The Role of Nutrient Availability in Therapeutic Response of Leukemia

Tumor environment influences the response to anti-cancer therapy, but which extracellular nutrients impact drug sensitivity is largely unknown. In this work, we used functional genomics to identify metabolic modifiers of the response to L-asparaginase (ASNase), a therapy that depletes plasma asparagine and targets leukemic cells with insufficient asparagine synthesis. Our approach revealed thiamine pyrophosphate kinase 1 (TPK1), which converts vitamin B1 (thiamine) into the cofactor thiamine pyrophosphate (TPP), as a metabolic dependency under ASNase treatment. In glutamine-anaplerotic leukemia cells, we found that TPP availability enables asparagine synthesis from extracellular glutamine. Mechanistically, TPP is critical for the activity of alpha-ketoglutarate dehydrogenase (AKGDH), a TCA cycle enzyme that catalyzes a step in the overall conversion of glutamine to asparagine. When TPP availability is limiting for cell proliferation of TPK1 KOs, ASNase sensitivity is significantly increased. Standard cell culture media formulations provide thiamine at a concentration that is ~100-fold higher than that observed in human plasma. While thiamine is generally not limiting for cell proliferation under standard culture conditions, a DNA-barcode competition assay identified a subset of leukemia cell lines that grow sub-optimally under lower, more physiological thiamine levels. These cell lines are characterized by low expression of SLC19A2, a high affinity thiamine transporter. Intriguingly, SLC19A2 expression was necessary for not only optimal growth, but also for maintaining ASNase resistance, when standard media thiamine was lowered to the concentration of human plasma. Importantly, analyzing RNAseq data of pediatric acute lymphoblastic leukemia (ALL) tumor samples revealed that SLC19A2 is the primary thiamine transporter expressed in these cancers, and that SLC19A2-low tumors exist among patients. To model such tumors, we used a SLC19A2-low cell line to generate orthotopic tumors in NSG mice. Remarkably, humanizing blood thiamine content of mice through diet sensitized these leukemia cells to ASNase in vivo. Altogether, our work reveals that utilization of thiamine is a determinant of ASNase response for some cancer cells, and that over-supplying vitamins may impact therapeutic response in leukemia. Additionally, our work adds to the recent literature that demonstrates how physiological levels of certain nutrients in cell culture can affect therapy. Specifically, our work provides the first proof of principle that humanizing the vitamin levels of both in vitro and in vivo models can affect drug sensitivity. This has broad implications for the screening and validation of new therapeutic candidates

Controlled, pulsatile release of thermostabilized inactivated polio vaccine from PLGA-based microspheres

Many vaccines, such as the inactivated polio vaccine (IPV), must be administered in several doses for full efficacy. Because patient access is a major challenge for vaccination efforts in developing countries, administering multiple doses per patient is impractical in those areas. Single-administration vaccines would greatly improve efforts to vaccinate populations in Third World countries, and the World Health Organization (WHO) Expanded Program for Immunization describes an ideal vaccine as one that is heat-stable, requires only one shot, and is easy to administer. Although already existing technologies, such as microspheres composed of poly(lactic-co-glycolic acid) (PLGA), are able to encapsulate vaccines and release them over an extended period of time up to several weeks, they are not able to maintain antigen stability over the longer time intervals in vivo. Vaccines such as IPV, however, are known to be unstable at elevated temperature, such as the 37°C environment of the body, as well as in the acidic environment of the degrading PLGA microspheres. Please click Additional Files below to see the full abstract

Thermostabilization of inactivated polio vaccine in PLGA-based microspheres for pulsatile release

AbstractVaccines are a critical clinical tool in preventing illness and death due to infectious diseases and are regularly administered to children and adults across the globe. In order to obtain full protection from many vaccines, an individual needs to receive multiple doses over the course of months. However, vaccine administration in developing countries is limited by the difficulty in consistently delivering a second or third dose, and some vaccines, including the inactivated polio vaccine (IPV), must be injected more than once for efficacy. In addition, IPV does not remain stable over time at elevated temperatures, such as those it would encounter over time in the body if it were to be injected as a single-administration vaccine. In this manuscript, we describe microspheres composed of poly(lactic-co-glycolic acid) (PLGA) that can encapsulate IPV along with stabilizing excipients and release immunogenic IPV over the course of several weeks. Additionally, pH-sensitive, cationic dopants such as Eudragit E polymer caused clinically relevant amounts of stable IPV release upon degradation of the PLGA matrix. Specifically, IPV was released in two separate bursts, mimicking the delivery of two boluses approximately one month apart. In one of our top formulations, 1.4, 1.1, and 1.2 doses of the IPV serotype 1, 2, and 3, respectively, were released within the first few days from 50mg of particles. During the delayed, second burst, 0.5, 0.8, and 0.6 doses of each serotype, respectively, were released; thus, 50mg of these particles released approximately two clinical doses spaced a month apart. Immunization of rats with the leading microsphere formulation showed more robust and long-lasting humoral immune response compared to a single bolus injection and was statistically non-inferior from two bolus injections spaced 1 month apart. By minimizing the number of administrations of a vaccine, such as IPV, this technology can serve as a tool to aid in the eradication of polio and other infectious diseases for the improvement of global health

