Therapeutic Potential in Wound Healing of Allogeneic Use of Equine Umbilical Cord Mesenchymal Stem Cells.

Wound healing after skin injury is a complex process, particularly in equines where leg wounds are prevalent and their repair is complicated due to the anatomical characteristics. Conventional treatments are not effective enough. The umbilical cord offers an unlimited source of adult mesenchymal stem cells (ucMSCs) from Wharton's jelly tissue. The present study aims to demonstrate the safety and therapeutic potential of the allogeneic use of equine ucMSCs (e-ucMSCs) in the healing of severe equine leg wounds. The methods employed were the isolation, culture and expansion of e-ucMSCs. Flow cytometry and a PCR assay were used for cell characterization. This study included an immunomodulation assay, a murine pre-clinical trial and the first phase of an equine clinical trial. Our results showed that e-ucMSCs express a functional HLA-G homolog, EQMHCB2. In the immunomodulation assay, the e-ucMSCs inhibited the proliferation of activated equine peripheral blood mononuclear cells (e-PBMCs). In the murine pre-clinical trial, e-ucMSCs reduced healing time by 50%. In the equine clinical trial, the injection of e-ucMSCs into severe leg lesions improved the closure time and quality of the tissues involved, regenerating them without fibrous tissue scar formation. In conclusion, the results of this study suggest that e-ucMSCs can be used allogeneically for wound healing by creating a tolerogenic environment.

HLA-G gene editing in tumor cell lines as a novel alternative in cancer immunotherapy.

Cancer immunotherapies based mainly on the blockade of immune-checkpoint (IC) molecules by anti-IC antibodies offer new alternatives for treatment in oncological diseases. However, a considerable proportion of patients remain unresponsive to them. Hence, the development of novel clinical immunotherapeutic approaches and/or targets are crucial.W In this context, targeting the immune-checkpoint HLA-G/ILT2/ILT4 has caused great interest since it is abnormally expressed in several malignancies generating a tolerogenic microenvironment. Here, we used CRISPR/Cas9 gene editing to block the HLA-G expression in two tumor cell lines expressing HLA-G, including a renal cell carcinoma (RCC7) and a choriocarcinoma (JEG-3). Different sgRNA/Cas9 plasmids targeting HLA-G exon 1 and 2 were transfected in both cell lines. Downregulation of HLA-G was reached to different degrees, including complete silencing. Most importantly, HLA-G - cells triggered a higher in vitro response of immune cells with respect to HLA-G + wild type cells. Altogether, we demonstrated for the first time the HLA-G downregulation through gene editing. We propose this approach as a first step to develop novel clinical immunotherapeutic approaches in cancer.

Integrin alpha-5 subunit is critical for the early stages of human pluripotent stem cell cardiac differentiation.

The stem cell niche has a strong influence in the differentiation potential of human pluripotent stem cells with integrins playing a major role in communicating cells with the extracellular environment. However, it is not well understood how interactions between integrins and the extracellular matrix are involved in cardiac stem cell differentiation. To evaluate this, we performed a profile of integrins expression in two stages of cardiac differentiation: mesodermal progenitors and cardiomyocytes. We found an active regulation of the expression of different integrins during cardiac differentiation. In particular, integrin α5 subunit showed an increased expression in mesodermal progenitors, and a significant downregulation in cardiomyocytes. To analyze the effect of α5 subunit, we modified its expression by using a CRISPRi technique. After its downregulation, a significant impairment in the process of epithelial-to-mesenchymal transition was seen. Early mesoderm development was significantly affected due to a downregulation of key genes such as T Brachyury and TBX6. Furthermore, we observed that repression of integrin α5 during early stages led to a reduction in cardiomyocyte differentiation and impaired contractility. In summary, our results showed the link between changes in cell identity with the regulation of integrin α5 expression through the alteration of early stages of mesoderm commitment.

Cell cycle dynamics of mouse embryonic stem cells in the ground state and during transition to formative pluripotency.

