Qin Dai

Researchers develop new method for delivering RNA and drugs into cells

Christopher.Sorensen — Mon, 16 Sep 2024 15:02:15 +0000

Researchers develop new method for delivering RNA and drugs into cells

Christopher.Sorensen Mon, 09/16/2024 - 11:02

Cutline

PhD candidate Kai Slaughter, left, and University Professor Molly Shoichet are exploring how ionizable drugs can be used to co-formulate small interfering RNA (siRNA) for more effective intracellular delivery (supplied images)

Qin Dai

Topic

Breaking Research

Institute of Biomedical Engineering

Princess Margaret Cancer Centre

Temerty Faculty of Medicine

Donnelly Centre for Cellular & Biomolecular Research

Faculty of Applied Science & Engineering

Research & Innovation

University Health Network

Subheadline

"This could be a game-changer for treating complex conditions where targeting multiple pathways is beneficial, such as cancer and viral infections"

Researchers at the University of Toronto and its hospital partners have developed a method for co-delivering therapeutic RNA and potent drugs directly into cells, potentially leading to a more effective treatment of diseases.

The research, published recently in the journal Advanced Materials, explores how ionizable drugs can be used to co-formulate small interfering RNA (siRNA) for more effective intracellular delivery.

The team – including Molly Shoichet, the study’s corresponding author and a University Professor in ��ֱ��’s department of chemical engineering and applied chemistry in the Faculty of Applied Science & Engineering – specifically targeted drug-resistant cells with the delivery of a relevant siRNA. The siRNA was discovered study co-author and collaborator David Cescon, a clinician scientist at the Princess Margaret Cancer Centre, University Health Network, and an associate professor in ��ֱ��’s Temerty Faculty of Medicine.

“We found that our co-formulation method not only potently delivered siRNA to cells but also simultaneously delivered active ionizable drugs,” said research lead author Kai Slaughter, a PhD candidate in Shoichet’s lab.

“This could be a game-changer for treating complex conditions where targeting multiple pathways is beneficial, such as cancer and viral infections.”

siRNA is a powerful tool in medicine, capable of silencing specific genes responsible for disease, but delivering these molecules into cells without degradation remains a significant challenge. While recent innovations in ionizable lipid design have led to efficiency improvements, traditional nanoparticle formulations are limited in the amount of small molecule drugs they can carry.

When therapeutic formulations are absorbed by cells, small molecule drugs and siRNA are often trapped in small compartments called endosomes, preventing them from reaching their target destination and reducing their effectiveness.

The research team discovered that combining siRNA with ionizable drugs – compounds that change their charge based on pH levels – enhances the stability and delivery efficiency of siRNA inside cells, helping both the siRNA and drug escape the endosome and more effectively reach their destination. This novel method utilizes the protective properties of lipids to safeguard siRNA during its journey through the body and ensure the release of RNA and the drug together within the target cells.

“One of the biggest hurdles in siRNA therapy has been getting these molecules to where they need to go without losing their potency,” Shoichet says.

“Our approach using ionizable drugs as carriers marks a significant step forward in overcoming this barrier, while also showing how drugs and RNA can be delivered together in the same nanoparticle formulation.”

Research team explores next-gen vaccines to guard against sexually transmitted infections

Christopher.Sorensen — Wed, 04 Sep 2024 16:07:53 +0000

Research team explores next-gen vaccines to guard against sexually transmitted infections

Christopher.Sorensen Wed, 09/04/2024 - 12:07

Cutline

Aereas Aung, an assistant professor in the Institute of Biomedical Engineering , is developing new tools to study and manipulate immune cells and their reaction to vaccines (photo by Tim Fraser)

Qin Dai

Topic

Breaking Research

Institute of Biomedical Engineering

Connaught Fund

Faculty of Applied Science & Engineering

Research & Innovation

Vaccines

Subheadline

"This work could lay the foundation for more effective vaccines that curb the spread of STIs, particularly in marginalized communities disproportionately affected by these diseases”

A research team from the University of Toronto is creating a new generation of vaccines that aims to overcome key hurdles faced by some existing formulations.

For example, a common shortcoming of many traditional vaccines is that they can’t produce antibodies in tissues where sexually transmitted infections (STIs) often enter the body.

“Most current vaccines fail to produce sufficient antibodies within mucosal tissues, leaving a significant gap in our defense against sexually transmitted infections,” says Aereas Aung, an assistant professor at the Institute of Biomedical Engineering in the Faculty of Applied Science & Engineering who is leading the research effort.

