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Ben Kleinstiver @bkleinstiver.bsky.social · 12/08/2026

Congrats on the really elegant and interesting work!

Reposted by Ben Kleinstiver

Connor Horton @connorhorton.bsky.social · 11/08/2026

I'm excited to share our work providing the first complete mechanistic picture of how R2 proteins nick the second strand, out today in @pnas.org! ✂️🧬 This step in retrotransposition has long been mysterious, but crucial for understanding R2's. Check it out: www.pnas.org/doi/10.1073/... A thread 🧵:

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Sternberg Lab @sternberglab.bsky.social · 03/08/2026

Out now! In collaboration with Hiroshi Nishimasu's lab, we uncover how a dual reverse transcriptase immune system builds double-stranded DNA from both RNA and protein templates. www.cell.com/cell/abstrac... Previous thread for the preprint: bsky.app/profile/ster...

cell.com

Coordinated RNA- and protein-templated synthesis of double-stranded DNA by a dual reverse transcriptase immune system

Bacterial reverse transcriptases defend against viruses, yet how their DNA products stop infection remains unknown. Bacteriophage inhibition of a host recombination enzyme activates the DRT3 defense s...

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

What's next? 🔮 With non-toxic DNA donors that can be delivered in vivo, we're optimistic that advances in enzyme engineering can move quickly ahead ⏩. One step closer to pan-mutation editing that can be more widely applied to broader sets of patients. 🤞

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

Together, our study showed that this new DNA format can enable efficient and non-toxic kilobase-scale DNA insertions into the genome 🧬🎉. Congrats to @connorjtou.bsky.social & the entire team of collaborators who enabled this work - a true multi-lab effort.

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

The net result is that oDNAs are no longer toxic and do not induce rapid lethality in mice like dsDNA. Importantly, we were able to observe in vivo kilobase-sized gene insertion in the liver of mice for the first time without using viruses to shuttle in the DNA cargo!

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

Cutting a very long story short: we found that oDNAs were immune stealth when injected into mice, and no longer provoked a rapid and immune response like what we observed even at a reasonable dose of dsDNA. Losing most of one DNA strand on the DNA donor makes this DNA format evasive to cGAS/STING!

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

How did we solve this challenge? 💡 To circumvent toxicity, @connorjtou.bsky.social hatched 🐣 a plan to develop circular single stranded DNAs (cssDNAs) that are 'stealth' to immune sensors, and annealing of a short DNA oligo should recreate a functional dsDNA enzyme binding site - called an oDNA ⭕️

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

Unfortunately, most approaches to insert kb-sized sequences into cells require large dsDNA donors, resulting in toxicity in cells & mice 🐭. This toxicity is a barrier for many leading-edge DNA insertion tools since they all require dsDNA templates (except for retrotransposases that use require RNAs)

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

It turns out, that delivering large pieces of double-stranded DNA into cells activates our innate immune response. These immune pathways have evolved to detect 'foreign' DNA in the cytoplasm of cells, alerting that something is wrong and initiating a signaling cascade. 🚨

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

What was the problem? 🤔 Gene editing technologies to insert large pieces of DNA into the genome are typically comprised of 2 or more components: (1) a DNA donor molecule that encodes the correct gene, & (2) an enzyme that mediates the insertion reaction. We found this process to be quite toxic...

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

Inserting a 'wild-type' gene could apply to many patients, which contrasts with correcting underlying genetic mutations one DNA letter at a time. Although fixing single base mutations is possible, there are challenges for scaling these approaches in terms of time, cost, & clinical regulatory paths.

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

Why was this an important advance? ⏩ Inserting large DNA segments into the genome could transform the development of therapies to enable their application across a wide diversity of patients. Think about inserting 1,000s of DNA letters (kb) encoding an entire gene into a precise genomic location.

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/07/2026

A belated re-post after a brief sci-media hiatus - congratulations to @connorjtou.bsky.social & the team! We sought to overcome a key challenge for inserting large DNAs into the genome: toxicity & innate immune responses. 🧬 🚫 Our paper was published in @nature.com: www.nature.com/articles/s41...

nature.com

Immune evasive DNA donors and recombinases license kilobase-scale writing - Nature

INSTALL overcomes fundamental challenges for DNA delivery and integration methods by synergizing immune-stealth nucleic acids with recombinases to enable kilobase-scale integration strategies without ...

