Development And Application Of Physical Biological Markers For Mesenchymal Stem Cells

Human mesenchymal stem cells(hMSCs)are important engineering cells for the ability of differentiating into multiple tissue lineages,such as adipocyte,osteocyte,and neuronal/glial precursor.The study of stem cell differentiation can not only help us to understand the process of human organ development,but also to develop regenerative medicine,which provide effective programs for a variety of disease treatment.Although the events in stem cell differentiation were intensively studied,key information regarding the earlier events that affect both cell fate choice and lineage commitment is still lacking.The lake of distinct and universally reliable biomarkers for hMSC differentiation,especially at the early stage,greatly hampers the successful identification of cell phenotype in the differentiation process.Therefore,the novel physical biological markers are need to be developed to help us get new information of stem cell development,which is difficult to obtain form conventional biochemical measurements.The new information may help us to identify stem cell early differentiation and in-depth understand of stem cell differentiation mechanisms.In this paper,we used the infrared technique based on synchrotron radiation source(SR-FTIR)and atomic force microscopy based on PF-QNM mode to study the stem cell early differentiation process.SR-FTIR microspectroscopy was used to track the biological macromolecules structural changes in the early hMSCs adiposities differentiation process.The whole process of adipogenesis and early adipogenesis stage characteristics of biological macromolecules were analyzed by SR-FTIR spectrum.The multivariate analysis of the SR-FTIR spectra distinguished the dynamic and significant changes of the lipids at early differentiation stage.These results proved that SR-FTIR is a powerful tool to study the stem cell fate determination and early differentiation events.Furthermore,PF-QNM was used to quantitatively measure the mechanical properties of hMSCs at single cell level.We obtained the nanomechanical spectroscopy of single cells and found that it is possible to discriminate the heterogeneous and anisotropic elastic properties of the cell by analyzing the nanomechanical spectroscopy.Then,we used newly established physical biological markers to analyze the regulation process of the ion and interfacial geometry on the hMSCs fate and behaviors.The application of the new markers also provide us new clue in the stem cell differentiation process.The process of lithium ion regulation on stem cell differentiation potential was analyzed by the established markers.Lithium ion was used as a cure for bipolar disorder early,and the regulation of lithium ion on hematopoietic processes suggest that lithium ion can regulate hMSCs differentiation.However,the mechanism of lithium ion regulation of hMSCs differentiation have not yet fully understood.Our results show that lithium chloride has a dose effect no human mesenchymal stem cells fate regulation,and in this dose effect adjustment process,different concentrations of lithium chloride can increase the Young's modulus of hMSCs.Further analysis revealed that the developed mechanical phenotype based on PF-QNM could effectively identify the small changes in the early differentiation of stem cells.The changes of biological macromolecules induced by lithium chloride in the dose effect was analyzed by SR-FTIR,and we found that hMSCs lipids dramatic changes during the regulation process.In order to study the response of stem cells to the surface nanostructures,we process nano-pit structures arranged in a rectangle on silicon substrate to study the hMSCs cellular membrane variety in the stem cells response interfacial geometric cues process.Experimental results show that nano-pit structures,which can induce the lipid bilayer membrane phase separation,significantly regulate stem cell fate and decrease cell plasma membrane fluidity.These results imply that,as the direct contact with interface components of cellular,stem cell lipid membrane state modulation is essential in the identifying/ responding interfacial geometric cues process.