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

通过移植细胞来再生丧失的组织功能，通常与生物材料作为人工基质相结合，是治疗各种疾病和组织缺损的一种有前途的方法。然而，基于细胞的治疗的成功很大程度上依赖于植入后细胞的供应，特别是氧气的供应。对于大多数组织工程方法，快速血运重建的策略是研究的主题。另一方面，有一些治疗方法打算避免移植细胞与血液中免疫成分的接触，以避免排斥反应，因此需要替代策略来有效地供氧。一个具有高度临床相关性的例子是移植同种(潜在的异种)朗格汉斯胰岛用于1型糖尿病患者。第一个短期实验证明了利用具有光合作用的微藻来覆盖胰岛的高需氧量的巨大潜力。在拟议的项目中，将通过生物打印的方式实现光合作用具有活性的微藻和哺乳动物细胞的共培养。这两种细胞类型将被封装(彼此分离)在水凝胶中；通过应用3D绘制成形的添加制造技术，将利用不同细胞类型在具有定义的几何形状的结构化水凝胶基质中空间定义的排列的优势。此外，还将开发一种具有光耦合和集成氧传感器的生物反应器系统，允许根据实际氧浓度对光合作用活动进行面向需求的控制。利用共培养/生物反应器系统，将为系统研究不同类型细胞之间的相互作用、氧气浓度对细胞的影响以及不同隔室之间的氧气运输奠定基础。此外，作为将共培养/生物反应器系统转化为胰岛移植临床应用的先决条件，应该实现高效和持久的哺乳动物细胞光合作用产生的氧气的供应。为了建立共培养，应确定一种能够在37℃下生长并具有较高光合作用速率的合适微藻菌株。将制定出满足两种细胞类型要求的共培养条件。详细研究了有机碳源对光自养微藻的影响以及光对异养哺乳动物细胞的影响。最后，期望微藻生物印花项目的研究成果将为生物技术的应用提供有价值的启示。

The regeneration of lost tissue functions by transplantation of cells, often in combination with biomaterials as artificial matrix, is a promising approach for the treatment of various diseases and tissue defects. However, the success of cell-based therapies strongly depends on the supply of the cells, especially with oxygen, immediately after implantation. For most tissue engineering approaches, strategies for a fast revascularization are subject of research. On the other side, there are treatment approaches which intend to circumvent contact of the implanted cells with immunological components in blood in order to avoid rejection and therefore need alternative strategies for efficient oxygen supply. One example of high clinical relevance is the transplantation of allogenic (potentially xenogenic) pancreatic islets of Langerhans in case of patients suffering from diabetes type 1. First short-term experiments demonstrated the great potential of the utilization of photosynthetically active microalgae for coverage of the high oxygen demand of pancreatic islets.In the proposed project, cocultures of photosynthetically active microalgae and mammalian cells will be realized by means of bioprinting. Both cell types will be encapsulated (separated from each other) in hydrogels; by applying the additive manufacturing technology of 3D plotting for shaping, the advantages of a spatially defined arrangement of the different cell types in a structured hydrogel matrix with defined geometry will be used. Beyond that, a bioreactor system with light coupling and integrated oxygen sensors will be developed that allows a demand-oriented control of the photosynthesis activity depending on the actual oxygen concentration. With the coculture/bioreactor system the fundamentals will be developed for a systematic investigation of the interaction between the different cell types, the influence of the oxygen concentration on the cells as well as the oxygen transport between the different compartments. Moreover, an efficient and long-lasting supply of the mammalian cells with photosynthetically generated oxygen should be achieved as prerequisite for the translation of the coculture/bioreactor system towards clinical application for islet transplantation. For the establishment of the coculture, a suitable microalgae strain should be identified which is able to growth at 37°C and is characterized by a high rate of photosynthesis. Coculture conditions will be worked out which meet the demands of both cell types. The influence of organic carbon sources on the photoautotrophic microalgae as well as the influence of light on the heterotrophic mammalian cells will be investigated in detail. Finally, it is expected that results of the project concerning the bioprinting with microalgae will provide valuable insights for biotechnological applications.