This study aims to explore the potential mechanisms through which mesenchymal stem cell (MSC) exosomes enhance the activity of pancreatic islet β-cells under hypoxic conditions.

Mouse pancreatic islet β-cells were cultured under three different conditions: normoxic (5% CO₂, 95% air) , hypoxic (2% O₂, 5% CO₂, 93% N₂) , and hypoxic conditions with MSC exosome (50 μg/mL) . The activity of β-cells was assessed using the Cell Counting Kit-8 (CCK-8) , while apoptosis was analyzed using a cell apoptosis detection kit. Differential expression of lncRNAs and mRNAs was investigated using Mouse Arraystar LncRNA microarray chips. Mouse Arraystar LncRNA microarray chips were used to analyze the differential expression of lncRNAs and mRNAs. Based on the chip analysis results, the t-test significance threshold was set at P≤0.05 and |Fold Change|≥2 to screen for differentially expressed lncRNAs and mRNAs. Pearson correlation coefficient analysis was used to analyze the correlation between lncRNAs and protein-coding genes among samples. Further enrichment analysis of GO and KEGG was conducted on the potential target genes corresponding to lncRNAs to explore the potential pathways of MSC exosome against hypoxia-induced β-cells apoptosis. T test was used for comparison between the two groups, One-way ANOVA was used for comparison among three groups, and then Dunnett's-t multiple comparison analysis was performed.

The CCK-8 results showed that under hypoxic conditions, the OD value of β-cells significantly decreased compared to normoxic conditions (0.44 ± 0.02 vs 0.53 ± 0.01) (t = 4.455, P < 0.05) , indicating decreased β-cell activity under hypoxic conditions. Apoptosis analysis showed that the apoptosis rate of β-cells under hypoxic conditions was significantly higher than that of the normoxic group (33.03%± 3.12%vs 11.27%± 2.69%) (t = 5.289, P < 0.01) . After intervention with MSC exosomes under hypoxic conditions, the activity of β-cells was significantly increased compared to the hypoxic group (OD value 0.42 ± 0.03 vs 0.33 ± 0.01) (P < 0.01) ; the apoptosis rate of β-cells was significantly decreased compared to the hypoxic group (15.23%± 0.62%vs 32.63%± 0.95%) (P < 0.01) . The LncRNA microarray chip was used to assess the expression levels of 35 923 lncRNAs and 24 881 mRNAs in mouse β-cells. Compared with the normoxic control group, hypoxia caused significant differences in the expression of 1 726 lncRNAs and 1 023 mRNAs; compared with the hypoxic group, addition of exosomes resulted in significant differences in the expression of 491 lncRNAs and 406 mRNAs. The intersection of differentially expressed lncRNAs and mRNAs under two comparison conditions yielded 112 shared lncRNAs and 60 shared mRNAs. Correlation analysis suggests that these 112 lncRNAs are associated with 1 582 potential target genes. GO and KEGG enrichment analysis of these target genes showed that differentially expressed lncRNA target genes were mainly associated with MAPK, autophagy, and other signaling pathways.

Hypoxia could induce apoptosis of β-cells, while MSC exosomes could enhance the activity of β-cells under hypoxic conditions and inhibit hypoxia-induced apoptosis of β-cells, possibly through lncRNA regulation of MAPK, autophagy, and other signaling pathways.