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Mutations in ATP-binding cassette A3 (ABCA3), a phospholipid transporter critical for surfactant homeostasis in pulmonary alveolar type II epithelial cells (AEC2s), are the most common genetic causes of childhood interstitial lung disease (chILD). Treatments for patients with pathological variants of ABCA3 mutations are limited, in part due to a lack of understanding of disease pathogenesis resulting from an inability to access primary AEC2s from affected children. Here, we report the generation of AEC2s from affected patient induced pluripotent stem cells (iPSCs) carrying homozygous versions of multiple ABCA3 mutations. We generated syngeneic CRISPR/Cas9 gene-corrected and uncorrected iPSCs and ABCA3-mutant knockin ABCA3:GFP fusion reporter lines for in vitro disease modeling. We observed an expected decreased capacity for surfactant secretion in ABCA3-mutant iPSC-derived AEC2s (iAEC2s), but we also found an unexpected epithelial-intrinsic aberrant phenotype in mutant iAEC2s, presenting as diminished progenitor potential, increased NFκB signaling, and the production of pro-inflammatory cytokines. The ABCA3:GFP fusion reporter permitted mutant-specific, quantifiable characterization of lamellar body size and ABCA3 protein trafficking, functional features that are perturbed depending on ABCA3 mutation type. Our disease model provides a platform for understanding ABCA3 mutation–mediated mechanisms of alveolar epithelial cell dysfunction that may trigger chILD pathogenesis.

 

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CReM Latest

Individuals homozygous for the ‘‘Z’’ mutation in alpha-1 antitrypsin deficiency are known to be at increased
risk for liver disease. It has also become clear that some degree of risk is similarly conferred by the heterozygous
state. A lack ofmodel systems that recapitulate heterozygosity in human hepatocytes has limited the
ability to study the impact of a single Z alpha-1 antitrypsin (ZAAT) allele on hepatocyte biology. Here, we
describe the derivation of syngeneic induced pluripotent stem cells (iPSCs) engineered to determine the
effects of ZAAT heterozygosity in iPSC-hepatocytes (iHeps). We find that heterozygous MZ iHeps exhibit
an intermediate disease phenotype and share with ZZ iHeps alterations in AAT protein processing and
downstream perturbations including altered endoplasmic reticulum (ER) and mitochondrial morphology,
reduced mitochondrial respiration, and branch-specific activation of the unfolded protein response in cell
subpopulations. Our model of MZ heterozygosity thus provides evidence that a single Z allele is sufficient
to disrupt hepatocyte homeostatic function.

 

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Dysfunction of alveolar epithelial type 2 cells (AEC2s), the facultative progenitors of lung alveoli,
is implicated in pulmonary disease pathogenesis, highlighting the importance of human in vitro
models. However, AEC2-like cells in culture have yet to be directly compared to their in vivo
counterparts at single-cell resolution. Here, we performed head-to-head comparisons among the
transcriptomes of primary (1°) adult human AEC2s, their cultured progeny, and human induced
pluripotent stem cell–derived AEC2s (iAEC2s). We found each population occupied a distinct
transcriptomic space with cultured AEC2s (1° and iAEC2s) exhibiting similarities to and differences
from freshly purified 1° cells. Across each cell type, we found an inverse relationship between
proliferative and maturation states, with preculture 1° AEC2s being most quiescent/mature and
iAEC2s being most proliferative/least mature. Cultures of either type of human AEC2s did not
generate detectable alveolar type 1 cells in these defined conditions; however, a subset of iAEC2s
cocultured with fibroblasts acquired a transitional cell state described in mice and humans to arise
during fibrosis or following injury. Hence, we provide direct comparisons of the transcriptomic
programs of 1° and engineered AEC2s, 2 in vitro models that can be harnessed to study human lung
health and disease.

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Centenarian Painting

Age-related changes in immune cell composition and functionality are associated with multimorbidity
and mortality. However, many centenarians delay the onset of aging-related disease suggesting the presence of elite
immunity that remains highly functional at extreme old age.

To identify immune-specific patterns of aging and extreme human longevity, we analyzed novel single cell
profiles from the peripheral blood mononuclear cells (PBMCs) of a random sample of 7 centenarians (mean age 106)
and publicly available single cell RNA-sequencing (scRNA-seq) datasets that included an additional 7 centenarians as
well as 52 people at younger ages (20–89 years).

