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Updated: Apr 14, 2026

Direct Protein Delivery to Mammalian Cells Using Cell-permeable Cys2-His2 Zinc-finger Domains
Published on: March 25, 2015
Efficient intracellular delivery of native proteins.
Diego S D'Astolfo1, Romina J Pagliero2, Anita Pras3
1KNAW-Hubrecht Institute, Uppsalalaan 8, 3584 CT Utrecht, the Netherlands; University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, the Netherlands.
We developed induced transduction by osmocytosis and propanebetaine (iTOP), a novel method for direct protein delivery into cells. This technique efficiently delivers proteins, including Cas9 for gene editing, into various cell types.
Area of Science:
- Cell Biology
- Molecular Biology
- Biotechnology
Background:
- Direct intracellular protein delivery is challenging, limiting cellular process intervention.
- Current methods often rely on indirect delivery via DNA or mRNA encoding effector proteins.
Purpose of the Study:
- To develop a novel method for direct and efficient intracellular protein delivery.
- To demonstrate the utility of this method for transient cell manipulation and gene editing.
Main Methods:
- Induced transduction by osmocytosis and propanebetaine (iTOP) utilizes hypertonicity-induced macropinocytosis and propanebetaine.
- iTOP facilitates the transduction of proteins into diverse primary cell types.
Main Results:
- iTOP achieves highly efficient protein transduction across various cell types.
- The method successfully delivered recombinant Cas9 protein and short guide RNA for non-integrative gene targeting.
Conclusions:
- iTOP provides a robust platform for direct protein delivery, overcoming previous limitations.
- This technique enables transient cellular manipulation for permanent cellular changes, exemplified by efficient CRISPR-Cas9 gene editing.
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