Newly combined digital pathology, artificial intelligence (AI), and omics technologies are providing anatomic pathologists and medical laboratory scientists with powerful diagnostic tools
Add “spatial transcriptomics” to the growing list of “omics” that have the potential to deliver biomarkers which can be used for earlier and more accurate diagnoses of diseases and health conditions. As with other types of omics, spatial transcriptomics might be a new tool for surgical pathologists once further studies support its use in clinical care.
Among this spectrum of omics is spatial transcriptomics, or ST for short.
Spatial Transcriptomics is a groundbreaking and powerful molecular profiling method used to measure all gene activity within a tissue sample. The technology is already leading to discoveries that are helping researchers gain valuable information about neurological diseases and breast cancer.
Marriage of Genetic Imaging and Sequencing
Spatial transcriptomics is a term used to describe a variety of methods designed to assign cell types that have been isolated and identified by messenger RNA (mRNA), to their locations in a histological section. The technology can determine subcellular localization of mRNA molecules and can quantify gene expression within anatomic pathology samples.
In “Spatial: The Next Omics Frontier,” Genetic Engineering and Biotechnology News (GEN) wrote, “Spatial transcriptomics gives a rich, spatial context to gene expression. By marrying imaging and sequencing, spatial transcriptomics can map where particular transcripts exist on the tissue, indicating where particular genes are expressed.”
In an interview with Technology Networks, George Emanuel, PhD, co-founder of life-science genomics company Vizgen, said, “Spatial transcriptomic profiling provides the genomic information of single cells as they are intricately spatially organized within their native tissue environment.
“With techniques such as single-cell sequencing, researchers can learn about cell type composition; however, these techniques isolate individual cells in droplets and do not preserve the tissue structure that is a fundamental component of every biological organism,” he added.
“Direct spatial profiling the cellular composition of the tissue allows you to better understand why certain cell types are observed there and how variations in cell state might be a consequence of the unique microenvironment within the tissue,” he continued. “In this way, spatial transcriptomics allows us to measure the complexity of biological systems along the axes that are most relevant to their function.”
According to 10x Genomics, “spatial transcriptomics utilizes spotted arrays of specialized mRNA-capturing probes on the surface of glass slides. Each spot contains capture probes with a spatial barcode unique to that spot.
“When tissue is attached to the slide, the capture probes bind RNA from the adjacent point in the tissue. A reverse transcription reaction, while the tissue is still in place, generates a cDNA [complementary DNA] library that incorporates the spatial barcodes and preserves spatial information.
“Each spot contains approximately 200 million capture probes and all of the probes in an individual spot share a barcode that is specific to that spot.”
“The highly multiplexed transcriptomic readout reveals the complexity that arises from the very large number of genes in the genome, while high spatial resolution captures the exact locations where each transcript is being expressed,” Emanuel told Technology Networks.
Spatial Transcriptomics for Breast Cancer and Neurological Diagnostics
In that paper, the authors wrote “we envision that in the coming years we will see simplification, further standardization, and reduced pricing for the ST protocol leading to extensive ST sequencing of samples of various cancer types.”
Spatial transcriptomics is also being used to research neurological conditions and neurodegenerative diseases. ST has been proven as an effective tool to hunt for marker genes for these conditions as well as help medical professionals study drug therapies for the brain.
“You can actually map out where the target is in the brain, for example, and not only the approximate location inside the organ, but also in what type of cells,” Malte Kühnemund, PhD, Director of Research and Development at 10x Genomics, told Labiotech.eu. “You actually now know what type of cells you are targeting. That’s completely new information for them and it might help them to understand side effects and so on.”
The field of spatial transcriptomics is rapidly moving and changing as it branches out into more areas of healthcare. New discoveries within ST methodologies are making it possible to combine it with other technologies, such as Artificial Intelligence (AI), which could lead to powerful new ways oncologists and anatomic pathologists diagnose disease.