Optimizing diffusion time prior to probe-mediated microwave heating of injected nanoparticles for hyperthermia treatment of tumors

Localized tumor hyperthermia therapy is a treatment that involves heating cancerous tissue to temperatures that result in tumor cell necrosis, while preventing damage to surrounding healthy tissue. Hyperthermia therapy treatments reported in the literature have shown that nanoparticles can be injected into a targeted tumor, allowing specific regions to undergo treatment and reducing the healthy tissue that is affected as well. Previous studies have shown that when the nanoparticles absorb specific wavelengths of radiation, they undergo resonance and emit heat. Thus, the targeted tumor can be heated through the actions of both tissue absorption, and heat emitted by the excited nanoparticles. This additional heat due to nanoparticles within a tumor can facilitate tumor heating over a given time-frame so as to prevent damage to surrounding healthy tissue. Our project aimed to investigate the efficacy of utilizing injectable ferromagnetic nanoparticles (with the properties of γ-hematite nanoparticles) to facilitate microwave heating of cancerous tissue. The first stage of our project was modeling the precise delivery and dispersion of a volume of nanoparticles in a targeted cancerous tissue. To do this, we built a 1D radially symmetric computational model in COMSOL to represent a tumor, and we computed the diffusion profile of the nanoparticles in this domain over the time directly after injection. Next, we built a 2D axisymmetric computational domain in COMSOL to model the heat treatment. This model included heating of the tumor tissue with a microwave probe, and then coupled this heating with heating due to the nanoparticle concentration in the tissue. Computing the heat and energy profiles for this heating model allowed us to then determine the optimal time after injection to begin the heat treatment to maximize cancer cell death, but minimize damage to healthy tissue. The optimal time was determined as the time when all cancerous tissue temperature had been raised above 43 °C, while the maximum surrounding healthy tissue temperature was still below 43 °C. In conjunction with finding the optimal heating interval, our goal was to also find the optimized injection nanoparticle concentration, nanoparticle diffusion time, and microwave radiation power level. Computed temperature profiles that took into account heating due to the presence of nanoparticles within the tumor computational domain showed only a slightly larger proportion of the tumor domain reaching temperatures in excess of 43 °C than could be achieved when heating is due to radiation absorption by the tissue alone. Our conclusion is that, within the model, the nanoparticles are indeed absorbing microwave radiation, but they are not subsequently emitting as much heat as was expected. As they are absorbing radiation, they are blocking the passage of energy into the tissue areas directly surrounding the nanoparticles. Without the nanoparticles in the tumor domain, the microwave radiation can be absorbed entirely by the tissue, resulting in more desirable temperature profiles. Thus, our model as implemented does not demonstrate that injecting γ-hematite nanoparticles into a tumor facilitates probe-mediated microwave heating of said tumor. However, several changes could be made to our model to achieve more desirable results. For example, if the nanoparticles were injected so as to enclose the tumor targeted for destruction, then they would effectively create a barrier for microwave radiation to pass through, thus restricting the radiation heating primarily to the enclosed tumor region. Alternatively, the ferromagnetic nanoparticles could be magnetically tuned (using a varying magnetic field) during microwave radiation so that they do actually undergo resonance significantly, resulting in greater heat emission and desirable temperature profiles. Regardless, we did successfully model probe-mediated microwave radiation of a tumor for hyperthermia treatment using a complete electromagnetism module in COMSOL, something that has never been done before in this course. We found the optimum microwave probe power level and radiation time required to maximize tumor death while minimizing healthy tissue damage in our model. It follows that localized tumor hyperthermia therapy that uses a microwave-emitting probe for tumor destruction can be modeled and fine-tuned using COMSOL. With appropriate model modifications, it could be shown that ferromagnetic nanoparticles can be used to direct the microwave heating in the targeted region. Mass transfer and heat transfer models similar to the ones used in this project can be built with specific tumor geometries, tissue properties, and probe properties, and such models can be used to plan clinical applications of using probe-mediated microwave heating of cancerous tissue

Mesoporous InN/In2O3 heterojunction with improved sensitivity and selectivity for room temperature NO2 gas sensing

