Microtubules Change Processes And Impacts During Adipogenesis Of Human Adipose-derived Stem Cells(hASCs)

Adipose-derived stem cells(ASCs)is non-specialized cell which have the ability of self-renewal and multiple differentiation potential.ASCs has the following characteristics:rich in body,convenient access to samples and minor tissue damage and have the ability of self-renewal and multiple differentiation potential,transfer deputy reaction is little.All these show that ASCs has huge potential application prospect in the field of regenerative medicine.Moreover,ASCs can avoid the ethical issues to human embryonic stem cells,therefore,ASCs gradually become a hot research area in tissue engineering,regenerative medicine and clinical research.Cytoskeleton is biological macromolecules in the mechanics,chemistry,biology coupling formed under the action of a dynamic balance system and formed by microtubule,microfilament and intermediate filament.Cytoskeleton involved in cellular mechanotransduction process which is a very important discovery recently.An increasing number of studies have found that cytoskeleton not only plays an important role in some physiological processes which include cell spreading,migration and growth but also plays a key role in stem cell differentiation and responses to environments.But the cytoskeleton tension change mechanism and involved signaling pathways and cytokines are not clear yet during stem cell differentiation.Therefore,the study of which the change of cytoskeleton in stem cell differentiation makes sense.In this study,we show that microtubule plays an active role in adipogenesis of hASCs.In undifferentiated hASCs(day 0),MTs were well organized in a regular arragement.When cells were under differentiation after adipogenesis was initiated(day 4),the density of MTs increased around the nucleus while peripheral MTs became sparse and were arranged into vacuole structure.In the middle-stage of adipocyte differentiation(day 7),MTs remained around the nucleus in high strength and formed a cobweb-like structure.Peripheral MT vacuole fused together and gradually formed a larger gap.As cells further matured(day 14),the strength of MTs around the nucleus reduced and translocated to the peripheral cytoplasm.To determine the affects of MT mechanical status changes on adipogenesis,we treated hASCs with nocodazole which interferes with MT polymerization and promotes MT disassembly,or taxol which stabilizes microtubules.7 days after adipogenic cocktail treatment,MT density decreased obviously in nocodazole treated cells,while gathered in the nucleus in taxol treated cells.Total content and size of lipid increased in nocodazole treated cells while decreased in taxol treated cells.These results show that adipogenesis could affected by MTs stress.More specifically,low stress MTs promotes adipogenesis while high stress MT is just the opposite.These results suggest that mechanical change of MTs can influence adipogenesis of hASCs.