Current Protocols in Stem Cell Biology最新文献

This unit describes a protocol for generation of lung organoids. A lung organoid is a 3D cell/hydrogel composite that resembles the morphology and cellular composition of the human distal lung. These tissue-engineered constructs provide an in vitro model of human lung and are best suited for disease modeling applications. The organoid generation methodology is flexible, allowing for easy scalability in the number of organoids produced and in the ability to accommodate a wide range of cell types. © 2018 by John Wiley & Sons, Inc.

Cell migration is strongly influenced by the organization of the surrounding 3-D extracellular matrix. In particular, within fibrous solid tumors, carcinoma cell invasion may be directed by patterns of aligned collagen in the extra-epithelial space. Thus, studying the interactions of heterogeneous populations of cancer cells that include the stem/progenitor-like cancer stem cell subpopulation and aligned collagen networks is critical to our understanding of carcinoma dissemination. Here, we describe a robust method to generate aligned collagen matrices in vitro that mimic in vivo fiber organization. Subsequently, a protocol is presented for seeding aligned matrices with distinct carcinoma cell subpopulations and performing live cell imaging and quantitative analysis of cell migration. Together, the engineered constructs and the imaging techniques laid out here provide a platform to study cancer stem cell migration in 3-D anisotropic collagen with real-time visualization of cellular interactions with the fibrous matrix. © 2018 by John Wiley & Sons, Inc.

Stem cell therapy has shown great promise for organ repair and regeneration. In the context of lung disease, such as radiation-induced lung damage (RILD) in cancer radiotherapy, mesenchymal stem cells (MSCs) have shown the ability to reduce damage possibly due to their immunomodulatory properties and other unknown mechanisms. However, once MSCs are transplanted into the body, little is known as to their localization or their mechanisms of action. In this work, we proposed, implemented, and validated a fluorescence endomicroscopy (FE) imaging technique that allows for the real-time detection and quantification of transplanted pre-labeled MSCs in vivo and tracking in a rat model. This protocol covers aspects related to MSCs extraction, labeling, FE imaging, and image analysis developed in a RILD rat model but applicable to other biological systems. © 2018 by John Wiley & Sons, Inc.

Human induced pluripotent stem cells (hiPSCs) offer great opportunities for the study of human development and disease modeling and have enormous potential for use in future clinical cell-based therapies. However, most current systems to create hiPSCs often expose the cells to animal feeder layers or xenogeneic reagents; this raises safety concerns about using hiPSC-derived cells for therapeutic purposes. Here, we describe protocols to generate hiPSCs without exposing the cells to xenogeneic materials that uses a defined, feeder-free reprogramming system. With this method, we were able to successfully reprogram not only patient-derived peripheral blood mononuclear cells but also amniocytes from the amniotic fluid of stillborn fetuses using two independent reprogramming platforms. Importantly, hiPSCs generated in this fashion expressed pluripotent markers and had normal karyotypes. The protocols allowed us to generate and culture hiPSCs under Good Manufacturing Practice–like conditions, a necessary step for the future clinical application of these cells. © 2018 by John Wiley & Sons, Inc.

New protocols to efficiently generate functional airway epithelial organoids from human pluripotent stem cells (PSCs) would represent a major advance towards effective disease modeling, drug screening and cell based therapies for lung disorders. This unit describes an approach using stage-specific signaling pathway manipulation to differentiate cells to proximal airway epithelium via key developmental intermediates. Cells are directed via definitive endoderm (DE) to anterior foregut, and then specified to NKX2-1+ lung epithelial progenitors. These lung progenitors are purified using cell surface marker sorting and replated in defined culture conditions to form three-dimensional, epithelial-only airway organoids. This directed differentiation approach using serum-free, defined media also includes protocols for evaluation of DE induction, intracellular FACS analysis of NKX2-1 specification efficiency and enrichment, and approaches for characterization and expansion of airway organoids. Taken together, this represents an efficient and reproducible approach to generate expandable airway organoids from human PSCs for use in numerous downstream applications. © 2018 by John Wiley & Sons, Inc.