“Our goal is to develop a novel strategy that leverages the strengths of parenteral vaccination while also targeting the mucosal immune system.”

Normally vaccines are injected parenterally, meaning it is injected into or under the skin, into the muscle or directly into the bloodstream. The vaccine then travels to lymph nodes, which are small glands that help produce antibodies. Mucosal tissues in the cervix and rectum present a unique challenge since the mucus in these areas can break down the vaccine quickly and wash it away, making it difficult to reach the lymph nodes and be effective.

Aung’s research proposes fusing a protein carrier to the disease antigens, allowing it to reach distant mucosal lymph nodes after injection.

“We aim to incorporate potent immunostimulatory components into our antigen construct, optimizing its distribution and enhancing mucosal antibody responses,” says Aung.

“If successful, this work could lay the foundation for more effective vaccines that curb the spread of STIs, particularly in marginalized communities disproportionately affected by these diseases.”

Aung’s project is one of 51 ��ֱ�� faculty members whose work is being supported by the Connaught New Researcher Awards in the most recent round – and one of eight at ��ֱ�� Engineering. The award helps early-career faculty members establish their research programs.

The other ��ֱ�� Engineering researchers whose projects are supported by the award are: 

Mohammed Basheer, department of civil and mineral engineering – Integrated hydrological-statistical method and tool for landslide susceptibility mapping in a changing climate
Daniel Franklin, Institute of Biomedical Engineering – Development of equitable pulse oximeters
Sarah Haines, department of civil and mineral engineering – Open Plenums & Indoor Environments (OPEN): Evaluating the impact of return air systems on indoor environmental quality
Mark Jeffrey, Edward S. Rogers Sr. department of electrical and computer engineering – Productively surmounting the memory wall with task parallelism
Caitlin Maikawa, Institute of Biomedical Engineering – Affinity-directed dynamic polymer materials for biomarker sensing
Mohamad Moosavi, department of chemical engineering and applied chemistry – Learning the Language of Metal-Organic Frameworks Topology
Cindy Rottmann, Institute for Studies in Transdisciplinary Engineering Education and Practice (ISTEP) – But I could be fired! How early career engineers hold the public paramount from organizationally subordinate locations

��ֱ�� researchers integrate crucial immune cells onto heart-on-a-chip platform

Christopher.Sorensen — Fri, 23 Aug 2024 12:56:51 +0000

��ֱ�� researchers integrate crucial immune cells onto heart-on-a-chip platform

Christopher.Sorensen Fri, 08/23/2024 - 08:56

Cutline

L-R: ��ֱ�� post-doctoral fellow Shira Landau, PhD alum Yimu Zhao and Professor Milica Radisic are three of the primary authors of a study that could lead to advancements in the creation of more stable and functional heart tissues (supplied images)

Qin Dai

Topic

Breaking Research

Institute of Biomedical Engineering

Toronto General Hospital

Donnelly Centre for Cellular & Biomolecular Research

Faculty of Applied Science & Engineering

Research & Innovation

University Health Network

Subheadline

The immune cells, known as primitive macrophages, were found to enhance heart tissue function and vessel stability

Researchers at the University of Toronto have discovered a novel method for incorporating primitive macrophages – crucial immune cells – into heart-on-a-chip technology, in a potentially transformative step forward in drug testing and heart disease modeling.

In a study published in Cell Stem Cell, an interdisciplinary team of scientists describe how they integrated the macrophages – which were derived from human stem cells and resemble those found in the early stages of heart development – onto the platforms. These macrophages are known to have remarkable abilities in promoting vascularization and enhancing tissue stability.

Corresponding author Milica Radisic, a senior scientist in the University Health Network's Toronto General Hospital Research Institute and professor in the Institute of Biomedical Engineering at ��ֱ��’s Faculty of Applied Science & Engineering, says the approach promises to enhance the functionality and stability of engineered heart tissues.

“We demonstrated here that stable vascularization of a heart tissue in vitro requires contributions from immune cells, specifically macrophages. We followed a biomimetic approach, re-establishing the key constituents of a cardiac niche,” says Radisic, who holds a Canada Research Chair in Functional Cardiovascular Tissue Engineering

“By combining cardiomyocytes, stromal cells, endothelial cells and macrophages, we enabled appropriate cell-to-cell crosstalk such as in the native heart muscle.”

