) and 11 weeks (5 g) post hatch, with a reduction in gill lamellar surface area, increase in gill diffusion distance, and proliferation of the parenchyma in the ABO. By using a variety of methods, we quantified the surface area and diffusion distances of the gills and skin, and the swim bladder volume and anatomical complexity from hatch to 11-week-old juveniles. In addition, we identified the presence of two ionocyte types in the gills and show how these change with development. Until 1.6 g, A. gigas possess only the H⁺ -excreting/Na⁺ -absorbing type, while 5-g fish and adults have an additional ionocyte which likely absorbs H⁺ and Cl^- and excretes HCO₃ ^- . The ionocyte density on the gill filaments increased with age and is likely a compensatory mechanism for maintaining ion transport while reducing gill surface area. In the transition from water- to air-breathing, A. gigas likely employs a trimodal respiration utilizing gills, skin, and ABO and thus avoid a respiratory-ion regulatory compromise at the gills.

Curcumin can prevent the loss of sinoatrial node cells in methionine-treated rats: A stereological study

Methionine (MET) rich diets, smoking, coffee and alcohol consumption, low physical activity, and aging are related to high plasma concentrations of homocysteine, which can jeopardize the heart health. Although hyperhomocysteinemia has been considered a recognized risk factor for cardiac dysrhythmia, the structural changes of the conductive system, including Sinoatrial (SA) node of the heart involved in the disorder, have not been completely clarified. Curcumin is the main component of turmeric and has shown some cardioprotective effects. This study aimed to evaluate the effect of curcumin on the structural changes of the SA node in L-MET-treated rats. These alterations were evaluated by means of stereological techniques, namely cavalieri principle for volume estimation and optical disector counting technique for cell counting. Both techniques used two-dimensional images for obtaining three-dimensional parameters. The rats were divided into four groups, including control, MET-treated (1 g/kg/day), curcumin-treated, (100 mg/kg/day), and MET + curcumin. The treatments were performed for 28 days. On the final day, SA nodes were dissected out for stereological investigation. Compared to the control rats, the volume of SA node, total volume of grape-like cell clusters, and number of SA node cells were respectively decreased by 42%, 34%, and 37% in the MET-treated group (p < 0.04). However, collagen density remained constant in all the study groups. Furthermore, treatment with curcumin could protect the SA node from cellular decline in the MET + curcumin group (p < 0.01). It can be concluded that curcumin could prevent the structural changes of the SA node in the rats treated with methionine.

Cardioprotection with esmolol-based cardioplegia for non-infarcted and infarcted rat hearts

OBJECTIVES

Esmolol-based cardioplegic arrest offers better cardioprotection than crystalloid cardioplegia but has been compared experimentally with blood cardioplegia only once. We investigated the influence of esmolol crystalloid cardioplegia (ECCP), esmolol blood cardioplegia (EBCP) and Calafiore blood cardioplegia (Cala) on cardiac function, metabolism and infarct size in non-infarcted and infarcted isolated rat hearts.

METHODS

Two studies were performed: (i) the hearts were subjected to a 90-min cardioplegic arrest with ECCP, EBCP or Cala and (ii) a regional myocardial infarction was created 30 min before a 90-min cardioplegic arrest. Left ventricular peak developed pressure (LVpdP), velocity of contractility (dLVP/dtmax), velocity of relaxation over time (dLVP/dtmin), heart rate and coronary flow were recorded. In addition, the metabolic parameters were analysed. The infarct size was determined by planimetry, and the myocardial damage was determined by electron microscopy.

RESULTS

In non-infarcted hearts, cardiac function was better preserved with ECCP than with EBCP or Cala relative to baseline values (LVpdP: 100 ± 28% vs 86 ± 11% vs 57 ± 7%; P = 0.002). Infarcted hearts showed similar haemodynamic recovery for ECCP, EBCP and Cala (LVpdP: 85 ± 46% vs 89 ± 55% vs 56 ± 26%; P = 0.30). The lactate production with EBCP was lower than with ECCP (0.6 ± 0.7 vs 1.4 ± 0.5 μmol/min; P = 0.017). The myocardial infarct size and (ECCP vs EBCP vs Cala: 16 ± 7% vs 15 ± 9% vs 24 ± 13%; P = 0.21) the ultrastructural preservation was similar in all groups.

CONCLUSIONS

In non-infarcted rat hearts, esmolol-based cardioplegia, particularly ECCP, offers better myocardial protection than Calafiore. After an acute myocardial infarction, cardioprotection with esmolol-based cardioplegia is similar to that with Calafiore.