“I think it’s going to be tricky for pathologists to look at that data,” Kühnemund said. “I think this will go hand in hand with the digital pathology revolution where computers are doing the analysis and they spit out an answer. That’s a lot more precise than what any doctor could possibly do.”
Spatial transcriptomics certainly is a new and innovative way to look at tissue biology. However, the technology is still in its early stages and more research is needed to validate its development and results.
Nevertheless, this is an opportunity for companies developing artificial intelligence tools for analyzing digital pathology images to investigate how their AI technologies might be used with spatial transcriptomics to give anatomic pathologists a new and useful diagnostic tool.
A Penn Medicine news release noted that “The RAPID technology … transforms the binding event between the SARS-CoV-2 viral spike protein and its receptor in the human body, the protein ACE2 (which provides the entry point for the coronavirus to hook into and infect human cells), into an electrical signal that clinicians and technicians can detect. That signal allows the test to discriminate between infected and healthy human samples. The signal can be read through a desktop instrument or a smartphone.”
Though still in its early stages, the technique potentially offers dramatically lower costs and faster results than traditional RT-PCR (reverse transcription polymerase chain reaction) molecular tests. Moreover, the RAPID technology might be useful for identifying other types of biomarkers and could be the basis for diagnostic tests that help reduce the cost-per-test in medical laboratory testing while providing comparable sensitivity and specificity to existing methodologies.
Clinical trials began on January 5, 2021, and the Penn Medicine researchers say the IVD test technology can be applied to other infectious diseases, which, if proven accurate, would be a boon to clinical laboratory testing.
Diagnostic Test Results in Four Minutes for Less than $5/Test
According to the news release, the RAPID 1.0 (Real-time Accurate Portable Impedimetric Detection prototype 1.0) biosensor test costs less than $5 and can deliver results in four minutes. The researchers reported overall accuracy of 87.1% on (139) nasal swab samples and 90% on (50) saliva samples.
The technology uses electrodes that can be mass-produced at low cost on commercially-available screen printers, the researchers said. Results can be read on electronic devices connected to a PC or smartphone.
Does Penn Medicine’s RAPID 1.0 Test Replace Traditional RT-PCR Testing?
In their published study, the Penn Medicine researchers cited the need for “fast, reliable, inexpensive, and scalable point-of-care diagnostics.”
RT-PCR tests, they said, “are limited by their requirement of a large laboratory space, high reagent costs, multistep sample preparation, and the potential for cross-contamination. Moreover, results usually take hours to days to become available.”
Researchers who have studied the SARS-CoV-2 coronavirus know that it uses a spike-like protein to bind to angiotensin-converting enzyme 2 (ACE2) receptors on the surfaces of human cells.
As described in Penn Medicine’s published study, the biosensor contains ACE2 and other biochemical agents anchored to an electrode. When the SARS-CoV-2 coronavirus attaches to the ACE2, the biosensor transforms the chemical reaction into an electrical signal that can be measured on a device known as a potentiostat.
The researchers tested their RAPID 1.0 technology with two commercially available potentiostat models:
The researchers initially developed the electrode as a printed circuit board, which is relatively expensive. To reduce costs, they constructed a version that uses filter paper as the main component. The researchers noted that one screen printer in a lab can produce 35,000 electrodes per day, including time needed to incorporate the chemical elements. “However, it must be noted that these steps can be fully automated into a production line for industrial purposes, drastically reducing time requirements,” they wrote.
The test can be performed at room temperature, they added, and total cost per unit is $4.67. Much of that—$4.50—is for functionalizing the ACE2 recognition agent. The cost for the bare electrode is just seven cents.
“The overall cost of RAPID may be further reduced through recombinant production of ACE2 and ACE2 variants,” the researchers said, adding that the RAPID 1.0 test can detect the SARS-CoV-2 coronavirus at low concentrations correlating to the earliest stages of the COVID-19 disease.
