Design and construction of a thermal neutron beam for BNCT at Tehran Research Reactor.

An irradiation facility has been designed and constructed at Tehran Research Reactor (TRR) for the treatment of shallow tumors using Boron Neutron Capture Therapy (BNCT). TRR has a thermal column which is about 3m in length with a wide square cross section of 1.2×1.2m(2). This facility is filled with removable graphite blocks. The aim of this work is to perform the necessary modifications in the thermal column structure to meet thermal BNCT beam criteria recommended by International Atomic Energy Agency. The main modifications consist of rearranging graphite blocks and reducing the gamma dose rate at the beam exit. Activation foils and TLD700 dosimeter have been used to measure in-air characteristics of the neutron beam. According to the measurements, a thermal flux is 5.6×10(8) (ncm(-2)s(-1)), a cadmium ratio is 186 for gold foils and a gamma dose rate is 0.57Gy h(-1).

Dormant phase and multinuclear cells: two key phenomena in early culture of murine bone marrow mesenchymal stem cells.

Special features of mesenchymal stem cells (MSCs) have made them a popular tool in cell therapy and tissue engineering. Although mouse animal models and murine MSCs are common tools in this field, our understanding of the effect of in vitro expansion on the behavior of these cells is poor and controversial. In addition, in comparison to human, isolation of MSCs from mouse has been reported to be more difficult and some unexplained features such as heterogeneity and slow growth rate in the culture of these cells have been observed. Here we followed mouse bone marrow MSCs for >1 year after isolation and examined the effect of expansion on changes in morphology, growth kinetics, plasticity, and chromosomal structure during in vitro culture. Shortly after isolation, the growth rate of the cells decreased until they stopped dividing and entered a dormant state. In this state the size of the cells increased and they became multinuclear. These large multinuclear cells then gave origin to small mononuclear cells, which after a while resumed proliferation and could be expanded immortally. The immortal cells had diminished plasticity and were aneuploid but could not form tumors in nude mice. These results suggest that mouse bone marrow MSCs bear several modifications when expanded in vitro, and therefore, the interpretation of the data obtained with these cells should be done more cautiously.

Expression of dopamine-associated genes on conjunctiva stromal-derived human mesenchymal stem cells.

Parkinson's disease (PD) is neurodegenerative diseases caused by the loss of dopaminergic neurons in the substantia nigra pars compacta. Stem cell therapy is one of the promising strategies in helping to cure PD. In the present study, human mesenchymal stem cells (MSCs) from eye conjunctiva stromal cells were differentiated into dopaminergic neurons. In this work, after conjunctiva biopsy, mesenchymal stem cells were obtained via adherence to the plastic culture dishes. Then, MSCs were treated with general neurogenic medium containing DMEM supplemented with RA, IBMX and dbcAMP for 6 days. RT-PCR, immunocytochemistry and flow cytometry were used for expression of dopaminergic genes such as TH. As a result, RT-PCR analysis revealed the expression of dopaminergic neuron genes such as TH, Ptx3, Nurr1. Furthermore, immunocytochemistry revealed that the differentiated CJMSCs not only express TH gene, but also express TH protein. Flow cytometry showed that TH, MAP-2 proteins increased significantly as increasing passage number. In conclusion, the reported results indicate that CJMSCs might be a suitable and available source for cell transplantation therapy for the central system diseases such as PD.