Professor Milica Radisic's research team have worked on developing a miniaturized version of cardiac tissue on heart-on-a-chip platforms for a decade (photo by Nick Iwanyshyn)

A major challenge in creating bioengineered heart tissue is achieving a stable and functional network of blood vessels. Traditional methods have struggled to maintain these vascular networks over extended periods, limiting their effectiveness for long-term studies and applications.

In their study, researchers demonstrated that the primitive macrophages could create stable, perfusable microvascular networks within the cardiac tissue, a feat that had previously been difficult to achieve.

Furthermore, the macrophages helped reduce tissue damage by mitigating cytotoxic effects, thereby improving the overall health and functionality of the engineered tissues.

“The inclusion of primitive macrophages significantly improved the function of cardiac tissues, making them more stable and effective for longer periods,” says Shira Landau, a post-doctoral fellow in Radisic’s lab and one of the study’s lead authors.

The breakthrough has far-reaching implications for the field of cardiac research. By enabling the creation of more stable and functional heart tissues, researchers can better study heart diseases and test new drugs in a controlled environment.

Researchers say this technology could lead to more accurate disease models and more effective treatments for heart conditions.

��ֱ�� researchers' AI model designs proteins to deliver gene therapy

Christopher.Sorensen — Mon, 29 Jan 2024 18:44:19 +0000

��ֱ�� researchers' AI model designs proteins to deliver gene therapy

Christopher.Sorensen Mon, 01/29/2024 - 13:44

Cutline

Michael Garton, left, an associate professor of biomedical engineering, and PhD candidate Suyue Lyu, right, used AI to custom-design variants of hexons that are distinct from natural sequences to help evade the immune system (photo by Qin Dai)

Qin Dai

Topic

Breaking Research

Institute of Biomedical Engineering

Artificial Intelligence

Faculty of Applied Science & Engineering

Gene Therapy

Graduate Students

Research & Innovation

Subheadline

Dubbed ProteinVAE, the model can be trained to learn the characteristics of a long protein using limited data

Researchers at the University of Toronto used an artificial intelligence framework to redesign a crucial protein involved in the delivery of gene therapy.

The study, published in Nature Machine Intelligence, describes new work optimizing proteins to mitigate immune responses, thereby improving the efficacy of gene therapy and reducing side effects.

“Gene therapy holds immense promise, but the body’s pre-existing immune response to viral vectors greatly hampers its success. Our research zeroes in on hexons, a fundamental protein in adenovirus vectors, which – but for the immune problem – hold huge potential for gene therapy,” says Michael Garton, an assistant professor at the Institute of Biomedical Engineering in the Faculty of Applied Science & Engineering.

“Immune responses triggered by serotype-specific antibodies pose a significant obstacle in getting these vehicles to the right target; this can result in reduced efficacy and severe adverse effects.”

To address the issue, Garton’s lab used AI to custom-design variants of hexons that are distinct from natural sequences.

“We want to design something that is distant from all human variants and is, by extension, unrecognizable by the immune system,” says PhD candidate Suyue Lyu, who is lead author of the study.

Traditional methods of designing new protein often involve extensive trial and error as well as mounting costs. By using an AI-based approach for protein design, researchers can achieve a higher degree of variation, reduce costs and quickly generate simulation scenarios before homing in on a specific subset of targets for experimental testing.

While numerous protein-designing frameworks exist, it can be challenging for researchers to properly design new variants because of the lack of natural sequences available and hexons’ relatively large size – consisting, on average, of 983 amino acids.

With this in mind, Lyu and Garton developed a different AI framework. Dubbed ProteinVAE, the model can be trained to learn the characteristics of a long protein using limited data. Despite its compact design, ProteinVAE exhibits a generative capability comparable to larger available models.

“Our model takes advantage of pre-trained protein language models for efficient learning on small datasets. We also incorporated many tailored engineering approaches to make the model suitable for generating long proteins,” says Lyu, adding that ProteinVAE was intentionally designed to be lightweight. “Unlike other, considerably larger models that demand high computational resources to design a long protein, ProteinVAE supports fast training and inference on any standard GPUs. This feature could make the model more friendly for other academic labs.

“Our AI model, validated through molecular simulation, demonstrates the ability to change a significant percentage of the protein’s surface, potentially evading immune responses.”