Mouse embryonic stem cells (mESCs) can be maintained as homogeneous populations in the ground state of pluripotency. Release from this state in minimal conditions allows to obtain cells that resemble those of the early post-implantation epiblast, providing an important developmental model to study cell identity transitions. However, the cell cycle dynamics of mESCs in the ground state and during its dissolution have not been extensively studied. By performing live imaging experiments of mESCs bearing cell cycle reporters, we show here that cells in the pluripotent ground state display a cell cycle structure comparable to the reported for mESCs in serum-based media. Upon release from self-renewal, the cell cycle is rapidly accelerated by a reduction in the length of the G1 phase and of the S/G2/M phases, causing an increased proliferation rate. Analysis of cell lineages indicates that cell cycle variables of sister cells are highly correlated, suggesting the existence of inherited cell cycle regulators from the parental cell. Together with a major morphological reconfiguration upon differentiation, our findings support a correlation between this in vitro model and early embryonic events.

Deep Learning Neural Networks Highly Predict Very Early Onset of Pluripotent Stem Cell Differentiation.

Deep learning is a significant step forward for developing autonomous tasks. One of its branches, computer vision, allows image recognition with high accuracy thanks to the use of convolutional neural networks (CNNs). Our goal was to train a CNN with transmitted light microscopy images to distinguish pluripotent stem cells from early differentiating cells. We induced differentiation of mouse embryonic stem cells to epiblast-like cells and took images at several time points from the initial stimulus. We found that the networks can be trained to recognize undifferentiated cells from differentiating cells with an accuracy higher than 99%. Successful prediction started just 20 min after the onset of differentiation. Furthermore, CNNs displayed great performance in several similar pluripotent stem cell (PSC) settings, including mesoderm differentiation in human induced PSCs. Accurate cellular morphology recognition in a simple microscopic set up may have a significant impact on how cell assays are performed in the near future.

Pluripotent Stem Cells as a Robust Source of Mesenchymal Stem Cells.

Mesenchymal stem cells (MSC) have been extensively studied over the past years for the treatment of different diseases. Most of the ongoing clinical trials currently involve the use of MSC derived from adult tissues. This source may have some limitations, particularly with therapies that may require extensive and repetitive cell dosage. However, nowadays, there is a staggering growth in literature on a new source of MSC. There is now increasing evidence about the mesenchymal differentiation from pluripotent stem cell (PSC). Here, we summarize the current knowledge of pluripotent-derived mesenchymal stem cells (PD-MSC). We present a historical perspective on the subject, and then discuss some critical questions that remain unanswered.

Cyclin Kinase-independent role of p21CDKN1A in the promotion of nascent DNA elongation in unstressed cells.

The levels of the cyclin-dependent kinase (CDK) inhibitor p21 are low in S phase and insufficient to inhibit CDKs. We show here that endogenous p21, instead of being residual, it is functional and necessary to preserve the genomic stability of unstressed cells. p21depletion slows down nascent DNA elongation, triggers permanent replication defects and promotes the instability of hard-to-replicate genomic regions, namely common fragile sites (CFS). The p21's PCNA interacting region (PIR), and not its CDK binding domain, is needed to prevent the replication defects and the genomic instability caused by p21 depletion. The alternative polymerase kappa is accountable for such defects as they were not observed after simultaneous depletion of both p21 and polymerase kappa. Hence, in CDK-independent manner, endogenous p21 prevents a type of genomic instability which is not triggered by endogenous DNA lesions but by a dysregulation in the DNA polymerase choice during genomic DNA synthesis.

Activation of apoptotic signalling events in human embryonic stem cells upon Coxsackievirus B3 infection.

