A team of cell biologists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB; Stuttgart, Germany) can now analyze living cells quickly and accurately with the help of Raman spectroscopy. The noninvasive optical method, which recognizes the molecular fingerprint of different materials, has primarily been employed in quality control for medications and pharmaceutical substances, but it can also investigate living cells without invasive techniques or altering them with dyes. To characterize stem cells or identify changes to tissues that are caused by tumors, inflammations, fungi, or bacteria, it is now sufficient to determine the individual cells' Raman spectrum.
The IGB research team used a specially developed Raman spectrometer jointly designed and built with physicists at the Fraunhofer Institute for Physical Measurement Techniques (IPM; Freiburg, Germany). With it, the scientists are accumulating the spectra they have recorded into a database. "Each cell has a unique, unmistakable Raman spectrum. Doctors are able to compare the sample from their patients' cells with our database and complete the diagnosis more quickly," says IGB professor Katja Schenke-Layland.
The technology is already being employed on a practical basis by industrial partners, and the scientists are currently working on a rapid test for cancer diagnosis. According to Schenke-Layland, doctors using mobile Raman spectrometers during an operation could determine whether or not a patient has cancer by comparing the cell sample with their database.
Cancer diagnoses are still complicated and prolonged. After excising the tissue for biopsy, it first must be prepared for further analysis--for example, by sectioning or dying it to identify biomarkers. "But this always requires intervention in the specimen and manipulating it in some way," explains Schenke-Layland. The specimen is then transferred to a pathologist, who analyzes whether the tissue contains malignant or benign cells. This method is error-prone and can lead to the specimen being unusable for other tests in the end. "Human error is reduced by a software-based comparison with our database," she adds.
There are numerous additional applications for their Raman spectroscopy method, especially in regenerative medicine. Artificially grown tissue may replace diseased cells in patients and thereby help the tissue to heal. To accomplish this, tissue-specific cells from bone marrow, for instance, must be removed and the stem cells extracted. Bone marrow is made up of highly diverse cells and it is complicated to differentiate the adult stem cells from the ordinary tissue cells. In addition, the stem cells must be 100% correctly identified and separated. If this does not happen and other types of cells are cultured into the implant, the body may not react as hoped, causing implant rejection or tumor formation.
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