The next step is experimental testing in a wet lab, Lyu adds.

Garton believes the AI-model can be utilized beyond gene therapy protein design and could likely be expanded to support protein design in other disease cases as well.

“This work indicates that we are potentially able to design new subspecies and even species of biological entities using generative AI,” he says, “and these entities have therapeutic value that can be used in novel medical treatments.”

The research was supported by the Canadian Institute of Health Research and the Natural Sciences and Engineering Research Council of Canada.

Researchers discover new protein needed for rapid wound repair

siddiq22 — Wed, 07 Jun 2023 20:35:11 +0000

Researchers discover new protein needed for rapid wound repair

siddiq22 Wed, 06/07/2023 - 16:35

Cutline

Katheryn Rothenberg, a postdoctoral researcher in ��ֱ��'s Quantitative Morphogenesis Lab, was lead author on the new study (photo by Qin Dai)

Qin Dai

Topic

Breaking Research

Institute of Biomedical Engineering

Cell and Systems Biology

Faculty of Applied Science & Engineering

Medical Research

Research & Innovation

Subheadline

A new study by researchers from ��ֱ��'s Faculty of Applied Science & Engineering examines the mechanisms underlying collective cell migration

Researchers from the University of Toronto's Faculty of Applied Science & Engineering have made progress in understanding the intricate cellular processes involved in tissue development and repair.

The findings, published in the journal Current Biology, shed light on the mechanisms underlying collective cell migration – a fundamental behaviour that plays a crucial role in both normal embryo development and pathological conditions such as cancer metastasis.

“This study advances our understanding of the molecular signals that coordinate cellular behaviours, in embryonic development and tissue repair, and likely also in tumour invasion,” says Rodrigo Fernandez-Gonzalez, a professor in the department of cell and systems biology and the Institute of Biomaterials and Biomedical Engineering who heads the Quantitative Morphogenesis Laboratory.

Researchers found that Rap1 – a molecular switch that regulates cell adhesion and signalling when turned on – plays a role in the formation and remodelling of adherens junctions (protein complexes that occur at cell–cell junctions and cell–matrix junctions in epithelial and endothelial tissue) and the cytoskeleton during the collective cell movements that drive the rapid, scar-less wound healing response in embryos, making it an attractive therapeutic target in the future.

In embryonic wound healing, the cells around the wound move together to seal the lesion. To that end, cells undergo a series of intricate molecular changes. At the centre of these changes, a unique structure called tricellular junction (TCJ) is formed. The TCJ acts as a hub that hosts a series of proteins that are essential in coordinating cell movements.

When researchers tagged the Rap1 protein with a sensor that could be detected by a microscope, they were able to visualize large concentrations of the protein accumulating around the wound, and specifically at the TCJs.

Upon establishing the localization of Rap1 in the hub of wound repair, the researchers set out to find its role in this complex process. By inactivating or reducing the amount of Rap1 in the embryo, they observed a significant reduction in the wound closure rate compared to normal embryos. Conversely, by activating Rap1, the wound closure rate was dramatically accelerated.

“The fact that collective migration speed can be modulated by Rap1 activity provides a potential pathway for either promoting cell migration – for example, to heal chronic wounds or stopping undesired migration like cancer metastasis,” says Katheryn Rothenberg, a postdoctoral researcher in Fernandez-Gonzalez’s lab who led the study.

Researchers also found that Rap1 plays a crucial role in interacting with cell-cell adhesion proteins necessary to maintain cells together as they move to close the wound, and cytoskeletal proteins that cells use to pull on each other and move collectively. They observed that any disruption to Rap1 can greatly impede the speed at which wounds close.

“By unravelling the intricate molecular mechanisms involved, we have uncovered potential targets for therapeutic interventions in various conditions that rely on collective cell migration,” Fernandez-Gonzalez says.

“We are now keen on understanding the upstream signals that turn Rap1 on during wound healing. This understanding would facilitate the development of tools to activate Rap1 in congenital disorders associated with deficient collective cell behaviour, or to inhibit Rap1 when it contributes to spread disease.”

