The effect of whole blood logistics on neutrophil non-specific activation and kinetics ex vivo

While the exquisite sensitivity of neutrophils enables their rapid response to infection in vivo; this same sensitivity complicates the ex vivo study of neutrophils. Handling of neutrophils ex vivo is fraught with unwanted heterogeneity and alterations that can diminish the reproducibility of assays and limit what biological conclusions can be drawn. There is a need to better understand the influence of ex vivo procedures on neutrophil behavior to guide improved protocols for ex vivo neutrophil assessment to improve inter/intra-experimental variability. Here, we investigate how whole blood logistics (i.e., the procedure taken from whole blood collection to delivery of the samples to analytical labs and storage before neutrophil interrogation) affects neutrophil non-specific activation (i.e., baseline apoptosis and NETosis) and kinetics (i.e., activation over time). All the experiments (60+ whole blood neutrophil isolations across 36 blood donors) are performed by a single operator with optimized isolation and culture conditions, and automated image analysis, which together increase rigor and consistency. Our results reveal: (i) Short-term storage (< 8 h) of whole blood does not significantly affect neutrophil kinetics in subsequent two-dimensional (2D) cell culture; (ii) Neutrophils from long-term storage (> 24 h) in whole blood show significantly higher stability (i.e., less non-specific activation) compared to the control group with the isolated cells in 2D culture. (iii) Neutrophils have greater non-specific activation and accelerated kinetic profiles when stored in whole blood beyond 48 h.

The effect of whole blood logistics on neutrophil non-specific activation and kinetics ex vivo

While the exquisite sensitivity of neutrophils enables their rapid response to infection in vivo; this same sensitivity complicates the ex vivo study of neutrophils. Handling of neutrophils ex vivo is fraught with unwanted heterogeneity and alterations that can diminish the reproducibility of assays and limit what biological conclusions can be drawn. There is a need to better understand the influence of ex vivo procedures on neutrophil behavior to guide improved protocols for ex vivo neutrophil assessment to improve inter/intra-experimental variability. Here, we investigate how whole blood logistics (i.e., the procedure taken from whole blood collection to delivery of the samples to analytical labs and storage before neutrophil interrogation) affects neutrophil non-specific activation (i.e., baseline apoptosis and NETosis) and kinetics (i.e., activation over time). All the experiments (60+ whole blood neutrophil isolations across 36 blood donors) are performed by a single operator with optimized isolation and culture conditions, and automated image analysis, which together increase rigor and consistency. Our results reveal: i) Short-term storage (<8 h) of whole blood does not significantly affect neutrophil kinetics in subsequent two-dimensional (2D) cell culture; ii) Neutrophils from long-term storage (>24 h) in whole blood show significantly higher stability (i.e., less non-specific activation) compared to the control group with the isolated cells in 2D culture. iii) Neutrophils have greater non-specific activation and accelerated kinetic profiles when stored in whole blood beyond 48 h.

Microphysiological head and neck cancer model identifies novel role of lymphatically secreted monocyte migration inhibitory factor in cancer cell migration and metabolism

Regional metastasis of head and neck cancer (HNC) is prevalent (approximately 50% of patients at diagnosis), yet the underlying drivers and mechanisms of lymphatic spread remain unclear. The complex tumor microenvironment (TME) of HNC plays a crucial role in disease maintenance and progression; however, the contribution of the lymphatics remains underexplored. We created a primary patient cell derived microphysiological system that incorporates cancer-associated-fibroblasts from patients with HNC alongside a HNC tumor spheroid and a lymphatic microvessel to create an in vitro TME platform to investigate metastasis. Screening of soluble factor signaling identified novel secretion of macrophage migration inhibitory factor (MIF) by lymphatic endothelial cells conditioned in the TME. Importantly, we also observed patient-to-patient heterogeneity in cancer cell migration similar to the heterogeneity observed in clinical disease. Optical metabolic imaging at the single cell level identified a distinct metabolic profile of migratory versus non-migratory HNC cells in a microenvironment dependent manner. Additionally, we report a unique role of MIF in increasing HNC reliance on glycolysis over oxidative phosphorylation. This multicellular, microfluidic platform expands the tools available to explore HNC biology in vitro through multiple orthogonal outputs and establishes a system with enough resolution to visualize and quantify patient-to-patient heterogeneity.