Testing Penn Medicine’s RAPID 1.0 Test
The researchers evaluated the technology in blinded tests with clinical samples from the Hospital of the University of Pennsylvania. The evaluation included 139 nasal swab samples, of which 109 were determined to be COVID-19 positive by RT-PCR tests and clinical assessments. Among these, the RAPID test successfully detected the SARS-CoV-2 coronavirus in 91 samples, for a sensitivity rate of 83.5%. One sample was from a patient diagnosed with the highly contagious SARS-CoV-2 Alpha variant B.1.1.7, which the test correctly identified as positive.
Among the 30 samples determined to be COVID negative, the RAPID test scored a specificity rate of 100%, meaning no false positives. Overall accuracy, including sensitivity and specificity, was 87.1%.
The researchers also analyzed 50 saliva samples: 13 COVID-positive and 37 COVID-negative. The test correctly identified all 13 positive samples but produced five false-positives among the 37 negative samples, for a specificity rate of 86.5%. The researchers speculated that this could be due to interactions between ACE2 and other biomolecules in the saliva but suggested that performance “will improve when using fresh saliva samples at the point-of-care.”
Are There Other Applications for the RAPID Test?
The Penn Medicine news release said the RAPID technology can be adapted to detect other viruses, including those that cause Influenza and sexually-transmitted diseases.
Robert Michel, Editor-in-Chief of Dark Daily and its sister publication The Dark Report, said the test points to one silver lining in the COVID-19 pandemic. “Researchers around the world intensified their work to find ways to identify the SARS-CoV-2 virus that are faster, cheaper, and more accurate than the diagnostic technologies that existed at the time of the outbreak. In this regard, the COVID-19 pandemic may have accelerated the development and refinement of useful diagnostic technologies that will disrupt long-established methods of testing.”
Marcelo Der Torossian Torres, PhD, postdoctoral researcher at Penn Medicine and lead author of the study, said in the news release, “Quick and reliable tests like RAPID allow for high-frequency testing, which can help identify asymptomatic individuals who, once they learn they are infected, will stay home and decrease spread.
“We envision this type of test being able to be used at high-populated locations such as schools, airports, stadiums, companies—or even in one’s own home,” he added.
Clinical laboratory managers may want to stay current on the development and possible commercialization of the RAPID 1.0 (Real-time Accurate Portable Impedimetric Detection prototype 1.0) biosensor test by the research team at Penn Medicine.
This investigation of the fruit fly’s transcriptome—the complete collection of the genome’s RNA—unearthed thousands of new genes, transcripts, and proteins
Scientists have teased another level of information out of the genome. This time, the new insights were developed from studies of the fruit fly’s transcriptome. This knowledge will give pathologists another channel of information that may be useful in developing assays to support more precise diagnosis and therapeutic decisions.
The findings were published in a recent issue of Nature. The study focused on the transcriptome—a complete collection of the genome’s RNA—of the common fruit fly−Drosophila melangogaster.(more…)
Researchers at Penn State identified 160,000 ‘transcription initiation machines’ throughout the human genome
DNA “dark matter” may have something in common with comedian Rodney Dangerfield, who liked to say, “I don’t get no respect!” As many pathologists know, for years the human exome that has been the focus of most research. This is the 1% of the human genome that contains the genes that produce proteins and do other useful functions.
Meanwhile, the remaining 99% of the human genome—sometimes called “junk DNA” and generally known as dark matter—got relatively little attention from researchers. But that is changing. At Pennsylvania State University, a research team has discovered that coding and noncoding RNA, or genomic dark matter, originates at the same types of locations along the human genome. (more…)
New cancer test may be as easy as a home-use pregnancy test
Early detection of certain types of cancer may eventually become as easy as taking a home pregnancy test. That’s the prediction of researchers who are developing a non-invasive early diagnostic test for gastric cancer that would not require a pathologist to assess a tissue specimen. Instead, this test detects biomarkers in the patient’s urine.
Surgical pathologists will recognize the potential of this discovery to create new tools for diagnosing cancer at earlier stages—and without the need to collect a tissue specimen. For clinical laboratories, the possibility of a urine-based test that could accurately detect different cancers would make it possible for them to offer diagnostic assays based on this technology to office-based physicians.