��ֱ�� researchers design microfluidic device to understand how air pollution affects lungs

geoff.vendeville — Thu, 04 Nov 2021 14:33:06 +0000

��ֱ�� researchers design microfluidic device to understand how air pollution affects lungs

geoff.vendeville Thu, 11/04/2021 - 10:33

Cutline

Edmond Young, of the Faculty of Applied Science & Engineering, and his research team have developed a microfluidic lung-on-a-chip that mimics breathing in human lungs (photo courtesy of Edmond Young)

Qin Dai

Topic

Breaking Research

Institute of Biomedical Engineering

Faculty of Applied Science & Engineering

Health

Pollution

University of Toronto researchers in biomedical engineering have developed a new technology that combines a microfluidic device with a novel airflow system to mimic lung airways. The technology enables scientists and engineers to perform particle exposure experiments to examine the pathological effects of air pollutants on respiratory health.

Siwan Park, a PhD candidate at the Institute of Biomedical Engineering in the Faculty of Applied Science & Engineering, and Edmond Young, an associate professor in the department of mechanical and industrial engineering, recently published their findings in Advanced Materials Technologies.

The microfluidic device-on-a-chip – known as E-FLOAT, short for Extractable Floating Liquid gel-based Organ-on-a-chip for Airway Tissue modelling under airflow – is an easily modifiable system where scientists can grow lung cells in a suspended hydrogel that resembles lung tissue.

The researchers developed the device by micro-milling and bonding layers of thermoplastic. It incorporates a special channel geometry for growing the cells. An airflow system connected to the device can generate various flow rates of warm and humidified air to simulate human breathing.

“We showed that lung airway tissue can be micro-engineered in the lab, exposed to various environmental conditions, including airflow and pollutants, and then be extracted for further interrogation as if it were a real lung tissue sample,” Young says.

In the E-FLOAT device, lung cells are suspended in a hydrogel to mimic how they would grow in normal lung tissue. The microfluidic devices simulate breathing and exposure to air pollutants (images courtesy Siwan Park and Edmond W. K. Young)

In many existing iterations of the technology, cells grown on microfluidic devices are limited to ‘on-chip’ analysis to assess the effect of external stimuli, such as airflow, on the health of the cells. This limits the analysis that can be carried out: while scientists can remove these cells from the device, this process changes the spatial location of the cells in relationship to the tissue, potentially skewing the results.

“One of the advantages of E-FLOAT is the ability to extract the biomimetic airway tissue that allows us to develop an in-depth knowledge through a wide array of imaging technologies,” Park says.

The researchers successfully delivered airborne particles onto the airway cells via controlled airflow to mimic how air pollutants would interact with lung cells. They then extracted the entire hydrogel and analyzed particulate and cell interactions.

“We were especially excited to obtain the stunning images of histology sections using the extracted hydrogel. Not only does it look beautiful, we believe that it may also be significant in histological and pathological perspectives. Also, depending on how we design the cell-matrix interactions in E-FLOAT, we may obtain a more physiologically accurate representation of multicellular airway tissue.”

“In the future, the plan is to use this technology to study the development of lung diseases like asthma – especially in the presence of air pollution – and to also use it as a preclinical model during drug development,” Young says.

“There is obviously a lot more work to be done, but we hope to collaborate with lung researchers and partner with pharma down the road to realize this plan.”

Researchers develop quantum dot smartphone device to diagnose and track COVID-19

Christopher.Sorensen — Thu, 17 Jun 2021 20:15:29 +0000

Researchers develop quantum dot smartphone device to diagnose and track COVID-19

Christopher.Sorensen Thu, 06/17/2021 - 16:15

Cutline

��ֱ�� PhD candidates Ayden Malekjahani and Johnny Zhang are co-authors of a study detailing the development of a portable, smartphone-based quantum barcode serological assay device for real-time surveillance of patients infected with SARS-CoV-2.

Qin Dai

Topic

Our Community

Coronavirus

Sunnybrook Health Sciences Centre

Donnelly Centre for Cellular & Biomolecular Research

Chemistry

Faculty of Applied Science & Engineering

Faculty of Arts & Science

Institute of Biomaterials and Biomedical Engineering

Mount Sinai Hospital

Research & Innovation

Researchers at the University of Toronto, in collaboration with Sunnybrook Health Sciences Centre, Public Health Ontario and Mount Sinai Hospital, have developed a COVID-19 antibody test that makes use of a smartphone camera.

The test could significantly improve the turnaround time and efficiency of infectious disease diagnosis, both for COVID-19 and beyond. The work is published in the latest issue of Nano Letters and involves ��ֱ�� researchers from the Institute of Biomedical Engineering, department of chemistry in the Faculty of Arts & Science and Donnelly Centre for Cellular and Biomolecular Research.