Voluntary activity reverses spermidine-induced myocardial fibrosis and lipid accumulation in the obese male mouse

Obesity due to high calorie intake induces cardiac hypertrophy and dysfunction, thus contributing to cardiovascular morbidity and mortality. Recent studies in aging suggest that oral supplementation with the natural polyamine spermidine has a cardioprotective effect. Here, the hypothesis was tested that spermidine or voluntary activity alone or in combination protect the heart from adverse effects induced by obesity. Therefore, C57Bl/6 mice (n = 8–10 per group) were subjected to control or high fat diet (HFD) and were left untreated, or either received spermidine via drinking water or were voluntarily active or both. After 30 weeks, the mice were killed and the left ventricle of the hearts was processed for light and electron microscopy. Design-based stereology was used to estimate parameters of hypertrophy, fibrosis, and lipid accumulation. HFD induced cardiac hypertrophy as demonstrated by higher volumes of the left ventricle, cardiomyocytes, interstitium, myofibrils and cardiomyocyte mitochondria. These changes were not influenced by spermidine or voluntary activity. HFD also induced myocardial fibrosis and accumulation of lipid droplets within cardiomyocytes. These HFD effects were enhanced in spermidine treated animals but not in voluntarily active mice. This was even the case in voluntarily active mice that received spermidine. In conclusion, the data confirm the induction of left ventricular hypertrophy by high-fat diet and suggest that—under high fat diet—spermidine enhances cardiomyocyte lipid accumulation and interstitial fibrosis which is counteracted by voluntary activity.

Ameliorative effects of quercetin on folliculogenesis in diabetic mice: a stereological study

A high risk of reproductive disorders can be seen in diabetic pregnancy. Reproductive disorders associated with diabetes may result from alterations in the function of the ovary. In this study, we investigated the ameliorative effects of quercetin as a phytoestrogen and antidiabetic agent on the folliculogenesis in diabetic mice. Streptozotocin-induced diabetic mice were treated with 30 mg/kg/day quercetin for four weeks. The volume of ovary, follicles, and corpus luteum were significantly decreased in the diabetic mice. The number of growing follicles (secondary, antral, and Graafian follicles) and corpus luteum was significantly decreased in the diabetic mice. Also, the volume of oocytes was significantly decreased in antral and Graafian follicles. Our results indicated that the administration of quercetin in diabetic mice increased the volume of the ovary and growing follicles, the number of growing follicles and corpus luteum. It also significantly decreased the number of atretic follicles. As a result, it may be concluded that the impaired follicular growth and development caused by hyperglycemia in diabetic mice can be alleviated by quercetin treatment.

Local Tranexamic Acid for Local Hemostasis in an Animal Liver Injury Model

Background:

Hyperfibrinolysis is a state of increased clot resolution often seen in trauma patients with ongoing hemorrhage. Tranexamic acid (TXA) inhibits fibrinolysis preventing clot resolution affecting hemorrhage continuation and is used by intravenous administration.

Aims:

The purpose of this study was to evaluate the local tranexamic acid application for hemostatic control in an experimental animal liver injury model.

Settings and Design:

This study was an experimental prospective treatment study to check the local TXA effects on liver injury. This study was approved by the Ethics Committee.

Materials and Methods:

Twenty adult male Sprague-Dawley white rats were equally randomized to two groups after a standardized liver injury was conducted under anesthesia. One group were “liver-packed” with gauze (TXA [−]) and the other group with gauze soaked in TXA (TXA [+]). Bleeding from the injured middle liver lobe was measured at 2 and 15 min, and at 48h second-look surgery, with euthanasia conducted at 14 days. The liver was sent for histopathological and stereological analysis.

Statistical Analysis and Results:

There was no difference in bleeding at 2 or 15 min after packing; however, larger amount of free blood at 48 h in the TXA (−) group was noticed. Five animals in the TXA (−) were alive at 14 days compared to eight animals in the TXA (+) group. Significantly larger volume density of fibrosis, granulation tissue, and amorphous tissue were seen in the TXA (+) group compared to the TXA (−) group at the stereological analysis.

Conclusion:

Local TXA application on the injured liver surface might offer better hemostatic control than packing alone. Further studies are mandated before the clinical application of our findings.

Intrinsic Heart Regeneration in Adult Vertebrates May be Strictly Limited to Low-Metabolic Ectotherms

The heart has a high-metabolic rate, and its "around-the-clock" vital role to sustain life sets it apart in a regenerative setting from other organs and appendages. The landscape of vertebrate species known to perform intrinsic heart regeneration is strongly biased toward ectotherms-for example, fish, salamanders, and embryonic/neonatal ectothermic mammals. It is hypothesized that intrinsic heart regeneration is exclusively limited to the low-metabolic hearts of ectotherms. The biomedical field of regenerative medicine seeks to devise biologically inspired regenerative therapies to diseased human hearts. Falsification of the ectothermy dependency for heart regeneration hypothesis may be a crucial prerequisite to meaningfully seek inspiration in established ectothermic regenerative animal models. Otherwise, engineering approaches to construct artificial heart components may constitute a more viable path toward regenerative therapies. A more strict definition of regenerative phenomena is generated and several testable sub-hypotheses and experimental avenues are put forward to elucidate the link between heart regeneration and metabolism. Also see the video abstract here https://youtu.be/fZcanaOT5z8.