The analysis confirmed known shifts in the ratio of lymphocytes to myeloid cells, and noncytotoxic to
cytotoxic cell distributions with aging, but also identified significant shifts from CD4+ T cell to B cell populations in
centenarians suggesting a history of exposure to natural and environmental immunogens. We validated several of
these findings using flow cytometry analysis of the same samples. Our transcriptional analysis identified cell type
signatures specific to exceptional longevity that included genes with age-related changes (e.g., increased expression of
STK17A, a gene known to be involved in DNA damage response) as well as genes expressed uniquely in centenarians’
PBMCs (e.g., S100A4, part of the S100 protein family studied in age-related disease and connected to longevity and
metabolic regulation).

Collectively, these data suggest that centenarians harbor unique, highly functional immune systems
that have successfully adapted to a history of insults allowing for the achievement of exceptional longevity.

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A robust method of producing mature T cells from iPSCs is needed to realize their therapeutic potential. NOTCH1 is known to be required for the production of hematopoietic progenitor cells with T cell potential in vivo. Here we identify a critical window during mesodermal differentiation when Notch activation robustly improves access to definitive hematopoietic progenitors with T/NK cell lineage potential. Low-density progenitors on either OP9-hDLL4 feeder cells or hDLL4-coated plates favored T cell maturation into TCRab+CD3+CD8+ cells that express expected T cell markers, upregulate activation markers, and proliferate in response to T cell stimulus. Single-cell RNAseq shows Notch activation yields a 6-fold increase in multi-potent hematopoietic progenitors that follow a developmental trajectory toward T cells with clear similarity to post-natal human thymocytes. We conclude that early mesodermal Notch activation during hematopoietic differentiation is a missing stimulus with broad implications for producing hematopoietic progenitors with definitive characteristics.

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For more than 20 years, a team of Boston University scientists have been on a quest to not just figure out how to treat incurable lung diseases, but also how to regenerate damaged lungs so they’re as good as new.

That is the goal of pulmonologist Darrell Kotton and his lab at the Center for Regenerative Medicine (CReM), a joint effort between the University and Boston Medical Center, BU’s primary teaching hospital. By refining their work using sophisticated stem cell technology, Kotton and his team are closer to realizing that vision than ever before.

In two new studies published in Cell Stem Cell, BU researchers detail how they engineered lung stem cells and successfully transplanted them into injured lungs of mice. Two lines of cells targeted two different parts of the lung: the airways, including the trachea and bronchial tubes, and the alveoli, the delicate air sacs that deliver oxygen to the bloodstream. Their findings could eventually lead to new ways for treating lung diseases, including severe cases of COVID-19, emphysema, pulmonary fibrosis, and cystic fibrosis, a disease caused by a genetic mutation.

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Neuroendocrine tumors (NETs) are rare cancers that most often arise in the gastrointestinal tract and pancreas. The fundamental mechanisms driving gastroenteropancreatic (GEP)–NET growth remain incompletely elucidated; however, the heterogeneous clinical behavior of GEP-NETs suggests that both cellular lineage dynamics and tumor microenvironment influence tumor pathophysiology. Here, we investigated the single-cell transcriptomes of tumor and immune cells from patients with gastroenteropancreatic NETs. Malignant GEP-NET cells expressed genes and regulons associated with normal, gastrointestinal endocrine cell differentiation, and fate determination stages. Tumor and lymphoid compartments sparsely expressed immunosuppressive targets commonly investigated in clinical trials, such as the programmed cell death protein–1/programmed death ligand–1 axis. However, infiltrating myeloid cell types within both primary and metastatic GEP-NETs were enriched for genes encoding other immune checkpoints, including VSIR (VISTA), HAVCR2 (TIM3), LGALS9 (Gal-9), and SIGLEC10. Our findings highlight the transcriptomic heterogeneity that distinguishes the cellular landscapes of GEP-NET anatomic subtypes and reveal potential avenues for future precision medicine therapeutics.

 

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Welcome to CReM

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The Wilson lab is focused on two major aspects of regenerative medicine:

1) Developing gene therapy approaches for the study and treatment of lung diseases: The ability to manipulate gene expression in specified lung cell populations has both experimental and therapeutic potential for lung disease. By developing viral vectors that transduce specific lung cell types in vivo, we hope to minimize potential off-target effects while maximizing our ability to target diseased cell populations. We work with lentiviral and AAV vectors to overexpress or knockdown expression of genes important to disease pathogenesis in the lung.

