Luisa Maria Gomes de Macedo Braga

In situ delivery of bone marrow cells and mesenchymal stem cells improves cardiovascular function in hypertensive rats submitted to myocardial infarction.

This work aimed to evaluate cardiac morphology/function and histological changes induced by bone marrow cells (BMCs) and cultured mesenchymal stem cells (MSCs) injected at the myocardium of spontaneously hypertensive rats (SHR) submitted to surgical coronary occlusion. Female syngeneic adult SHR, submitted (MI) or not (C) to coronary occlusion, were treated 24 h later with in situ injections of normal medium (NM), or with MSCs (MSC) or BMCs (BM) from male rats. The animals were evaluated after 1 and 30 days by echocardiography, histology of heart sections and PCR for the Y chromosome. Improved ejection fraction and reduced left ventricle infarcted area were observed in MSC rats as compared to the other experimental groups. Treated groups had significantly reduced lesion tissue score, increased capillary density and normal (not-atrophied) myocytes, as compared to NM and C groups. The survival rate was higher in C, NM and MSC groups as compared to MI and BM groups. In situ injection of both MSCs and BMCs resulted in improved cardiac morphology, in a more physiological model of myocardial infarction represented by surgical coronary occlusion of spontaneously hypertensive rats. Only treatment with MSCs, however, ameliorated left ventricle dysfunction, suggesting a positive role of these cells in heart remodeling in infarcted hypertensive subjects.

Influence of age and sex on the spontaneous DNA damage detected by Micronucleus test and Comet assay in mice peripheral blood cells

We have investigated the normal variations in basal DNA damage detected by Comet assay in leukocytes and micronucleated erythrocytes (MNE) using the Micronucleus test (MN) in peripheral blood cells from 45 female and male mice from different age groups (newborns, 3.5, 12, and 104 weeks) to clarify age and sex‐related changes. Comparison of basal DNA damage detected by Comet assay showed significantly increased values in 104 weeks old mice in relation to the other ages (P ≤ 0.01), and newborn mice showed higher values in MNE frequency when compared to all the other groups (P ≤ 0.01). A positive correlation was observed between Damage Frequency (r = 0.382, P = 0.010) and Damage Index (r = 0.640, P < 0.001) and age. Age was also correlated with the ratio of polychromatic erythrocytes/normachromatic erythrocytes (PCE/NCE) (r = − 0.473, P = 0.001), and the MNE frequency was positively correlated with the ratio of PCE/NCE (r = 0.454, P = 0.002). These results suggest an age‐related slow down of DNA repair efficiency of DNA damage and/or DNA damage accumulation. Furthermore, data on the spontaneous MNE frequency indicate that the reticuloendothelial system matures with age, and there is a close relationship between erythropoiesis and micronucleus induction in erythrocytes. The influence of sex in the parameters analyzed was less clear. In conclusion, age seems to influence in basal DNA damage and should be considered in genotoxicity studies using mice. Finally, comparisons between assays must be made with care when different cells are compared (e.g. leukocytes and erythrocytes), as found with the Comet assay and MN test.

Acupoint Injection of Autologous Stromal Vascular Fraction and Allogeneic Adipose-Derived Stem Cells to Treat Hip Dysplasia in Dogs

Stem cells isolated from adipose tissue show great therapeutic potential in veterinary medicine, but some points such as the use of fresh or cultured cells and route of administration need better knowledge. This study aimed to evaluate the effect of autologous stromal vascular fraction (SVF, n = 4) or allogeneic cultured adipose-derived stem cells (ASCs, n = 5) injected into acupuncture points in dogs with hip dysplasia and weak response to drug therapy. Canine ASCs have proliferation and differentiation potential similar to ASCs from other species. After the first week of treatment, clinical evaluation showed marked improvement compared with baseline results in all patients treated with autologous SVF and three of the dogs treated with allogeneic ASCs. On days 15 and 30, all dogs showed improvement in range of motion, lameness at trot, and pain on manipulation of the joints, except for one ASC-treated patient. Positive results were more clearly seen in the SVF-treated group. These results show that autologous SVF or allogeneic ASCs can be safely used in acupoint injection for treating hip dysplasia in dogs and represent an important therapeutic alternative for this type of pathology. Further studies are necessary to assess a possible advantage of SVF cells in treating joint diseases.

