3D Bioprinting of functional islets with adipose-derived stromal cells in an Alginate/Nanocellulose scaffold
Shadab Abadpour1,2,3, Essi M. Niemi 2,3,4, Linnea Strid Orrhult 5, Liebert Parreiras Nogueira 6, Håvard Jostein Haugen6, Dag Josefsen7, Gunnar Kvalheim7, Stefan Krauss 3, Paul Gatenholm 5,8, Hanne Scholz 1,2,3.
1Department of Transplant Medicine, Oslo University Hospital, Oslo, Norway; 2Institute for Surgical Research, Oslo university Hospital, Oslo, Norway; 3Centre of Excellence- Hybrid Technology Hub, University of Oslo, Oslo, Norway; 4Department of Vascular Surgery, Aker Hospital, Oslo University Hospital, Oslo, Norway; 53D Bioprinting Centre, Department of Chemistry, Chalmers University of Technology, Gothenburg, Sweden; 6Institute for Clinical Dentistry, University of Oslo, Oslo, Norway; 7Section for Cell Therapy, Radiumhospitalet, Oslo University Hospital, Oslo, Norway; 8CELL HEAL AS, Sandvika , Norway
Islet isolation procedure destroys islet vasculature and extra cellular matrix molecules, which can negatively affect islet function post transplantation. Developing scaffold that favors islet micro-environment is one solution to preserve islet function post isolation. 3D bioprinting of islets using hydrogel-based bioinks has been reported previously. However, modifying bioinks and presence of supporting cells such as adipose-derived stromal cells (ASCs) can improve survival and reduce cellular stress in islet scaffolds.
We designed an implantable multi-layered 3D bioprinted scaffold for human or mouse islets -/+ human ASCs (1.2 ×106 ASCs/scaffold). Cells were embedded in alginate/nanocellulose bioink and printed with INKREDIBLE 3D Bioprinter from CELLINK AB. Micro-CT was used to study the distribution of islets inside scaffolds. In vitro cell viability and function were assessed using FDA/PI staining and glucose stimulated insulin secretion on day 1, 8 and 14 post print. The level of secreted human- and mouse-specific cytokines, IP-10, MCP-1 and GRO-α were measured on day 1, 8 and 14 post print. Islet scaffolds -/+ ASCs were transplanted intraperitoneal (IP) in diabetic immune-compromised mouse model and followed for 60 days post transplantation.
We printed 100 islets/scaffold for in vitro and 400 islets/scaffold for in vivo studies. In vitro viability analysis revealed viable islets and ASCs throughout the studies. However, scaffolds with human and mouse islets + ASCs showed improved insulin secretion in response to glucose compared to the islet alone group on day 1, 8 and 14 post print (selected data points for human islets-day 8: islet+ASC, basal insulin 2387 ± 1262, stimulated insulin 4312 ± 606.8, recovery insulin post stimulation 1637 ± 100.1 pmol/L, * p< 0.05 vs stimulated insulin. Islet alone, basal insulin 2358 ± 887.9, stimulated insulin 1149 ± 352.6, recovery insulin post stimulation 999.0 ± 267.7 pmol/L, n=4). This is followed by significant reduction in the level of both human and mouse IP-10, MCP-1 and GRO-α in islet+ASC group compared to the islet alone group on day 1, 8 and 14 post print. IP transplantation of mouse islets -/+ ASCs to diabetic mice normalizes random blood glucose in both groups starting from day 6 post transplantation for islet+ASC group and day 40 for islet alone group. We detected c-peptide in both groups on day 3 and 13 post transplantation. However, at termination of the studies, the level of c-peptide was significantly higher in islet+ASC compared to the islet alone group (islet+ASC 94.01 ± 14.47 vs. islet alone 27.08 ± 18.93, p<0.05).
This study presents a successful multi-layered scaffold design for islets and ASCs. Presence of ASCs in the scaffold can create a favorable micro-environment for the islets, resulting in reduced islet loss and improved islet function.