Aging of bone marrow mesenchymal stromal/stem cells: Implications on autologous regenerative medicine.

With their proliferation, differentiation into specific cell types, and secretion properties, mesenchymal stromal/stem cells (MSC) are very interesting tools to be used in regenerative medicine. Bone marrow (BM) was the first MSC source characterized. In the frame of autologous MSC therapy, it is important to detect donor's parameters affecting MSC potency. Age of the donors appears as one parameter that could greatly affect MSC properties. Moreover, in vitro cell expansion is needed to obtain the number of cells necessary for clinical developments. It will lead to in vitro cell aging that could modify cell properties. This review recapitulates several studies evaluating the effect of in vitro and in vivo MSC aging on cell properties.

Original approach for cartilage tissue engineering with mesenchymal stem cells.

Cartilage tissue engineering gives the ability to product adaptable neocartilage to lesion with autologous cells. Our work aimed to develop a stratified scaffold with a simple and progressive spraying build-up to mimic articular cartilage environment. An Alginate/Hyaluronic Acid (Alg/HA) hydrogel seeded with human Mesenchymal Stem Cells (hMSC) was construct by spray. First, cells repartition and actin organization were study with confocal microscopy. Then, we analyzed cells viability and finally, metabolic activity. Our results indicated a homogenous cells repartition in the hydrogel and a pericellular actin repartition. After 3 days of culture, we observed about 52% of viable cells in the scaffold. Then, from day 7 until the end of culture (D28), the proportion of living cells and their metabolic activity increased, what indicates that culture conditions are not harmful for the cells. We report here that sprayed method allowed to product a scaffold with hMSCs that confer a favorable environment for neocartilage construction: 3D conformation and ability of cells to increase their metabolic activity, therefore with few impact on hMSCs.

Are FoxO transcription factors implicated in osteoarthritis? Influence of Diacerhein.

The FoxO family of Forkhead transcription factors functions at the interface of tumor suppression, energy metabolism and organismal longevity. FoxO factors are key downstream targets of insulin, growth factor, nutrient and oxidative stress stimuli that coordinate a wide-range of cellular outputs. These transcription factors could participate in the regulation of different phenomena found in the osteoarthritis pathology, like apoptosis, chondrocyte proliferation, cell dedifferentiation or resistance to oxidative stress. Moreover, we found recently that FoxO transcription factors could be involved on Diacerhein mode of action, a drug that reduces the IL-1ß deleterious effects on osteoarthritis cartilage through inhibition of the expression of degrading enzymes. It could explain the downregulated proliferation and the increased p27 expression observed on human osteoarthritic chondrocytes in the presence of Diacerhein.