Human embryonic stem cells (hESCs) are self-renewing pluripotent cells that can differentiate to a wide range of specialized cells and hold great promise as models for human development and disease, as well as for drug discovery and cell-replacement therapies. Group B Coxsackie viruses (CVBs) produce acute myocarditis, pancreatitis, non-septic meningitis and encephalitis in neonates, children and young adults. Moreover, CVBs can produce spontaneous miscarriage after early embryo infection. It was reported that hESCs express CVBs receptors and are susceptible to CVB3 infection. Apoptosis is one of the hallmarks of CVBs infection although details regarding CVB3 involvement in the apoptotic processes remain elusive. In order to evaluate the mechanisms of cell death induced by CVB3 in these pluripotent cells, we infected HUES-5 (H5) and WA01 (H1) hESC lines with CVB3. After validating the maintenance of stemness in these hESC lines when grown as confluent monolayers in feeder-free conditions, we analysed several aspects of programmed cell death triggered by CVB3. In all cases, we detected chromatin condensation, DNA fragmentation and caspase-9 and 3 cleavages. Moreover, we observed the presence of cleaved PARP product which was preceded by the appearance of p17, the catalytically active fragment of caspase-3. Mitochondrial function assays revealed a MOI dependent decrease in cell viability at 24 h post-infection (pi). No appreciable modifications in Bcl-2, Bcl-X(L) and Bax protein levels were observed upon CVB3 infection during 5-24 h observation period. However, a marked decrease in pro-apoptotic Bad abundance was detected without changes in its mRNA levels. In this study we found that the hESCs are highly susceptible to CVB3 infection and display elevated apoptosis rates, thus emerging as suitable human non-transformed in vitro models to study CVB3-induced apoptosis and resulting relevant to understand CVBs pathogenesis.

Human embryonic stem cells and derived contractile embryoid bodies are susceptible to Coxsakievirus B infection and respond to interferon Iß treatment.

We studied the susceptibility of human embryonic stem cells and derived contractile embryoid bodies from WAO9, HUES-5 and HUES-16 cell lines to Coxsackievirus B infection. After validating stem cell-like properties and cardiac phenotype, Coxsackievirus B receptors CAR and DAF, as well as type I interferon receptors were detected in all cell lines and differentiation stages studied. Real-time PCR analysis showed that CAR mRNA levels were 3.4-fold higher in undifferentiated cells, while DAF transcript levels were 2.78-fold more abundant in differentiated cultures (P<0.05). All cell lines were susceptible to Coxsackievirus serotypes B1-5 infection as shown by RT-PCR detection of viral RNA, immunofluorescence detection of viral protein and infectivity titration of cell culture supernatants resulting in cell death. Supernatants infectivity titers 24-48 h post-infection ranged from 105-106 plaque forming units (PFU)/ml, the highest titers were detected in undifferentiated cells. Cell viability detected by a colorimetric assay, showed inverse correlation with infectivity titers of cell culture supernatants. Treatment with 100 U of interferon Iß significantly reduced viral replication and associated cell death during a 24-48 h observation period, as detected by reduced infectivity titers in the supernatants and increased cell viability by a colorimetric assay, respectively. We propose human embryonic stem cell and derived contractile embryoid bodies as a valid model to study cardiac Coxsackievirus B infection.

Prediction of severe cardiovascular events by VE/VCO2 slope versus peak VO2 in systolic heart failure: a meta-analysis of the published literature.

BACKGROUND: Peak VO2 has traditionally been used for prognostic evaluation in systolic heart failure. However, in the past years, VE/VCO2 slope has been shown to be similar or even superior in many studies. We performed a systematic review and a meta-analysis of diagnostic studies of VE/VCO2 slope to assess its ability to predict cardiovascular events in systolic heart failure. METHODS: We searched the published literature in PubMed and ISI Web of Science for VE/VCO2 slope in heart failure, and performed a systematic review and a meta-analysis of diagnostic studies in articles fulfilling previously established selection criteria. End points were serious cardiovascular events defined as death or the combined end point of death, ventricular assist device implantation, or heart transplant. A sub-analysis was also performed with those articles providing enough data to compare VE/VCO(2) slope prognostic ability to that of peak VO2. RESULTS: Four hundred ninety-one articles that are potentially relevant were identified, and 12 studies were selected based on our predefined criteria. No heterogeneity or evidence of publication bias was found. The 12 studies included a total of 2,628 patients with a mean follow-up of 31 months (95% CI 16-46 months). The combined event rate at 1 year was 11.2% (95% CI 7.8%-14.6%). Diagnostic odds ratio and area under the curve for serious cardiovascular events were 5.02 (95% CI 4.06-6.21) and 0.75 (95% CI 0.72-0.78), respectively. Six studies provided sufficient data for VE/VCO2 slope and peak VO2 comparison. Both variables showed similar performance, although VE/VCO(2) did present a trend to superiority. CONCLUSIONS: In this meta-analysis, VE/VCO2 slope represents a reasonable ability to predict serious cardiovascular events in systolic heart failure, and is at least as effective as peak VO2.

