Triiodothyronine Has No Enhancement Effect on the Osteogenic or Chondrogenic Differentiation of Equine Adipose Tissue Stem Cells.

The study investigates the impact of different triiodothyronine (T3) concentrations on the ability of equine adipose-derived mesenchymal stem cells (AD-MSCs) to differentiate into bone and cartilage cells. Findings show that T3 does not enhance these differentiation abilities and may sometimes affect cell density and matrix synthesis negatively depending on the concentration and the duration of culture.

Methods and Key Findings

• The researchers assessed the effects of two different concentrations of T3 (0.01 and 1,000 nM) on the transformation of equine AD-MSCs into bone and cartilage cells.
• A range of assays, including alkaline phosphatase activity (ALP), cell viability, density, and the formation of mineralized nodules, were used to gauge the effect of T3 on bone cell differentiation at Days 7, 14, and 21 in culture.
• On the other hand, ALP assay, mitochondrial metabolism, cell density, and the formation of periodic acid-Schiff-positive (PAS+) matrix were used to test T3’s effect on cartilage cell formation at Days 7 and 14.
• In the experiments involving osteogenesis, differences among the variable groups were not observed on Day 7. However, on Day 14, the lower T3 concentration resulted in reduced cell density, and fewer mineralized nodules, even though ALP activity and mitochondrial metabolism increased (P<.05). Similarly, ALP activity rose when the T3 concentration was higher (P<.05).
• By Day 21, the lower T3 concentration showed increased ALP activity compared to the control treatment (P<.05), while high concentration of T3 manifested a reduction in both mitochondrial metabolism and cell density (P<.05).
• In the chondrogenic study, both T3 concentrations increased cell density compared to the control treatment at Day 7. By Day 14 though, cell density, ALP activity, mitochondrial metabolism, and the percentage of PAS+ chondrogenic matrix had decreased when compared with the control (P<.05).

Conclusions

• The findings show that T3 does not enhance the differentiation of equine AD-MSCs into bone or cartilage cells despite its known biological activity.
• This hormone may, depending on its concentration and the time in culture, negatively impact cell density and matrix synthesis, thus cautioning against its use in promoting stem cell differentiation.
• Further research is required to establish the mechanisms through which T3 influences cell density and matrix synthesis in stem cell differentiation.