Nature Biomedical Engineering最新文献

Biomolecular condensates, which arise from liquid–liquid phase separation within cells, may provide a means of enriching and prolonging the retention of small-molecule drugs within cells. Here we report a method for the controlled in situ formation of biomolecular condensates as reservoirs for the enrichment and retention of chemotherapeutics in cancer cells, and show that the approach can be leveraged to enhance antitumour efficacies in mice with drug-resistant tumours. The method involves histones as positively charged proteins and doxorubicin-intercalated DNA strands bioorthogonally linked via a click-to-release reaction between trans-cyclooctene and tetrazine groups. The reaction temporarily impaired the phase separation of histones in vitro, favoured the initiation of liquid–liquid phase separation within cells and led to the formation of biomolecular condensates that were sufficiently large to be retained within tumour cells. The controlled formation of biomolecular condensates as drug reservoirs within cells may offer new options for boosting the efficacies of cancer therapies.

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) lack nanoscale structures essential for efficient excitation–contraction coupling. Such nanostructures, known as dyads, are frequently disrupted in heart failure. Here we show that the reduced expression of cardiomyopathy-associated 5 (CMYA5), a master protein that establishes dyads, contributes to dyad disorganization in heart failure and to impaired dyad assembly in hiPSC-CMs, and that a miniaturized form of CMYA5 suitable for delivery via an adeno-associated virus substantially improved dyad architecture and normalized cardiac function under pressure overload. In hiPSC-CMs, the miniaturized form of CMYA5 increased contractile forces, improved Ca²⁺ handling and enhanced the alignment of sarcomere Z-lines with ryanodine receptor 2, a protein that mediates the sarcoplasmic release of stored Ca²⁺. Our findings clarify the mechanisms responsible for impaired dyad structure in diseased cardiomyocytes, and suggest strategies for promoting dyad assembly and stability in heart disease and during the derivation of hiPSC-CMs.

In mammalian cells, signalling pathways orchestrate cellular growth, differentiation and survival, as well as many other processes that are essential for the proper functioning of cells. Here we describe cutting-edge genetic-engineering technologies for the rewiring of signalling networks in mammalian cells. Specifically, we describe the recombination of native pathway components, cross-kingdom pathway transplantation, and the development of de novo signalling within cells and organelles. We also discuss how, by designing signalling pathways, mammalian cells can acquire new properties, such as the capacity for photosynthesis, the ability to detect cancer and senescent cell markers or to synthesize hormones or metabolites in response to chemical or physical stimuli. We also review the applications of mammalian cells in biocomputing. Technologies for engineering signalling pathways in mammalian cells are advancing basic cellular biology, biomedical research and drug discovery.

Circularization can improve RNA persistence, yet simple and scalable approaches to achieve this are lacking. Here we report two methods that facilitate the pursuit of circular RNAs (cRNAs): cRNAs developed via in vitro circularization using group II introns, and cRNAs developed via in-cell circularization by the ubiquitously expressed RtcB protein. We also report simple purification protocols that enable high cRNA yields (40-75%) while maintaining low immune responses. These methods and protocols facilitate a broad range of applications in stem cell engineering as well as robust genome and epigenome targeting via zinc finger proteins and CRISPR-Cas9. Notably, cRNAs bearing the encephalomyocarditis internal ribosome entry enabled robust expression and persistence compared with linear capped RNAs in cardiomyocytes and neurons, which highlights the utility of cRNAs in these non-dividing cells. We also describe genome targeting via deimmunized Cas9 delivered as cRNA and a long-range multiplexed protein engineering methodology for the combinatorial screening of deimmunized protein variants that enables compatibility between persistence of expression and immunogenicity in cRNA-delivered proteins. The cRNA toolset will aid research and the development of therapeutics.

The paucity of high-quality medical imaging datasets could be mitigated by machine learning models that generate compositionally diverse images that faithfully represent medical concepts and pathologies. However, large vision-language models are trained on natural images, and the diversity distribution of the generated images substantially differs from that of medical images. Moreover, medical language involves specific and semantically rich vocabulary. Here we describe a domain-adaptation strategy for large vision-language models that overcomes distributional shifts. Specifically, by leveraging publicly available datasets of chest X-ray images and the corresponding radiology reports, we adapted a latent diffusion model pre-trained on pairs of natural images and text descriptors to generate diverse and visually plausible synthetic chest X-ray images (as confirmed by board-certified radiologists) whose appearance can be controlled with free-form medical text prompts. The domain-adaptation strategy for the text-conditioned synthesis of medical images can be used to augment training datasets and is a viable alternative to the sharing of real medical images for model training and fine-tuning.