Aim. The effects of cryopreservation on adipose tissue-derived mesenchymal stem cells are not clearly documented, as there is a growing body of evidence about the importance of adipose-derived mesenchymal stem cells for regenerative therapies. The aim of this study was to analyze human adipose tissue-derived mesenchymal stem cells phenotypic expression (CD34, CD45, CD73, CD90, CD105, and CD49d), colony forming unit ability, viability, and differentiation potential before and after cryopreservation. Materials and Methods. 12 samples of the adipose tissue were collected from a healthy donor using the liposuction technique. The cell isolation was performed by enzymatic digestion and then the cells were cultured up to passage 2. Before and after cryopreservation the immunophenotype, cellular viability analysis by flow cytometer, colony forming units ability, differentiation potential into adipocytes and osteoblasts as demonstrated by Oil Red O and Alizarin Red staining, respectively. Results. The immunophenotypic markers expression was largely preserved, and their multipotency was maintained. However, after cryopreservation, the cells decreased α4-integrin expression (CD49d), cell viability, and number of colony forming units. Conclusions. These findings suggest that ADMSC transplanted after cryopreservation might compromise the retention of transplanted cells in the host tissue. Therefore, further studies are warranted to standardize protocols related to cryopreservation to attain full benefits of stem cell therapy.

Bone marrow-derived stem cells (BMDSCs) play an essential role in organ repair and regeneration. The molecular mechanisms by which hormones control BMDSCs proliferation and differentiation are unclear. Our aim in this study was to investigate how a lack of ovarian or/and thyroid hormones affects stem cell number in bone marrow lineage. To examine the effect of thyroid or/and ovarian hormones on the proliferative activity of BMDSCs, we removed the thyroid or/and the ovaries of adult female rats. An absence of ovarian and thyroid hormones was confirmed by Pap staining and Thyroid Stimulating Hormone (TSH) measurement, respectively. To obtain the stem cells from the bone marrow, we punctured the iliac crest, and aspirated and isolated cells by using a density gradient. Specific markers were used by cytometry to identify the different BMDSCs types: endothelial progenitor cells (EPCs), precursor B cells/pro-B cells, and mesenchymal stem cells (MSCs). Interestingly, our results showed that hypothyroidism caused a significant increase in the percentage of EPCs, whereas a lack of ovarian hormones significantly increased the precursor B cells/pro-B cells. Moreover, the removal of both glands led to increased MSCs. In conclusion, both ovarian and thyroid hormones appear to have key and diverse roles in regulating the proliferation of cells populations of the bone marrow.

Chagas cardiomyopathy still remains a challenging problem that is responsible for high morbidity and mortality in Central and Latin America. Chagas disease disrupts blood microcirculation via various autoimmune mechanisms, causing loss of cardiomyocytes and severe impairment of heart function. Different cell types and delivery approaches in Chagas Disease have been studied in both preclinical models and clinical trials. The main objective of this article is to clarify the reasons why the benefits that have been seen with cell therapy in preclinical models fail to translate to the clinical setting. This can be explained by crucial differences between the cellular types and pathophysiological mechanisms of the disease, as well as the differences between human patients and animal models. We discuss examples that demonstrate how the results from preclinical trials might have overestimated the efficacy of myocardial regeneration therapies. Future research should focus, not only on studying the best cell type to use but, very importantly, understanding the levels of safety and cellular interaction that can elicit efficient therapeutic effects in human tissue. Addressing the challenges associated with future research may ensure the success of stem cell therapy in improving preclinical models and the treatment of Chagas disease.

Existing therapies for the treatment of chronic heart failure still have some limitations and there is a pressing need for the development of new therapeutic modalities. The amniotic membrane has been used for the treatment of various diseases, such as conjunctive defects; however, the mechanisms behind its repair functions are still unclear. Regenerative medicine is seeking newer alternatives and among them, biomaterials have emerged in recent years for developing and manipulating molecules, cells, tissues or organs grown in laboratories in order to replace human body parts. Many such materials have been used for this purpose, either synthetically or biologically, in order to provide new medical devices. This review provides a wider view of the regeneration potential of the use of amniotic membrane as a potential biomaterial to facilitate the implementation of new research in surgical procedures. Amniotic membrane appears to be an alternative source of stem cells as well as an excellent biomaterial for cell-based therapeutic applications in engineering heart tissue.