Advancing Treatment of Bone Metastases through Novel Translational Approaches Targeting the Bone Microenvironment

Bone metastases represent a lethal condition that frequently occurs in solid tumors such as prostate, breast, lung, and renal cell carcinomas, and increase the risk of skeletal-related events (SREs) including pain, pathologic fractures, and spinal cord compression. This unique metastatic niche consists of a multicellular complex that cancer cells co-opt to engender bone remodeling, immune suppression, and stromal-mediated therapeutic resistance. This review comprehensively discusses clinical challenges of bone metastases, novel preclinical models of the bone and bone marrow microenviroment, and crucial signaling pathways active in bone homeostasis and metastatic niche. These studies establish the context to summarize the current state of investigational agents targeting BM, and approaches to improve BM-targeting therapies. Finally, we discuss opportunities to advance research in bone and bone marrow microenvironments by increasing complexity of humanized preclinical models and fostering interdisciplinary collaborations to translational research in this challenging metastatic niche.

CRISPR/Cas9-mediated introduction of the sodium/iodide symporter gene enables noninvasive in vivo tracking of induced pluripotent stem cell-derived cardiomyocytes

Techniques that enable longitudinal tracking of cell fate after myocardial delivery are imperative for optimizing the efficacy of cell‐based cardiac therapies. However, these approaches have been underutilized in preclinical models and clinical trials, and there is considerable demand for site‐specific strategies achieving long‐term expression of reporter genes compatible with safe noninvasive imaging. In this study, the rhesus sodium/iodide symporter (NIS) gene was incorporated into rhesus macaque induced pluripotent stem cells (RhiPSCs) via CRISPR/Cas9. Cardiomyocytes derived from NIS‐RhiPSCs (NIS‐RhiPSC‐CMs) exhibited overall similar morphological and electrophysiological characteristics compared to parental control RhiPSC‐CMs at baseline and with exposure to physiological levels of sodium iodide. Mice were injected intramyocardially with 2 million NIS‐RhiPSC‐CMs immediately following myocardial infarction, and serial positron emission tomography/computed tomography was performed with ¹⁸F‐tetrafluoroborate to monitor transplanted cells in vivo. NIS‐RhiPSC‐CMs could be detected until study conclusion at 8 to 10 weeks postinjection. This NIS‐based molecular imaging platform, with optimal safety and sensitivity characteristics, is primed for translation into large‐animal preclinical models and clinical trials.

CRISPR/Cas9-Based Safe-Harbor Gene Editing in Rhesus iPSCs

NHP iPSCs provide a unique opportunity to test safety and efficacy of iPSC-derived therapies in clinically relevant NHP models. To monitor these cells in vivo, there is a need for safe and efficient labeling methods. Gene insertion into genomic safe harbors (GSHs) supports reliable transgene expression while minimizing the risk the modification poses to the host genome or target cell. Specifically, this protocol demonstrates targeting of the adeno-associated virus site 1 (AAVS1), one of the most widely used GSH loci in the human genome, with CRISPR/Cas9, allowing targeted marker or therapeutic gene insertion in rhesus macaque induced pluripotent stem cells (RhiPSCs). Furthermore, detailed instructions for screening targeted clones and a tool for assessing potential off-target nuclease activity are provided. © 2017 by John Wiley & Sons, Inc.

