Single Cell Analysis of Cancer Related Samples using Raman Optical Tweezers and Associated Techniques

Abstract

Raman Spectroscopy is widely used in biomedical research. It can combine with laser tweezers to provide a platform for single cell classification based on the cells’ biochemistry. This technique is known as laser tweezers Raman spectroscopy (LTRS). This technique is highly effective and beneficial in relatively small cell population analyses. Moreover, it is useful for single cell analysis in cancer research where identification and characterisation of cells can be done in mix-cell populations. In this work, the LTRS prototype system was redesigned. The performance of the system is improved by reducing the number of optical components involved and restricting the optical path to a single horizontal plane. The upgraded LTRS system was also adapted to become a user-friendly turn-key system, which is also safe to use by unexperienced users. In this project, the upgraded LTRS system was used for classifying the invasive and non-invasive bladder cancer cells. Seven bladder cancer cell lines: T24, J82, 5637, RT-112, UMUC-3, HT-1376, and T24-CDDPR have been studied. The results show that the most invasive cell line, T24, can be clearly separated from the other wildtype cell lines with high sensitivities when using quadratic discriminant analysis and Random Forest tests. In addition to being the most invasive the T24 cells were also reported to be the most cisplatin resistant among the six wildtype cell lines. In order to establish if the classification of T24 was based on invasiveness or cisplatin-resistance a cisplatin-resistant T24-CDDPR cell line was then introduced into the classification in the second part of the work. This was done because the T24-CDDPR can also be separated in the mix-cell population with high sensitivity by using different classification methods i.e. both the invasive and cisplatin resistant characteristics can be identified by using LTRS. Fourier-transform infrared (FTIR) microscopy, was used here as a complementary method to classify the seven bladder cell lines. However, the results show that only the cisplatin-resistant cell line can be classified with reasonable sensitivity (>80%). It was believed to be due to the lower intensity of the amide III bands in FTIR spectra, which was found to be the key composition for classifying the invasiveness of the bladder cancer cell line by LTRS. The Raman system reported in this work had also been coupled with a commercial shear flow microfluidic system. It was used to study the uptake of D31-palmitic acid (PA) by PC-3 cells, aimed at improving our understanding of the complex nature of the prostate cancer progression related to dietary fats. The results obtained show that omega-3 fatty acids (FAs) clearly supressed the uptake of the D31-PA. In addition the cells’ lipid uptake behaviour under normoxic and hypoxic condition are different. This indicates the importance of conducting experiments closely match to the actual physiological environment when studying the behaviour of prostate cancer cells.

Date of Award	31 Dec 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Peter Gardner (Supervisor)