A bone marrow-on-a-chip that maintains hematopoietic regenerative capacity in vitro

Thesis (Ph.D.)--Boston UniversityThe bone marrow niche is composed of a complex set of cellular, chemical, structural and physical cues that are required to maintain viability and function of the hematopoietic system. [1-5]. The source of all differentiated blood cells, the hematopoietic stem cell (HSC), is housed within the protective confines of the bone marrow where the complex microenvironment regulates its ability to undergo self-renewal or to differentiate into all of the mature functional blood cell types that constitute the hematopoietic system [4-7]. Engineering an artificial bone marrow that reconstitutes the critical inductive cues of naturally occurring bone marrow in vivo that maintains them in vitro could lead to new models of hematopoietic diseases, as well as enable expansion of bone marrow for therapeutic transplantation and manufacturing of differentiated blood cell replacements. It has proven difficult, however, to identify or combine the correct set of biomaterials and biological signals necessary to recreate the complex bone marrow microenvironment or to maintain functional, multi-potent, self-renewing HSCs in culture [8-13]. Here, we describe a microfluidic bone marrow-on-a-chip created in vivo by combining microsystems and tissue engineering strategies to produce bone that contains a complex bone marrow niche. The hematopoietic compartment of the engineered bone marrow (eBM) has a distribution of HSCs, hematopoietic progenitor cells, and differentiated blood cell types that is virtually identical to natural marrow. Moreover, these hematopoietic populations are retained in normal proportions and the HSCs maintain their full regenerative capacity when the eBM is explanted and cultured in the microfluidic bone marrow chip in vitro. After four days of culture on-chip, hematopoietic cells isolated from the eBM engrafted a lethally-irradiated mouse, reconstituted the compromised bone marrow, and fully restored all differentiated blood cell lineages. Preliminary work with human umbilical cord blood (hCB) suggests that the bone marrow-on-a-chip platform may be extended beyond the mouse to support human HSCs and hematopoietic progenitors in vitro. This ability to engineer a complex bone marrow niche that is capable of maintaining functional HSCs offers new tools for expansion of cells for transplantation, manufacturing. differentiated blood cells, evaluation of drug efficacy and toxicities, and study of hematopoietic diseases

Antibiotic Treatment Expands the Resistance Reservoir and Ecological Network of the Phage Metagenome

The mammalian gut ecosystem has significant influence on host physiology1–4, but the mechanisms that sustain this complex environment in the face of different stresses remain obscure. Perturbations to this ecosystem, such as through antibiotic treatment or diet, are currently interpreted at the level of bacterial phylogeny5–7. Less is known about the contributions of the abundant population of phage to this ecological network. Here, we explore the phageome as a potential genetic reservoir for bacterial adaptation by sequencing murine fecal phage populations following antibiotic perturbation. We show that antibiotic treatment leads to the enrichment of phage-encoded genes that confer resistance via disparate mechanisms to the administered drug as well as genes that confer resistance to antibiotics unrelated to the administered drug, and we demonstrate experimentally that phage from treated mice afford aerobically cultured naïve microbiota increased resistance. Systems-wide analyses uncover post-treatment phage-encoded processes related to host colonization and growth adaptation, indicating that the phageome broadly enriches for functionally beneficial genes under stress-related conditions. We also show that antibiotic treatment expands the interactions between phage and bacterial species, leading to a more highly connected phage-bacterial network for gene exchange. Our work implicates the phageome in the emergence of multidrug resistance and indicates that the adaptive capacity of the phageome may represent a community-based mechanism for protecting the gut microflora, preserving its functional robustness during antibiotic stress

Micro-sensor thin-film anemometer

A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14.degree. half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique

Bone Marrow–on–a–Chip Replicates Hematopoietic Niche Physiology in Vitro

Current in vitro hematopoiesis models fail to demonstrate the cellular diversity and complex functions of living bone marrow; hence, most translational studies relevant to the hematologic system are conducted in live animals. Here we describe a method for fabricating 'bone marrow–on–a–chip' that permits culture of living marrow with a functional hematopoietic niche in vitro by first engineering new bone in vivo, removing it whole and perfusing it with culture medium in a microfluidic device. The engineered bone marrow (eBM) retains hematopoietic stem and progenitor cells in normal in vivo–like proportions for at least 1 week in culture. eBM models organ-level marrow toxicity responses and protective effects of radiation countermeasure drugs, whereas conventional bone marrow culture methods do not. This biomimetic microdevice offers a new approach for analysis of drug responses and toxicities in bone marrow as well as for study of hematopoiesis and hematologic diseases in vitro.Engineering and Applied Science

Micro-sensor thin-film anemometer

A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14 deg half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique

