Luiz Fernando Bouzas

Stability of human mesenchymal stem cells during in vitro culture: considerations for cell therapy

Ex vivo expansion and manipulation of human mesenchymal stem cells are important approaches to immunoregulatory and regenerative cell therapies. Although these cells show great potential for use, issues relating to their overall nature emerge as problems in the field. The need for extensive cell quantity amplification in vitro to obtain sufficient cell numbers for use, poses a risk of accumulating genetic and epigenetic abnormalities that could lead to sporadic malignant cell transformation. In this study, we have examined human mesenchymal stem cells derived from bone marrow, over extended culture time, using cytogenetic analyses, mixed lymphocyte reactions, proteomics and gene expression assays to determine whether the cultures would retain their potential for use in subsequent passages. Results indicate that in vitro cultures of these cells demonstrated chromosome variability after passage 4, but their immunomodulatory functions and differentiation capacity were maintained. At the molecular level, changes were observed from passage 5 on, indicating initiation of differentiation. Together, these results lead to the hypothesis that human mesenchymal stem cells cultures can be used successfully in cell therapy up to passage 4. However, use of cells from higher passages would have to be analysed case by case.

Cytogenetic analysis of 100 consecutive newly diagnosed cases of acute lymphoblastic leukemia in Rio de Janeiro.

We report the cytogenetic analysis of newly diagnosed Brazilian children with acute lymphocytic leukemia (ALL). We investigated 100 ALL cases from four different institutions in Rio de Janeiro. The frequency of chromosomal abnormalities was 92.3%. The karyotype profile and recurrent abnormalities found in this study do not differ essentially from those described by other groups. Although the Brazilian population is usually the product of different ethnic groups, our results show that the frequency of each recurrent abnormality is similar to that found in populations without our degree of diverse ethnic composition. Hence, our results suggest that childhood ALL in Brazil has the same biological features as that in developed countries, supporting the use of similar treatment protocols. We can therefore expect to reach the same survival rates in the coming years, depending possibly on the efficacy of the support therapy and extent of social assistance.

Immunological recovery after bone marrow transplantation for severe aplastic anaemia: a Brazilian experience.

Abstract: Twenty‐nine patients with severe aplastic anaemia (SAA) were submitted to bone marrow transplantation (BMT) and their immunological recovery analysed. Total lymphocyte counts, estimation of B lymphocytes, T lymphocytes and their subsets, natural‐killer (NK) activity were performed. Cells with the CD8 + phenotype and NK activity were the first signs of immunological recovery, whereas the CD4 + subset recovered later in patients who suffered from acute graft versus host disease (GvHD) and infections. Acute and chronic GvHD, cirrhosis, rejection and HIV viral infection contributed to the persistence of the profound immunodeficiency status observed after BMT. Our results did not differ greatly from the others and confirmed that BMT may be performed in underdeveloped countries despite the difficulties it might pose.

Diretrizes para o diagnóstico, classificação, profilaxia e tratamento da doença enxerto contra hospedeiro crônica

A falta de criterios diagnosticos padronizados, amplamente utilizados, pode comprometer tanto a avaliacao real da incidencia da doenca contra hospedeiro cronica bem como a correlacao de sua gravidade com a taxa de mortalidade pos-transplante. Na I Reuniao de Diretrizes da Sociedade Brasileira de Transplante de Medula Ossea, realizada em junho de 2009, o Grupo de Estudos de DECH Brasil - Seattle (GEDECH), baseado na realidade dos Centros brasileiros, apresentou as recomendacoes para diagnostico, classificacao, profilaxia e tratamento da doenca enxerto contra hospedeiro cronica propostas pelo National Institutes of Health. Estas propostas incluiram padronizacao das caracteristicas utilizadas no diagnostico e ferramentas para a pontuacao dos orgaos envolvidos e avaliacao global da gravidade a serem utilizados em estudos clinicos da doenca enxerto contra hospedeiro cronica. Estes criterios sao uteis para uma melhor analise da incidencia desta doenca, alem de poder avaliar a gravidade do comprometimento de um orgao ou sitio envolvido e a influencia na mortalidade tardia do transplante. A profilaxia e os tratamentos propostos para esta importante complicacao dos transplantes de celulas-tronco hematopoeticas foram discutidos e graduados de acordo com niveis de evidencia estabelecidos pelo National Institutes of Health.

Transient chromosomal rearrangements in three children with acute lymphoblastic leukemia after unrelated cord blood transplantation

Transient chromosomal rearrangements in three children with acute lymphoblastic leukemia after unrelated cord blood transplantation