Vitamin D Sufficiency Has a Limited Effect on Placental Structure and Pathology: Placental Phenotypes in the VDAART Trial

Vitamin D insufficiency during pregnancy is widespread. The effects of active vitamin D on the human placenta in vivo are unknown. We test the hypotheses that 25(OH)D sufficiency (arbitrarily defined as 25(OH)D ≥32 ng/mL) modulates placental structure and function in vivo in a population of women whose offspring are at risk for childhood asthma, and that placental pathology is more common in offspring that evolve asthma at age 3. Pregnant volunteers in the St. Louis, MO, cohort of the Vitamin D Antenatal Asthma Reduction Trial (VDAART, NIH grant #HL091528) participated in a nested case-control study and consented for the study of placentas after delivery. Maternal concentrations of 25(OH)D were measured at trial entry and in the third trimester. The histopathology of the placentas from women with sufficient 25(OH)D, versus insufficient, showed no clinically significant differences, but morphometry revealed villi of women with sufficient third-trimester 25(OH)D had a higher villous surface density. Notably, analyses of transcripts, extracted from formalin-fixed paraffin-embedded specimens, revealed higher expression of INTS9, vWF, MACC1, and ARMS2, and diminished expression of the CNTN5 genes in the insufficient group. A larger proportion of placentas showed chronic chorioamnionitis in offspring with versus without asthma at age 3. These findings suggest that maternal 25(OH)D insufficiency has a limited effect on human placental villous histopathology and morphometry, but attenuates a small number of placental gene expression profiles in this selected population. The association of placental chronic chorioamnionitis and offspring asthma is worthy of further study.

Morphometric characterization of collagen and fat in normal ventricular myocardium

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Automated image analysis is a useful tool for cardiac tissue quantification.

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Collagen and fat proportions are demonstrably higher in the right ventricle.

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We present reference values for collagen and fat proportions in normal myocardium.

Objective

We used automated image analysis software to determine the proportion of collagen, fat, and myocytes across six histological regions of normal ventricular myocardium.

Methods

Twenty-nine non-cardiac death cases referred to our national cardiac pathology center were included in this study. Whole hearts were macroscopically and microscopically normal following expert histopathological evaluation. Tissue sections from the right ventricular outflow tract, right ventricle (RV), anterior interventricular septum (IVS), posterior IVS, anterior left ventricle (LV), and posterior LV were stained with Picrosirius red for collagen and scanned using a high-resolution slide scanner. Quantification of collagen, fat, and myocyte proportions was performed using Visiopharm software after automated exclusion of perivascular collagen.

Results

The majority of decedents were male (25/29; 86%) with a mean age at death of 32.1 ± 9.9 (range 18-54) and mean BMI 28.7 ± 7.3. We report predicted values (collagen %, fat %, myocytes %) for cardiac tissue composition within the RV, IVS, and LV (including epicardial and endocardial layers). The proportion of collagen and fat were higher in the RV compared with the LV (ratios 1.61 [1.45-1.78]; 2.63 [1.99-3.48], respectively) and RV compared with the IVS (ratios 1.77 [1.60-1.97]; 8.41[6.35-11.13], respectively). The ratio of epicardial versus endocardial fat was increased in both ventricles (RV: ratio 4.49 [3.67-5.49]; LV: ratio 3.46 [2.49-4.81]). In multivariable analysis, there was no significant association between collagen or fat proportion and sex (p=0.12; p=0.08, respectively), age at death (p=0.36; p=0.23, respectively), or BMI (p=0.45; p=0.43, respectively).

Conclusions

Our findings provide location and sex-specific proportions of myocardial histological tissue composition that may aid quantitative evaluation of pathology in future studies.

Limb Blood Flow Restriction Plus Mild Aerobic Exercise Training Protects the Heart Against Isoproterenol-Induced Cardiac Injury in Old Rats: Role of GSK-3β

The present study was conducted to evaluate the effect of blood flow restriction (BFR) training on cardiac resistance to isoproterenol (ISO) induced heart injury in old rats and examined the hypothesis that BFR training may interfere with age-associated impairment of mitochondria by the inhibitory phosphorylation of GSK-3β at Ser9. Old male Wistar rats were divided into the following six groups: CTL (control), ISO (isoproterenol-treated), Sh + ISO (sham-operated plus ISO), BFR + ISO (blood flow restriction plus ISO), Sh-Ex + ISO (sham-operated subjected to exercise and ISO), and BFR-Ex + ISO (blood flow restriction along with exercise and ISO). 10 weeks of exercise training was considered. Then, cardiac injury was induced and physiological, histological, and biochemical parameters were recorded and assessed. Compared to CTL group, isoproterenol administration significantly reduced the systolic arterial pressure (SAP), left-ventricular systolic pressure (LVSP), and ± dp/dt max (P < 0.05). BFR training improved these parameters in the way that BFR-Ex + ISO group had higher SAP, LVSP and ± dp/dt max (P < 0.05) and lower LVEDP (left-ventricular end diastolic pressure) (P < 0.01) than untrained and Sh-Ex + ISO groups. The pS9-GSK-3β and pS9-GSK-3β/GSK-3β ratio were increased in the BFR-Ex + ISO group compared to CTL, ISO, Sh + ISO, and BFR + ISO groups (P < 0.05). The level of plasma cardiac Troponin-I and the severity of the injuries were significantly reduced in BFR-Ex + ISO group versus other cardiac damaged groups. In conclusion, our findings clearly confirmed the cardio-protective effect of BFR training against ISO-induced myocardial injury. Increased phosphorylated GSK-3β and angiogenesis in this model of exercise justify the resistance of old hearts facing stressful situations.

