Stem Cell Tracing Through MR Molecular Imaging

Stem cell therapy opens a new window in medicine to overcome several diseases that remain incurable. It appears such diseases as cardiovascular disorders, brain injury, multiple sclerosis, urinary system diseases, cartilage lesions and diabetes are curable with stem cell transplantation. However, some questions related to stem cell therapy have remained unanswered. Stem cell imaging allows approval of appropriated strategies such as selection of the type and dose of stem cell, and also mode of cell delivery before being tested in clinical trials. MRI as a non-invasive imaging modality provides proper conditions for this aim. So far, different contrast agents such as superparamagnetic or paramagnetic nanoparticles, ultrasmall superparamagnetic nanoparticles, fluorine, gadolinium and some types of reporter genes have been used for imaging of stem cells. The core subject of these studies is to investigate the survival and differentiation of stem cells, contrast agent's toxicity and long term following of transplanted cells. The promising results of in vivo and some clinical trial studies may raise hope for clinical stem cells imaging with MRI.

Melatonin ameliorates the production of COX-2, iNOS, and the formation of 8-ohdg in non-targeted lung tissue after pelvic irradiation

2 [COX-2], inducible nitric oxide synthase [iNOS], and 8-hydroxydeoxyguanosine [8-OHdG] in lung tissues of Sprague-Dawley rats with and without pre-administration of melatonin. A 2x2 cm[2] area of the pelvis of male Sprague-Dawley rats with and without pre-administration of melatonin [100 mg/kg] by oral and intraperitoneal injection was irradiated with a 3 Gy dose of 1.25 MeV gamma-rays. Alterations in the levels of COX-2, iNOS, and 8-OHdG in the out-of-field lung areas of the animals were detected by enzyme immunoassay. The bystander effect significantly increased COX-2, iNOS, and 8-OHdG levels in non-targeted lung tissues [P<0.05]. Melatonin ameliorated the bystander effect of radiation and significantly reduced the level of all examined biomarkers [P<0.05]. The results indicated that the ameliorating effect of a pre-intraperitoneal [IP] injection of melatonin was noticeably greater compared to oral pre-administration. Our findings revealed that the bystander effect of radiation could induce oxidative DNA damage and increase the levels of imperative COX-2 and iNOS in non-targeted lung tissues. Interestingly, melatonin could modulate the indirect destructive effect of radiation and reduce DNA damage in non-targeted cells