Exploring the delayed effect of microgravity on neural crest stem cells (NCSC)-pancreatic islets interactions and beta cell proliferation in 3D islet organoid and diabetic animal model

Microgravity (mG) induces various systemic changes in organisms, and stress-related changes in cellular structure and gene expression, but also has beneficial cellular effects, representing appealing opportunities for space exploitation and ground-based biomedicine.Our previous research has shown that boundary cap neural crest stem cells (BCs) induce insulin-producing beta-cell proliferation in pancreatic islets.

Beta-cells usually do not proliferate.

Therefore, a loss of beta-cells, which is the underlying process of type 1 diabetes, cannot be repaired by endogenous mechanisms.

Our results from the Maser 14 sounding rocket flight experiment demonstrated increased proliferation of BCs and upregulation of genes associated with proliferation and survival prompted us to investigate whether mG induces the proliferation of beta-cells alone or in combination with BCs. The potential growth of beta-cell mass might open the possibilities for clinical application.

For some type 1 diabetic patients, transplantation of pancreatic islets is an option to fight this uncurable disease.In Maser 15 experiment, murine pancreatic islets, or human beta-cells alone or in combination with BCs, were assembled in dedicated hardware to allow some cells to undergo mG, whereas other cells were placed in a 1G centrifuge onboard, serving as control.

Cultures were either free-floating or imprinted into 3D-scaffolds.

Such a setting allowed us to investigate whether mG itself or mG-induced proliferating BCs, triggered proliferation of beta-cells in different culture conditions.We collected specimens immediately after the space flight to detect the mG effect for genetic, secretome, and morphological analysis. Whereas analysis is still on the way, the morphological analysis has been performed.

The results indicate an exceptionally high beta-cell proliferation rate in mG conditions of some pancreatic islets when cultured alone.

On the contrary, islets surrounded by proliferating BCs reduced their insulin production and proliferation rate compared to islets alone.

Examining cultures from a human beta-cell line, grown alone or combined with BCs, did not result in differences directly after space voyage.

However, and unexpectedly, we observed a substantial increase in beta-cell survival and mitochondrial activity on day seven post-flight only. This result suggests that the mG has a delayed effect that not appears directly after the exposure.

Furthermore, in 3D-printed scaffolds a high proliferation was revealed in some pancreatic islets cultured alone or combined with BC three weeks after mG exposure.

Interestingly, most proliferating cells were insulin-positive in the islets alone group, whereas in the mixed group of islets and BCs, proliferating cells were insulin negative.A prolonged effect of mG on biological samples is well documented.

In contrast, our data from Maser 15 experiment shows hidden and delayed effects of mG in addition to its direct and prolonged effects.

The mG influence on beta-cell proliferation must also be translated to ground-based facility experiments to investigate the mG-induced mechanisms of beta-cell proliferation and to explore the potential for clinical applications.In this project, we aim (i) to determine whether these effects are mediated through cell-intrinsic properties or factors which were secreted during the mG phase; (ii) to investigate the extent of delayed mG effects on the various combination of BCs, beta-cells, and pancreatic islets cultured in free-floating condition or 3D printed in optimal biomatrix.

The required experiments to answer the questions shall be performed on a Random Positioning Machine to simulate mG on the ground and cells and medium collected for proliferation, viability, physiological, genetic and secretome tests.

As endpoints of the project, the results will be implemented in creating an islet organoid for in vitro exploitation and implantation into an animal model of type 1 diabetes.