Poly-L-lysine hydrobromide (MW 150000-300000) is a high-molecular-weight, positively charged synthetic polypeptide widely used to enhance cell adhesion to culture surfaces. Poly-L-lysine hydrobromide exhibits excellent water solubility and biocompatibility and serves as an essential reagent for the culture of primary neurons, epithelial cells, and stem cells[1-2]. When coated onto substrates, Poly-L-lysine hydrobromide forms a stable, uniform layer that resists detachment during long-term culture[3], and Poly-L-lysine hydrobromide is also employed as a drug-delivery vehicle[4].
In vitro, Poly-L-lysine hydrobromide (20μg/mL) applied to HeLa cells for 30min–2h significantly inhibits tumor-cell DNA, RNA, and protein synthesis, alters membrane permeability, induces leakage of intracellular small molecules, and causes cell rounding, granulation, and lysis[5]. Treatment of Jurkat T-cells, THLE-3 hepatocyte-like cells, and human umbilical vein endothelial cells (HUVEC) with Poly-L-lysine hydrobromide(10–30μg/ml) for 24h markedly induces apoptosis, as evidenced by mitochondrial membrane potential loss, cytochrome c release, and activation of caspase-9 and caspase-3.[6].
In vivo, Poly-L-lysine hydrobromide (50mg/kg/day; i.v.) administered to C57BL/6 mice bearing subcutaneous B16F10 melanoma on days 1 and 2 post-inoculation markedly suppresses tumor neovascularization, induces widespread tumor-cell apoptosis/necrosis, and delays solid-tumor growth[7]. A single intraluminal insertion of a 5-0 monofilament nylon suture coated with 0.1%w/v Poly-L-lysine hydrobromide into the internal carotid artery of C57BL/6 mice produces 30–180min middle-cerebral-artery occlusion followed by 24h reperfusion, resulting in 100% consistent infarcts in expected ipsilateral regions (striatum, thalamus, hippocampus, frontoparietal cortex) and time-dependent neurological deficits[8].
References:
[1] Olivera-Ardid S, Bello-Gil D, Tuzikov A et al, et al. Poly-L-Lysine-Based αGal-Glycoconjugates for Treating Anti-αGal IgE-Mediated Diseases. Front Immunol. 2022 Mar 31;13:873019.
[2] Hatcher JM, Zwirek M, Sarhan AR, et al. Development of a highly potent and selective degrader of LRRK2. Bioorg Med Chem Lett. 2023 Oct 1;94:129449.
[3] Tengberg JF, Russo F, Benned-Jensen T, et al. LRRK2 and RAB8A regulate cell death after lysosomal damage in macrophages through cholesterol-related pathways. Neurobiol Dis. 2024 Nov;202:106728.
[4] Harsiddharay RK, Gupta A, Singh PK, et al. Poly-L-lysine Coated Oral Nanoemulsion for Combined Delivery of Insulin and C-Peptide. J Pharm Sci. 2022 Dec;111(12):3352-3361.
[5] Arnold LJ Jr, Dagan A, Gutheil J, et al. Antineoplastic activity of poly(L-lysine) with some ascites tumor cells. Proc Natl Acad Sci U S A. 1979 Jul;76(7):3246-50.
[6] Symonds P, Murray JC, Hunter AC, et al. Low and high molecular weight poly(L-lysine)s/poly(L-lysine)-DNA complexes initiate mitochondrial-mediated apoptosis differently. FEBS Lett. 2005 Nov 7;579(27):6191-8.
[7] Al-Jamal KT, Al-Jamal WT, Akerman S, et al. Systemic antiangiogenic activity of cationic poly-L-lysine dendrimer delays tumor growth. Proc Natl Acad Sci U S A. 2010 Mar 2;107(9):3966-71.
[8] Belayev L, Busto R, Zhao W, et al. Middle cerebral artery occlusion in the mouse by intraluminal suture coated with poly-L-lysine: neurological and histological validation. Brain Res. 1999 Jul 3;833(2):181-90.
Experimental Protocol:
1. Prepare a 1mg/mL poly-lysine stock solution in sterile water, sterilize by filtration through a 0.22μm microporous filter, and store in aliquots at -20°C.
2. Dilute to 0.1mg/mL with sterile ultrapure water before use.
Note: It is recommended to use plastic containers and graduated cylinders when mixing or storing the solution and coating slides. Do not add fresh solution to used solution.
3. Equilibrate the diluted poly-lysine working solution to room temperature (18–26°C) before use.
4. Add the poly-lysine working solution to the culture vessel, gently rock to ensure even coverage, and incubate at room temperature for 5–10 minutes.
5. Aspirate the working solution, wash the culture vessel 1–2 times with PBS, and dry in an oven at 60°C for 1 hour or at room temperature (18–26°C) overnight.
Note: Poly-lysine is cytotoxic; the concentration of the coating solution may be reduced depending on specific experimental requirements.