Biology subjects

Abedi, M. H.

Publications and source records attributed to Abedi, M. H..

6 recordsLinked to original sources

bioRxiv2025

Thermally controlled state switches for macrophage immunotherapy

Advances in cellular immunotherapy promise new treatments for conditions such as cancer, autoimmune disease, and heart disease. While engineered cells have the ability to recognize clinically relevant signals, traffic to disease sites and interface with the host immune system, their activity must be tightly controlled to minimize undesirable effects in healthy tissues. One approach to obtaining specificity is to activate the cells spatially using externally applied energy, such as ultrasound-delivered heating. To facilitate such control, we designed and characterized a genetic circuit that enables stable transcriptional activation of macrophages after a brief thermal stimulus, resulting in the expression of reporters or secretion of the cytokine IL-12. We demonstrate that in vivo activation of a mouse macrophage cell line containing this bioswitch results in spatially localized gene expression for at least 14 days after ultrasound heating. This thermal bioswitch provides a precise control element for cell-therapeutic agents.

bioengineering↗

bioRxiv2024

Design of facilitated dissociation enables control over cytokine signaling duration

Protein design has focused primarily on the design of ground states, ensuring they are sufficiently low energy to be highly populated1. Designing the kinetics and dynamics of a system requires, in addition, the design of excited states that are traversed in transitions from one low-lying state to another2,3. This is a challenging task as such states must be sufficiently strained to be poorly populated, but not so strained that they are not populated at all, and because protein design methods have generally focused on creating near-ideal structures4-7. Here we describe a general approach for designing systems which use an induced-fit power stroke8 to generate a structurally frustrated9 and strained excited state, allosterically driving protein complex dissociation. X-ray crystallography, double electron-electron resonance spectroscopy, and kinetic binding measurements demonstrate that incorporating excited states enables design of effector-induced increases in dissociation rates as high as 6000-fold. We highlight the power of this approach by designing cytokine mimics which can be dissociated within seconds from their receptors.

biochemistry↗

bioRxiv2024

Non-invasive imaging of cell-based therapies using acoustic reporter genes

Cell-based therapies are a major emerging category of medicine. The ability of engineered cells to traffic to and function at specific anatomical locations is a major aspect of their performance. However, there is a lack of non-invasive, non-ionizing, cost-accessible methods to track these therapies inside the body and ensure proper function. Here, we establish a platform for in vivo imaging of primary cell therapies using ultrasound - a ubiquitously accessible technology for high-resolution non-invasive imaging. We introduce and optimize a lentiviral delivery system to express acoustic reporter genes based on gas vesicles in primary mammalian cells such as T cells, showing that this results in robust ultrasound contrast. Additionally, we develop genetic circuits making it possible to monitor T cell activation via activity-dependent promoters. We apply this technology to primary human T cells, using it to non-invasively track their accumulation and proliferation as a targeted therapy in a mouse tumor xenograft model and compare it to invasive, terminal measures such as immunohistology. By making it possible to visualize cell-based therapies and their function inside opaque living organs with unprecedented resolution and accessibility, this technology has the potential to significantly accelerate their development and effective use.

bioengineering↗

bioRxiv2024

Engineered Receptors for Soluble Cell-to-Cell Communication

Despite recent advances in mammalian synthetic biology, there remains a lack of modular synthetic receptors that can robustly respond to soluble ligands and in turn activate cellular functions. Such receptors would have extensive clinical potential to regulate the activity of engineered therapeutic cells, but to date only receptors against cell surface targets have approached clinical translation. To address this gap, we developed a receptor architecture based on synNotch, called SyNthetic Intramembrane Proteolysis Receptor (SNIPR), that has the added ability to be activated by soluble ligands, both natural and synthetic, with remarkably low baseline activity and high fold activation. SNIPRs are able to access an endocytic, pH-dependent cleavage mechanism to achieve soluble ligand sensing, in addition to employing a canonical-like pathway for detecting surface-bound ligands. We demonstrate the therapeutic capabilities of the receptor platform by localizing the activity of CAR T-cells to solid tumors where soluble disease-associated factors are expressed, bypassing the major hurdle of on-target off-tumor toxicity in bystander organs. We further applied the SNIPR platform to engineer fully synthetic signaling networks between cells orthogonal to natural signaling pathways, expanding the scope of synthetic biology. Our design framework enables cellular communication and environmental interactions, extending the capabilities of synthetic cellular networking in clinical and research contexts.

bioengineering↗

bioRxiv2021

Genomically Mined Acoustic Reporter Genes Enable On-Demand In Vivo Monitoring of Tumor-Homing Bacteria

A major outstanding challenge in the fields of biological research, synthetic biology and cell-based medicine is visualizing the function of natural and engineered cells noninvasively inside opaque organisms. Ultrasound imaging has the potential to address this challenge as a widely available technique with a tissue penetration of several centimeters and spatial resolution below 100 m. Recently, the first genetically encoded acoustic reporters were developed based on bacterial gas vesicles to link ultrasound signals to molecular and cellular function. However, the properties of these first-generation acoustic reporter genes (ARGs) resulted in limited sensitivity and specificity for imaging gene expression in vivo. Here, we describe second-generation ARGs with greatly improved acoustic properties and expression characteristics, identified through a phylogenetic screen of candidate gene clusters from diverse bacteria and archaea. The resulting constructs offer major qualitative and quantitative improvements, including much stronger ultrasound contrast, the ability to produce nonlinear signals distinguishable from background tissue, and stable long-term expression. We demonstrate the capabilities of these next-generation ARGs by imaging in situ gene expression in mouse models of breast cancer and tumor-homing therapeutic bacteria, noninvasively revealing the unique spatial distributions of tumor growth and colonization by therapeutic cells in living subjects and providing real-time guidance for interventions such as needle biopsies.

bioengineering↗

bioRxiv2020

Thermal Control of T-cell Immunotherapy

Genetically engineered T-cells are being developed to perform a variety of therapeutic functions. However, no robust mechanisms exist to externally control the activity of T-cells at specific locations within the body. Such spatiotemporal control could help mitigate potential off-target toxicity due to incomplete molecular specificity in applications such as T-cell immunotherapy against solid tumors. Temperature is a versatile external control signal that can be delivered to target tissues in vivo using techniques such as focused ultrasound and magnetic hyperthermia. Here, we test the ability of heat shock promoters to mediate thermal actuation of genetic circuits in primary human T-cells in the well-tolerated temperature range of 37-42{degrees}C, and introduce genetic architectures enabling the tuning of the amplitude and duration of thermal activation. We demonstrate the use of these circuits to control the expression of chimeric antigen receptors and cytokines, and the killing of target tumor cells. This technology provides a critical tool to direct the activity of T-cells after they are deployed inside the body.

bioengineering↗