Improved expression of Sirt1 on thymic epithelial cells of SAMP10 after Intrabone marrow-bone marrow transplantation

Sirtuin 1: A Dilemma in Transplantation

Sirtuin 1, a member of sirtuin family of histone deacetylase enzymes, has been implicated in a variety of physiologic and pathologic events, including energy metabolism, cell survival, and age-related alterations. In view of the anti-inflammatory properties of sirtuin 1 along with its protective role in ischemia reperfusion injury, it might be considered as contributing to the promotion of transplantation outcome. However, the potential ability of sirtuin 1 to induce malignancies raises some concerns about its overexpression in clinic. Moreover, despite the findings of sirtuin 1 implication in thymic tolerance induction and T regulatory (Treg) cells survival, there is also evidence for its involvement in Treg suppression and in T helper 17 cells differentiation. The identification of sirtuin 1 natural and synthetic activators leads to the proposal of sirtuin 1 as an eligible target for clinical interventions in transplantation. All positive and negative consequences of sirtuin 1 overactivation/overexpression in the allograft should therefore be studied thoroughly. Herein, we summarize previous findings concerning direct and indirect influences of sirtuin 1 manipulation on transplantation.

Immune Dysfunction Associated with Abnormal Bone Marrow-Derived Mesenchymal Stroma Cells in Senescence Accelerated Mice

Senescence accelerated mice (SAM) are a group of mice that show aging-related diseases, and SAM prone 10 (SAMP10) show spontaneous brain atrophy and defects in learning and memory. Our previous report showed that the thymus and the percentage of T lymphocytes are abnormal in the SAMP10, but it was unclear whether the bone marrow-derived mesenchymal stroma cells (BMMSCs) were abnormal, and whether they played an important role in regenerative medicine. We thus compared BMMSCs from SAMP10 and their control, SAM-resistant (SAMR1), in terms of cell cycle, oxidative stress, and the expression of PI3K and mitogen-activated protein kinase (MAPK). Our cell cycle analysis showed that cell cycle arrest occurred in the G0/G1 phase in the SAMP10. We also found increased reactive oxygen stress and decreased PI3K and MAPK on the BMMSCs. These results suggested the BMMSCs were abnormal in SAMP10, and that this might be related to the immune system dysfunction in these mice.

Stem cell transplantation upregulates Sirt1 and antioxidant expression, ameliorating fatty liver in type 2 diabetic mice

Nonalcoholic fatty liver disease (NAFLD) is associated with insulin resistance, oxidative stress, and obesity. The db/db mouse model displays increased levels of insulin resistance, obesity, and an over-accumulation of hepatic triglycerides, making it an excellent model for studying NAFLD. In db/db mice, intra-bone marrow-bone marrow transplantation plus thymus transplantation (IBM-BMT+TT) improves type 2 diabetes mellitus (T2 DM) by normalizing the T-cell imbalance. We hypothesized that this approach would improve Sirt1 expression in the liver and benefit liver development. The db/db mice were treated with IBM-BMT+TT, and plasma MCP-1, IL-6, adiponection, LDL, Sirt1, and HO-1 levels were then assessed. Stem cell transplantation decreased the levels of plasma inflammatory cytokines and LDL while it increased the expression of Sirt1 and HO-1, resulting in decreased progression of fatty liver. Moreover, Sirt1 and HO-1 expression were both detected in the thymus and many HO-1-positive cells were observed in the bone marrow. This is the first report of stem cell transplantation improving the antioxidant function in the liver, thymus, and bone marrow of db/db mice by increasing the levels of Sirt1 and HO-1. This approach may prove useful in the treatment of nonalcoholic steatohepatitis and its clinical manifestations.

Assessment and refinement of intra-bone marrow transplantation in mice

Intra-bone marrow transplantation (IBMT) may improve the seeding efficiency of transplanted hematopoietic stem cells compared to the routinely used intravenous injection. Current IBMT protocols are optimized for ease of use and to improve experimental results. However, there have been no investigations to assess the impact of IBMT on animal welfare. Here, we report the results of pain assessment after IBMT and the effects of refinements to the current standard procedure. IBMT was performed in either the tibia or the femur of a recipient mouse under general anesthesia. Impact was determined using clinical scoring of different parameters (lameness, grip capacity, body weight loss, footprint analysis), behavioural tests (burrowing, open-field), monitoring of stress hormones and post-mortem histology. The results revealed that IBMT definitely induces severe post-operative distress. Although IBMT in the tibia is technically easier, the degree of impairment and the distress observed were consistently higher than for transplantation in the femur. A refinement for IBMT in the tibia was achieved by using 30- instead of 26-gauge needles and by sparing the patellar tendon. Consequently, for IBMT, we recommend either using the femur, or if the tibia is required due to its better feasibility, using our refined protocol. Furthermore, IBMT should definitely be limited to one leg per animal.

Stem cell treatment for Alzheimer's disease

Alzheimer’s disease (AD) is a progressive and neurodegenerative disorder that induces dementia in older people. It was first reported in 1907 by Alois Alzheimer, who characterized the disease as causing memory loss and cognitive impairment. Pathologic characteristics of AD are β-amyloid plaques, neurofibrillary tangles and neurodegeneration. Current therapies only target the relief of symptoms using various drugs, and do not cure the disease. Recently, stem cell therapy has been shown to be a potential approach to various diseases, including neurodegenerative disorders, and in this review, we focus on stem cell therapies for AD.