Retinal oxygen supply shaped the functional evolution of the vertebrate eye

The retina has a very high energy demand but lacks an internal blood supply in most vertebrates. Here we explore the hypothesis that oxygen diffusion limited the evolution of retinal morphology by reconstructing the evolution of retinal thickness and the various mechanisms for retinal oxygen supply, including capillarization and acid-induced haemoglobin oxygen unloading. We show that a common ancestor of bony fishes likely had a thin retina without additional retinal oxygen supply mechanisms and that three different types of retinal capillaries were gained and lost independently multiple times during the radiation of vertebrates, and that these were invariably associated with parallel changes in retinal thickness. Since retinal thickness confers multiple advantages to vision, we propose that insufficient retinal oxygen supply constrained the functional evolution of the eye in early vertebrates, and that recurrent origins of additional retinal oxygen supply mechanisms facilitated the phenotypic evolution of improved functional eye morphology.

A transmural gradient of myocardial remodeling in early-stage heart failure with preserved ejection fraction in the pig

Heart failure with preserved ejection fraction (HFpEF) is characterized by diastolic dysfunction. This study aimed to analyze whether early HFpEF is already associated with ultrastructural alterations and whether they differ quantitatively among the layers of the left ventricular wall. HFpEF was induced in pigs by deoxy-corticosterone acetate (DOCA) treatment along with a high-salt/high lipid diet over 3 months and compared with weight-matched normal pigs (n = 5 each). Samples of the left ventricle were taken and processed for light and electron microscopy. Interstitial fibrosis, subcellular composition of cardiomyocytes and mean cardiomyocyte diameter were evaluated by stereology in subendocardial, midmyocardial and subepicardial regions. DOCA enhanced the mean cardiomyocyte diameter in all locations of the ventricle wall to the same degree. The subcellular composition did not differ between the locations and was not altered by DOCA. The volume fraction of interstitium was smaller in the subendocardium of DOCA group than of control group. Within the interstitium, the volume fraction of collagen fibrils (between cardiomyocytes) was increased in the subendocardial and midmyocardial wall layers of the DOCA group but not in the subepicardial layer. Although the capillary length density and average supply area were not altered in response to DOCA in any of the wall layers, the volume fraction of blood vessels related to the interstitial space was enhanced in the subendocardium of the DOCA group but not in the other wall layers. In conclusion, cardiomyocyte changes due to DOCA were similar in subepicardial, midmyocardial and subendocardial regions but DOCA-induced changes in the interstitium appeared to be more pronounced in the subendocardial ventricular wall layers. This suggests a pivotal role of the subendocardial interstitium in the pathogenesis of HFpEF.

Cardioprotective effects of curcumin and carvacrol in doxorubicin-treated rats: Stereological study

Doxorubicin (DOX) is a cardiotoxic drug. To reduce the harmful effects of DOX, two plant-derived components, including curcumin (CUR) and carvacrol (CAR), were considered. This study aimed to assess the protective effects of CUR and CAR on DOX-induced cardiotoxicity using physiological and stereological evaluations. Male rats were randomly allocated to six groups. Group's I-VI received phosphate-buffered saline (PBS), CUR (100 mg kg-1 day-1), CAR (50 mg kg-1 day-1), DOX (4 mg kg-1 week-1), DOX-CUR, and DOX-CAR, respectively. On day 24, plasma troponin I and ECG were analyzed and the left ventricle underwent stereological assessment. The results showed a fivefold increase in troponin I in the DOX-treated animals compared to the PBS ones. Additionally, heart rate and QRS amplitude, respectively, reduced by 18% and 31% and QT interval and QRS duration, respectively, increased by 41% and 24% in the DOX group in comparison with the PBS rats (p < .05). The total volume of the myocardium and vessels and the number of cardiomyocyte nuclei also, respectively, decreased by 30%, 45%, and 43% in the DOX group compared to the PBS animals (atrophy of the ventricular tissues, p < .01). Besides, the mean volumes of the connective tissue and cardiomyocytes, respectively, increased by 46% and 52% in the DOX group (p < .01). In the DOX-CUR and DOX-CAR groups, the changes were prevented extensively in comparison with the DOX group (p < .01). Co-administration of CUR or CAR and doxorubicin for 24 days could improve the heart function and structural changes.