“The goal of the study is to make COVID-19 antibody tests more accessible.” said Johnny Zhang, a PhD candidate at the Institute of Biomedical Engineering and department of chemistry who is one of the co-first authors of the publication.

“The end result is that the patients can take a self-diagnosis for COVID-19 with their phone, and that data can be immediately accessed digitally by medical professionals.”

The typical workflow for infectious disease diagnostic testing involves obtaining a sample from the patient, sending it to a laboratory for diagnostic testing and distributing the result to clinical personnel for decision making. The processes are often siloed and have a long turn-around time.

A device developed at ��ֱ��'s Institute of Biomedical Engineering makes use of an ordinary smartphone camera to rapidly detect COVID-19. (Image courtesy of Matthew Osborne and Hongmin Chen)

By contrast, the ��ֱ�� and hospital researchers developed a portable smartphone-based quantum barcode serological assay device for real-time surveillance of patients infected with SARS-CoV-2. They engineered quantum dot barcoded microbeads and a secondary label to search for antibodies against COVID-19 antigen in a patient’s blood. Finding the antibodies leads to a change in microbead emission colour.

The beads are then loaded into the device, activated with a laser, and the signal is imaged using a smartphone camera. An app is designed to process the image to identify the bead’s emission change. Finally, the data are interpreted and transmitted remotely across the world for data collection and decision making.

“The beauty of the system is that everything is integrated into one portable unit.” said Zhang.

This technology, by which quantum dot microbead detection can measure minuscule amounts of key biomarkers in blood, has been in development for the past 10 years.

“We really wanted to improve the performance and utility of the technology this time around,” said PhD candidate Ayden Malekjahani, the other co-first author of this study.

“Being able to detect traces of target in patients is not enough. We wanted to add more functions to the device. We designed the device to simultaneously detect multiple antibodies from different sample types, so each test run is packed with information. The results are then uploaded to an online dashboard where medical professionals and the public can see trends in real time.”

The researchers tested the device with 49 patient blood samples where varying degrees of COVID-19 infection were present, and were able to achieve 84-88 per cent sensitivity. Although this result is not as high as traditional tests, it is still approximately three times higher than lateral flow assays, which are currently the most commonly available portable antibody tests.

This result also means detecting COVID-19 antibody can now be done outside of the centralized facilities without a big drop in accuracy.

This research was a collaboration with the Public Health Ontario, Sunnybrook Hospital and Mount Sinai Hospital, where clinical samples were provided to the researchers to test and evaluate this new system.

“This device can be a game-changer in the way we monitor the spread of infectious diseases and a patient’s response to vaccines.” said Professor Warren Chan, director of the Institute of Biomedical Engineering, and the corresponding author of this research.

Researchers develop credit-card sized tool to understand how cancer cells invade host tissues

lanthierj — Mon, 20 Jul 2020 15:52:57 +0000

Researchers develop credit-card sized tool to understand how cancer cells invade host tissues

lanthierj Mon, 07/20/2020 - 11:52

Cutline

“Using the tool we developed, researchers in the future can develop therapeutics that target some of these genes to halt the cancer metastasis,” Betty Li said. (photo by Michael Dryden)

Qin Dai

Topic

Breaking Research

Institute of Biomedical Engineering

Donnelly Centre for Cellular & Biomolecular Research

Cancer

Chemistry

Faculty of Applied Science & Engineering

Faculty of Medicine

Research & Innovation

Subheadline

“We think this type of tool will be quite useful to the community”

A group of researchers from the University of Toronto has developed a credit-card sized tool for growing cancer cells outside the human body, which they believe will enhance their understanding of breast cancer metastasis.

The device, described in a paper published on July 15 in Science Advances, reproduces various environments within the human body where breast cancer cells live. Studying the cells as they go through the process of invasion and metastasis could point the way toward new biomarkers and drugs to diagnose and treat cancer.

“Metastasis is what makes cancer so deadly,” said the publication's corresponding author Aaron Wheeler, a professor in the Institute of Biomedical Engineering in the Faculty of Applied Science & Engineering, whose lab is located in the Donnelly Centre for Cellular and Biomolecular Research in ��ֱ��'s Faculty of Medicine.

“If cancer cells would simply stay in one spot, it would be ‘easy’ to excise them and cure the disease. But when cancer metastasizes, cancer cells move through the body, making the disease difficult to treat.

