title: Emergence of clonal chromosomal alterations during the mesenchymal stromal cell cultivation.
abstract: BACKGROUND
  Use of human mesenchymal stromal cells (MSCs) is a promising strategy for cell therapy in injured tissues recovery. However, MSCs acquire genetic changes when cultivated in vitro that make them more susceptible to undergo neoplastic transformation. Therefore, genomic integrity of stem cells should be monitored carefully for the use in basic research and clinical trials, including karyotype analysis to confirm the absence of genetic instability. Here, we report a case of a male 67-year-old patient selected to join the study: "Autologous transplantation of mesenchymal cells for treatment of severe and refractory ischemic cardiomyopathy". He underwent nephrectomy for malignant tumor on the right kidney. Cytogenetic analysis on a bone marrow sample showed a normal karyotype: 46,XY[20]. However, the MSC at second passage showed a hyperdiploid clone, with clonal trisomies of chromosomes 4, 5, 10 and X. In order to investigate more, another sample from the same patient was used for a second cultivation and, at third passage, these cells showed a clonal translocation t(9;18)(p24;q11). The recurrent aberrations in MSC may indicate the beginning of a spontaneous transformation in culture, so, these cells were not used for cell therapy. Several analyses were performed at the Center for Cell Technology (152 samples), however this was the only case to show clonal cytogenetic abnormalities. Interestingly, two distinct clonal alterations were seen in two parallel cell cultivations from the same patient, suggesting a propensity for genetic instability. This highlights the need to evaluate these cells on a case-by-case basis, especially in patients with a history of cancer. Although there is controversy about the use of cells with cytogenetic abnormality for therapy, because their tumorigenic doubtful potential, we decided against the use of these cells for regenerative medicine.
  
  
  METHODS
  Here, we report a case of a male 67-year-old patient selected to join the study: "Autologous transplantation of mesenchymal cells for treatment of severe and refractory ischemic cardiomyopathy". He underwent nephrectomy for malignant tumor on the right kidney. Cytogenetic analysis on a bone marrow sample showed a normal karyotype: 46,XY[20]. However, the MSC at second passage showed a hyperdiploid clone, with clonal trisomies of chromosomes 4, 5, 10 and X. In order to investigate more, another sample from the same patient was used for a second cultivation and, at third passage, these cells showed a clonal translocation t(9;18)(p24;q11). The recurrent aberrations in MSC may indicate the beginning of a spontaneous transformation in culture, so, these cells were not used for cell therapy. Several analyses were performed at the Center for Cell Technology(152 samples), however this was the only case to show clonal cytogenetic abnormalities. Interestingly, two distinct clonal alterations were seen in two parallel cell cultivations from the same patient, suggesting a propensity for genetic instability. This highlights the need to evaluate these cells on a case-by-case basis, especially in patients with a history of cancer.
  
  
  CONCLUSIONS
  Although there is controversy about the use of cells with cytogenetic abnormality for therapy, because their tumorigenic doubtful potential, we decided against the use of these cells forregenerative medicine.
authors.affiliation: Centro de Tecnologia Celular (CTC), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná Brazil ; Cytogenetic Laboratory of Centro de Tecnololgia Celular (CTC), PUCPR, Curitiba, Brazil.
authors.forename: Tamara
authors.identifier: 0000-0002-2947-2824
authors.initials: T
authors.lastname: Borgonovo
authors.affiliation: Centro de Tecnologia Celular (CTC), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná Brazil ; Cytogenetic Laboratory of Centro de Tecnololgia Celular (CTC), PUCPR, Curitiba, Brazil.
authors.forename: Maria Marlene
authors.initials: MM
authors.lastname: Solarewicz
authors.affiliation: Centro de Tecnologia Celular (CTC), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná Brazil ; Cytogenetic Laboratory of Centro de Tecnololgia Celular (CTC), PUCPR, Curitiba, Brazil.
authors.forename: Isadora May
authors.initials: IM
authors.lastname: Vaz
authors.affiliation: Centro de Tecnologia Celular (CTC), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná Brazil.
authors.forename: Debora
authors.initials: D
authors.lastname: Daga
authors.affiliation: Centro de Tecnologia Celular (CTC), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná Brazil.
authors.forename: Carmen Lúcia Kuniyoshi
authors.initials: CL
authors.lastname: Rebelatto
authors.affiliation: Centro de Tecnologia Celular (CTC), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná Brazil.
authors.forename: Alexandra Cristina
authors.initials: AC
authors.lastname: Senegaglia
authors.affiliation: Departamento de Genética, Universidade Federal do Paraná (UFPR), Curitiba, Paraná Brazil.
authors.forename: Enilze
authors.initials: E
authors.lastname: Ribeiro
authors.affiliation: Departamento de Genética, Universidade Federal do Paraná (UFPR), Curitiba, Paraná Brazil.
authors.forename: Iglenir João
authors.initials: IJ
authors.lastname: Cavalli
authors.affiliation: Centro de Tecnologia Celular (CTC), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná Brazil.
authors.forename: Paulo Slud
authors.initials: PS
authors.lastname: Brofman
keywords: Genomic integrity; Karyotype; Mesenchymal stromal cells; Regenerative medicine