Non-invasive, quantitative assessment of the morphology of γ-irradiated human mesenchymal stem cells and periosteal cells using digital holographic microscopy.

Purpose: To assure the quality of cells to be used in cell therapy, we examined the applicability of digital holographic microscopy (DHM) for non-invasive, quantitative assessment of changes in cell morphology.
Materials and Methods: Mesenchymal stem cells derived from adipose tissue (MSC-AT) and bone marrow (MSC-BM), in addition to human alveolar periosteal cells (PC) as a reference, were γ-ray irradiated (1 and 4 Gy), and their morphological changes were quantified without fixation using holographic microscopy. After detachment and fixation with ethanol, cell number and surface antigen expression were determined using an automated cell counter kit and flow-cytometry, respectively.
Results: Among various indexes, only indexes related to cell size were significantly changed after γ-irradiation. Both BMC-AT and BMC-BM were enlarged and more sensitive to a low dose of γ-irradiation than PC. In contrast to PC, proteins related to DNA damage repair (γ-H2AX, p21 ^waf1 , p53 and Rb) were not substantially upregulated or sustained for a week in either MSC-AT or MSC-BM.
Conclusion: Instead of DNA damage markers, we suggest that cell morphological parameters (e.g. cell volume) that are monitored by DHM could be a useful and more stable marker of MSC quality.