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Reposted by Ben Kleinstiver

ACTA2 Alliance @acta2alliance.bsky.social · Sep 12

Back in June, at our MSMDS conference, we shared how researchers were advancing their work on gene editing for ACTA2 R179H.

Today, we can celebrate that this effort is now peer-reviewed & published in @nature.com! 🎉
t.co/6WjTMRnAOi

#MSMDS #ACTA2 @markelindsay.bsky.social @bkleinstiver.bsky.social

https://bit.ly/gene_therapy_R179H

t.co

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

Thanks, John! Hope all is well

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

Please check out these links:
- free link to our manuscript: rdcu.be/eFAEz
- MGH press release: www.massgeneralbrigham.org/en/about/new...
- coverage in Fierce Biotech: www.fiercebiotech.com/research/cus...
- coverage in Precision Medicine Online: www.precisionmedicineonline.com/regulatory-n...

Treatment of a severe vascular disease using a bespoke CRISPR–Cas9 base editor in mice

Nature Biomedical Engineering - Engineering a mutant-specific customized base editor precisely corrects a mutation while minimizing bystander edits, leading to substantial phenotypic recovery in...

rdcu.be

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

Together, our results demonstrate the value in using the mutant allele as a substrate in engineering campaigns, resulting in a bespoke enzyme with improved efficacy and safety compared to wild-type SpCas9 base editors.
🔧🧬 🚀

This was a wonderful collaboration and was funded by $$ from the NIH.

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

In vivo base editing via AAV9 or a smooth muscle cell tropic capsid AAV-PR (@casey-maguire-lab.bsky.social) substantially extended lifespan of treated MSMDS mice (+ key phenotypic changes). Notably, most AAV-ABE treated MSMDS mice died from bowel impaction, which should be avoidable in human.

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

@markelindsay.bsky.social and Dr. Musolino's labs created an MSMDS mouse model (that recapitulated many human phenotypes!), which we then utilized for in vivo experiments to deliver our optimized enhanced VRQR (eVRQR) ABE via a dual AAV approach. 🐁

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

We then performed a comprehensive off-target nomination workflow via an updated GUIDE-seq2 pipeline and the base editor-specific CHANGE-seq-BE assay, followed by rhAmpSeq-based validation of OTs (finding evidence of a small number of intergenic OTs).

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

To maximize on-target editing at this NGA PAM target site, we undertook a mutant allele-specific engineering approach to develop a bespoke enzyme with enhanced efficiency. Stacking activity-potentiating mutations with VRQR improved correction with minimal bystanders! 💯 ⬆️

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

To avoid this bystander we spatially minimized access to the M178 adenine by shifting the edit window of the ABE by 4 nt. Using either a PAM-relaxed SpG enzyme (@russelltwalton.bsky.social) or our more selective SpCas9-VRQR, this new target site dramatically minimized the M178V bystander! 🍻

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

By testing the impact of ACTA2 variant overexpression in human smooth muscle cells, we found that the M178V bystander edit resulted in disrupted actin polymerization; not as severely as the MSMDS R179H mutation, but this is a bystander edit that should be avoided. 🫨

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

When testing latest generation ABEs in an ACTA2 R179H cell line, we observed high levels of R179H correction (🎉!), but unfortunately most corrected alleles also contained a bystander edit that causes an ACTA2 M178V mutation (😩🤔). Does this bystander edit matter?

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

MSMDS is caused by a point mutation in the ACTA2 gene, which results in an R179H amino acid substitution - a mutation that should be correctable using adenine base editors (ABEs).

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

Multi-systemic smooth muscle dysfunction syndrome (MSMDS) is a rare a genetic vascular disease affecting children that Dr. Musolino sees in clinic, known to cause stroke, aortic dissection, and death. There are no therapies, motivating us to explore genome editing-based Tx for these patients.

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

This project has been a 5+ yr collaboration with Patricia Musolino and @markelindsay.bsky.social's groups, involving 30 co-authors! 🤝🙏🤲

Huge thanks to co-first authors Christiano Alves, Sabya Das, and Vijay Krishnan, and members from my group Leillani Ha, Hannah Stutzman, Lauren Fox, and others!

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Ben Kleinstiver @bkleinstiver.bsky.social · Sep 12

Optimization of a bespoke base editor to treat a severe pediatric vascular disease! 🫀🧬
Our manuscript describes:
1️⃣ Engineering a target-specific BE🧬
2⃣ A *must avoid* bystander edit that occurs with WT SpCas9 BEs! 🙅‍♂️
3⃣ Extension of lifespan after in vivo editing! 🐁✅

www.nature.com/articles/s41...

