Low-level laser irradiation induces in vitro proliferation of mesenchymal stem cells / Laser de baixa intensidade induz à proliferação in vitro de células-tronco mesenquimais

Objective : To evaluate the effect of low-level laser irradiation on the proliferation and possible nuclear morphological changes of mouse mesenchymal stem cells. Methods : Mesenchymal stem cells derived from bone marrow and adipose tissue were submitted to two applications (T0 and T48 hours) of low-level laser irradiation (660nm; doses of 0.5 and 1.0J/cm2). The trypan blue assay was used to evaluate cell viability, and growth curves were used to analyze proliferation at zero, 24, 48, and 72 hours. Nuclear alterations were evaluated by staining with DAPI (4’-6-diamidino-2-phenylindole) at 72 hours. Results : Bone marrow-derived mesenchymal stem cells responded to laser therapy in a dose-dependent manner. Higher cell growth was observed when the cells were irradiated with a dose of 1.0J/cm2, especially after 24 hours (p<0.01). Adipose-derived mesenchymal stem cells responded better to a dose of 1.0J/cm2, but higher cell proliferation was observed after 48 hours (p<0.05) and 72 hours (p<0.01). Neither nuclear alterations nor a significant change in cell viability was detected in the studied groups. Conclusion : Low-level laser irradiation stimulated the proliferation of mouse mesenchymal stem cells without causing nuclear alterations. The biostimulation of mesenchymal stem cells using laser therapy might be an important tool for regenerative therapy and tissue engineering. .

Objetivo : Avaliar o efeito da terapia com laser de baixa intensidade sobre a proliferação e as possíveis alterações morfológicas nucleares em células-tronco mesenquimais de camundongos. Métodos : Células-tronco mesenquimais derivadas da medula óssea e do tecido adiposo foram submetidas a duas aplicações (T0 e T48 horas) de laser de baixa intensidade (660nm; doses de 0,5 e 1,0J/cm2). O ensaio de azul de tripan foi utilizado para a avaliação da viabilidade celular, e curvas de crescimento foram usadas para avaliar a proliferação das células em zero, 24, 48, e 72 horas. Alterações nucleares foram avaliadas por coloração com DAPI (4-6-diamidino-2-fenilindolo) em 72 horas. Resultados : As células-tronco mesenquimais derivadas da medula óssea responderam a terapia com laser de forma dose-dependente. Um maior crescimento celular foi observado quando as células foram irradiadas com dose de 1,0J/cm2, especialmente depois de 24 horas (p<0,01). As células-tronco mesenquimais derivadas do tecido adiposo responderam melhor à dose de 1,0J/cm2, com maior proliferação após 48 (p<0,05) e 72 horas (p<0,01). Nem alterações nucleares nem a mudança significativa na viabilidade celular foi detectada nos grupos estudados. Conclusão : Laser de baixa intensidade estimulou a proliferação de células-tronco mesenquimais sem causar alterações nucleares. A bioestimulação de células-tronco mesenquimais por laserterapia pode ser uma ferramenta importante para a terapia regenerativa e a engenharia tecidual. .

[Effect of low electromagnetic fields on fetal death and bone marrow megakaryocytes in NMRI mouse neonates]

Low electromagnetic fields [LEMF] are produced by instruments which are works with electricity. This study was done to determine the effect of LEMF on fetal death and bone marrow megakaryocytes in NMRI mouse neonates. In this experimental study 64 females' mice with 6-8 old weeks were used. 2 female mice coupled with one male, and positive vaginal plaque was interpreted as the zero day of pregnancy [GD=0], The pregnant mice were randomly categorized into control and experimental groups. The experimental group were exposed to 50HZ, 0.5 mT Low electromagnetic fields on 7-11 days of pregnant period [8h/d]. The weight of neonate and death fetus were studied after delivery. The live neonates were dissected on 15[th] day, and 1 ml of bone marrow was extracted from Tibia and vertebral column, by pressing method. The bone marrow cells suspended in 1:1 IMDM in 15cc [FULCON] tubule and cells was counted with neobar lam. The data were tested by t-student test; significance was set up at p<0.05. There was significant differences between the mean weight of one day neonate in cases with controls [P<0.05]. The mean of dead fetus in experimental group was higher than controls [P<0.05]. The mean of megakaryocytes numbers higher than controls, but this differences was not significant. This study showed that the number of megakaryocytes and fetal death were increased by low electromagnetic fields exposure during pregnancy

Hematological toxicities and treatment interruption due to craniospinal irradiation

To assess the frequency and severity of myelosuppression due to cranio-spinal irradiation to identify patients at high risk of haematological toxicity who may require supportive therapy. Between 1998 and 2002, 45 patients received craniospinal axis radiotherapy as part of the treatment of primary CNS tumours at departement of radiotherapeutic oncology of cancer Institute. The dose to the whole brain ranged from 30 to 40 Gy in 1.5-1.85 Gy/f. The usual dose to the posterior fossa or to the site of primary disease was 50- 55 Gy in 6-8 weeks for adults and was reduced to 45-50 Gy in 6-7 weeks for children aged, 3 years. Complete blood counts [CBC] were obtained during radiation therapy. Any interruption in treatment due hematologic toxicity [G3-4] lasting 2 days was defined as a significant treatment interruption. In 45 patients who received craniospinal irradiation [CSI] 19 patients had treatment interruption more than 2 days. The median dose at interruption was 21.6 +/- 8.7 Gy and the the frequency of grade 3,4 hematologic toxicity occurred with peack incidence in fourth week of CSI[median day of interruption was day 23,range 8-38]. The median WBC count was 1900[range 100-2140].The mean of interruption period was 7 +/- 8 days [one patient died from neutropenic fever then he didn't finish his treatment. In 19 patients who had treatment interruption,13 of them were under 12 years while 5 patients were greater than 12 years .With Mann-Whitney U test the median age of patients with treatment interruption was lower; 10.2 years and 16.2 years respectively[P=.059].].In 24 patients with dose/fraction =<1.6 Gy 12 patients [50%] had treatment interruption but in 21 patients with dose/fraction >1.6 Gy 7 [33%] had treatment interruption[P=.2] but interruption period was longer in patients with dose/ fraction >1.6 Gy .From 12 patients who had dose/fraction <=1.6Gy,7 patients had interruption period less than 5 days while in group with dose/fraction >1.6 Gy all patients had treatment interruption period more than 5 days[P=.016,CI 95% for interruption period difference =1.2-4.7]. In summary, in our study 42% of patients undergoing CSI had treatment interruption. The risk was higher in children and in patients who received higher spinal dose fraction the treatment interruption was longer, but the overall treatment-related morbidity was low. In a population at risk of hematological toxicity where further studies of HGFs should be targeted