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Updated: Jan 4, 2026
Delivery of Therapeutic siRNA to the CNS Using Cationic and Anionic Liposomes
Published on: July 23, 2016
Cholesterol grafted cationic lipopolymers: Potential siRNA carriers for selective chronic myeloid leukemia therapy
K C Remant1, Bindu Thapa2, Juliana Valencia-Serna3
1Department of Chemical & Material Engineering, Faculty of Engineering, University of Alberta, Edmonton, Alberta, Canada.
Abstract:
Synthetic siRNA technology has emerged as a promising approach for molecular therapy of cancer but, despite its potential for post-transcriptional gene silencing, there is an urgent need to develop efficient delivery systems particularly for difficult-to-transfect, anchorage-independent cells. In this study, we designed highly hydrophobic cationic lipopolymers by grafting cholesterol (Chol) onto low-molecular weight (0.6, 1.2, and 2.0 kDa) polyethylenimines (PEIs) to enable specific siRNA therapy to chronic myeloid leukemia (CML) cells. The siRNA binding by PEI-Chol led to nano-sized (100-200 nm diameter) polyplexes with enhanced ζ-potential (+20 to +35 mV) and ability to protect the loaded siRNA completely in fresh serum. The siRNA delivery to CML (K562) cells was proportional to degree of substitution and, unexpectedly, inversely proportional to molecular size of the polymeric backbone. Chol grafting with as little as ~1.0 Chol/PEI on 0.6 and 1.2 kDa PEIs enabled silencing of the reporter Green Fluorescent Protein gene as well as the endogenous BCR-Abl oncogene in K562 cells. The PEI-Chol mediated delivery of siRNAs specific for BCR-Abl and KSP genes significantly arrested the growth the cells which was significantly reflected in colony formation potency of K562 cells. BCR-Able siRNA mediated therapeutic efficacy was also observed in significantly increased caspase activity and apoptosis of K562 cells. Thus, Chol-grafted low-molecular weight PEIs appear to be unique siRNA carriers to realize the molecular therapy in CML cells.
Insights
Researchers developed cholesterol-grafted polyethylenimines (PEI-Chol) for targeted siRNA delivery to chronic myeloid leukemia (CML) cells. This novel system effectively silenced cancer genes, inhibiting CML cell growth and promoting apoptosis for potential molecular therapy.
Area of Science:
- Biotechnology
- Nanomedicine
- Molecular Biology
Background:
- Synthetic small interfering RNA (siRNA) holds promise for cancer molecular therapy via post-transcriptional gene silencing.
- Efficient delivery systems are crucial, especially for challenging, anchorage-independent cancer cells like those in chronic myeloid leukemia (CML).
Purpose of the Study:
- To design and evaluate novel, hydrophobic cationic lipopolymers for targeted siRNA delivery to CML cells.
- To investigate the efficacy of these carriers in gene silencing and therapeutic effects on CML cells.
Main Methods:
- Grafting cholesterol (Chol) onto low-molecular weight polyethylenimines (PEIs) to create PEI-Chol lipopolymers.
- Characterization of PEI-Chol/siRNA polyplexes for size, ζ-potential, and serum stability.
- Assessment of siRNA delivery, gene silencing (GFP, BCR-Abl, KSP), cell growth arrest, colony formation, caspase activity, and apoptosis in K562 CML cells.
Main Results:
- Nano-sized (100-200 nm) PEI-Chol polyplexes with enhanced ζ-potential (+20 to +35 mV) were formed, protecting siRNA in serum.
- siRNA delivery and gene silencing efficacy correlated with cholesterol substitution and inversely with PEI molecular weight.
- PEI-Chol effectively silenced BCR-Abl and KSP genes, significantly inhibiting K562 cell growth, colony formation, and inducing apoptosis.
Conclusions:
- Cholesterol-grafted low-molecular weight PEIs are effective carriers for siRNA delivery to CML cells.
- This technology shows potential for realizing molecular therapy in CML by targeting specific oncogenes.
- PEI-Chol offers a unique approach for overcoming delivery challenges in difficult-to-transfect cancer cells.
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