Quorum-Quenching Human Designer Cells for Closed-Loop Control of Pseudomonas aeruginosa Biofilms

Current antibiotics gradually lose their efficacy against chronic Pseudomonas aeruginosa infections due to development of increased resistance mediated by biofilm formation, as well as the large arsenal of microbial virulence factors that are coordinated by the cell density-dependent phenomenon of quorum sensing. Here, we address this issue by using synthetic biology principles to rationally engineer quorum-quencher cells with closed-loop control to autonomously dampen virulence and interfere with biofilm integrity. Pathogen-derived signals dynamically activate a synthetic mammalian autoinducer sensor driving downstream expression of next-generation anti-infectives. Engineered cells were able to sensitively score autoinducer levels from P. aeruginosa clinical isolates and mount a 2-fold defense consisting of an autoinducer-inactivating enzyme to silence bacterial quorum sensing and a bipartite antibiofilm effector to dissolve the biofilm matrix. The self-guided cellular device fully cleared autoinducers, potentiated bacterial antibiotic susceptibility, substantially reduced biofilms, and alleviated cytotoxicity to lung epithelial cells. We believe this strategy of dividing otherwise coordinated pathogens and breaking up their shielded stronghold represents a blueprint for cellular anti-infectives in the postantibiotic era.

Optogenerapy: When bio-electronic implant enters the modern syringe era

Resort to medications dates back million years ago with the use of medicinal plants. In the nineteenth century, significant contributions in medicine appeared in different domains, among which the invention of a specific drug delivery device; the syringe. Nowadays, injection therapy of bio-manufactured drugs is routine practice for chronic diseases but remains constraining and painful. New emerging advanced therapies invest in genetic, electronics and cell-based therapy for addressing unmet needs for the caregivers and the patient. As digital process in health (eHealth) gains momentum, connected advanced bio-electronic devices now offer new strategies for personalized injection therapies. In this review, we take a journey along the genesis path of a new drug delivery system: the Optogenerapy, a synergy between optogenetic and gene therapy. Inside a bio-electronic implant, electronics and optogenetics are interfaced by light as a traceless inducer signal. By controlling a synthetic optogenetic pathway in the cell, therapeutics delivery can be fine-tuned with a precise spatiotemporal control. The technology holds promise of a new modern syringe era capable of producing a drug of interest at will directly inside the patient.

Synthetic biology-inspired therapies for metabolic diseases

Our ability to engineer mammalian cells with effective therapeutic behaviors has brought new hope for treating metabolic diseases. Synthetic gene networks have been customized to interface with the host metabolism, discriminate between healthy and diseased states, and respond by producing an adjusted dose of the therapeutic molecule. Such devices have the potential to treat a range of dysfunctions that are simply not addressable using conventional therapies. Recently, the repurposing of native signaling pathways has formed the basis of autonomous therapeutic programs genetically installed in mammalian cells and has greatly expanded the possibilities to effectively tackle metabolic disorders. Here, we outline network topologies that have been successfully validated in animal models of metabolic diseases and discuss future developments that will be important for bringing this technology closer to clinical application.

Mammalian synthetic biology in the age of genome editing and personalized medicine

The recent expansion of molecular tool kits has propelled synthetic biology toward the design of increasingly sophisticated mammalian systems. Specifically, advances in genome editing, protein engineering, and circuitry design have enabled the programming of cells for diverse applications, including regenerative medicine and cancer immunotherapy. The ease with which molecular and cellular interactions can be harnessed promises to yield novel approaches to elucidate genetic interactions, program cellular functions, and design therapeutic interventions. Here, we review recent advancements in the development of enabling technologies and the practical applications of mammalian synthetic biology.

Large-scale design of robust genetic circuits with multiple inputs and outputs for mammalian cells

Genetic circuits engineered for mammalian cells often require extensive fine-tuning to perform their intended functions. To overcome this problem, we present a generalizable biocomputing platform that can engineer genetic circuits which function in human cells with minimal optimization. We used our Boolean Logic and Arithmetic through DNA Excision (BLADE) platform to build more than 100 multi-input-multi-output circuits. We devised a quantitative metric to evaluate the performance of the circuits in human embryonic kidney and Jurkat T cells. Of 113 circuits analysed, 109 functioned (96.5%) with the correct specified behavior without any optimization. We used our platform to build a three-input, two-output Full Adder and six-input, one-output Boolean Logic Look Up Table. We also used BLADE to design circuits with temporal small molecule-mediated inducible control and circuits that incorporate CRISPR/Cas9 to regulate endogenous mammalian genes.

Recent progress in the use and tracking of transplanted islets as a personalized treatment for type 1 diabetes

INTRODUCTION

Type 1 diabetes mellitus (T1DM) is an autoimmune disease in which the pancreas produces insufficient amounts of insulin. T1DM patients require exogenous sources of insulin to maintain euglycemia. Transplantation of naked or microencapsulated pancreatic islets represents an alternative paradigm to obtain an autonomous regulation of blood glucose levels in a controlled and personalized fashion. However, once transplanted, the fate of these personalized cellular therapeutics is largely unknown, justifying the development of non-invasive tracking techniques.

AREAS COVERED

In vivo imaging of naked pancreatic islet transplantation, monitoring of microencapsulated islet transplantation, visualizing pancreatic inflammation, imaging of molecular-genetic therapeutics, imaging of beta cell function.

EXPERT COMMENTARY

There are still several hurdles to overcome before (microencapsulated) islet cell transplantation will become a mainstay therapy. Non-invasive imaging methods that can track graft volume, graft rejection, graft function (insulin secretion) microcapsule engraftment, microcapsule rupture, and pancreatic inflammation are currently being developed to design the best experimental transplantation paradigms.

Designing β Cells

Diabetes is a growing epidemic, and many patients depend on insulin injections to control the disease and minimize long-term complications. In a recent manuscript published in Science, Xie et al. (2016) generate insulin-producing cells from a somatic embryonic kidney cell line through minimal genetic modification capable of regulating glucose levels in diabetic mice.