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Reposted by Ben Kleinstiver

CGM at MGB @cgm-mgh.bsky.social · 12/05/2026

Congratulations to Emily King, PhD (mentored by @bkleinstiver.bsky.social) who successfully defended her PhD thesis last week! The broader goal of her work is to shorten the path between technology development and therapeutic translation.

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Reposted by Ben Kleinstiver

Nicholas Southern @neuroscinikolai.bsky.social · 05/07/2026

This project was driven by @m--mueller.bsky.social, a sharp and hardworking student who I had the pleasure of supervising the past 1.5 years (Here he is rocking one of our new POGO-PANCE t-shirts). He's now moved on to @bkleinstiver.bsky.social's group for an internship — definitely one to watch! 😄

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Reposted by Ben Kleinstiver

CGM at MGB @cgm-mgh.bsky.social · 16/03/2026

Congratulations to CGM and Pathology Faculty Dr. Benjamin Kleinstiver (@bkleinstiver.bsky.social), winner of the 2026 Martin Prize in Fundamental Research!

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Ben Kleinstiver @bkleinstiver.bsky.social · 10/03/2026

Here's a link to the job posting where you can apply in the MGB career portal: massgeneralbrigham.wd1.myworkdayjobs.com/MGBExternal/... Learn more about our research here: www.kleinstiverlab.org

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Ben Kleinstiver @bkleinstiver.bsky.social · 10/03/2026

We're seeking candidates, typically graduating seniors, for ~2 years of post-bac research experience before applying to graduate school, medical school, etc. If you're interested to learn more about the next generation of medicines, please reach out and apply!

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Ben Kleinstiver @bkleinstiver.bsky.social · 10/03/2026

Interested in gaining research experience, and curious about genome editing tool development and their application to treat human diseases? 🧬 🧫 We are hiring!! Join us at Mass General Hospital in Boston! 📣 massgeneralbrigham.wd1.myworkdayjobs.com/MGBExternal/...

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/10/2025

An inspirational panel this morning with none other than baby KJ himself - highlighting the stories of heroes @ahrensnicklas.bsky.social & @kiranmusunuru.bsky.social ( hosted by @jasonmast.bsky.social). Crescendo: KJ's Dad on watching 🏈 with his son: "This is what we thought we would never get". ❤️👏

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/10/2025

Congrats to @connorjtou.bsky.social on being named a 2025 #STATWunderkind. His enthusiasm in the lab is contagious and he thrives on doing really hard things. Really well deserved recognition for an innovator and emerging leader in our field! 👏 🙌 @mgbresearch.bsky.social @harvardmed.bsky.social

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Reposted by Ben Kleinstiver

ACTA2 Alliance @acta2alliance.bsky.social · 12/09/2025

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

t.co

https://bit.ly/gene_therapy_R179H

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Ben Kleinstiver @bkleinstiver.bsky.social · 12/09/2025

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...

rdcu.be

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...

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Ben Kleinstiver @bkleinstiver.bsky.social · 12/09/2025

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 · 12/09/2025

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 · 12/09/2025

@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 · 12/09/2025

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 · 12/09/2025

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 · 12/09/2025

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 · 12/09/2025

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 · 12/09/2025

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 · 12/09/2025

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 · 12/09/2025

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 · 12/09/2025

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 · 12/09/2025

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...

nature.com

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 ...

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Reposted by Ben Kleinstiver

Martin Pacesa @martinpacesa.bsky.social · 27/08/2025

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 · 03/07/2025

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 · 23/05/2025

🚨 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 · 16/05/2025

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..

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Reposted by Ben Kleinstiver

Sternberg Lab @sternberglab.bsky.social · 15/05/2025

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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pdhsu.bsky.social @pdhsu.bsky.social · 15/05/2025

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 · 16/05/2025

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...

nytimes.com

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

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/05/2025

For more about how Rachel created this bespoke Cas9 protein, see here! bsky.app/profile/bkle...

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Ben Kleinstiver @bkleinstiver.bsky.social · 16/05/2025

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 🙏

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Eric Topol @erictopol.bsky.social · 15/05/2025

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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Michael Baym @baym.lol · 14/05/2025

Yesterday, the NIH R35 “Outstanding Investigator” grant to fund scientists in my lab studying antibiotic resistance was terminated for reasons not related to the content of the science, or any actions taken by me or members of my lab

A screenshot of the termination notice showing "Outstanding Investigator Grants"

A screenshot of the termination notice with "This award is terminated effective the date of this award, due to unsafe antisemitic actions that suggest the institution lacks concern for the safety and wellbeing of Jewish students." highlighted

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