Treatment of a severe vascular disease using a bespoke CRISPR–Cas9 base editor in mice - Nature Biomedical Engineering

Engineering a mutant-specific customized base editor precisely corrects a mutation while minimizing bystander edits, leading to substantial phenotypic recovery in mouse models of multisystemic smooth ...

www.nature.com

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Reposted by Ben Kleinstiver

Martin Pacesa @martinpacesa.bsky.social · Aug 27

Exciting to see our protein binder design pipeline BindCraft published in its final form in @Nature ! This has been an amazing collaborative effort with Lennart, Christian, @sokrypton.org, Bruno and many other amazing lab members and collaborators.

www.nature.com/articles/s41...

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Reposted by Ben Kleinstiver

Max Wilkinson @maxewilkinson.bsky.social · Jul 3

If you like transposons...
If you you love genome editing...
Or if you just like random bird animations,

we have the paper for you!

We (@kedmonds.bsky.social et al) are happy to share our work turning a songbird retrotransposon into a genome editing tool. 🐣 (1/n)

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Reposted by Ben Kleinstiver

Dimitrios L. Wagner @dlwagner.bsky.social · May 23

🚨 Our work on optimizing single-stranded DNA donors with Cas12a binding moieties is published at @moltherapy.bsky.social Nucleic Acids! 🧪

Since the preprint, we added two super interesting findings. Short 🧵👇 (1/5)

www.cell.com/molecular-th...

#ImmunoSky #GeneEditing #CARTcells

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Ben Kleinstiver @bkleinstiver.bsky.social · May 16

Less than one day to celebrate a major win for science, before returning to our regularly scheduled programming of destruction of the American scientific enterprise and capitulation..

Chiara Masnovo @chiaramasnovophd.bsky.social · May 16

Having a hard time processing this. HHMI is pausing all competitions. Very demoralizing for early career scientists like me @hhmi.org

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Reposted by Ben Kleinstiver

Sternberg Lab @sternberglab.bsky.social · May 15

1/10 Today in @science.org in collaboration with
the Liu group we report the development of a laboratory-evolved CRISPR-associated transposase (evoCAST) that supports therapeutically relevant levels of RNA-programmable gene insertion in human cells. drive.google.com/file/d/1I-Ub...

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Reposted by Ben Kleinstiver

pdhsu.bsky.social @pdhsu.bsky.social · May 15

Genomes encode biological complexity, which is determined by combinations of DNA mutations across millions of bases

In new work @arcinstitute.org, we report the discovery and engineering of the first programmable DNA recombinases capable of megabase-scale human genome rearrangement

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Reposted by Ben Kleinstiver

Nature Biotechnology @natbiotech.nature.com · May 16

A gene-editing treatment used on a 9½-month-old boy with a rare condition has the potential to help people with thousands of other uncommon genetic diseases #NBTNewsBeat www.nytimes.com/2025/05/15/h...

Baby Is Healed With World’s First Personalized Gene-Editing Treatment

www.nytimes.com

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Ben Kleinstiver @bkleinstiver.bsky.social · May 16

For more about how Rachel created this bespoke Cas9 protein, see here!

bsky.app/profile/bkle...

Ben Kleinstiver @bkleinstiver.bsky.social · Apr 22

In @nature.com we describe the use of scalable #proteinengineering & #machinelearning to predict millions of bespoke CRISPR enzymes, offering safer & more efficient genome editing tools 🧬🖥️ @rachelsilverstein9.bsky.social @mgbresearch.bsky.social @harvardmed.bsky.social
www.nature.com/articles/s41...

Custom CRISPR—Cas9 PAM variants via scalable engineering and machine learning - Nature

Nature - Custom CRISPR—Cas9 PAM variants via scalable engineering and machine learning

www.nature.com

Ben Kleinstiver @bkleinstiver.bsky.social · May 16

An incredible collaborative effort led by @kiranmusunuru.bsky.social @ahrensnicklas.bsky.social @urnov.bsky.social & others.
Congratulations to @rachelsilverstein9.bsky.social who designed the Cas9 enzyme that went into this drug.
Wishing K.J. & his family all the best 🙏

NPR @npr.org · May 15

For the first time, doctors have created a customized treatment using the revolutionary gene-editing technique known as CRISPR to treat a baby with a rare, life-threatening genetic disorder.

A promising genetic treatment tailor-made for a baby born with a rare disorder

For the first time, doctors have created a customized treatment using the revolutionary gene-editing technique known as CRISPR to treat a baby with a rare, life-threatening genetic disorder.

www.npr.org

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Reposted by Ben Kleinstiver

Eric Topol @erictopol.bsky.social · May 15

Today "a milestone in the evolution of personalized therapies for rare & ultra-rare inborn errors of metabolism"
—the 1st human to undergo custom genome editing
—from decades of NIH funded research
www.nejm.org/doi/full/10....
@nejm.org
www.nejm.org/doi/full/10....
www.nytimes.com/2025/05/15/h...

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