ABSTRACT
BACKGROUND: Mesenchymal stem cells (MSCs) are protective for islets when cotransplanted in a hypoxic environment. However, the risk of neoplasia is increased when MSCs are transplanted into immunosuppressed patients. This initial study aimed to investigate whether the production of protective factors from MSC can be stimulated by different culture conditions to benefit human islets cultured in hypoxia. METHODS: MSC were isolated from human adipose tissue and cultured for 2 days in supplemented Minimum Essential Media α (MEMα) and 21% (21%-MEMα) or 1% oxygen (1%-MEMα). Native MEMα served as control. After MSC harvesting, cell-depleted media were frozen at -20°C until use for human islet culture in 2% oxygen for 72-96 hours before islet characterization. Data were normalized to control islets cultured in native MEMα and 2% oxygen (mean ± SEM). RESULTS: After culture in 21%- or 1%-MEMα, islet recovery increased to 117 ± 12% (NS) and 138 ± 12% (P < .05), respectively. Viability did not change after culture in native MEMα (59 ± 2%), 21%-MEMα (59 ± 3%), or 1%-MEMα (61 ± 3%). Compared with control samples, the glucose stimulation index was increased after culture in 21%-MEMα (P < .05) or 1%-MEMα (P < .05). Overall survival was higher in 1%-MEMα (143 ± 14%) than in 21%-MEMα (119 ± 14%; NS) or native MEMα (P < .05). CONCLUSIONS: This study demonstrates that MSC-preconditioned MEMα increases survival and in vitro function of hypoxic human islets. These findings indicate that hypoxic MSCs seem to produce factors that improve survival of islets suffering from hypoxia.
