Non-contact discrimination of human bone marrow-derived mesenchymal stem cells and fibroblasts using Raman spectroscopy

Background: Human bone marrow-derived mesenchymal stem cells (BM-MSCs) are a promising cell source for regenerative medical applications because they can be easily isolated and expanded ex vivo. However, due to the lack of specific cell surface markers, it is difficult to identify whether ex vivo isolated BM-MSC populations are free of stromal fibroblasts. Bright-field microscopical analyses are insufficient to determine fibroblastic contaminations since these two cell types have similar cell morphologies. Materials and methods: We employed and compared traditional flow cytometric (FACS) analysis, in vitro differentiation assays, and Raman spectroscopy to distinguish between human BM-MSCs and fibroblasts. Results: We found that FACS analysis, utilizing previously described fibroblast-identifying antibodies, was inadequate in separating stromal fibroblasts from BM-MSCs as over 75% of the BM-MSCs shared these antigens. In vitro differentiation assays revealed that, in con trast to fibroblasts, BM-MSCs could be successfully differentiated into adipocytes, osteoblasts and chondrocytes. Using this method it was possible to discriminate between the two cell types. However, the need for prolonged in vitro culture periods of up to 4 weeks is a major disadvantage of this test method. Raman spectroscopy, a non-contact technique measuring the wavelength and intensity of inelastic scattered light from molecules by employing high-power near-infrared lasers, distinguished ultra-fast between BM-MSCs and fibroblasts (integration time of 100. s/cell). Conclusion: Based on the results, we conclude that Raman spectroscopy is a suitable tool for the rapid detection of fibroblastic contaminations in BM-MSC cultures.