Despite the promise of emerging organoid-based approaches, building additional complexity, such as the vascular network, remains a major challenge toward regenerative therapy. Recently, we developed a complex organoid engineering method by "self-condensation," wherein mesenchymal cell–dependent contraction enables large-scale condensation from heterotypic multiple progenitors. Here, we describe the adaptation of this protocol for generating three-dimensional (3D) pancreatic condensates from dissociated β cell lines (MIN6) together with blood vessel–forming progenitors. This protocol achieves 3D pancreatic islet-like organoid self-organization with endothelialized networks through mesenchymal stem cell–dependent contraction. Transplantation of pancreatic islet-like organoids treats diabetes in mice effectively. Given the donor shortage associated with clinical islet transplantation, our approach offers a promising alternative toward therapeutic organoid transplantation. © 2018 by John Wiley & Sons, Inc.

Human pluripotent stem cells (hPSCs) represent a formidable tool for disease modeling, drug discovery, and regenerative medicine using human cells and tissues in vitro. Evolving techniques of targeted genome editing, specifically the CRISPR/Cas9 system, allow for the generation of cell lines bearing gene-specific knock-outs, knock-in reporters, and precise mutations. However, there are increasing concerns related to the transfection efficiency, cell viability, and maintenance of pluripotency provided by genome-editing techniques. The procedure presented here employs transient antibiotic selection that overcomes reduced transfection efficiency, avoids cytotoxic flow sorting for increased viability, and generates multiple genome-edited pluripotent hPSC lines expanded from a single parent cell. Avoidance of xenogeneic contamination from feeder cells and reduced operator workload, owing to single-cell passaging rather than clump passaging, are additional benefits. The outlined methods may enable researchers with limited means and technical experience to create human stem cell lines containing desired gene-specific mutations. © 2018 by John Wiley & Sons, Inc.

An adult human retinal pigment epithelial layer (ahRPE) model derived from stem cells isolated from native RPE monolayers (ahRPE-SCs) exhibits key physiological characteristics of native tissue and therefore provides the means to create a human “disease in a dish” model to study RPE diseases. Traditionally, RPE lines are established from whole globes dedicated to research. Here we describe a new technique for establishing primary RPE lines from the posterior poles of globes used for corneal transplants. Since tissues from corneal transplants are derived from younger and healthier donors than those used for research, we have hypothesized that RPE cells isolated from corneal transplantation globes will result in improved primary RPE line establishment. Our new procedure increases the rate of establishing successful RPE cultures and improves the total cell number yield. Use of this advanced methodology can provide a new source of high-quality primary RPE line cultures. © 2018 by John Wiley & Sons, Inc.

In the field of orthopedics, translational research of novel therapeutic approaches involves the use of large animal models (such as sheep, goat, pig, dog, and horse) due to the similarities with humans in weight, size, joint structure, and bone/cartilage healing mechanisms. Particularly in the development of cell-based therapies, the lack of manageable immunocompromised preclinical large animal models prevents the use of human cells, which makes it necessary to produce equivalent homologous cell types for the study of their pharmacodynamics, pharmacokinetics, and toxicology. The methods described herein allow for the isolation, expansion, manipulation, and characterization of fibroblastic-like ovine bone marrow–derived multipotent mesenchymal stromal cells (BM-MSC) that, similar to human BM-MSC, adhere to standard plastic surfaces; express specific surface markers such as CD44, CD90, CD140a, CD105, and CD166; and display trilineage differentiation potential in vitro. Homogeneous cell cultures result from a 3-week bioprocess yielding cell densities in the range of 2–4 × 10⁴ MSC/cm² at passage 2, which corresponds to ∼8 cumulative population doublings. Large quantities of BM-MSC resulting from following this methodology can be readily used in proof of efficacy and safety studies in the preclinical development stage. © 2018 by John Wiley & Sons, Inc.

The difficulties involved in conditionally perturbing complex gene expression networks represent major challenges toward defining the mechanisms controlling human development, physiology, and disease. We developed an OPTimized inducible KnockDown (OPTiKD) platform that addresses the limitations of previous approaches by allowing streamlined, tightly-controlled, and potent loss-of-function experiments for both single and multiple genes. The method relies on single-step genetic engineering of the AAVS1 genomic safe harbor with an optimized tetracycline-responsive cassette driving one or more inducible short hairpin RNAs (shRNAs). OPTiKD provides homogeneous, dose-responsive, and reversible gene knockdown. When implemented in human pluripotent stem cells (hPSCs), the approach can be then applied to a broad range of hPSC-derived mature cell lineages that include neurons, cardiomyocytes, and hepatocytes. Generation of OPTiKD hPSCs in commonly used culture conditions is simple (plasmid based), rapid (two weeks), and highly efficient (>95%). Overall, this method facilitates the functional annotation of the human genome in health and disease. © 2018 by John Wiley & Sons, Inc.