Abstract 193: CRISPR-mediated Introduction of the Sodium-iodide Symporter to Enable Non-invasive Monitoring of Macaque Induced-pluripotent Stem Cell-derived Cardiomyocytes

Due to the limited regenerative capacity of mature cardiomyocytes, cardiac cell therapies constitute an exciting strategy for myocardial repair. However, there is limited understanding of the spatio-temporal distribution and survival of transplanted cells. Hence, there is demand for technologies enabling long-term non-invasive tracking of transplanted cellular therapeutics. Sodium-iodide symporter (NIS)-based in vivo imaging has many potential advantages, including predicted safety and immunotolerance due to reliance on an endogenous species-specific gene and on widely available imaging technologies. We believe that non-human primates represent ideal models for investigating the biology of allogenic or autologous cellular grafts, because of close physiologic similarity to humans. We report the development of NIS-based in vivo imaging to detect and track rhesus induced pluripotent stem cell (RhiPSC)-derived teratomas as a proof-of-concept model tested in mice, and characterization of NIS-positive RhiPSC (NIS-RhiPSC)-derived cardiomyocytes (CM). NIS-RhiPSCs were generated by CRISPR/Cas9-mediated integration of the rhesus NIS cDNA within the AAVS1 safe harbor locus. NIS was stably expressed and radiotracer uptake by NIS-RhiPSCs was demonstrated in vitro . To evaluate viability of NIS-mediated imaging in RhiPSCs, undifferentiated NIS-RhiPSCs were introduced intramuscularly into immunodeficient mice, and NIS imaging was performed via PET/CT at 2, 4, and 6-weeks post-injection. NIS-positive teratomas were readily detectable as early as 2 weeks post-injection, prior to development of any palpable mass. Using our previously established differentiation protocol, NIS-RhiPS-CMs were derived with high purity, exhibited spontaneous beating in culture, and were similar in all aspects to parental RhiPS-CMs. NIS-RhiPS-CMs maintained stable NIS expression that was comparable to undifferentiated NIS-RhiPSCs, suggesting that in vivo imaging of transplanted NIS-RhiPS-CMs should be feasible. Further functional characterization of NIS-RhiPS-CMs, including in vitro radiotracer uptake, post-transplantation imaging in a mouse myocardial infarction model, and electrophysiologic analysis is ongoing and data will be presented.

Rhesus Macaque iPSC Generation and Maintenance

The rhesus macaque (Macaca mulatta) is physiologically and phylogenetically similar to humans, and therefore represents an invaluable model for the pre-clinical assessment of the safety and feasibility of iPSC-derived cell therapies. The use of an excisable polycistronic lentiviral STEMCCA vector to reprogram rhesus fibroblasts or bone marrow stromal cells (BMSCs) into RhiPSCs is described. After reprogramming, the pluripotency transgenes can be removed by transient expression of Cre, leaving a residual genetic tag that may be useful for identification of RhiPSC-derived tissues in vivo. Finally, the steps to maintain pluripotency during passaging of RhiPSCs, required for successful utilization of RhiPSCs, is described. © 2017 by John Wiley & Sons, Inc.

Rhesus iPSC Safe Harbor Gene-Editing Platform for Stable Expression of Transgenes in Differentiated Cells of All Germ Layers

Nonhuman primate (NHP) induced pluripotent stem cells (iPSCs) offer the opportunity to investigate the safety, feasibility, and efficacy of proposed iPSC-derived cellular delivery in clinically relevant in vivo models. However, there is need for stable, robust, and safe labeling methods for NHP iPSCs and their differentiated lineages to study survival, proliferation, tissue integration, and biodistribution following transplantation. Here we investigate the utility of the adeno-associated virus integration site 1 (AAVS1) as a safe harbor for the addition of transgenes in our rhesus macaque iPSC (RhiPSC) model. A clinically relevant marker gene, human truncated CD19 (hΔCD19), or GFP was inserted into the AAVS1 site in RhiPSCs using the CRISPR/Cas9 system. Genetically modified RhiPSCs maintained normal karyotype and pluripotency, and these clones were able to further differentiate into all three germ layers in vitro and in vivo. In contrast to transgene delivery using randomly integrating viral vectors, AAVS1 targeting allowed stable transgene expression following differentiation. Off-target mutations were observed in some edited clones, highlighting the importance of careful characterization of these cells prior to downstream applications. Genetically marked RhiPSCs will be useful to further advance clinically relevant models for iPSC-based cell therapies.