Three-Dimensional Bioreactor Technologies for the Cocultivation of Human Mesenchymal Stem/Stromal Cells and Beta Cells

Abstract

Diabetes is a prominent health problem caused by the failure of pancreatic beta cells. One therapeutic approach is the transplantation of functional beta cells, but it is difficult to generate sufficient beta cells in vitro and to ensure these cells remain viable at the transplantation site. Beta cells suffer from hypoxia, undergo apoptosis, or are attacked by the host immune system. Human mesenchymal stem/stromal cells (hMSCs) can improve the functionality and survival of beta cells in vivo and in vitro due to direct cell contact or the secretion of trophic factors. Current cocultivation concepts with beta cells are simple and cannot exploit the favorable properties of hMSCs. Beta cells need a three-dimensional (3D) environment to function correctly, and the cocultivation setup is therefore more complex. This review discusses 3D cultivation forms (aggregates, capsules, and carriers) for hMSCs and beta cells and strategies for large-scale cultivation. We have determined process parameters that must be balanced and considered for the cocultivation of hMSCs and beta cells, and we present several bioreactor setups that are suitable for such an innovative cocultivation approach. Bioprocess engineering of the cocultivation processes is necessary to achieve successful beta cell therapy.

Calculation of Mass Transfer and Cell-Specific Consumption Rates to Improve Cell Viability in Bioink Tissue Constructs

“…This phase was characterized by a steady state of cell proliferation and cell death, due to the limited supply, production, and accumulation of products or metabolites and the available growth area for expansion of the cells. Our empirically determined growth rate of 0.04 h −1 during the exponential phase agreed with previous findings for the same cells (0.035 h −1 ) [ 19 ]. The values were slightly higher than reported for other standard cell lines, such as hybridomas (0.03 h −1 ) [ 16 ], Chinese hamster ovary cells (0.023 h −1 ) [ 18 ], and baby hamster kidney cells (0.021 h −1 ) [ 17 ].…”

“…The glucose consumption and lactate production rates were similar to those previously reported for murine hybridomas: 1.35·10 −11 mg·s −1 ·cell −1 glucose and 1.13·10 -11 mg·s −1 ·cell −1 lactate [ 16 ]. Previous experiments with 1.1B4 pancreatic β-cells consumed a 6.75-fold lower value for glucose [ 19 ], which may reflect the consumption rate dependency of concentration [ 16 ]. Our glutamine consumption and ammonia production rates were in the mid-range compared to values previously reported for standard cell lines and may also depend on the initial concentration [ 16 ].…”

“…Moreover, the assumed static cell culture differs from the in vivo environment, which features a systemic circulation and a more complex linked network of biochemical pathways. For example, glutamine supplies may increase in vivo due to the balance between glutamine and glutamate [ 28 ], which would make oxygen the limiting factor [ 19 ].…”

“…In contrast, the cell-specific consumption rates for standard cell lines have been reported by many researchers [ 16 , 17 , 18 ]. However, these should be verified under the experimental conditions unique to bioink applications, including differences in oxygen requirements for different cells and their organization [ 19 ].…”

Bioprocess Development for Human Mesenchymal Stem Cell Therapy Products

“…For the expansion step, it can be sufficient to improve the growth of beta cells using conditioned medium from the cultivation of MSCs. Alternatively, the expansion and functionalization of beta cells can be combined in one process step [101]. The CPPs for such a complex process can be difficult to identify, but the CQAs of the beta cells are most relevant if the aim of the process is to produce functionalized beta cells for drug screening or cell therapy.…”