Our scientists are helping to build the next generation of kidney disease models to support drug discovery and development
One in every ten people around the world is affected by chronic kidney disease (CKD), a progressive disease that currently has no fully curative treatment. This number is predicted to rise due to the increasing prevalence of risk factors including diabetes, hypertension, obesity and an ageing population. Compounding this situation, there remains an unmet need for new, innovative medicines to help CKD patients.
This is why AstraZeneca is focused on a distinctive approach to evaluate Cardiovascular, Renal and Metabolic diseases in a holistic way and address patients’ multiple risk factors together. In particular, scientists at our Research and Development (R&D) centre in Gothenburg, Sweden have been focusing on developing new kidney cellular models with the aim of addressing the current lack of effective in vitro models with high translatability to human pathophysiology. An objective of the application of such models would be to enable scientists to identify and validate therapeutic targets for diseases.
New research about our 3D human kidney model developed in Gothenburg, and recently published in Kidney International, demonstrates our progress towards these goals.
The need for new cellular kidney models
A nephron is the basic structural and functional unit of a kidney. Within nephrons, glomerular filtration and tubular reabsorption take place, which help maintain homeostasis in the body. As of today, there are no reports of adequate in vitro cellular model to mimic the kidney function. Human primary patient-derived cells are desirable to recapitulate disease states in a laboratory setting and to test potential drug candidates. However, such cells present challenges to scientists, including limited availability, loss of their physiological characteristics when in culture, and the fact that it is difficult to expand them to the scale needed for in vitro assays.
In view of these challenges, our scientists turned to induced pluripotent stem cells (iPSC) in their work to create cellular kidney models.
Why induced pluripotent stem cells?
In contrast to the human embryonic stem cells, iPSCs are derived by converting mature human cells to a stem cell state. Generating iPSCs does not require using human embryos as a source of cells. Moreover, iPSC lines can be easily derived from a variety of genetic backgrounds. These advantages have caused these cells to emerge as a very attractive option for the creation of complex cell models.
Utilising these cells and building on recent advances that have been made in 3-dimensional (3D) organoid cultures, our scientists combined and further developed the protocols to turn iPSCs into nephron progenitors and finally into kidney organoids.
Creating a new, scalable solution with organoids
An organoid is a cluster of cells containing several cell types needed for the full organ to function. These work collaboratively to recreate a number of the functions operating in the original organ. Although the structure is not identical to the actual organ, the mixture of cells creates interactions between them, which are similar to the situation in vivo. These provide substantial advantages compared with simpler models such as monocultures (one cell type) and 2D models (flat culture instead of 3D).
Using paraffin-embedded sectioning and whole-mount immunostaining, our team demonstrated that organoids grown in suspension culture express key markers of kidney biology and vasculature within renal cortical structures. Moreover, the organoids resemble the profile of human kidney transcriptomics, which strengthens the translatability of our in vitro model.
By combining CRISPR/Cas9 technology with a 3D differentiation protocol, the scientists established a system in which kidney differentiation, glomerular maturation, and podocyte health can be monitored in living cells using fluorescently tagged kidney lineage markers. The process can be scaled up in various formats to create millions of progenitor cells. In addition, the organoids are formed in AggreWell™ plates which can generate thousands of organoids per batch. Scientists can then transfer the organoids to a suspension culture format that is scalable, and, potentially, managed through automated technology.
Immunocytochemistry images staining kidney-specific cells, such as podocytes, proximal tubuli cells, and vessels, within the kidney organoid model.
What this could mean for patients
The organoid model can be used as an advanced 3D screening in vitro tool, in which scientists can use various stressors, stimuli and toxins to affect relevant cell types, as well as look at their cross-talk and functional properties. This will enable us to learn more about the organ and potentially design drug candidates with improved properties with the aim of treating patients with kidney disease.
As a next step, the kidney organoid team has shared and continues to share this model with other scientific teams, both internally and externally, for example the MRC Laboratory of Molecular Biology (LMB) in Cambridge, UK.
A testament to the role of collaboration, within and outside of the lab
AstraZeneca has a strong focus on collaboration, both as a mindset and within the physical lab and office environments. The kidney organoid work illustrated and benefited from both of these collaborative elements.
Work on kidney organoids began as an idea for a postdoc project several years ago with the aim to advance novel science. The progress and success with the kidney platform then culminated in publications, further post docs, and the application of 2D, 3D and kidney organoids in a wide variety of activities within safety and metabolism as well as the disease area. With joint commitment from both Discovery Sciences, Drug Safety and Metabolism (DSM) and Cardiovascular, Renal and Metabolism (CVRM), the model evolved and has now been implemented within numerous projects at AstraZeneca beyond only kidney disease.
The collaborative mindset of the people involved, both the scientists in the lab as well as management, allowed this progress to occur. Specifically, the opportunity to share and discuss data in an open and honest way engendered a feeling of ownership within the team that empowered innovation and discovery. In total, more than 50 AstraZeneca scientists with expertise in molecular biology, cell biology, bioinformatics, and disease biology collaborated to deliver these results.
A precursor to Lab4Life
The teams working on the kidney organoids took full advantage of the Gothenburg open-access lab and office environment. When it opened six years ago, the advanced cell lab was a unique, open access lab space, creating an environment in which scientists could work side by side. This provided the opportunity for many scientific and technical discussions.
The evidence of successful collaboration around the kidney organoid work is one of the many reasons that AstraZeneca invested in Lab4Life in Gothenburg, a site initiative to create flexible working environments that stimulate and encourage collaboration between scientists from different therapy areas and disciplines. To date, Lab4Life has opened our first-ever activity-based lab, the new Chemistry Centre of Excellence, and the Sample Management Lab among other milestones, with many more to come this year.
To learn more about the kidney organoid project as published in Kidney International, please click here: https://www.kidney-international.org/article/S0085-2538(18)30356-9/pdf