CCAAT/enhancer-binding protein alpha (CEBPA) gene haploinsufficiency does not alter hematopoiesis or induce leukemia in Lck-CALM/AF10 transgenic mice

Although rare, CALM/AF10 is a chromosomal rearrangement found in immature T-cell acute lymphoblastic leukemia (T-ALL), acute myeloid leukemia, and mixed phenotype acute leukemia of T/myeloid lineages with poor prognosis. Moreover, this translocation is detected in 50% of T-ALL patients with gamma/delta T cell receptor rearrangement, frequently associated with low expression of transcription factor CCAAT/enhancer-binding protein alpha (CEBPA). However, the relevance of CEBPA low expression for CALM/AF10 leukemogenesis has not yet been evaluated. We generated double mutant mice, which express the Lck-CALM/AF10 fusion gene and are haploinsufficient for the Cebpa gene. To characterize the hematopoiesis, we quantified hematopoietic stem cells, myeloid progenitor cells, megakaryocyte-erythrocyte progenitor cells, common myeloid progenitor cells, and granulocyte-macrophage progenitor cells. No significant difference was detected in any of the progenitor subsets. Finally, we tested if Cebpa haploinsufficiency would lead to the expansion of Mac-1+/B220+/c-Kit+ cells proposed as the CALM/AF10 leukemic progenitor. Less than 1% of bone marrow cells expressed Mac-1, B220, and c-Kit with no significant difference between groups. Our results showed that the reduction of Cebpa gene expression in Lck-CALM/AF10 mice did not affect their hematopoiesis or induce leukemia. Our data corroborated previous studies suggesting that the CALM/AF10 leukemia-initiating cells are early progenitors with lymphoid/myeloid differentiating potential.

Qualitative analysis of striated skeletal muscles in thedystrophynopathy of mdx mice submitted to physical activity

Duchenne’s Muscular Dystrophy (DMD) is a recessive hereditary myopathy linked to the chromosome X,caused by a mutation in the dystrophin gene, which strengthens and stabilizes the sarcolemma during the stressof muscular contraction and, when absent, the sarcollema ruptures and allows calcium to enter, which causesthe muscle fiber to necrotize. The object of the present study was to perform the morphologic analysis of theanterior tibial and the gastrocnemius muscles with (w/pa) or without (n/pa) physical activity for five weeks.We used 72 mice, divided in 12 experimental groups – 6 of them mdx and 6 control groups (C57/10J) aged4, 7, and 10 weeks. The samples were collected, processed and stained with hematoxylin-eosin. They wereanalyzed by light microscopy, selected and photomicrographed. On the cross-sections of control animals aged4, 7 and 10 weeks w/pa and n/pa, polygonal muscle fibers of many different sizes, ellipse-shaped and withseveral peripheral nucleuses were observed. In the mdx mice w/pa aged 4, 7 and 10 weeks, the muscle fibersshowed different shapes, sizes and stain affinities, rounded edges, anuclear or centered nucleuses; hyalines andmyofibrillas were highly contracted. Muscular regeneration and nectrotic areas with inflammatory infiltrateswere identified in the mdx animals aged 4, 7 and 10 weeks w/pa, as well as in animals aged 10 weeks n/pa.With the progression of the disease in the animals submitted to physical activity, there was evidence of failurein the regeneration and muscular degeneration, intensified and characterized by the gradual replacement ofthe striated skeletal muscle tissue by fibroadipose connective tissue.

Sclerocorneal limbal stem cell autograft transplantation in dogs

The effects of sclerocorneal limbal stem cell autograft transplantation in dogs with corneal wounds were studied. Eighteen dogs were divided in two groups (GI and GII). The animals of GI (n=12) underwent limbal transplantation 30 days after the destruction of limbal stem cells. The dogs of GII (n=6) only underwent destruction of stem cells (control group). Light microscopy examination of the right eye was performed on days 3, 7, 14, 30, 60, and 120 after limbal transplantation (GI), and on days 33, 37, 44, 60, 90, and 150 after limbal destruction (GII). Results showed a complete destruction of limbal stem cells with loss of corneal transparency. Limbal transplantation prevented conjunctivalization in grafted area. Corneal vascularization and a 360º corneal conjunctivalization were noted in the control dogs (GII). Corneal transparency was restored from day 60th after surgery. Histological examination did not distinguish the transition between the graft and the normal corneal epithelium at anytime. Goblet cells were found in control animals (GII) on 33, 37, 60, and 150 days, whereas a single grafted dog (GI) presented a few goblet cells on day 60th post-transplantation. Limbal autograft transplantation was effective in restoring corneal clarity with no development of ocular complications

Avaliaram-se os efeitos do transplante de células tronco autógenas do limbo esclerocórneo de cães, sobre lesões córneo-limbais. Empregaram-se 18 cães, distribuídos em dois grupos, GI e GII. Nos animais do GI (n=12), foram realizados transplantes de limbo, após 30 dias da destruição das células tronco-límbicas. Nos do GII (n=6), realizou-se apenas a destruição do limbo (controle). Aos 3, 7, 15, 30, 60 e 120 dias do transplante de limbo (GI) e aos 33, 37, 45, 60, 90 e 150 dias da destruição do limbo (GII), os olhos foram coletados por enucleação subconjuntival, para estudos em microscopia de luz. A destruição do limbo resultou em completa excisão das células tronco, com perda da transparência corneal. O transplante do limbo evitou a conjuntivalização na área em que foi realizado. Os animais do grupo-controle manifestaram conjuntivalização em 360º e vascularização corneal. Na anatomopatologia, em nenhum dos períodos foi possível distinguir o enxerto do epitélio corneal normal. As células caliciformes foram observadas nos animais do GII, nos períodos 33, 37, 60, 150 dias. No GI, apenas um cão manifestou células caliciformes de forma discreta, aos 60 dias do transplante. O transplante autógeno foi eficiente em possibilitar a melhoria da transparência córnea, sem intercorrências oculares