The protective effect of Stevia rebaudiana Bertoni on serum hormone levels, key steroidogenesis enzymes, and testicular damage in testes of diabetic rats

Diabetes Mellitus (DM) is a kind of metabolic endocrine diseases, which has various effects on the gonadal system. The current study aimed to examine the effect of Stevia rebaudiana Bertoni extract on the mRNA expression involved in testosterone synthesis, and stereological parameters in rat testes, for improving diabetes complications. In this study, 48 rats were randomly classified into control, diabetic (streptozocin 60 mg/kg + nicotinamide 120 mg/kg), diabetic + Stevia (400 mg/kg), and diabetic + metformin (500 mg/kg) groups. Finally, Fasting Blood Sugar (FBS) level, the serum level of LH and testosterone, the Star, Cyp11a1, and Hsd17b3 gene expressions, and changes in the testis histology were evaluated. The results indicated a decrease in body weight, serum LH and testosterone level, the star gene expression, stereological changes of testes, and an increase in the FBS level in diabetic group, compared with the control group (P<0.05). Nonetheless, Stevia significantly reduced the FBS and increased the serum LH level, in comparison with diabetic rats (P<0.05), but no significant differences in the serum testosterone level and the Star gene expression has been found. Stevia also resulted in an increase in weight, testis volume, the number of sexual lineage cells, and sperm count and motility, compared to diabetic rats (P<0.05). Due to its antioxidant properties, Stevia enhanced the alteration in spermatogenesis and stereological characteristics in diabetic rat testes. Hence, Stevia could diminish the reproductive system problems and improve infertility in diabetic male rats.

Human Bone Marrow Mesenchymal Stem Cell Conditioned Medium Promotes Wound Healing in Deep Second-Degree Burns in Male Rats

Burn wound treatment is difficult and one of the most challenging problems in the clinic. Researchers have examined the applications of mesenchymal stem cells as a cell-based therapy for skin regeneration. But the role of human bone marrow mesenchymal stem cell conditioned medium (hBM-MSC-CM) in the treatment of burn injury remains unclear. This research aims at detecting whether hBM-MSC-CM can increase the wound healing of deep second-degree burns in male rats. In this study, 32 adult male rats per each time point were randomly divided into four groups: (1) control group, (2) sham group (DMEM), (3) common treatment group (CT), and (4) conditioned media group (CM). A 3 × 3 cm circular burn was created on the back of the rats. On postsurgical days 7, 15, and 28, the wound closure area of each wound was measured and then the skin samples were removed and analyzed using stereological methods. Wound closure area was significantly increased in the CM and CT groups on the 15th and the 28th day after burn injury compared to the control and DMEM groups. The stereological parameters and immunohistochemistry analysis of the wounds revealed significantly improved healing in the CM group compared to the control and other groups. It is concluded that these findings indicate that hBM-MSC-CM promotes skin wound healing by increasing cell proliferation, regulating collagen synthesis and collagen composition, and inducing angiogenesis at the injury site.

Mesenchymal stem cells improve survival in ischemic diabetic random skin flap via increased angiogenesis and VEGF expression

Random skin flaps (RSFs) are cutaneous flaps. Despite the negative impact of diabetes mellitus (DM) on RSF viability, they are commonly used in diabetic patients. In this study, we have assessed bone marrow mesenchymal stem cell (BMMSC) treatment on RSF survival, tensiometrical parameters, angiogenesis, and mast cells (MCs) count in an ischemic RSF model in rats with type 1 DM (T1DM). We induced T1DM in 30 Wistar adult male rats. The animals were assigned to three groups of 10 rats per group as follows: group 1 (control); group 2 (placebo), and group 3 (BMMSCs). A 30  ×  80  mm RSF was created in each rat. On day 7, we measured the viable portion of each RSF. A sample was taken for histological and immunohistochemistry studies, fibroblasts, MCs, angiogenesis, collagen bundle density, and the presence of vascular endothelial growth factor (VEGF)+ cells. An additional sample was taken to evaluate the flap's incision strength. Treatment with BMMSCs (17.8  ±  0.37) significantly increased RSF survival compared with the control (13.3  ±  0.35) and placebo (16.1  ±  0.27) groups (one-way analysis of variance, P  =  .000; least significant difference, P  =  .000, P  =  .002). There was a significant improvement in angiogenesis, as confirmed by stereologic examination. Assessment of VEGF+ cells showed prominent neovascularization in BMMSC-treated RSFs compared with the control and placebo groups. Subdermal injection of BMMSC significantly increased ischemic RSF survival as a result of stimulated neovascularization in T1DM rats. Treatment of diabetic RSF with BMMSCs showed no beneficial effects in the fibroblast number and biomechanical parameters for the repair of ischemic wounds in the rat model. Treatment with BMMSCs significantly increased collagen bundle density.

