Fraunhofer vs. Corona

Drugs that have already been approved for comparable diseases could make a quick and important contribution to the containment of a pandemic. Indeed, a number of clinical trials are testing the efficacy of known drugs against the corona virus (repurposing). However, while the number of COVID 19 studies is an impressive 8,311, to date, only 11 studies have been focused on repurposing (source: clinictrial.gov).

A large amount of effort is required to identify suitable drug candidates in advance (at the preclinical stages) and this presents a barrier to the wider implementation of this technique. Given this, in vitro test models (i.e., tissues cultivated in test tubes) can bring significant advantages. The use of human 3D or 2D tissue models of the conducting airways cultured at the medium-air interface and of alveolar lung tissue organoids offers the possibility of rapidly identifying suitable agents during the preclinical phase that could prevent viruses like SARS-CoV-2 replicating in human cells.

This is why the Translational Center for Regenerative Therapies (TLC-RT) and the associated Chair of Tissue Engineering and Regenerative Medicine (TERM) at the University of Würzburg have, within the scope of the interdisciplinary RoboCure Project, focused on exploring the use of flexible and interactive robotic technology in the production of in vitro organoid cell culture models of the respiratory tract. In the medium term, this process is to be carried out under stringent regulatory GMP conditions (medical devices: ISO 13485, pharmaceuticals: GMP (Good Manufacturing Practice)) taking into account relevant quality assurance criteria for individualized diagnostics and therapy.

Robot-assisted production enables rapid and standardized preclinical identification and qualification of substances that have already been approved for other applications (repurposing studies), thus shortening the route to immediate clinical translation.

By automating the complex manufacturing process of these human tissue models, the RoboCure project will not only enable time savings in the generation of these models but will also increase standardization and reproducibility. The project is based on preliminary work such as previously developed cell culture models and the automated system for skin tissue production. Moreover, a different project is already seeing organoid models for intestine models being produced at the facility. Significant barriers have been overcome, such as the handling of viscous media by means of a bioplotter. As a result, it can be assumed that, in the short term, this project is well placed to contribute to tackling the crisis. In the medium to long term, technological know-how will allow for a broadly applicable automated testing platform to be established.

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The Corona pandemic has shown that rapid and, above all, accurate testing used to identify infected individuals as early and as reliably as possible is essential to slowing the spread of a major epidemic. “Early” and “reliable” are paramount to successful testing because it is only when these two characteristics are combined that citizens are motivated to behave in a correspondingly responsible way.

In light of this, the Fraunhofer Translational Center for Regenerative Therapies (TLC-RT) had, in fact, already begun deliberating on how best to increase both sensitivity and reliability in testing when Fraunhofer-Gesellschaft issued its call to participate in the Fraunhofer vs Corona program and proposed its funding opportunities.

SARS-CoV-2 can be detected using three different testing methods:

The WHO did not recommend using antibodies (AB) against the virus which are present in the blood for detection purposes because AB are usually detected in patients after the infectious period of SARS-CoV-2. This means that the spread of the virus during an ongoing epidemic/pandemic cannot be effectively prevented in this way.

The other two types of testing provide information earlier and faster:
A PCR test directly detects the genetic material of the pathogen and is currently considered to be the most reliable and sensitive testing method as it responds to very low viral loads. Since special equipment is required for this, the method has to be carried out in public or company testing laboratories. A rapid antigen test does not detect the pathogens, but instead detects so-called spike proteins (proteins on the viral envelope). This method is also known as a self-test, since all that is needed for testing is an appropriate test kit. The method is not as sensitive as a PCR test as the viral load must be significantly higher in order to be detected.

In both procedures, samples are taken by using a swab stick inserted in the nasal/pharyngeal cavity in order to obtain samples of the nasal mucosa for analysis. Ultimately, the quality of the test depends on the quality of these samples. The more suitable the material of the swab stick is for collecting the antigens or genetic components of the viruses, the more sensitive and reliable the test result will be. The aim of the COVID-Tip project was therefore to develop an innovative swab stick that absorbs the components required for analysis from the nasal mucosa in a concentrated form and releases them completely during the subsequent analysis process. This selective adsorption was achieved at TLC-RT with the help of fiber technology and specific post-treatment of the fibers produced for this purpose. This research was supplemented by the biomedical know-how of the interdisciplinary project team. Initial talks with interested parties have already opened up fields of application beyond use in the current pandemic.    

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Since the outbreak of the corona pandemic, there has been an urgent need for medication to treat severely ill corona virus patients. As the development and approval of new drugs is very time-consuming and cost-intensive, scientists worldwide are investigating whether drugs that have already been approved for other medical applications are suitable for treating COVID 19. This process, known as drug repurposing, can significantly shorten the approval process.

As part of the Fraunhofer vs. Corona anti-corona research program, the DRECOR (Drug Repurposing for Corona) consortium tested over 20 previously approved drugs to examine their antiviral properties against severe acute respiratory syndrome coronavirus type 2. Fraunhofer scientists investigated whether these substances could inhibit the entry of the coronavirus into the target cells or prevent the virus from replicating in the cells, and also whether they would be safe to use. A selection of these identified drug molecules were specially packaged so that they could be inhaled through an inhaler device and reach the respiratory tract specifically.

