A Comparative Study of Equine Hoof Progenitor Cells and Adipose-Derived Stem Cells in Hyperinsulinemia

Abstract

Recently, we isolated and characterized a new pool of mesenchymal stem cells- HPC (Hoof Progenitor Cells), which reside in the coronary corium of equine hooves. We hypothesize, that due to their location, HPC may be involved in the pathogenesis of laminitis, and could possibly be utilized in its treatment. The aim of this study was to compare the newly described HPC to a well-established cell pool-ASC (Adipose Stem Cells). The two cell populations were maintained either in standard culture conditions or under a hyperinsulinemic milieu as hyperinsulinemia is often observed alongside laminitis. Cell cycle dynamics, mitochondrial membrane potential and oxidative stress were analyzed with microcapillary cytometry. Furthermore, the expression of key markers of mitochondrial metabolism, oxidative stress, apoptosis, immunomodulation and insulin signalling were analyzed with the RT-qPCR method. Additionally, a selected panel of miRNA was analyzed with the RT-qPCR method. In standard culture conditions, ASC exhibit higher proliferation than HPC while in hyperinsulinemia a shift towards S phase was observed in both populations. As for the mitochondrial membrane potential, in standard culture conditions, HPC was characterized by a higher percent of live cells. Hyperinsulinemia did not strongly affect the mitochondrial membrane potential of the analyzed populations. Our findings indicate that HPC are characterized by higher activity in terms of mitochondrial dynamics, mitophagy, and mitochondrial biogenesis under standard culture conditions. Yet in both populations, a diminished mitochondrial dynamic and metabolism was observed in hyperinsulinemia. The analysis of oxidative stress revealed, that HPC might possess somewhat higher resistance towards oxidative stress than ASC. Minimal change was observed in the expression of key markers of apoptosis in ASC and HPC under hyperinsulinemia. The analysis of key immunomodulatory markers indicated that HPC may help the cytokine storm for a more effective phenotype change to an immunosuppressing pool of cells with better migratory and healing abilities under hyperinsulinemia than ASC. As for insulin signalling, the obtained data suggests that HPC might be more resistant to hyperinsulinemia and may have greater therapeutic potential in reducing laminitis. Obtained results demonstrated that HPC possesses better potential to modulate the PTEN-AKT pathway by miR-21 and reverse high glucose and high insulin-induced insulin resistance. Taken together, the obtained results indicate that HPC may be a very promising cell pool with therapeutic potential in laminitis treatment, and could be more effective than ASC.