Targeted miR-17 Integration in CHO Cells Boosts Recombinant ACE2 Production in Proof-of-Concept Study

Chinese hamster ovary (CHO) cells are the workhorse of the biopharmaceutical industry, producing a large share of the world’s recombinant therapeutic proteins. A team of researchers has now reported a proof-of-concept method for inserting a specific microRNA into a defined genomic location of these cells, an intervention that was associated with substantially higher output of a recombinant protein in the clones they examined.

The study, published in BMC Biotechnology on 5 October 2026, was led by Setare Adibzadeh, Elham Bayat, Samira Komijani, Negin Sadat Hashemi Aval, Mohammad Ali Shokrgozar and Fatemeh Davami.

The central innovation lies in where the genetic payload was placed. Conventional microRNA engineering in CHO cells typically relies on random integration, in which transgenes land at unpredictable genomic sites. That randomness can introduce variability in transgene expression from clone to clone, complicating the selection of stable production lines. The researchers instead combined two genome-engineering approaches: CRIS-PITCh, a CRISPR-assisted precision integration method, and recombinase-mediated cassette exchange, or RMCE.

First, the team used CRIS-PITCh to install a Bxb1-compatible landing pad near the S100A locus in the CHO genome. This landing pad then served as a docking site for RMCE, allowing the researchers to swap in either a cassette expressing miR-17 or a scrambled control cassette at the same defined position. Because both the miR-17 construct and the control were integrated at an identical genomic site, differences in productivity between the resulting clones could be attributed more cleanly to the microRNA itself rather than to position effects.

Engineered clones were characterized using a battery of molecular assays, including junction PCR to confirm the intended integration events, flow cytometry, quantitative PCR, and reverse-transcription quantitative PCR. The researchers then evaluated cell growth, viability, and hrsACE2 production in the engineered lines.

The results were striking in the clones examined.

Productivity gains followed. The miR-17-expressing clone showed an approximately 2.3-fold increase in volumetric productivity and an approximately 2.8-fold increase in estimated specific productivity compared with the scramble control clone.

The authors note that microRNA engineering represents a potential strategy for this purpose, and their targeted approach is designed to sidestep the expression variability that plagues random integration methods.

The researchers are careful to frame the work as a proof of concept. The findings demonstrate the feasibility of combining CRIS-PITCh and RMCE for targeted microRNA engineering in recombinant CHO cells and suggest that targeted miR-17 expression may improve hrsACE2 production and culture longevity. However, the reported effects come from representative single-copy clones, and the authors explicitly state that further evaluation across independently derived clones is required to establish the generalizability of these effects. In other words, the productivity and viability benefits observed here cannot yet be assumed to hold across a broader panel of clones or in industrial-scale conditions.

Even with those caveats, the study adds a practical tool to the CHO engineering toolbox.

Subject of Research: Targeted integration of miR-17 in CHO cells using a CRIS-PITCh/RMCE hybrid system and its effect on recombinant ACE2 production

Article Title: Targeted integration of miR-17 using CRIS-PITCh/RMCE hybrid system in CHO cells is associated with increased recombinant ACE2 production

Article References: Adibzadeh, S., Bayat, E., Komijani, S., Hashemi Aval, N. S., Shokrgozar, M. A., & Davami, F. (2026). Targeted integration of miR-17 using CRIS-PITCh/RMCE hybrid system in CHO cells is associated with increased recombinant ACE2 production. BMC Biotechnology. https://doi.org/10.1186/s12896-026-01230-1

Image Credits: AI Generated

DOI: 10.1186/s12896-026-01230-1

Keywords: CHO cells, miR-17, CRIS-PITCh, RMCE, recombinant ACE2, hrsACE2, microRNA engineering, cell line engineering, volumetric productivity, specific productivity, culture longevity, BMC Biotechnology