title: Biotransport and intracellular ice formation phenomena in freezing human embryonic kidney cells (HEK293T).
abstract: The objective of this study is to determine the cryobiological characteristics of human embryonic kidney (HEK293T) cells. The cell membrane hydraulic conductivity (L(pg)) and the activation energy of water transport (E(Lp)) were determined in the absence/presence of cryoprotectant agent (CPA), while the nucleation rate kinetic and thermodynamic parameters (Ωo(SCN) and κo(SCN)) were determined in the absence of CPA. Since dehydration and intracellular ice formation (IIF) are two factors that may cause damage to cells during the freezing process, systematical freezing experiments were carried out at different cooling rates (5, 10, 15, 20, 30, and 60°C/min) under the commercial available cryomicroscopy (FDCS 196, Linkham, Waterfield, UK) to further explore the cryoinjury mechanism for HEK293T cells. By simultaneously fitting the water transport equation to the experimentally measured volumetric shrinkage data at 5, 10, and 15°C/min, the "combined best fit" membrane permeability parameters for HEK293T cells in both phosphate buffer saline (PBS) and CPA media (0.75M Me2SO in PBS) are determined. They are L(pg)=2.85×10(-14)m/s/Pa (0.17μm/min/atm), E(Lp)=142.91kJ/mol (34.13kcal/mol) (R(2)=0.990), and L(pg)[cpa]=2.73±0.44×10(-14)m/s/Pa (0.16±0.03μm/min/atm), E(Lp)[cpa]=152.52±27.69kJ/mol (36.42±6.61kcal/mol) (R(2)=0.993), respectively. An optimal cooling rate B(opt) (the highest cooling rate without IIF) was determined to be 14.24°C/min in the absence of CPA. Additionally, the ice nucleation parameters (Ωo(SCN) and κo(SCN)) were averaged to be 1.31±0.11×10(8)m(-2)s(-1) and 7.67±2.55×10(9)K(5) for the cooling rates 20, 30, and 60°C/min.
authors.affiliation: Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, China.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, China. Electronic address: ZhaoG@ustc.edu.cn.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
authors.affiliation: School of Mechanical, Electronic and Industrial Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China. Electronic address: zhouxm@uestc.edu.cn.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, China.
authors.forename: Weiping
authors.initials: W
authors.lastname: Ding
authors.affiliation: Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA.
authors.forename: Zhiquan
authors.initials: Z
authors.lastname: Shu
authors.affiliation: Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA.
authors.forename: Dayong
authors.initials: D
authors.lastname: Gao
mesh_terms: D001692:Biological Transport / Q000502:physiology*; D002463:Cell Membrane Permeability; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology; D005615:Freezing; D057809:HEK293 Cells / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D007053:Ice
chemical_list: D003451:Cryoprotective Agents; D007053:Ice
keywords: Cryomicroscopy; Cryopreservation; HEK293T; Intracellular ice formation (IIF); Optimal cooling rate; Water transport