2) Utilizing induced pluripotent stem cells (iPSC) to study human lung and liver diseases: The Wilson lab is interested in the application of patient-derived iPS cells for the study of lung and liver diseases, such as alpha-1 antitrypsin deficiency (AATD).

The Hawkins Lab is interested in how the human lung develops and responds to injury to better understand human lung disease. Induced pluripotent stem cells (iPSCs) offer a unique opportunity to model human lung disease and bridge the gap between research in animal models and humans.

Using this iPSC platform, we are focused on understanding the molecular mechanisms that control human lung development. We hope to apply this knowledge to advance our understanding of and develop precision medicine approaches for lung disease.

The Murphy laboratory is composed of dynamic and passionate researchers who utilize multiple stem cell-based platforms to answer basic biological questions and combat disease. Central directions of the laboratory include: developmental hematopoiesis, the modeling of blood-borne disease, and discovery and therapeutic intervention in sickle cell disease, amyloidosis, and aging.

The Murphy Lab has pioneered: The world’s largest sickle cell disease-specific iPSC library and platforms and protocols that can used to recapitulate hematopoietic ontogeny and to develop and validate novel therapeutic strategies for the disease; The successful modeling of a protein folding disorder called familial amyloidosis demonstrating the ability to model a long-term, complex, multisystem disease in a relatively short time, using lineage-specified cells (hepatic, cardiac and neuronal) derived from patient-specific stem cells; The first iPSC library created from subjects with exceptional longevity (centenarians) that serves as an unlimited resource of biomaterials to fuel the study of aging and the development of novel therapeutics for aging-related disease.

www.murphylaboratory.com

@DRGJMurphy

The Serrano Lab studies neurodevelopment and cardiovascular development in the context of rare multi-systemic disorders originated by pathogenic variants in epigenetic modifiers like KMT2D.  

We aim to identify shared molecular and cellular mechanisms driving cardiovascular and brain development with particular interest in cell differentiation, migration, and cell cycle progression.  

Our lab combines rare disease modeling in zebrafish together with cardiovascular and neurobiology techniques and human iPSC-derived brain organoids and endothelial cells.  

We believe that a patient-forward focus to our projects will help us to get better understanding of disease mechanisms through basic science research. To this end, we are active in the collaborative community among field experts and rare disease patient-advocacy groups who drive our research program to identify therapeutic targets in patient-specific iPS cells. 

The Mostoslavsky Lab is a basic science laboratory in the Section of Gastroenterology in the Department of Medicine at Boston University.

Our goal is to advance our understanding of stem cell biology with a focus on their genetic manipulation via gene transfer and their potential use for stem cell-based therapy.

The Mostoslavsky’s Lab designed and constructed the STEMCCA vector for the generation of iPS cells, a tool that has become the industry standard for nuclear reprogramming. Project areas in the lab focuses on the use of different stem cell populations, including embryonic stem cells, induced Pluripotent Stem (iPS) cells, hematopoietic stem cells and intestinal stem cells and their genetic manipulation by lentiviral vectors.

Our laboratory have already established a large library of disease-specific iPS cells with a particular interest in utilizing iPS cells to model diseases of the liver, the gastrointestinal tract, prion-mediated neurodegenerative diseases and immune-based inflammatory conditions, using iPSC-derived microglia, macrophages and T/NK cells.

The Gouon-Evans lab investigates cellular and molecular mechanisms driving liver development, regeneration and cancer. We specifically interrogate the role of progenitor/stem cells and how they share similar molecular signature and functions during these 3 processes.

Our innovative tools include: 1) directed differentiation of human pluripotent stem cells (PSC) to generate in vitro liver progenitors and their derivative hepatocytes, the main functional cell type of the liver, 2) mouse models with lineage tracing strategy to track in vivo the fate of progenitor cells, 3) PSC derivative cell transplantation into mouse models with damaged livers as cell therapy for liver diseases, 3) dissection of liver cancer specimens from patients to identify and define the impact of specific cancer stem cells in liver oncogenesis.

Projects in the Gouon-Evans lab will lead to a better understanding of the liver development, to the establishment of multi-modular approaches for improving liver regeneration with PSC derivatives, and will reveal the impact of specific cancer stem cells as a target for diagnosis and therapy in liver oncogenesis.