Pressure overload induced right ventricular remodeling is not attenuated by the anti-fibrotic agent pirfenidone

Cardiac fibrosis contributes to the development of heart failure in pulmonary hypertension. We aimed to assess the development of fibrosis and the effects of treatment with the anti-fibrotic agent pirfenidone in pressure overload induced right ventricular (RV) failure. Wistar rat weanlings were randomized to pulmonary trunk banding (PTB) or sham surgery. One week after the procedure, PTB rats were randomized into two groups with either six weeks on standard chow or treatment with pirfenidone mixed in chow (700 mg/kg/day). RV hemodynamic effects were evaluated by echocardiography, cardiac magnetic resonance imaging (MRI), and pressure-volume measurements. Sections from the isolated RV, left ventricle, and septum were sampled systematically; stereological point grids and the nucleator were used to estimate volume of fibrosis and cardiac hypertrophy, respectively. PTB caused RV failure in all rats subjected to the procedure. The volume fraction of fibrosis in the RV increased threefold in PTB rats corresponding to a sixfold increase in total volume of RV fibrosis. Volume fraction of fibrosis and total volume of fibrosis also increased in the septum and in the left ventricle. Pirfenidone reduced body weight but did not improve RV hemodynamics or reduce cardiac fibrosis. RV cardiomyocyte profile area was increased twofold in PTB rats without any effect of pirfenidone. RV pressure overload after PTB induced not only RV but also septal and left ventricular fibrosis assessed by stereology. Treatment with pirfenidone reduced body weight but did not reduce the development of cardiac fibrosis or delay the progression of RV failure.

Stereological Comparison of Imbibed Fibrinogen Gauze versus Simple Gauze in External Packing of Grade IV Liver Injury in Rats

Objective

To evaluate the effect of imbibed fibrinogen gauze on survival, bleeding and healing in liver trauma.

Methods

This animal experimental study was conducted on 20 adult male Sprague-Dawley rats; with a mean weight of 300±50 gram; divided into two groups. Grade IV injury was induced to the subjects' liver. Then, the bleeding site was packed with simple gauze in the control group, and imbibed fibrinogen gauze in the experimental group. All animals were re-evaluated for liver hemostasis 48 hours after the initial injury. Bleeding in the intra peritoneal cavity was measured using Tuberculosis Syringe in the first and second operations. Subjects were followed-up for 14 days. Eventually, the rats were sacrificed and their livers were sent to a lab for stereological assessment. Statistical comparisons were performed via Mann-Whitney U-test using SPSS. P-Values less than 0.05 were considered to be statistically significant.

Results

Half of the rats in the control group died, while all the rats in the imbibed fibrinogen gauze group survived after two weeks (p= 0.032). Bleeding in the imbibed fibrinogen gauze was significantly less than control group, 48 hours' post-surgery (p<0.001). According to the stereological results, granulation tissue in the imbibed fibrinogen gauze group were more than the control group (P= 0.032). Also, fibrosis in the imbibed fibrinogen gauze group were more than the control group (P= 0.014).

Conclusion

Our study indicated that imbibed fibrinogen gauze can potentially control liver bleeding and improve survival through increasing granulation tissue and fibrosis in injured liver.

Co-exposure to an Aryl Hydrocarbon Receptor Endogenous Ligand, 6-Formylindolo[3,2-b]carbazole (FICZ), and Cadmium Induces Cardiovascular Developmental Abnormalities in Mice

6-Formylindolo[3,2-b]carbazole (FICZ) is a signal substance and an endogenous activator of aryl hydrocarbon receptor (AHR). Cadmium (Cd) is an environmental pollutant that can activate both AHR and Wnt/β-catenin signaling pathways. We aimed to determine how dysregulated signaling through AHR-Wnt/β-catenin cross-talk can influence mice heart development. Mice fetuses were exposed to Cd alone or in combination with FICZ in gestation day (GD) 0. In GD18, fetuses were harvested and randomly divided into two parts for stereological and molecular studies. Stereological and tessellation results revealed that when fetuses were co-exposed with FICZ and Cd, abnormalities were synergistically raised. In the presence of FICZ, mRNA expression levels of Wnt/β-catenin target genes significantly enhanced, especially when animals co-treated with FICZ and Cd. Based on these findings, we propose that chemical pollutants can interfere with the normal function of AHR that has a physiological role in regulating Wnt/β-catenin during cardiogenesis.

Cardioprotection by spermidine does not depend on structural characteristics of the myocardial microcirculation in aged mice

AIMS

Ageing is associated with cardiovascular disease and reduced cardiac function. This cardiac functional decline is accompanied by cardiac remodeling and alterations in cardiomyocyte composition. Recently, it was shown that the natural polyamine spermidine preserves cardiac function and cardiomyocyte composition in old mice. As cardiac function critically relies on blood supply, we tested whether spermidine has also beneficial effects on ageing-associated changes of the myocardial microcirculation.