The usefulness of adult stem cells in research and therapeutic applications highly relies on their genomic integrity and stability. Many laboratories including ours have addressed this concern using methods such as karyotyping, Qbanding, fluorescent in situ hybridization, array CGH, flow cytometry and Pap test to evaluate number and structure of chromosomes and cellular phenotype. This review attempts to summarize the findings reported so far for the studies on chromosomal aberrations in adult stem cells and warrant to perform certain basic tests before transplantation to avoid any adverse reactions, which will thus aid in better therapeutic output after cellular transplantation in the treatment of various diseases.

ResumoOs proto-oncogenes desempenham importante papel na regulação do ciclo celular, e são críticos à tumorigênese. Nessa categoria se encontra a família RAS, que, devido ao elevado potencial transformante dos genes que a compõem, é uma das mais bem descritas e estudadas. É formada pelos genes H-, K-e N-RAS, que codificam proteínas altamente relacionadas expressas em vários tipos de células, denominadas p21. Estas atuam na transdução de sinal da membrana ao núcleo, estão envolvidas no controle da proliferação, diferenciação e morte celular e são reguladas pela interação com GDP (inativa) e GTP (ativa). As proteínas p21 diferem em apenas 10-15% da sua estrutura primária, na porção C-terminal, denominada região hipervariante. Quando na forma oncogênica, permanecem ativas, e conferem estímulo contínuo à proliferação celular. Dentre os genes RAS, K-RAS tem sido o mais estudado, por apresentar mutações mais freqüentes e presentes em tumores mais agressivos, e implicar em menor sobrevida aos pacientes. Pelo importante papel já demonstrado na formação de tumores e relativa carência de bibliografia em língua portuguesa acerca dessa família gênica, apresentamos neste trabalho uma revisão sistematizada e atualizada sobre os proto-oncogenes RAS. Palavras-chave: K-RAS, p21. Oncogene. Transdução de sinal. AbstractProto-oncogenes play an important role in the regulation of the cellular cycle, being critical to the tumorigenesis. In this category we can find the RAS family. Due to the high transformation potential of these genes, this family is the best described and most studied one. It is formed by the H-, K-and the N-RAS genes, that codify highly related proteins expressed in several types of cells, denominated p21.These proteins act in the sign transduction from the membrane to the nucleus, as well as in the control of proliferation, differentiation and cellular death, and they are regulated by the interaction with GDP (inactive) and GTP (active). These proteins show variation in only 10 -15% of the primary structure, in the C-terminal portion denominated hyper-variant region. When in the oncogenic form, the p21 proteins remain active, providing continuous stimuli to the cellular proliferation. Among the RAS genes, K-RAS ones have been the most studied for presenting more frequent mutations and for being present in more aggressive tumors, implying the patients' shorter survival time. Due to these facts and relative bibliography lack in the Portuguese language on this family, we presented in this work a systematized and updated review on the RAS genes.

The aim of this study was to analyze adipose tissue-derived mesenchymal stem cells (AT-MSCs) using the Pap test as a first screening step to evaluate genetic stability. Human adipose tissue from six healthy female donors was obtained from elective liposuction procedures. The cells were isolated, cultivated at P2/P3, characterized by flow cytometric analysis, and differentiation induced. The AT-MSCs were stained by Papanicolaou staining and analyzed according to the Bethesda classification, and viability-apoptosis relationships were evaluated. The results of the Pap test for Sample I indicated high-grade alterations consistent with genetic instability; for Samples II-V, atypical cells of undetermined significance; and for Sample VI, normal cells. These results demonstrate the potential of using the Pap test as an initial screening step to evaluate the genetic stability of cultured AT-MSCs and also suggest its use for other adherent cells such as embryonic stem cells or induced pluripotent stem cells.

A construção do conhecimento em Biologia depende da compreensão do conceito de variabilidade genética e de sua importância nos vários níveis de organização dos seres vivos. Devido à sua relevância didática e a atual disponibilidade de um grande número de notícias sobre pesquisas contemporâneas para uso como recurso pedagógico, propomos uma atividade interativa que simula e reforça os conceitos de genes, alelos e variabilidade genética.