The effect of gamma and microwave radiation sterilization on periodontological grafts for microbiological evaluation.

Periodontological grafts are materials used in dentistry to regenerate lost gingival soft tissues or bone parts. In the case of direct contact with blood, the possibility of disease transmission from the source to the patient is high. This source can be an animal or a human. Therefore, the sterilization of grafts before implanting to the patient is of significant importance. The purpose of this study was to evaluate gamma radiation and microwave sterilization processes from microbiological and sterility perspectives and to compare the effectiveness of these two sterilization methods. Grafts were irradiated with 2, 4, 5, 10, 25 and 50 kGy doses of gamma radiation. Another group of same materials was irradiated by microwave for 1, 2, 3 and 4 min at 24,500 MHz and 900 W. Gamma radiation and microwave sterilization methods were evaluated as successful at minimum doses as 5 kGy and 3 min, respectively. Both gamma and microwave sterilization successfu lly sterilized periodontological grafts coded as PBG1, HBG1, HL1, PDG1, MBG3, MDG2 and PDG3. Moreover, microwave sterilization can be used as an alternative novel method to gamma radiation sterilization.

[Radiotherapy and immune suppression: A short review]. / Radiothérapie et immunosuppression : synthèse de la littérature.

The management of patients undergoing immunosuppressive agents is really challenging. Based on precaution principle, it seems mandatory to stop immunosuppressive (or immunomodulating) agents during radiation. Yet, it is impossible in grafted patients. It is possible in patients with autoimmune disease, but in this case, the autoimmune disease might modify patient's radio-sensitivity. We provide a short review about the safety of radiotherapy in grafted/auto-immune patients. The literature is limited with data coming from outdated case-report or case-control studies. It seems that radiotherapy is feasible in grafted patients, but special dose-constraints limitations must probably be considered for the transplant and the other organs at risk. There is very little data about the safety of radiotherapy, when associated with immunomodulating agents. The most studied drug is the methotrexate but only its prescription as a chemotherapy (high doses for a short period of time) was reported. When used as an immunomodulator, it should probably be stopped 4 months before and after radiation. Apart from rheumatoid arthritis, it seems that collagen vascular diseases and especially systemic scleroderma and systemic lupus erythematous feature increased radio-sensitivity with increased severe late toxicities. Transplanted patients and collagen vascular disease patients should be informed that there is very little data about safety of radiation in their case.

Electrical stimulation promotes the angiogenic potential of adipose-derived stem cells.

Autologous fat transfer (AFT) is limited by post-operative volume loss due to ischemia-induced cell death in the fat graft. Previous studies have demonstrated that electrical stimulation (ES) promotes angiogenesis in a variety of tissues and cell types. In this study we investigated the effects of ES on the angiogenic potential of adipose-derived stem cells (ASC), important progenitor cells in fat grafts with proven angiogenic potential. Cultured human ASC were electrically stimulated for 72 hours after which the medium of stimulated (ES) and non-stimulated (control) ASC was analysed for angiogenesis-related proteins by protein array and ELISA. The functional effect of ES on angiogenesis was then assessed in vitro and in vivo. Nine angiogenesis-related proteins were detected in the medium of electrically (non-)stimulated ASC and were quantified by ELISA. The pro-angiogenic proteins VEGF and MCP-1 were significantly increased following ES compared to controls, while the anti-angiogenic factor Serpin E1/PAI-1 was significantly decreased. Despite increased levels of anti-angiogenic TSP-1 and TIMP-1, medium of ES-treated ASC significantly increased vessel density, total vessel network length and branching points in chorio-allantoic membrane assays. In conclusion, our proof-of-concept study showed that ES increased the angiogenic potential of ASC both in vitro and in vivo.