METHODS

Using transmission electron microscopy, the left ventricular capillaries of young (4-months old) and aged (24-months old) C57BL/6J male mice were investigated by stereology. Aged mice were subdivided into an untreated group and a group that was fed spermidine late in life for 6 months. Specifically, total volume, surface area and length of capillaries as well as endothelial thickness were estimated. Additionally, the total length of precapillary arterioles was assessed. The protein level of VEGF-A was measured using Western blot.

RESULTS

Ageing was associated with whole heart and left ventricular hypertrophy. All total capillary-related values (including volume, surface area and length) were significantly higher in 24-month-old mice compared with 4-month-old mice. Moreover, VEGF-A expression was significantly enhanced in aged mice. The mean thickness of the endothelium was not different, but the mean area of myocardium supplied by capillaries was smaller in old mice. Spermidine treatment had no significant effect on the ageing-associated structural changes or VEGF-A expression.

CONCLUSIONS

In conclusion, in the left ventricles of aged mice the growth of capillaries and arterioles supplying cardiomyocytes were in proportion to whole organ hypertrophy. Spermidine had no effect on quantitative characteristics of capillaries or arterioles, suggesting that the beneficial effects of spermidine on the ageing heart do not depend on the quantitative structural characteristics of the microcirculation which does not exclude potential functional differences between the groups.

Sinoatrial node remodels in chronic sleep-restricted rats

Chronic Sleep Restriction (CSR) is known as a risk factor for cardiovascular diseases. However, the structural changes of Sinoatrial (SA) node cells have received less attention. This study aimed to evaluate the effects of CSR on SA node in an animal model using stereological methods. Adult male Sprague-Dawley rats were randomly divided into CSR, grid-floor, and control groups. The CSR procedure was designed such a way that the animals had a full cycle of sleep (6 hours) per day, while they were unable to have a Rapid Eye Movement (REM) sleep during the remaining 18 hours. This was induced by a multiplatform box containing water. The grid-floor animals were placed in the same multiplatform box with a grid-floor covering to prevent falling in water. After 21 days, the right atria were dissected out. Then, the location of the SA node was determined and evaluated by stereological techniques. The total volume of the SA node, the total volume of the main node cells, the volume of the connective tissue, and mean volume of the node cells were respectively enlarged by 60%, 47%, 68%, and 51% in the CSR animals compared to the grid-floor rats (p < 0.05). However, no significant changes were detected in these parameters in the control and grid-floor animals. The population of the main node cells remained constant in all animal groups. In addition, the three-dimensional reconstruction of the SA node in the CSR group showed a hypertrophied appearance. In conclusion, CSR induced hypertrophic changes in the rats' SA node structures without alteration in the number of main node cells.

Protective effect of vitamin E and vitamin C alone and in combination on testicular damage induced by sodium metabisulphite in rats: A stereological study

The existing investigation was directed to consider the protective role of vitamin C and E alone and in combination on sodium metabisulphite-induced damage on testicular. Experimental animals were received sodium metabisulphite (520 mg/kg) alone and in combination with vitamin E (100 mg/kg), vitamin C (100 mg/kg) and vitamin E + C, while the control groups received 0.9% saline solution and olive oil (the solvent of the vitamin E). Finally, the changes in the testis histology were examined stereologically. Lipid peroxidation was assessed through the measurement of malondialdehyde (MDA) levels in testis tissues. Also, serum testosterone concentrations were measured. The results indicated that 80%-90% (spermatogonia A and B, spermatocyte and Leydig) and 40% of the Sertoli cells were missed in the rats that received sodium metabisulphite, respectively, compared with the controls. The co-supplementation of vitamin E with vitamin C significantly decreased MDA (p = 0.006) and increased testosterone (p = 0.001) concentrations in the rats received SMB which were as much as control and olive groups. Co-supplementation of vitamin E and vitamin C due to their synergistic effects could be an appropriate strategy in preventing testicular from sodium metabisulphite-induced damage.

Adaptive growth changes in the liver remnant are affected by the size of hepatectomy in rats

In this study we investigated the dynamics of hepatocyte hyperplasia and hypertrophy in rats subjected to increasing sizes of partial hepatectomy (PH). A total of 104 rats were randomized according to the size of PH. On postoperative days (PODs) 1, 3 and 5, blood was drawn and the remnant liver removed for stereological analysis. Liver parameters and regeneration rate were significantly affected by size of PH. On POD 1, hepatocyte volumes had increased significantly in all PH groups. On POD 3, all groups showed hepatocyte volumes approximating baseline. On POD 5, hepatocyte volumes were significantly lower in PH (90) than in baseline, sham and PH (30) rats. Increasing hepatocyte proliferation was not observed following PH (30). Following PH (70), cell proliferation was significantly elevated on PODs 1 and 3, and following PH (90) on PODs 3 and 5. In conclusion, general hypertrophy of hepatocytes after different size of PH was followed by hepatocyte proliferation only in the liver remnant of PH (70) and PH (90).