Alterations in oxidative markers in the cerebellum and peripheral organs in MPS I mice.

Mucopolysaccharidosis type I is a lysosomal storage disease with alterations in several organs. Little is known about the pathways that lead to the pathology. Evidences point oxidative stress on lysosomal storage diseases and mucopolysaccharidosis type I. The aim of the present study was to evaluate oxidative biomarkers on mucopolysaccharidosis type I mice model. We evaluated antioxidant enzymatic activity, protein damage and lipid peroxidation in the forebrain, cerebellum, heart, lung, diaphragm, liver, kidney and spleen. Superoxide dismutase activity was increased on cerebellum, lung, diaphragm, liver and kidney of mucopolysaccharidosis type I mice. Catalase activity was increased on cerebellum, spleen and lung. There was no alteration on glutathione peroxidase activity on any of the analyzed organs. Mucopolysaccharidosis type I mice showed increased carbonyl groups on cerebellum, heart and spleen. There was a decrease of thiobarbituric acid-reactive substances on the cerebellum of mucopolysaccharidosis type I mice. The results indicate a oxidative imbalance in this model. As lysosomes are very susceptible to oxidative damage, leading inclusive to cellular death, and lysosomal storage diseases present several alterations on this organelles, this finding can help to elucidate the cellular damage pathways on mucopolysaccharidosis type I.

Systemic delivery of adult stem cells improves cardiac function in spontaneously hypertensive rats

1 Heart regeneration after myocardial infarction (MI) can occur after cell therapy, but the mechanisms, cell types and delivery methods responsible for this improvement are still under investigation. In the present study, we evaluated the impact of systemic delivery of bone marrow cells (BMC) and cultivated mesenchymal stem cells (MSC) on cardiac morphology, function and mortality in spontaneously hypertensive rats (SHR) submitted to coronary occlusion. 2 Female syngeneic adult SHR, submitted or not (control group; C) to MI, were treated with intravenous injection of MSC (MI + MSC) or BMC (MI + BM) from male rats and evaluated after 1, 15 and 30 days by echocardiography. Systolic blood pressure (SBP), functional capacity, histology, mortality rate and polymerase chain reaction for the Y chromosome were also analysed. 3 Myocardial infarction induced a decrease in SBP and BMC, but not MSC, prevented this decrease. An improvement in functional capacity and ejection fraction (38 ± 4, 39 ± 3 and 58 ± 2% for MI, MI + MSC and MI + BM, respectively; P < 0.05), as well as a reduction of the left ventricle infarcted area, were observed in rats from the MI + BM group compared with the other three groups. Treated animals had a significantly reduced lesion tissue score. The mortality rate in the C, MI + BM, MI + MSC and MI groups was 0, 0, 16.7 and 44.4%, respectively (P < 0.05 for the MI + MSC and MI groups compared with the C and MI + BM groups). 4 The results of the present study suggest that systemic administration of BMC can improve left ventricular function, functional capacity and, consequently, reduce mortality in an animal model of MI associated with hypertension. We speculate that the cells transiently home to the myocardium, releasing paracrine factors that recruit host cells to repair the lesion.

Nonviral in vivo gene transfer in the mucopolysaccharidosis I murine model.

