Cell-penetrating peptide conjugates delivered antisense molecules that restored MBNL1 protein levels and improved disease symptoms in a myotonic dystrophy mouse model without toxicity.
5.38-fold better therapeutic windowThe best CPP-PMO candidates achieved effective MBNL1 restoration at doses far below toxic levels, offering a much wider safety margin than previous approaches.
What the researchers found
Peptide-conjugated antisense oligonucleotides (CPP-PMOs) targeting miR-23b and miR-218 significantly increased MBNL1 protein levels in myotonic dystrophy type 1 (DM1) cells. Some candidates achieved this at concentrations nearly two orders of magnitude below the median toxic concentration, with up to a 5.38-fold better therapeutic window compared to previous antagomiR approaches.
In HSALR mouse models, intravenous injections of CPP-PMOs improved molecular, histopathological, and functional disease phenotypes without signs of toxicity, demonstrating successful in vivo delivery to affected tissues.
Why it matters
Myotonic dystrophy type 1 currently has no approved treatment that addresses its root molecular cause. A major barrier has been delivering therapeutic molecules to affected muscle and nerve tissues. By conjugating antisense oligonucleotides to cell-penetrating peptides, this study demonstrates a delivery strategy that works both in cells and in living animals — a critical step toward viable DM1 therapy.
How the study worked
The researchers designed antisense oligonucleotides (antimiRs) using phosphorodiamidate morpholino oligonucleotide (PMO) chemistry, conjugated to cell-penetrating peptides. These CPP-PMOs were tested in DM1 patient-derived cells to measure MBNL1 protein levels and toxicity, then administered via intravenous injection in HSALR transgenic mice — an established DM1 animal model — to assess molecular, tissue-level, and functional outcomes.
Who was studied
DM1 patient-derived cells and HSALR transgenic mice
What this study cannot tell us
The study used a mouse model (HSALR) that mimics DM1 but does not perfectly replicate the human disease. Long-term safety and efficacy beyond the study period were not assessed. Translation from mouse to human dosing and tissue distribution remains uncertain. The sample sizes for animal experiments were not specified in the abstract.
How to read the evidence
This is a preclinical study combining in vitro cell experiments with in vivo mouse model testing. While it demonstrates promising proof-of-concept results, it has not yet been tested in human clinical trials.
When this study was published
Published in 2023, this study represents recent progress in peptide-based delivery for rare disease therapeutics and is highly current.
The bigger picture
Delivering therapeutics to the right tissues is one of the biggest challenges in treating neuromuscular diseases like DM1. This study shows that cell-penetrating peptides can solve that delivery problem for antisense therapies, potentially opening the door not just for DM1 treatment but for other diseases where getting drugs inside cells is the bottleneck.
Questions still open
- Will these CPP-PMO conjugates show the same safety and efficacy profile in human patients as they did in mice?
- Could this peptide-conjugated delivery approach be adapted for other neuromuscular diseases beyond DM1?
- What is the optimal dosing schedule for long-term treatment in a clinical setting?
Common questions
What is myotonic dystrophy type 1 and why is it hard to treat?
How do cell-penetrating peptides help in this study?
Read the original research
Peptide-conjugated antimiRs improve myotonic dystrophy type 1 phenotypes by promoting endogenous MBNL1 expression.
Molecular therapy. Nucleic acids, 34, 102024
Citation
González-Martínez, Irene; Cerro-Herreros, Estefanía; Moreno, Nerea; García-Rey, Andrea; Espinosa-Espinosa, Jorge; Carrascosa-Sàez, Marc; Piqueras-Losilla, Diego; Arzumanov, Andrey; Seoane-Miraz, David; Jad, Yahya; Raz, Richard; Wood, Matthew J; Varela, Miguel A; Llamusí, Beatriz; Artero, Rubén. (2023). Peptide-conjugated antimiRs improve myotonic dystrophy type 1 phenotypes by promoting endogenous MBNL1 expression.. Molecular therapy. Nucleic acids, 34, 102024. https://doi.org/10.1016/j.omtn.2023.09.001