A Human-derived Dual MRI/PET Reporter Gene System with High Translational Potential for Cell Tracking

Evaluation of DNA minicircles for delivery of adenine and cytosine base editors using activatable gene on "GO" reporter imaging systems

Over 30,000 point mutations are associated with debilitating diseases, including many cancer types, underscoring a critical need for targeted genomic solutions. CRISPR base editors, like adenine base editors (ABEs) and cytosine base editors (CBEs), enable precise modifications by converting adenine to guanine and cytosine to thymine, respectively. Challenges in efficiency and safety concerns regarding viral vectors used in delivery limit the scope of base editing. This study introduces non-viral minicircles, bacterial-backbone-free plasmids, as a delivery vehicle for ABEs and CBEs. The research uses cells engineered with the "Gene On" (GO) reporter gene systems for tracking minicircle-delivered ABEs, CBEs, or Cas9 nickase (control), using green fluorescent protein (GFPGO), bioluminescence reporter firefly luciferase (LUCGO), or a highly sensitive Akaluciferase (AkalucGO) designed in this study. The results show that transfection of minicircles expressing CBE or ABE resulted in significantly higher GFP expression and luminescence signals over controls, with minicircles demonstrating the most substantial editing. This study presents minicircles as a new strategy for base editor delivery and develops an enhanced bioluminescence imaging reporter system for tracking ABE activity. Future studies aim to evaluate the use of minicircles in preclinical cancer models, facilitating potential clinical applications.

Current Applications of PET/MR: Part I: Technical Basics and Preclinical/Clinical Applications

Positron emission tomography/magnetic resonance (PET/MR) imaging has gone through major hardware improvements in recent years, making it a reliable state-of-the-art hybrid modality in clinical practice. At the same time, image reconstruction, attenuation correction, and motion correction algorithms have significantly evolved to provide high-quality images. Part I of the current review discusses technical basics, pre-clinical applications, and clinical applications of PET/MR in radiation oncology and head and neck imaging. PET/MR offers a broad range of advantages in preclinical and clinical imaging. In the preclinic, small and large animal-dedicated devices were developed, making PET/MR capable of delivering new insight into animal models in diseases and facilitating the development of methods that inform clinical PET/MR. Regarding PET/MR's clinical applications in radiation medicine, PET and MR already play crucial roles in the radiotherapy process. Their combination is particularly significant as it can provide molecular and morphological characteristics that are not achievable with other modalities. In addition, the integration of PET/MR information for therapy planning with linear accelerators is expected to provide potentially unique biomarkers for treatment guidance. Furthermore, in clinical applications in the head and neck region, it has been shown that PET/MR can be an accurate modality in head and neck malignancies for staging and resectability assessment. Also, it can play a crucial role in diagnosing residual or recurrent diseases, reliably distinguishing from oedema and fibrosis. PET/MR can furthermore help with tumour characterization and patient prognostication. Lastly, in head and neck carcinoma of unknown origin, PET/MR, with its diagnostic potential, may obviate multiple imaging sessions in the near future.

GFP-labeled Schwann cell-like cells derived from hair follicle epidermal neural crest stem cells promote the acellular nerve allografts to repair facial nerve defects in rats

BACKGROUND

Acellular nerve allografts (ANAs) have been successfully applied to bridge facial nerve defects, and transplantation of stem cells may enhance the regenerative results. Up to now, application of hair follicle epidermal neural crest stem cell-derived Schwann cell-like cells (EPI-NCSC-SCLCs) combined with ANAs for bridging facial nerve defects has not been reported.

METHODS

The effect of ANAs laden with green fluorescent protein (GFP)-labeled EPI-NCSC-SCLCs (ANA + cells) on bridging rat facial nerve trunk defects (5-mm-long) was detected by functional and morphological examination, as compared with autografts and ANAs, respectively.

RESULTS

(1) EPI-NCSC-SCLCs had good compatibility with ANAs in vitro. (2) In the ANA + cells group, the GFP signals were observed by in vivo imaging system for small animals within 8 weeks, and GFP-labeled EPI-NCSC-SCLCs were detected in the tissue slices at 16 weeks postoperatively. (3) The facial symmetry at rest after surgery in the ANA + cells group was better than that in the ANA group (p < 0.05), and similar to that in the autograft group (p > 0.05). The initial recovery time of vibrissal and eyelid movement in the ANA group was 2 weeks later than that in the other two groups. (4) The myelinated fibers, myelin sheath thickness and diameter of the axons of the buccal branches in the ANA group were significantly worse than those in the other two groups (P < 0.05), and the results in the ANA + cells group were similar to those in the autograft group (p > 0.05).