Establishing heterostructures is a good strategy to improve gas sensing performance, and has been studied extensively. In this work, mesoporous InN/In2O3 composite (InNOCs) heterostructures were prepared through a simple two-step strategy involving hydrothermal synthesis of In2O3 and subsequent nitriding into InN-composite In2O3 heterostructures. We found that the InN content has great influence on the resistance of InNOCs, and thus, the gas sensing performance. In particular, InNOC-36.9 (with InN content of 36.9% in the composites) shows an excellent sensing response towards different concentrations of NO2, as well as good stability after one week of exposure to 200 ppb NO2 at room temperature. The highest sensing response (Delta R/R-0) is up to 1.8 for the low NO2 concentration of 5 ppb. Even more significantly, the theoretical limit of detection (LOD) of the InNOC-36.9 sensor is 31.7 ppt based on a signal-to- noise ratio of 3 (the measured LOD is 5 ppb), which is far below the US NAAQS. value (NO2: 53 ppb). In addition, a rational band structure model combined with a surface reaction model is proposed to explain the sensing mechanism

Mesoporous WN/WO3-Composite Nanosheets for the Chemiresistive Detection of NO2 at Room Temperature

Composite materials, which can optimally use the advantages of different materials, have been studied extensively. Herein, hybrid tungsten nitride and oxide (WN/WO3) composites were prepared through a simple aqueous solution route followed by nitriding in NH3, for application as novel sensing materials. We found that the introduction of WN can improve the electrical properties of the composites, thus improving the gas sensing properties of the composites when compared with bare WO3. The highest sensing response was up to 21.3 for 100 ppb NO2 with a fast response time of ~50 s at room temperature, and the low detection limit was 1.28 ppb, which is far below the level that is immediately dangerous to life or health (IDLH) values (NO2: 20 ppm) defined by the U.S. National Institute for Occupational Safety and Health (NIOSH). In addition, the composites successfully lower the optimum temperature of WO3 from 300 °C to room temperature, and the composites-based sensor presents good long-term stability for NO2 of 100 ppb. Furthermore, a possible sensing mechanism is proposed

Geopolymer for use in heavy metals adsorption, and advanced oxidative processes: A critical review

Geopolymer for use in heavy metals adsorption, and advanced oxidative processes: A critical revie

Mesoporous WN/WO[subscript 3]-composite nanosheets for the chemiresistive detection of NO[subscript 3] at room temperature

Composite materials, which can optimally use the advantages of different materials, have been studied extensively. Herein, hybrid tungsten nitride and oxide (WN/WO[subscript 3]) composites were prepared through a simple aqueous solution route followed by nitriding in NH[subscript 3], for application as novel sensing materials. We found that the introduction of WN can improve the electrical properties of the composites, thus improving the gas sensing properties of the composites when compared with bare WO[subscript 3]. The highest sensing response was up to 21.3 for 100 ppb NO[subscript 2] with a fast response time of ~50 s at room temperature, and the low detection limit was 1.28 ppb, which is far below the level that is immediately dangerous to life or health (IDLH) values (NO[subscript 2]: 20 ppm) defined by the U.S. National Institute for Occupational Safety and Health (NIOSH). In addition, the composites successfully lower the optimum temperature of WO[subscript 3] from 300 °C to room temperature, and the composites-based sensor presents good long-term stability for NO[subscript 2] of 100 ppb. Furthermore, a possible sensing mechanism is proposed. ©2016 Keywords: WN/WO3 composite; nanosheets; gas sensor; NO2; room temperatur

Thermostabilization of inactivated polio vaccine in PLGA-based microspheres for pulsatile release

Vaccines are a critical clinical tool in preventing illness and death due to infectious diseases and are regularly administered to children and adults across the globe. In order to obtain full protection from many vaccines, an individual needs to receive multiple doses over the course of months. However, vaccine administration in developing countries is limited by the difficulty in consistently delivering a second or third dose, and some vaccines, including the inactivated polio vaccine (IPV), must be injected more than once for efficacy. In addition, IPV does not remain stable over time at elevated temperatures, such as those it would encounter over time in the body if it were to be injected as a single-administration vaccine. In this manuscript, we describe microspheres composed of poly(lactic-co-glycolic acid) (PLGA) that can encapsulate IPV along with stabilizing excipients and release immunogenic IPV over the course of several weeks. Additionally, pH-sensitive, cationic dopants such as Eudragit E polymer caused clinically relevant amounts of stable IPV release upon degradation of the PLGA matrix. Specifically, IPV was released in two separate bursts, mimicking the delivery of two boluses approximately one month apart. In one of our top formulations, 1.4, 1.1, and 1.2 doses of the IPV serotype 1, 2, and 3, respectively, were released within the first few days from 50 mg of particles. During the delayed, second burst, 0.5, 0.8, and 0.6 doses of each serotype, respectively, were released; thus, 50 mg of these particles released approximately two clinical doses spaced a month apart. Immunization of rats with the leading microsphere formulation showed more robust and long-lasting humoral immune response compared to a single bolus injection and was statistically non-inferior from two bolus injections spaced 1 month apart. By minimizing the number of administrations of a vaccine, such as IPV, this technology can serve as a tool to aid in the eradication of polio and other infectious diseases for the improvement of global health.Bill & Melinda Gates Foundation (OPP1095790