WEB Interaction of Microcarriers with hMSCs and Physical Characterization of the hMSCs
Stem cells have the unique capability to differentiate into specialized cell types if appropriate growth conditions are provided. Human mesenchymal stem cells (hMSCs) are thought to have a great therapeutic and biotechnological potential. However, their use in cell therapy and regenerative medicine is still limited by cell source quantity. The hMSCs are only available in small numbers in the human body and still their isolation and expansion are very limited. Therefore, an effective expansion process is crucial for achieving a therapeutic dose which is 100,000 to 200,000 times of the initial patient sample. The main goal of this Interreg project, Improve STEM, is the enhancement of the cell number of hMSCs by using microcarrier cultivation and by a correlation of the hMSC's properties (morphology, elasticity and adhesion) and properties of microcarriers (zeta potential, wettability, roughness). In this contribution, the focus lies on the elasticity of the hMSCs isolated from the Wharton’s jelly of umbilical cords. The Young’s modulus of the hMSCs is determined by scanning force spectroscopy (SFS). Employing this method, we are able to take a precise point elasticity measurement on a single cell to identify the local variation due to the cell structure. A combination of SFS and fluorescence microscopy provides accurate Young’s modulus analysis of cell regions around the nucleus, with cytoplasm and on the substrate. In addition, the Young’s modulus is compared for cells cultured under four different conditions: varying hypoxia and normoxia as well as presence of human platelet lysate and fetal bovine serum. We found a considerable difference in the elasticity of the analyzed hMSCs, reflected by a range of the Young’s modulus (2-19 kPa). The different elasticity on a single cell or from one cell to the other suggests that the elasticity of the cell could serve as the basis of understanding the cell functions. Further measurements will help to understand it in detail. In addition, the detachment force between microcarrier and stem cell is investigated by SFS. The detachment force varies remarkably depending on the cell measured. Furthermore, the detachment work shows the same trend. Additional measurements must be carried out to determine the influence of the cell age and of the elasticity of the cell on these measured variables.