Understanding the risk of hyperkalaemia in heart failure: role of aldosterone antagonism.

The risk of hyperkalaemia in patients with heart failure has increased in the past few years together with the evolution of pharmacological treatment for these patients. This significant change has been associated with the introduction of angiotensin converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and aldosterone antagonists. High potassium concentrations in heart failure could lead to life threatening events, and therefore should be taken seriously. In this review we summarise the information about potassium homeostasis in heart failure and the current risk of developing potentially serious hyperkalaemia, particularly in association with the use of aldosterone antagonists.

Diferenciación en cardiomiocitos a partir de células madre embrionarias humanas / Differentiation of Human Embryonic Stem Cells into Cardiomyocytes

Introducción Las células madre son motivo de intensa investigación debido a la posibilidad de su utilización en el tratamiento de numerosas enfermedades, en particular las cardiovasculares. La diferenciación de células madre embrionarias humanas en cardiomiocitos se ha realizado exitosamente in vitro. Se han establecido métodos de cultivo y diferenciación, señales involucradas en la cardiogénesis y los cardiomiocitos generados se han utilizado en modelos de regeneración miocárdica. Sin embargo, aún quedan muchos interrogantes que se están investigando activamente. Objetivo Desarrollar una metodología que permita el cultivo de células embrionarias y su diferenciación en cardiomiocitos. Material y métodos Se utilizaron cuatro líneas de células madre embrionarias humanas. Se cultivaron y diferenciaron a través de los métodos publicados previamente en la bibliografía. El estado indiferenciado y la diferenciación en cardiomiocitos se verificaron por medio de inmunomarcación fluorescente y RT-PCR. Resultados La metodología utilizada permitió cultivar las células y mantenerlas en estado indiferenciado. Aunque con eficacia dispar, se logró la diferenciación en cardiomiocitos de las cuatro líneas celulares utilizadas. La confirmación se realizó por medio de la expresión de factores de transcripción miocárdicos y proteínas estructurales cardíacas. Conclusiones El cultivo y la diferenciación de células madre embrionarias humanas fue posible en nuestro sistema. Estos resultados preliminares nos impulsan a continuar y a desarrollar nuestros métodos con células pluripotentes inducidas.

Background The role of stem cells in the treatment of several conditions, especially heart diseases, is under permanent investigation. Human embryonic stem cells have been successfully differentiated in vitro into cardiomyocytes. Methods of cell culture and cardiomyocyte differentiation are well established; signals regulating cardiogenesis have been identified and the cardiomyocytes generated have been used in models of myocardial regeneration. However, several questions still remain and are currently under active investigation. Objective To develop a culture system that is suitable for the induction of embryonic stem cells to cardiomyocyte differentiation. Material and Methods Four human embryonic stem cell lines were used. The cells were cultured and differentiation was induced using methods previously described. The presence of cells in an undifferentiated state and cardiomyocyte differentiation was detected by immunohistochemical studies (fluorescent staining) and RT-PCR. Results The methodology used allowed stem cells growth in the culture, and maintained them in an undifferentiated state. Cardiomyocyte differentiation was achieved in the four cell lines used, yet with uneven efficacy. This was confirmed by the expression of myocardial transcription factors and heart structural proteins. Conclusions Our system allowed human embryonic stem cell growth and differentiation in the culture. These preliminary results encourage us to continue developing our methods with induced pluripotent stem cells.