SummaryMucopolysaccharidosis I (MPS I) is a lysosomal disorder characterized by a deficiency of the enzyme α-L-iduronidase (IDUA), which is responsible for the degradation of glycosaminoglycans (GAGs). This deficiency leads to the accumulation of dermatan and heparan sulphate in lysosomes. Presently available treatments include bone marrow transplantation and enzyme replacement therapies, both of which are limited in their effects. In this work, knockout (KO) MPS I mice were treated with a nonviral vector containing the human IDUA cDNA. KO mice were transfected by hydrodynamic injection of pRIDUA in the caudal vein (i.v., n = 3) or by intraperitoneal injection of pRIDUA/Superfect complexes (i.p., n = 3). GAG concentration and IDUA activity were analysed in the kidneys, spleen, lungs, brain and liver. The expression of IDUA in the organs of i.v.- and i.p.-treated mice was also analysed by real-time reverse-transcription (RT) PCR and compared by relative quantification. The concentration of GAGs in the organs differed between KO and wild-type mice. In the spleen and liver, GAG levels were lower in i.v.- and i.p.-treated KO mice than in control nontreated animals. Real-time RT-PCR showed that the transgene is expressed in all the analysed organs of i.p.- and i.v.-treated KO mice. Enzyme activity was similarly observed in all the organs analysed. Our data suggest that this kind of transfection may be a useful tool for studies of nonviral protocols for gene therapy of MPS.

Long-term memory for aversive training is impaired in Idua(-/-) mice, a genetic model of mucopolysaccharidosis type I.

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disease that leads to neurodegeneration and neurological deficits, among other pathological and clinical consequences. The aim of the present study was to evaluate neurobehavioral parameters in a genetic mouse model of mucopolysaccharidosis type I (MPS I). During exploration of an open field, adult MPS I (Idua(-/-)) mice showed normal locomotion and anxiety but reduced number of rearings. Idua(-/-) mice performed normally in a novel object recognition memory task and showed normal short-term retention of inhibitory avoidance training. By contrast, long-term retention of inhibitory avoidance was impaired in Idua(-/-) mice. The deficit in inhibitory avoidance memory could not be attributed to reduced footshock reactivity. The results indicate that Idua(-/-) mice present deficits in long-term memory for aversive training and reduced exploratory behavior.

Methodology, biology and clinical applications of human mesenchymal stem cells.

Stem cells are known by their capacity of self-renewal and differentiation into at least one specialized cell type. Mesenchymal stem cells (MSCs) were isolated initially from bone marrow but are now known to exist in any vascularized organ or tissue in adults. MSCs have a great therapeutic potential, due to their ability to migrate to sites of tissue injury and secrete trophic factors that hasten endogenous repair. They have also been shown to present immunosuppressive properties that may be used in the treatment of autoimmune or graft-versus-host diseases. Clinical trials employing MSCs show that the therapy is safe, but the efficiency needs to be in tested in phase III and IV studies. We describe here protocols for the isolation of human MSCs from human bone marrow and adipose tissue. The safe use of these cells demand a thorough in vitro characterization, as described in protocols of immunophenotyping by flow cytometry and analysis of their capacity to differentiate into adipogenic, osteogenic, and chondrogenic lineages.

Molecular mapping of the regenerative niche in a murine model of myocardial infarction

Adult stem cells are distributed through the whole organism, and present a great potential for the therapy of different types of disease. For the design of efficient therapeutic strategies, it is important to have a more detailed understanding of their basic biological characteristics, as well as of the signals produced by damaged tissues and to which they respond. Myocardial infarction (MI), a disease caused by a lack of blood flow supply in the heart, represents the most common cause of morbidity and mortality in the Western world. Stem cell therapy arises as a promising alternative to conventional treatments, which are often ineffective in preventing loss of cardiomyocytes and fibrosis. Cell therapy protocols must take into account the molecular events that occur in the regenerative niche of MI. In the present study, we investigated the expression profile of ten genes coding for chemokines or cytokines in a murine model of MI, aiming at the characterization of the regenerative niche. MI was induced in adult C57BL/6 mice and heart samples were collected after 24 h and 30 days, as well as from control animals, for quantitative RT-PCR. Expression of the chemokine genes CCL2, CCL3, CCL4, CCL7, CXCL2 and CXCL10 was significantly increased 24 h after infarction, returning to baseline levels on day 30. Expression of the CCL8 gene significantly increased only on day 30, whereas gene expression of CXCL12 and CX3CL1 were not significantly increased in either ischemic period. Finally, expression of the IL-6 gene increased 24 h after infarction and was maintained at a significantly higher level than control samples 30 days later. These results contribute to the better knowledge of the regenerative niche in MI, allowing a more efficient selection or genetic manipulation of cells in therapeutic protocols.