Current Opinion in Biomedical Engineering最新文献

Protein circuit design is still in its infancy in terms of programmability. DNA nanotechnology, however, excels at this property and its community has created a myriad of circuits and assemblies following modular hierarchical design rules. In this mini-review, we reason that the rationales behind DNA nanotechnology can nurture protein circuit design, and the unique versatility orchestrated by groups of proteins can be further exploited to program cells. Community efforts to develop databases and design algorithms for standardizing and customizing protein modules could bring the programmability of protein circuits to a level comparable to DNA nanotechnology, ultimately empowering modular hierarchical protein circuit design.

Mammalian synthetic biology aims to engineer cellular behaviors for therapeutic applications, such as enhancing immune cell efficacy against cancers or improving cell transplantation outcomes. Programming complex biological functions necessitates an understanding of molecular mechanisms governing cellular responses to stimuli. Traditionally, synthetic biology has focused on transcriptional circuits, but recent advances have led to the development of synthetic protein circuits, leveraging programmable binding, proteolysis, or phosphorylation to modulate protein interactions and cellular functions. These circuits offer advantages including robust performance, rapid functionality, and compact design, making them suitable for cellular engineering or gene therapies. This review outlines the post-translational toolkit, emphasizing synthetic protein components utilizing proteolysis or phosphorylation to program mammalian cell behaviors. Finally, we focus on key differences between rewiring native signaling pathways and creating orthogonal behaviors, alongside a proposed framework for translating synthetic protein circuits from tool development to pre-clinical applications in biomedicine.

Engineering synthetic regulatory circuits with precise input–output behavior—a central goal in synthetic biology—remains encumbered by the inherent molecular complexity of cells. Non-linear, high-dimensional interactions between genetic parts and host cell machinery make it difficult to design circuits using first-principles biophysical models. We argue that adopting data-driven approaches that integrate modern machine learning (ML) tools and high-throughput experimental approaches into the synthetic biology design/build/test/learn process could dramatically accelerate the pace and scope of circuit design, yielding workflows that rapidly and systematically discern design principles and achieve quantitatively precise behavior. Current applications of ML to circuit design are occurring at three distinct scales: 1) learning relationships between part sequence and function; 2) determining how part composition determines circuit behavior; 3) understanding how function varies with genomic/host-cell context. This work points toward a future where ML-driven genetic design is used to program robust solutions to complex problems across diverse biotechnology domains.

The spatial distribution of the signaling molecules that mediate cell–cell communication and pattern formation is an important consideration for natural and engineered multicellular systems.

Signaling molecule concentration profiles directly impact cell response profiles, and various experimental techniques can be utilized to modulate these spatial distributions. Current strategies focused on physically or chemically modifying the extracellular space to affect signal distribution include performing experiments in microfluidic devices with dynamic user-controlled inputs and flow rates or adjusting the mesh sizes and protein binding affinities of extracellular matrix-mimicking hydrogels. Recent advances in synthetic biology have paved the way for new approaches that involve directly engineering the signaling molecules, their interactors, and their downstream effectors for fully orthogonal communication platforms.

The ability to precisely control cellular function in response to external stimuli can enhance the function and safety of cell therapies. In this review, we will detail how the modularity of protein domains has been exploited for cellular control applications, specifically through design of multifunctional synthetic constructs and controllable split moieties. These advances, which build on techniques developed by biologists, protein chemists and drug developers, harness natural evolutionary tendencies of protein domain fusion and fission. In this light, we will highlight recent advances towards the development of novel immunoreceptors, base editors, and cytokines that have achieved intriguing therapeutic potential by taking advantage of well-known protein evolutionary phenomena and have helped cells learn new tricks via synthetic biology. In general, protein modularity, i.e., the relatively facile separation or (re)assembly of functional single protein domains or subdomains, is becoming an enabling phenomenon for cellular engineering by allowing enhanced control of phenotypic responses.

Surgical reattachment of tendon to bone is a clinical challenge, with unacceptably high retear rates in the early period after repair. A primary reason for these repeated tears is that the multiscale toughening mechanisms found at the healthy tendon enthesis are not regenerated during tendon-to-bone healing. The need for technologies to improve these outcomes is pressing, and the tissue engineering community has responded with many advances that hold promise for eventually regenerating the multiscale tissue interface that transfers loads between the two dissimilar materials, tendon, and bone. This review provides an assessment of the state of these approaches, with the aim of identifying a critical agenda for future progress.

Osteochondral tissue represents a complex biochemical and biophysical gradient between two distinctly different types of tissue. Its poor regeneration capabilities necessitate tissue engineering intervention; however, its complex structure and composition pose an immense engineering challenge. Though bone and cartilage engineering separately have seen success, fabricating the graded interface between these two dissimilar tissue types requires understanding and collaboration between multiple often-disunited disciplines. This review showcases innovative tissue engineering strategies utilised for fabrication of osteochondral interfaces in an attempt to bridge this gap, and highlights the potential of biofabrication techniques – namely 3D bioprinting – in providing a path towards future advancement in osteochondral and interfacial tissue engineering.