The Chan Zuckerberg Initiative (CZI) has introduced rBio, an innovative AI model that reasons about cellular biology using detailed virtual cell simulations instead of traditional lab experiments, marking a notable shift toward computational methods in biomedical research. Published via bioRxiv, the model employs a “soft verification” approach—leveraging simulation-derived predictions as training signals—to flip the conventional ratio of wet-lab to computational work. According to Ana-Maria Istrate, senior research scientist at CZI and lead author, the aim is to invert the historical 90 percent experimental, 10 percent computational model, enabling more hypothesis testing digitally. Early results show rBio outperforms baseline large language models on benchmarks like PerturbQA, even rivaling versions trained with real experimental data. The design also emphasizes openness: tools, models, and platforms—including CZI’s virtual cell infrastructure—are being made open source to advance scientific collaboration.
Sources: ChanZuckerberg.com, Getco AI, Venture Beat
Key Takeaways
– Paradigm Shift: rBio flips the traditional biology workflow by prioritizing simulated training over physical lab experiments.
– Performance Gains: In benchmark tasks like gene perturbation prediction, rBio exceeds baseline AI models and matches experimental-data-trained variants.
– Open Science Commitment: CZI is making rBio and its supporting virtual cell platform freely accessible to accelerate research collaboration and innovation.
In-Depth
The Chan Zuckerberg Initiative’s release of rBio marks a careful and meaningful advancement in biomedical research—one that emphasizes efficiency without sacrificing rigor. At its heart, rBio represents the first AI model trained to understand and reason about cellular behavior using only virtual cell simulations. Historically, the process of biology has been labor-intensive, with most hypotheses tested in the lab first. CZI’s approach wisely proposes flipping that ratio. By using “soft verification,” rBio is trained on predictive signals from virtual cell models instead of relying exclusively on expensive and time-consuming experiments.
Notably, rBio doesn’t just suggest a theoretical shift—it delivers tangible results. Across various challenges, including the PerturbQA benchmark, it outperformed standard large language model baselines and matched the accuracy of variants trained on actual experimental data. That kind of performance suggests this method won’t merely supplement lab work—it may reshape how biology is conducted.
Still, rBio maintains a measured emphasis on responsibility and transparency. The model is being released through CZI’s open virtual cell platform, alongside code, tutorials, and associated tools. This open approach safeguards against black-box science and ensures that the broader community can scrutinize, build on, and benefit from the technology.
In sum, rBio represents a promising, pragmatic step toward faster, more cost-effective biomedical research. By combining AI with virtual cell models in a transparent and collaborative manner, CZI is not abandoning traditional methods—but rather enhancing them for a new era of science.