K2-HERMES II. Planet-candidate properties from K2 Campaigns 1-13

Accurate and precise radius estimates of transiting exoplanets are critical for understanding their compositions and formation mechanisms. To know the planet, we must know the host star in as much detail as possible. We present complete results for planet-candidate hosts from the K2-HERMES survey, which uses the HERMES multi-object spectrograph on the AngloAustralian Telescope to obtain R ∼ 28 000 spectra for more than 30 000 K2 stars. We present complete host-star parameters and planet-candidate radii for 224 K2 candidate planets from C1-C13. Our results cast severe doubt on 30 K2 candidates, as we derive unphysically large radii, larger than 2RJup. This work highlights the importance of obtaining accurate, precise, and self-consistent stellar parameters for ongoing large planet search programs - something that will only become more important in the coming years, as TESS begins to deliver its own harvest of exoplanets

Potentiating antibacterial activity by predictably enhancing endogenous microbial ROS production

The ever-increasing incidence of antibiotic-resistant infections combined with a weak pipeline of new antibiotics has created a global public health crisis1. Accordingly, novel strategies for enhancing our antibiotic arsenal are needed. As antibiotics kill bacteria in part by inducing reactive oxygen species (ROS)2–4, we reasoned that targeting microbial ROS production might potentiate antibiotic activity. Here we show that ROS production can be predictably enhanced in Escherichia coli, increasing the bacteria’s susceptibility to oxidative attack. We developed an ensemble, genome-scale metabolic modeling approach capable of predicting ROS production in E. coli. The metabolic network was systematically perturbed and its flux distribution analyzed to identify targets predicted to increase ROS production. In silico–predicted targets were experimentally validated and shown to confer increased susceptibility to oxidants. Validated targets also increased susceptibility to killing by antibiotics. This work establishes a systems-based method to tune ROS production in bacteria and demonstrates that increased microbial ROS production can potentiate killing by oxidants and antibiotics

Parenthood in survivors of Hodgkin lymphoma: an EORTC-GELA general population case-control study.

Contains fulltext : 108966.pdf (publisher's version ) (Open Access)PURPOSE: We investigated the impact of Hodgkin lymphoma (HL) on parenthood, including factors influencing parenthood probability, by comparing long-term HL survivors with matched general population controls. PATIENTS AND METHODS: A Life Situation Questionnaire was sent to 3,604 survivors treated from 1964 to 2004 in successive clinical trials. Responders were matched with controls (1:3 or 4) for sex, country, education, and year of birth (10-year groups). Controls were given an artificial date of start of treatment equal to that of their matched case. The main end point was presence of biologic children after treatment, which was evaluated by using conditional logistic regression analysis. Logistic regression analysis was used to analyze factors influencing spontaneous post-treatment parenthood. RESULTS: In all, 1,654 French and Dutch survivors were matched with 6,414 controls. Median follow-up was 14 years (range, 5 to 44 years). After treatment, the odds ratio (OR) for having children was 0.77 (95% CI, 0.68 to 0.87; P < .001) for survivors compared with controls. Of 898 survivors who were childless before treatment, 46.7% achieved post-treatment parenthood compared with 49.3% of 3,196 childless controls (OR, 0.87; P = .08). Among 756 survivors with children before treatment, 12.4% became parents after HL treatment compared with 22.2% of 3,218 controls with children before treatment (OR, 0.49; P < .001). Treatment with alkylating agents, second-line therapy, and age older than 35 years at treatment appeared to reduce the chances of spontaneous post-treatment parenthood. CONCLUSION: Survivors of HL had slightly but significantly fewer children after treatment than matched general population controls. The difference concerned only survivors who had children before treatment and appears to have more personal than biologic reasons. The chance of successful post-treatment parenthood was 76%

The EHA Research Roadmap : Malignant Lymphoid Diseases

Peer reviewe

Multiple mechanisms disrupt the let-7 microRNA family in neuroblastoma

Poor prognosis in neuroblastoma is associated with genetic amplification of MYCN. MYCN is itself a target of let-7, a tumour suppressor family of microRNAs implicated in numerous cancers. LIN28B, an inhibitor of let-7 biogenesis, is overexpressed in neuroblastoma and has been reported to regulate MYCN. Here we show, however, that LIN28B is dispensable in MYCN-amplified neuroblastoma cell lines, despite de-repression of let-7. We further demonstrate that MYCN messenger RNA levels in amplified disease are exceptionally high and sufficient to sponge let-7, which reconciles the dispensability of LIN28B. We found that genetic loss of let-7 is common in neuroblastoma, inversely associated with MYCN amplification, and independently associated with poor outcomes, providing a rationale for chromosomal loss patterns in neuroblastoma. We propose that let-7 disruption by LIN28B, MYCN sponging, or genetic loss is a unifying mechanism of neuroblastoma development with broad implications for cancer pathogenesis.United States. National Institutes of Health (R01GM107536)Alex's Lemonade Stand FoundationHoward Hughes Medical InstituteBoston Children's Hospital. Manton Center for Orphan Disease ResearchNational Institute of General Medical Sciences (U.S.) (T32GM007753