Alhazzaa, Ramez, Sinclair, Andrew J. and Turchini, Giovanni M. 2013, Bioconversion of α‐Linolenic Acid into n‐3 Long‐Chain polyunsaturated fatty acid in hepatocytes and ad hoc cell culture

This study aimed to establish optimal conditions for a cell culture system that would allow the measurement of 18:3n-3 (ALA) bioconversion into n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA), and to determine the overall pathway kinetics. Using rat hepatocytes (FaO) as model cells, it was established that a maximum 20:5n-3 (EPA) production from 50 mM ALA initial concentration was achieved after 3 days of incubation. Next, it was established that a gradual increase in the ALA concentration from 0 up to 125mM lead to a proportional increase in EPA, without concomitant increase in further elongated or desaturated products, such as 22:5n-3 (DPA) and 22:6n-3 (DHA) in 3 day incubations. Of interest, ALA bioconversion products were observed in the culture medium. Therefore, in vitro experiments disregarding the medium fatty acid content are underestimating the metabolism efficiency. The novel application of the fatty acid mass balance (FAMB) method on cell culture system (cells with medium) enabled quantifying the apparent enzymatic activities for the biosynthesis of n-3 LC-PUFA. The activity of the key enzymes was estimated and showed that, under these conditions, 50% (Km) of the theoretical maximal (Vmax = 3654 mmol.g of cell protein.hour) Fads2 activity on ALA can be achieved with 81 mM initial ALA. Interestingly, the apparent activity of Elovl2 (20:5n-3 elongation) was the slowest amongst other biosynthesis steps. Therefore, the possible improvement of Elovl2 activity is suggested toward a more efficient DHA production from ALA. The present study proposed and described an ad hoc optimised cell culture conditions and methodology towards achieving a reliable experimental platform, using FAMB, to assist in studying the efficiency of ALA bioconversion into n-3 LC-PUFA in vitro. The FAMB proved to be a powerful and inexpensive method to generate a detailed description of the kinetics of n-3 LC-PUFA biosynthesis enzymes activities in vitro. Citation: Alhazzaa R, Sinclair AJ, Turchini GM (2013) Bioconversion of a-Linolenic Acid into n-3 Long-Chain Polyunsaturated Fatty Acid in Hepatocytes and Ad Hoc Cell Culture Optimisation. PLoS ONE 8(9): e73719. doi:10.1371/journal.pone. 0073719 Editor: Ayyalasomayajula Vajreswari, National Institute of Nutrition, India Received April 3, 2013; Accepted July 23, 2013; Published September 11, 2013 Copyright: 2013 Alhazzaa et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by the Australian Research Council’s Discovery Projects funding scheme (Project DP1093570). The views expressed herein are those of the authors and are not necessarily those of the Australian Research Council. R. Alhazzaa is an Alfred Deakin Post-doctoral Research Fellow at the School of Life and Environmental Sciences and the Centre for Chemistry and Biotechnology of Deakin University. G. Turchini’s contribution to this study was made whilst holding an Australian Research Fellowship (ARF) from the Australian Research Council. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: ramez.alhazzaa@deakin.edu. au