Paula Hansen Suss

Transplantation of SNAP-treated adipose tissue-derived stem cells improves cardiac function and induces neovascularization after myocardium infarct in rats

Stem cell therapy has been considered a promise for damaged myocardial tissue. We have previously shown that S-nitroso-N-acetyl-D,L-penicillamine (SNAP) increases the expression of several muscular markers and VEGF in mesenchymal stem cells, indicating that transplantation of SNAP-treated cells could provide better functional outcomes. Here, we transplanted SNAP-treated adipose tissue-derived stem cells (ADSCs) in rat infarcted myocardium. After 30days, we observed a significant improvement of the ejection fraction in rats that received SNAP-treated ADSCs, compared with those that received untreated cells (p=0.008). Immunohistochemical reactions showed an increased expression of troponin T-C and von Willebrand factor, and organized vascular units in the infarcted area of tissue transplanted with treated ADSCs. SNAP exposure induced intracellular S-nitrosation, a decreased GSH/GSSG ratio, but did not increase cGMP levels. Collectively, these results indicate that SNAP alters the redox environment of ADSCs, possibly associated with a pre-differentiation state, which may improve cardiac function after transplantation.

Expansão de células-tronco da medula óssea e do sangue de cordão umbilical humano

Celulas-tronco/progenitoras frequentemente nao estao disponiveis em quantidade suficiente para restauracao de orgaos e tecidos danificados, sendo necessaria sua expansao in vitro. Instalacoes fisicas adequadas, pessoal tecnico qualificado, reagentes de grau clinico e protocolos bem definidos de acordo com as condicoes de boas praticas de fabricacao sao imprescindiveis para assegurar a qualidade e seguranca das celulas infundidas no paciente. A medula ossea e o sangue de cordao umbilical ainda sao as fontes de celulas mais utilizadas em terapias. Protocolos bem sucedidos de expansao utilizando celulas-tronco hematopoeticas, celulas-tronco mesenquimais e celulas progenitoras endoteliais ja tem sido empregados em estudos pre-clinicos e clinicos. A escolha do tipo celular adequado deve ser direcionada pelo tamanho da lesao ou natureza do tecido tratado e pelo efeito terapeutico desejado. Estudos recentes tem demonstrado que propriedades de diferentes celulas expandidas in vitro podem ser combinadas para obtencao de um resultado melhor no tratamento de algumas doencas. Celulas em culturas de longo termo precisam ser acompanhadas por meio de diversas tecnicas de citogenetica classica e molecular para demonstrar que nao ha evidencias de transformacao espontânea ou sinais de imortalizacao. Ensaios utilizando a infusao de celulas expandidas atraves da barreira alogeneica e xenogeneica, apresentaram melhora funcional e foram alcancados sem imunossupressao e sem evidencias de infiltrados celulares que indicariam resposta imune. Porem, mais estudos precisam ser realizados para avaliar a imunogenicidade destas celulas e garantir a seguranca da terapia celular alogenica permitindo sua consolidacao no uso clinico. Aqui apresentamos uma atualizacao sobre expansao celular associada com seu uso clinico.

DIRECT INTRACARDIAC INJECTION OF UMBILICAL CORD-DERIVED STROMAL CELLS AND UMBILICAL CORD BLOOD-DERIVED ENDOTHELIAL CELLS FOR THE TREATMENT OF ISCHEMIC CARDIOMYOPATHY

The development of new therapeutic strategies is necessary to reduce the worldwide social and economic impact of cardiovascular disease, which produces high rates of morbidity and mortality. A therapeutic option that has emerged in the last decade is cell therapy. The aim of this study was to compare the effect of transplanting human umbilical cord-derived stromal cells (UCSCs), human umbilical cord blood-derived endothelial cells (UCBECs) or a combination of these two cell types for the treatment of ischemic cardiomyopathy (IC) in a Wistar rat model. IC was induced by left coronary artery ligation, and baseline echocardiography was performed seven days later. Animals with a left ventricular ejection fraction (LVEF) of ≤40% were selected for the study. On the ninth day after IC was induced, the animals were randomized into the following experimental groups: UCSCs, UCBECs, UCSCs plus UCBECs, or vehicle (control). Thirty days after treatment, an echocardiographic analysis was performed, followed by euthanasia. The animals in all of the cell therapy groups, regardless of the cell type transplanted, had less collagen deposition in their heart tissue and demonstrated a significant improvement in myocardial function after IC. Furthermore, there was a trend of increasing numbers of blood vessels in the infarcted area. The median value of LVEF increased by 7.19% to 11.77%, whereas the control group decreased by 0.24%. These results suggest that UCSCs and UCBECs are promising cells for cellular cardiomyoplasty and can be an effective therapy for improving cardiac function following IC.