Distribution of Connective Tissue in the Male and Female Porcine Liver: Histological Mapping and Recommendations for Sampling

The pig is a large animal model that is often used in experimental medicine. The aim of this study was to assess, in normal pig livers, sexual dimorphism in the normal fraction of hepatic interlobular and intralobular connective tissue (CT) in six hepatic lobes and in three macroscopical regions of interest (ROIs) with different positions relative to the liver vasculature. Using stereological point grids, the fractions of CT were quantified in histological sections stained with aniline blue and nuclear fast red. Samples (415 tissue blocks) were collected from healthy piglets, representing paracaval, paraportal and peripheral ROIs. There was considerable variability in the CT fraction at all sampling levels. In males the mean fraction of interlobular CT was 4.7 ± 2.4% (mean ± SD) and ranged from 0% to 11.4%. In females the mean fraction of the interlobular CT was 3.6 ± 2.2% and ranged from 0% to 12.3%. The mean fraction of intralobular (perisinusoidal summed with pericentral) CT was <0.2% in both sexes. The interlobular CT represented >99.8% of the total hepatic CT and the fractions were highly correlated (Spearman r = 0.998, P <0.05). The smallest CT fraction was observed in the left medial lobe and in the paracaval ROI and the largest CT fraction was detected in the quadrate lobe and in the peripheral ROI. For planning experiments involving the histological quantification of liver fibrosis and requiring comparison between the liver lobes, these data facilitate the power analysis for sample size needed to detect the expected relative increase or decrease in the fraction of CT.

Stereological and molecular studies on the combined effects of photobiomodulation and human bone marrow mesenchymal stem cell conditioned medium on wound healing in diabetic rats

We investigated the effects of conditioned medium (CM) from human bone marrow mesenchymal stem cells (h BMMSC)s and pulse wave photobiomodulation (PW PBM), applied alone or in combination, on the stereological parameters and gene expression of some growth factors, during wound healing in a streptozotocin (STZ)-induced rat model of type one diabetes mellitus (T1DM). T1DM was induced in 72 rats and two incisions were made in each animal. The rats were assigned to one of four groups: a control (placebo) group, a Laser group (890 nm, 80 Hz, 0.2 J/cm²); a CM group, and a combined CM + Laser group. On post-surgical days 4, 7, and 15, skin samples were extracted for stereology and reverse transcription PCR (RT-PCR) analyses of gene expression of basic fibroblast growth factor (bFGF), hypoxia-inducible factor (HIF-1α), and stromal cell-derived factor-1α (SDF-1α). The stereological examinations of the proximal and distal wounds revealed significantly enhanced healing in all the treated groups, compared to the control group. The extent of healing was significantly greater in the CM + Laser group than in the other treatment groups. The RT-PCR results also indicated greater gene expression in the CM + Laser and Laser groups than in the CM and control groups. Application of CM and PW PBM, alone or in combination accelerated the process of wound healing in T1DM rats. The results of combined application of CM and PW PBM, indicated a synergistic effect, and the combination treatment was statistically more effective than single applications of CM or PW PBM.

IUGR decreases cardiomyocyte endowment and alters cardiac metabolism in a sex- and cause-of-IUGR-specific manner

Intrauterine growth restriction (IUGR) increases the risk of ischemic heart disease in adulthood. Studies in rats suggest cardiac vulnerability is more pronounced in males and in offspring that were exposed to hypoxia in utero. Therefore, we aimed to test the hypotheses that 1) IUGR adolescent males, but not females, have fewer cardiomyocytes and altered expression of cardiometabolic genes compared with controls; and 2) IUGR due to hypoxia has a greater effect on these parameters compared with IUGR due to nutrient restriction. IUGR was induced in guinea pigs by maternal hypoxia (MH; 10% O₂, n = 9) or maternal nutrient restriction (MNR; ~30% reduction in food intake, n = 9) in the second half of pregnancy and compared with control ( n = 11). At 120 days of age, postmortem was performed and the left ventricle perfusion fixed for stereological determination of cardiomyocyte number or snap frozen to determine the abundance of cardiometabolic genes and proteins by quantitative RT-PCR and Western blotting, respectively. MH reduced the number of cardiomyocytes in female ( P < 0.05), but not male or MNR, adolescent offspring. Furthermore, IUGR males had decreased expression of genes responsible for fatty acid activation in the sarcoplasm ( FACS) and transport into the mitochondria ( AMPK-a₂ and ACC; P < 0.05) and females exposed to MH had increased activation/phosphorylation of AMP-activated protein kinase-α ( P < 0.05). We postulate that the changes in cardiomyocyte endowment and cardiac gene expression observed in the present study are a direct result of in utero programming, as offspring at this age did not suffer from obesity, hypertension, or left ventricular hypertrophy.