Toward 3D-bioprinting of an endocrine pancreas: A building-block concept for bioartificial insulin-secreting tissue

Abstract

Three-dimensional bioprinting of an endocrine pancreas is a promising future curative treatment for patients with insulin secretion deficiency. In this study, we present an end-to-end concept from the molecular to the macroscopic level. Building-blocks for a hybrid scaffold device of hydrogel and functionalized polycaprolactone were manufactured by 3D-(bio)printing. Pseudoislet formation from INS-1 cells after bioprinting resulted in a viable and proliferative experimental model. Transcriptomics showed an upregulation of proliferative and ß-cell-specific signaling cascades, downregulation of apoptotic pathways, overexpression of extracellular matrix proteins, and VEGF induced by pseudoislet formation and 3D-culture. Co-culture with endothelial cells created a natural cellular niche with enhanced insulin secretion after glucose stimulation. Survival and function of pseudoislets after explantation and extensive scaffold vascularization of both hydrogel and heparinized polycaprolactone were demonstrated in vivo. Computer simulations of oxygen, glucose and insulin flows were used to evaluate scaffold architectures and Langerhans islets at a future perivascular transplantation site.

Vascularization in Bioartificial Parenchymal Tissue: Bioink and Bioprinting Strategies

“…In silico modeling for defined architectures can predict postimplantation viability and function in vivo [ 50 ]. Defining a construct geometry in silico is a process commonly required in all additive manufacturing technologies.…”

“…Defining a construct geometry in silico is a process commonly required in all additive manufacturing technologies. Computer-aided design and in silico analysis of these geometries prior to the manufacturing process itself showed the potential to improve on trial-and-error experimental approaches [ 50 , 51 ] ( Table 1 ). Previous studies on the bioprinting of insulin-producing constructs showed the potential of finite element analysis for simulation of diffusional processes of oxygen, glucose, and insulin outflow [ 50 , 51 , 52 ].…”

“…Computer-aided design and in silico analysis of these geometries prior to the manufacturing process itself showed the potential to improve on trial-and-error experimental approaches [ 50 , 51 ] ( Table 1 ). Previous studies on the bioprinting of insulin-producing constructs showed the potential of finite element analysis for simulation of diffusional processes of oxygen, glucose, and insulin outflow [ 50 , 51 , 52 ]. The advantage of such approaches was to define boundary conditions, e.g., the filament thickness of the extruded hydrogel and, thus, the maximum diffusion distance for effector cells to remain viable and functional [ 50 ] ( Table 1 ).…”

“…Previous studies on the bioprinting of insulin-producing constructs showed the potential of finite element analysis for simulation of diffusional processes of oxygen, glucose, and insulin outflow [ 50 , 51 , 52 ]. The advantage of such approaches was to define boundary conditions, e.g., the filament thickness of the extruded hydrogel and, thus, the maximum diffusion distance for effector cells to remain viable and functional [ 50 ] ( Table 1 ). We previously showed that without a sufficiently uniform perfusion system throughout the construct, cells are more likely to populate the periphery of the bioprinted construct without uniform cell density [ 50 ].…”

“…The advantage of such approaches was to define boundary conditions, e.g., the filament thickness of the extruded hydrogel and, thus, the maximum diffusion distance for effector cells to remain viable and functional [ 50 ] ( Table 1 ). We previously showed that without a sufficiently uniform perfusion system throughout the construct, cells are more likely to populate the periphery of the bioprinted construct without uniform cell density [ 50 ]. Especially for highly metabolically active cells such as insulin-producing ß-cells, vascularization strategies are necessary [ 4 ].…”