The TLC solution and application

Since these drug molecules for novel applications cannot be tested directly on humans, scientists at the TLC-RT produced complex tissue models of the human respiratory tract that resemble the tissue structure and function in vivo (Steinke et al. 2014, Sivarajan et al. 2021, Fig. 1A).
The research team succeeded in incorporating three of these drugs into a synthetic matrix and in spraying them into very fine particles. Spraying in the sub-μ range is crucial in order for the incorporated drugs to reach the deep airways. The TLC team demonstrated that the particles would attach themselves to the mucus of the airway models and reach the target cells in the tissue model.

In collaboration with the University of Würzburg (Institute of Virology and Immunobiology, Prof. Jochen Bodem), the team was able to identify a small antiviral effect of the remdesivir and nafamostat drug molecules against SARS-CoV-2 and an interaction of the particle matrix with the virus. We are following up on this exciting observation in current experiments and now need to determine whether the particles inactivate SARS-CoV-2 or inhibit viral entry into the target cells.

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Plant extracts and natural substances are often said to have immune-strengthening or healing effects. Diseases caused by viruses, such as measles, herpes, and Covid 19, are also among the infections that can be positively influenced by herbal substances. For the treatment of SARS-CoV-2 viruses, which mainly settle in the pharynx, throat sprays are a suitable means of applying anti-viral extracts. However, to date, the use of throat sprays has not been particularly efficient. The active ingredient that is applied by the throat spray only remains in the pharyngeal or upper throat region for a few minutes, limiting the duration of the effective period.

Encapsulated active ingredient formulations for long-term efficacy

The research team at the Fraunhofer Translational Center for Regenerative Therapies (TLC-RT) based at the Fraunhofer Institute for Silicate Research (ISC) has found a solution to the problem of a limited effective period. By encapsulating the plant extracts, the active ingredient is immobilized in the area of infection enabling a delayed release that can extend over a period of hours or even days. During this project, ethanolic extracts of the medicinal plants Echinacea, Cistus and Artemisia vulgaris were encapsulated in absorbable inorganic materials.

The active ingredients could then be electrosprayed in the form of silica gel and titanium oxalate particles combined with brine sprays. Subsequently, the corresponding particles could be dispersed in an ethanolic or silica-saturated aqueous phosphate buffer solution and applied to the pharyngeal or upper throat region.
To spray the encapsulated natural anti-viral substances, the research team has also designed and built an electrospraying system. It enables particles with a size of 1 μm to 2 μm (the nasal and pharyngeal target size) to be applied. With the development of the pharyngeal spray, the Anti-Viral Herbs project offers an over-the-counter supplement to existing preventive and therapeutic measures.
 

Delayed release of active ingredients in pharmaceutical and cosmetic products

The results of the project can also be applied to other natural substances, irrespective of their anti-viral effect since other ethanol-soluble, plant-based active ingredients are also able to be used in the newly developed particle systems. This allows a delayed release of the active ingredient for pharmaceutical ointments and cosmetic products in order to achieve the desired effective period.

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SARS-CoV-2 has clearly demonstrated the need for new therapeutic approaches to rapidly changing and fast spreading infectious diseases. A large consortium of five Fraunhofer Institutes (including the ISC) and partner universities have joined forces to develop new therapeutic strategies and platform technologies that can be used to counter »new« diseases quickly and reliably.

The BEAT-COVID project decided to focus on three main therapeutic process development objectives: prevent the virus from entering host cells, combat the virus directly, and control the excessive immune response triggered by the virus (which has, in many cases, contributed to the severe progression of the disease). Work on the first two objectives involved investigating a therapeutic approach based on viral vectors and siRNA (small interfering RNA). The third objective – to control the excessive immune response – was achieved by using anti-inflammatory antibodies that can be inhaled and so able to reach the lungs quickly and directly.

Various in vitro testing methods were used to validate the efficacy of these therapeutic strategies. The advantages of these methods are two-fold. On the one hand, in terms of efficiency, they are quick and accurate. On the other hand, they reduce the need for animal experiments by using human cell material. As a result, screening for potential drugs (including those that have already been approved for other diseases) can be carried out more easily and can provide more substantive results.

The ISC Translational Center for Regenerative Therapies contributed to this project by providing its expertise in tissue engineering and in vitro test models. In vitro tissue culture models were developed which are able to reproduce the functionality and three dimensionality of mucosa from the upper respiratory tract and lung from human cells as naturally as possible, both as healthy control tissue and as infected, diseased tissue. These in vitro models of the respiratory tract make it possible to obtain a comprehensive picture of the processes that are likely to occur in humans after a viral infection and, therefore, enable both the infection process itself and the effect of the therapeutic approaches developed within the framework of the BEAT-COVID project to be observed.

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