INTRODUCTION: There are  clinical trials report using stem cell-derived β cells as an innovative and future-proof solution for the treatment of T1D. Stem cell-derived β cells are expected to replace non-functioning pancreatic islets. However, in order to make this possible, it is necessary to create their 3D conformations, which has been proven by subsequent in vitro studies. However, apart from functionality, attention should be paid to the possibility of clinical use of beta cells. The process of transplanting claster β cells even from 3D cultures,  into the portal vein carries a high risk of damage and lack of functionality, as well as the risk of an undetermined final location of the cells.

AIM: Therefore, the aim of this experiment was to evaluate the survival and functionality of β-cells in artificial, 3D bioprinted with the inkjet method, pancreatic islets.

MATERIAL AND METHODS: INS-1E cells were used in the study. Two bioinks were used as the encapsulation carrier: 2% methacrylated hyaluronic acid + 20% methacrylated LAP gelatin (GROUP: H-G_INS); 2% Methacrylated Hyaluronic Acid + 20% Methacrylated Gelatin + dECM with LAP (GROUP: ECM_INS). The control group was INS-1E in traditional 2D culture. Cell functionality was assessed in the GSIS test. In addition, FDA/PI vital staining was performed. One test sample contained 3.5 million β cells. Three biological replicates were performed for each group.

RESULTS: During the 21-day observation, it was shown that the cells encapsulated by the inkjet method show practically 100% viability. The only dead cells (stained red by the FDA/Pi assay) were visible in the control samples. However, they accounted for no more than 15% of the examined pool of cells. Cells suspended in the tested variants of hydrogels retained a stable structure and did not disintegrate. On the second day of the experiment, there was no difference in cell activity. Groups of encapsulated cells showed significantly improved functionality from day 7 onwards. Both groups showed over 30% higher functionality compared to the control group. On the 14th day of the experiment, cells suspended in bioink with dECM showed a definite superiority in response to the administered glucose. Compared to the control group, the increase was over 50% (p=0.0005), and with the H-G_INS over 30% (p=0.0073). Day 21 of the experiment also showed a functional advantage in the ECM_INS, almost 30% higher activity compared to the control group (p=0.0040).

CONCLUSION: dECM a 3D conformation of cells within a bioprinted islets is a key component for maintaining the proper functionality of insulin-secreting cells. In addition, the developed bioink composition and the method used enable the production of stable 3D structures that can be transplanted in a stable and safe manner without disintegrating in physiological temperature conditions.