Effects of hepatocyte secreted factors on obese and normal weight adipose spheroids
Raatikainen, Seeri (2025)
2025
Bioteknologian ja biolääketieteen tekniikan maisteriohjelma - Master's Programme in Biotechnology and Biomedical Engineering
Lääketieteen ja terveysteknologian tiedekunta - Faculty of Medicine and Health Technology
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Hyväksymispäivämäärä
2025-08-22
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202508228409
https://urn.fi/URN:NBN:fi:tuni-202508228409
Tiivistelmä
Obesity is a growing threat to public and individual health. Obesity predisposes to other conditions such as type 2 diabetes and non-alcoholic fatty liver disease (also known as metabolic dysfunction-associated steatotic liver disease). The prevalence of obesity creates a need for accurate three-dimensional (3D) human adipose tissue in vitro models to conduct research on obesity and the related diseases. In addition, to adipose tissue, obesity affects liver, and there is a need for adipose tissue – liver models, to study the combined effects.
The aim of this thesis was to study the effects of hepatocyte secreted factors on 3D adi-pose spheroids.
Adipose spheroids were formed from adipose stromal/stem cells extracted from donors with obesity and normal weight donors, using a low detachment round bottom well plate. Spheroids were differentiated for 21 days in adipogenic medium (AM). At day 21 tumor ne-crosis factor alpha (TNF-α) was added for 24 hours to induce the inflammatory conditions to adipose spheroids. On day 22, adipose spheroids were treated with hepatocyte conditioned medium (HCM) for 48 hours. Hepatocyte medium alone acted as a control condition and rest of the spheroids were cultured in AM as second control condition. On day 24, the effects of HCM on adipokine secretion, gene expression, cell viability and metabolic activity of adipose spheroids were studied using enzyme-linked-immunosorbent-assays, real time quantitative polymerase chain reaction, and cell viability assays, as well as with immunocytochemistry stainings and confocal imaging.
Results showed that the metabolic activity between obese and normal weight spheroids differed from each other, with obese spheroids being more metabolically active and secret-ing more leptin when compared to normal weight spheroids. TNF-α did not have significant effects on the adipose spheroid metabolism, viability or gene expression, when compared to the AM condition only. HCM on the other hand downregulated the expression of leptin, adi-ponectin, peroxisome proliferator-activated receptor γ, and fatty acid binding protein 4, and decreased leptin secretion. HCM also downregulated the expression of interleukin 1B and upregulated the expression of interleukin 6. In addition, HCM increased cell damage in obese spheroids. However, it remains unclear whether these effects come from the hepato-cyte secreted factors or hepatocyte medium alone.
More research is needed to further solidify these effects of HCM on adipose spheroid functions, gene expression, and viability, and whether the effects differ from the effects of hepatocyte medium. Quantitative lipid droplet size analysis is needed in the future to make definite statement about the effects of HCM on the lipid droplet size in adipose spheroid.
The aim of this thesis was to study the effects of hepatocyte secreted factors on 3D adi-pose spheroids.
Adipose spheroids were formed from adipose stromal/stem cells extracted from donors with obesity and normal weight donors, using a low detachment round bottom well plate. Spheroids were differentiated for 21 days in adipogenic medium (AM). At day 21 tumor ne-crosis factor alpha (TNF-α) was added for 24 hours to induce the inflammatory conditions to adipose spheroids. On day 22, adipose spheroids were treated with hepatocyte conditioned medium (HCM) for 48 hours. Hepatocyte medium alone acted as a control condition and rest of the spheroids were cultured in AM as second control condition. On day 24, the effects of HCM on adipokine secretion, gene expression, cell viability and metabolic activity of adipose spheroids were studied using enzyme-linked-immunosorbent-assays, real time quantitative polymerase chain reaction, and cell viability assays, as well as with immunocytochemistry stainings and confocal imaging.
Results showed that the metabolic activity between obese and normal weight spheroids differed from each other, with obese spheroids being more metabolically active and secret-ing more leptin when compared to normal weight spheroids. TNF-α did not have significant effects on the adipose spheroid metabolism, viability or gene expression, when compared to the AM condition only. HCM on the other hand downregulated the expression of leptin, adi-ponectin, peroxisome proliferator-activated receptor γ, and fatty acid binding protein 4, and decreased leptin secretion. HCM also downregulated the expression of interleukin 1B and upregulated the expression of interleukin 6. In addition, HCM increased cell damage in obese spheroids. However, it remains unclear whether these effects come from the hepato-cyte secreted factors or hepatocyte medium alone.
More research is needed to further solidify these effects of HCM on adipose spheroid functions, gene expression, and viability, and whether the effects differ from the effects of hepatocyte medium. Quantitative lipid droplet size analysis is needed in the future to make definite statement about the effects of HCM on the lipid droplet size in adipose spheroid.