CONCLUSIONS

EPI-NCSC-SCLCs could promote functional and morphological recovery of rat facial nerve defects, and GFP labeling could track the transplanted EPI-NCSC-SCLCs in vivo for a certain period of time. These may provide a novel choice for clinical treatment of peripheral nerve defects.

A synthetic notch (synNotch) system linking intratumoral immune-cancer cell communication to a synthetic blood biomarker assay

Introduction: Cellular immunotherapy has greatly improved cancer treatment in recent years. For instance, chimeric antigen receptor (CAR) T cell therapy has been proven highly effective in treating hematological malignancies, and many CAR cell designs are being explored for solid tumors. However, many questions remain why responses differ across patients and some tumor types are resistant. Improved and relatively inexpensive ways to monitor these cells could provide some answers. Clinically, blood tests are regularly used to monitor these therapies, but blood signals often do not reflect the activity of immune cells within the tumor(s). Here, using the synthetic Notch (synNotch) receptor that tethers antigen binding to customized transgene expression, we linked intratumoral immune-cancer cell communication to a simple secreted reporter blood test. Specifically, we engineered immune cells with a CD19-targeted synNotch receptor and demonstrated that binding to CD19 on cancer cells in vivo resulted in the production of secreted embryonic alkaline phosphatase (SEAP) at levels that are readily detected in the blood. Methods and Results: Jurkat T cells were engineered via sequential lentiviral transduction of two components: an anti-CD19 synNotch receptor and a synNotch response element encoding SEAP. Co-culture of engineered cells with CD19+, but not CD19-, Nalm6 cells, resulted in significantly elevated SEAP in media. Nod-scid-gamma (NSG) mice were subcutaneously injected with either CD19+ or CD19- Nalm6 cells. Intratumoral injection of engineered T cells (1x107) resulted in significantly elevated blood SEAP activity in mice bearing CD19+ tumors (n = 7), but not CD19- tumors (n = 5). Discussion: Our synNotch reporter system allows for the monitoring of antigen-dependent intratumoral immune-cancer cell interactions through a simple and convenient blood test. Continued development of this system for different target antigens of interest should provide a broadly applicable platform for improved monitoring of many cell-based immunotherapies during their initial development and clinical translation, ultimately improving our understanding of design considerations and patient-specific responses.

Development of a Suite of Gadolinium-Free OATP1-Targeted Paramagnetic Probes for Liver MRI

Five amphiphilic, anionic Mn(II) complexes were synthesized as contrast agents targeted to organic anion transporting polypeptide transporters (OATP) for liver magnetic resonance imaging (MRI). The Mn(II) complexes are synthesized in three steps, each from the commercially available trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA) chelator, with T1-relaxivity of complexes ranging between 2.3 and 3.0 mM-1 s-1 in phosphate buffered saline at an applied field strength of 3.0 T. Pharmacokinetics were assessed in female BALB/c mice by acquiring T1-weighted images dynamically for 70 min after agent administration and determining contrast enhancement and washout in various organs. Uptake of Mn(II) complexes in human OATPs was investigated through in vitro assays using MDA-MB-231 cells engineered to express either OATP1B1 or OATP1B3 isoforms. Our study introduces a new class of Mn-based OATP-targeted contrast that can be broadly tuned via simple synthetic protocols.

Reporter Genes for Brain Imaging Using MRI, SPECT and PET

The use of molecular imaging technologies for brain imaging can not only play an important supporting role in disease diagnosis and treatment but can also be used to deeply study brain functions. Recently, with the support of reporter gene technology, optical imaging has achieved a breakthrough in brain function studies at the molecular level. Reporter gene technology based on traditional clinical imaging modalities is also expanding. By benefiting from the deeper imaging depths and wider imaging ranges now possible, these methods have led to breakthroughs in preclinical and clinical research. This article focuses on the applications of magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) reporter gene technologies for use in brain imaging. The tracking of cell therapies and gene therapies is the most successful and widely used application of these techniques. Meanwhile, breakthroughs have been achieved in the research and development of reporter genes and their imaging probe pairs with respect to brain function research. This paper introduces the imaging principles and classifications of the reporter gene technologies of these imaging modalities, lists the relevant brain imaging applications, reviews their characteristics, and discusses the opportunities and challenges faced by clinical imaging modalities based on reporter gene technology. The conclusion is provided in the last section.