Microencapsulation of cellular aggregates composed of diferentiated insulin and glucagon-producing cells from human mesenchymal stem cells derived from adipose tissue

Abstract

Background: In type I diabetes mellitus (T1DM) pancreatic β cells are destroyed. Treatment entails exogenous insulin administration and strict diet control, yet optimal glycemic control is hardly attainable. Islet transplant could be an alternative in patients with poor glycemic control, but inefcient islet purifcation and autoimmune response of patients is still a challenge. For these reasons, it is necessary to explore new cellular sources and immunological isolation methods oriented to develop T1DM cell-based therapies. Aims: We postulate human adipose-derived stem cell (hASC) as an adequate source to generate pancreatic islet cells in vitro, and to produce islet-like structures. Furthermore, we propose microencapsulation of these aggregates as an immunological isolation strategy. Methods: hASC obtained from lipoaspirated fat tissue from human donors were diferentiated in vitro to insulin (Ins) and glucagon (Gcg) producing cells. Then, insulin producing cells (IPC) and glucagon producing cells (GPC) were cocultured in low adhesion conditions to form cellular aggregates, and later encapsulated in a sodium alginate polymer. Expression of pancreatic lineage markers and secretion of insulin or glucagon in vitro were analyzed. Results: The results show that multipotent hASC efciently diferentiate to IPC and GPC, and express pancreatic markers, including insulin or glucagon hormones which they secrete upon stimulation (fvefold for insulin in IPC, and fourfold for glucagon, compared to undiferentiated cells). In turn, calculation of the Feret diameter and area of cellular aggregates revealed mean diameters of ~80 µm, and 65% of the aggregates reached 4000 µm2 at 72 h of formation. IPC/GPC aggregates were then microencapsulated in sodium-alginate polymer microgels, which were found to be more stable when stabilized with Ba2+, yielding average diameters of ~300 µm. Interestingly, Ba2+-microencapsulated aggregates respond to high external glucose with insulin secretion.