“We decided to apply our expertise in microfluidics to develop a new tool to aid in studying how cancer cells begin to invade into surrounding tissues in the first steps in metastasis.”

Normally metastasis is studied in a petri dish cell culture or in whole animals. However, these model systems present problems in terms of cost, efficiency, or lack of representation.

“An oversimplified system like cells in petri dishes doesn’t mimic what happens in the body, while in an animal model, it’s difficult to isolate and study parameters that govern the invasiveness of a cell,” said Betty Li, a senior Institute of Biomedical Engineering PhD student and lead author of the paper.

“Our system gives us control over all the specific parameters that we want to look at, while allowing us to make structures that better resemble what happens to the body.”

The device consists of patterned metal electrodes which can move extremely small droplets around through the use of electric fields. By selectively changing the water-repelling properties of the surface at various points, researchers can ‘pinch’ off the water droplets and form precise shapes.

In the paper, the researchers describe how they used a collagen matrix coated with a layer of basal membrane extract to mimic the structure of the breast tissue seen by breast cancer cells during the first step of metastasis.

By placing cancer cells outside of these tissue mimics, researchers could observe the invasion process in detail, including measurements of speed and location.

“One interesting thing we observed is that not all cancer cells within the same population have the same invasiveness,” Li said. “Some invaded into the tissue mimics while others did not, which prompted us to look at what gives the invaded cells such an advantage.”

Li and her team extracted cancer cells at various distances from the invasion point and subjected these cells to genetic sequencing.

“We identified 244 different genes that are differentially expressed between the cancer cells that invaded versus the ones that didn’t invade,” Li said. “This means that using the tool we developed, researchers in the future can develop therapeutics that target some of these genes to halt the cancer metastasis.”

“We think this type of tool will be quite useful to the community, as cell invasion is important in cancer and also a host of other (non-pathological) processes, like tissue growth, differentiation and repair,” Wheeler said.

This research was funded by the National Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, the Province of Ontario, and by ��ֱ��'s Medicine by Design initiative, which receives funding from the Canada First Research Excellence Fund.

��ֱ�� researchers use diphtheria toxin to target genes in cancer cells

Christopher.Sorensen — Wed, 06 May 2020 17:08:52 +0000

��ֱ�� researchers use diphtheria toxin to target genes in cancer cells

Christopher.Sorensen Wed, 05/06/2020 - 13:08

Cutline

Modified diphtheria toxin used to reduce the activity of genes connected to the propagation of glioblastoma, a type of brain cancer.

Topic

Faculty of Applied Science & Engineering

Faculty of Medicine

Graduate Students

Hospital for Sick Children

Institute of Biomaterials and Biomedical Engineering

Research & Innovation

A group of researchers from the University of Toronto and the Hospital for Sick Children have developed a new way to deliver molecules that target specific genes within cells. The platform, which uses a modified form of diphtheria toxin, has been shown to “downregulate” critical genes in cancer cells, and could be used for other genetic diseases as well.

The team, led by University Professor Molly Shoichet of the Faculty of Applied Science & Engineering and Roman Melnyk, an associate professor the department of biochemistry in the Faculty of Medicine and a senior scientist at SickKids, found inspiration from an unexpected source: diphtheria toxin.

The research was published recently in the journal Science Advances.

“A major challenge in the field of drug delivery is most therapeutic vehicles cannot escape the acid environment of the endosome once they get into the cell,” says Shoichet, the corresponding author of the research. “The diphtheria toxin platform as a delivery vehicle effectively solves that.”

Scientists looking to place molecules inside cells have a number of existing tools to choose from, but most suffer from the same drawback: while the molecule gets inside the cell, it remains trapped in a kind of bubble called an endosome. If the goal is to deliver therapeutics that will interact with the cell’s DNA, breaking out of the endosome is critical.

As a natural defence mechanism, bacteria such as Corynebacterium diphtheriae produce a protein-based toxin that enters surrounding cells, eventually killing them. Critically, this toxin is known to be capable of escaping from endosomes, which led to the idea of re-engineering it as a delivery platform.

Melnyk’s lab specializes in bacterial toxins and invented a non-toxic version of the diphtheria toxin, known as attenuated diphtheria toxin. This new molecule has the capacity to enter the cell and efficiently escape the endosome – and thus excels as a delivery vehicle without any of the toxic effects of diphtheria toxin.