Comparison of two surgical techniques for creating an acute myocardial infarct in rats

OBJECTIVE To perform a comparative assessment of two surgical techniques that are used creating an acute myocardial infarc by occluding the left anterior descending coronary artery in order to generate rats with a left ventricular ejection fraction of less than 40%. METHODS The study was completely randomized and comprised 89 halothane-anaesthetised rats, which were divided into three groups. The control group (SHAM) comprised fourteen rats, whose left anterior descending coronary artery was not occluded. Group 1 (G1): comprised by 35 endotracheally intubated and mechanically ventilated rats, whose left anterior descending coronary artery was occluded. Group 2 (G2): comprised 40 rats being manually ventilated using a nasal respirator whose left anterior descending coronary artery was occluded. Other differences between the two techniques include the method of performing the thoracotomy and removing the pericardium in order to expose the heart, and the use of different methods and suture types for closing the thorax. Seven days after surgery, the cardiac function of all surviving rats was determined by echocardiography. RESULTS No rats SHAM group had progressed to death or had left ventricular ejection fraction less than 40%. Nine of the 16 surviving G1 rats (56.3%) and six of the 20 surviving G2 rats (30%) had a left ventricular ejection fraction of less than 40%. CONCLUSION The results indicate a tendency of the technique used in G1 to be better than in G2. This improvement is probably due to the greater duration of the open thorax, which reduces the pressure over time from the surgeon, allowing occlusion of left anterior descending coronary artery with higher accuracy.

In vitro evaluation of bovine pericardium after a soft decellularization approach for use in tissue engineering: XXXX

Pericardial membrane derived from bovine heart tissues is a promising source of material for use in tissue‐engineering applications. However, tissue processing is required for its use in humans due to the presence of animal antigens. Therefore, the purpose of this study was to evaluate the structural integrity and biocompatibility of the bovine pericardium (BP) after a soft decellularization process with a 0.1% sodium dodecyl sulfate (SDS) solution, with the aim to remove xenoantigens and preserve extracellular matrix (ECM) bioactivity. The decellularization process promoted a mean reduction of 77% of the amount of DNA in the samples in which cell nuclei staining was undetectable. The ECM content was maintained as mostly preserved after decellularization as well as its biomechanical properties. In addition, the decellularization protocol has proven to be efficient in removing the xenoantigen alpha‐gal, which is responsible for immune rejection. The decellularized BP was noncytotoxic in vitro and allowed human adipose‐derived stem cell (hASC) adhesion. Finally, after 7 days in culture, the tissue scaffold became repopulated by hASCs, and after 30 days, the ECM protein pro‐collagen I was seen in the scaffold. Together, these characteristics indicated that soft BP decellularization with 0.1% SDS solution allows the acquirement of a bioactive scaffold suitable for cell repopulation and potentially useful for regenerative medicine.

Conventional culture method and qPCR using 16S rDNA for tissue bank: a comparison using a model of cardiac tissue contamination

Real-time polymerase chain reaction (qPCR) using 16S rDNA is an alternative to conventional culture-based tests. The aim of this study was to compare the conventional culture method with qPCR using 16S rDNA in a model of cardiac tissue contamination. Samples of cardiac tissue for artificial contamination with Escherichia coli and control samples were submitted for DNA extraction, which was conducted by selective and alkaline lysis and purification steps. A standard curve for 16S rDNA was constructed to determine the efficiency and analytical sensitivity of the assay in concentrations from 106 to 102 c.f.u. ml-1 using TaqMan Master Mix. 16S rDNA was detected in all contaminated samples; however, it was not detected in the the final washing step solution of the sample with a bioburden of 102 c.f.u. ml-1. Using qPCR is a potential alternative to conventional culture for microbiological safety testing of allograft tissues for biobanking, reducing the time and labour input required.

Fresh decellularized versus standard cryopreserved pulmonary allografts for right ventricular outflow tract reconstruction during the Ross procedure: a propensity-matched study†

OBJECTIVES Recent studies have shown favourable early results with decellularized allografts (DAs) for right ventricular outflow tract reconstruction during the Ross procedure. However, mid- and long-term outcome data are still scarce. The objective of this study was to compare the durability of fresh DAs with standard cryopreserved allografts (SCAs) in patients undergoing the Ross procedure. METHODS Two hundred patients underwent the Ross procedure with DA and 202 with SCA. Using propensity score matching, mid- and long-term clinical outcome and echocardiographic allograft function over time were compared. RESULTS One hundred and thirty DA patients (median age 28 years, 71.5% men, mean follow-up 4.2 ± 2.6 years) were matched with 130 SCA patients (median age 30 years, 69.2% men, mean follow-up 13 ± 4.5 years). After matching, there were no differences in baseline characteristics. In the matched DA vs SCA groups, actuarial 8-year freedom from allograft dysfunction (DA = 86.7% vs SCA = 87.3%, P = 0.183) and freedom from allograft reintervention (DA = 99.2% vs SCA = 97.6%, P = 0.642) were comparable. Longitudinal echocardiographic analyses showed a significantly lower progression rate of peak right ventricular outflow tract gradients in the DA group during the first 3 years after the operation. Absolute gradients over time were slightly lower in DA when compared with SCA, although 95% confidence intervals overlapped. CONCLUSIONS Up to 8 years of follow-up, DA and SCA used for right ventricular outflow tract reconstruction in the Ross procedure are associated with comparably excellent clinical and haemodynamic outcome. Longer follow-up and dedicated echocardiographic studies are still necessary to confirm the long-term performance of the DAs.