Project Details
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Application of additive manufacturing technologies for the realization of clinically relevant cocultures of mammalian cells and microalgae

Subject Area Biomaterials
Term from 2019 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 417020100
 
Final Report Year 2024

Final Report Abstract

The restoration of lost tissue functions by transplanting cells is a promising treatment approach – the success of which depends crucially on the supply of oxygen to the cells. One example with clinical relevance is the allogeneic transplantation of pancreatic islets of Langerhans in type 1 diabetes patients in immunoisolating hydrogel capsules. The co-cultivation of mammalian cells with photosynthetically active microalgae is a new approach to solving the problem of oxygen supply in the absence of vascularization. The method of bioprinting allows a controlled arrangement of mammalian cells and microalgae without direct contact in a structured hydrogel matrix. In the project, fundamental investigations were carried out that enabled the establishment of a bioprinted coculture of insulin-producing beta cells and microalgae. Coculture conditions. Microalgae require light for photosynthesis - most mammalian cells are not naturally exposed to light. Studies on the influence of continuous light exposure on viability and function of different cell types showed that red light had no negative effects on mammalian cells, in contrast to white and blue light. A coculture medium was developed that is suitable for microalgae and beta cells. A critical component is glucose, which is essential for mammalian cells and is also metabolized by mixotrophic microalgae and can therefore inhibit photosynthesis. Microalgae partner. Four thermotolerant strains were tested for suitability for bioprinting and compatibility with coculture conditions. Scenedesmus sp. was the only strain that showed no reduced photosynthetic activity and viability under red light and in coculture medium and high viability and photosynthetic activity in bioprinted hydrogel; in the presence of glucose it retained a high photoautotrophic fraction of its metabolism and was selected for coculture. Process development, proof-of-concept. All process steps and parameters were developed for the bioprinting of the cocultures and the subsequent transfer to cultivation under hypoxia (1% O2). Scenedesmus was able to reverse the hypoxic state. For the model cell line INS-1 it could be shown that its function, the glucose-stimulated insulin secretion, was restored. This has not yet been demonstrated for murine islets of Langerhans, but it has been shown that the formation of necrotic zones under hypoxia is prevented by coculture with Scenedesmus. Regulation of the O2 concentration is crucial for future work. Bioreactor development, modeling. To make this possible, miniaturized bioreactors with integrated O2 measurement technology, light coupling and control loop were developed. For the modeling, oxygen formation/consumption rates were determined using photorespirometry.

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