To prove that the concept would work, the researchers used the system to deliver molecules that they believed would be effective against glioblastoma, a form of brain cancer.

“Glioblastoma is a highly invasive disease and patients have a very short life expectancy after initial diagnosis,” says Shoichet. “We want to change this and have thus pursued the delivery of gene therapeutics to treat glioblastoma.”

The group first targeted glioblastoma neural stem cells, which are thought to be resistant to chemotherapeutics. Specifically, the researchers focused on delivering silencing RNA (siRNA) against two genes: integrin beta 1 (ITGB1), which is associated with the highly invasive nature of glioblastoma (and other cancers), and eukaryotic translation initiation factor 3 sub-unit b (eIF-3b), which is an essential survival gene. By eliminating this invasive trait, the researchers could potentially limit progression in diseases like cancer.

“ITGB1 is involved in cancer cell migration, which contributes to glioblastoma’s invasion into healthy brain tissues,” says Laura Smith, a senior PhD student on the publication. “We used an innovative three-dimensional culture system to significantly reduce cell invasion after treatment with our siRNA-attenuated diphtheria toxin system, which suggests that it may be effective in slowing disease progression.”

To demonstrate the breadth of this platform, the researchers also delivered a different nucleic sequence that knocks down eIF-3b, which participates in the “survival pathway” of cancer cells.

“We treated the cells with the attenuated diphtheria toxin-siRNA against eIF-3b and observed downregulation at genetic and phenotypic levels,” says Amy E. Arnold, a recent PhD graduate from the Shoichet lab and first author on the paper.

The group is planning on using this delivery vehicle to treat other diseases in the future.

“We recognize the strength of this platform strategy and are actively testing it for the delivery of RNA and other cargoes,” Shoichet says.

The research received support from the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council of Canada, among others.

��ֱ�� startup’s "buddy badge" encourages handwashing in hospitals, could help stem COVID-19 spread

Christopher.Sorensen — Mon, 13 Apr 2020 19:14:25 +0000

��ֱ�� startup’s "buddy badge" encourages handwashing in hospitals, could help stem COVID-19 spread

Christopher.Sorensen Mon, 04/13/2020 - 15:14

Cutline

(photo by Christine Sandu via Unsplash)

Qin Dai

Topic

Our Community

Coronavirus

Faculty of Applied Science & Engineering

Faculty of Medicine

Institute of Biomaterials and Biomedical Engineering

Research & Innovation

A researcher at the Institute of Biomaterials and Biomedical Engineering (IBBME) is developing a wearable technology that reminds front line health-care workers to wash their hands. It’s believed the technology could significantly reduce the spread of hospital-acquired infections, including COVID-19.

Dubbed the “Buddy Badge,” the wearable device acts as a transponder, using a system of sensors connected to hand-washing stations, doorways and critical routes to patient rooms. If the badge wearer has not washed their hands before entering a patient’s room, for example, it will discreetly vibrate to remind them to do so.

“The idea we are proposing is a nurse or physician arrives at work, retrieves a personalized device and carries on with their day as normal,” says Geoff Fernie, a senior scientist and former director of the Toronto Rehabilitation Institute, as well as a professor at IBBME and in the Faculty of Medicine. “The device will remind them about hand-washing throughout the day.”

With the recent COVID-19 outbreak, Fernie says “the need for this system is more crucial than ever.” The additional COVID-19 cases have significantly increased the workload for health-care professionals, making it easier to miss opportunities when washing hands as recommended.

In a large intensive care unit, a nurse may encounter as many as 350 occasions during a single 12-hour shift where washing or sanetizing his or her hands may be warranted.

“Studies in some hospitals showed that our device has doubled the hand hygiene rate, which should reduce the infection rates,” says Fernie. “We hope this system helps change the habits of health-care workers, making it safer for everyone.”

Better adherence to hand hygiene could reduce infection and death rates since estimates of hand washing before and after interacting with a patient currently range from 30 to 60 per cent.

Fernie and his team have been working on wearable technology for 17 years. In 2018, this technology formed the basis of startup company Hygienic Echo, with the primary goal of reducing infections in communal settings. The idea was published in 20 peer-reviewed scientific articles and has been the subject of nine patent filings.

Fernie plans to deploy the technology in a hospital setting this summer and in a nursing home this fall.

Qin Dai

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