Improving stemness and functional features of mesenchymal stem cells from Wharton's jelly of a human umbilical cord by mimicking the native, low oxygen stem cell niche. (July 2019) - Obradovic, Hristina
Abstract: Introduction: Mesenchymal stem cells from Wharton's Jelly of a human umbilical cord (WJ-MSCs) are a potential tool in regenerative medicine based on their availability, proliferative potential and differentiation capacity. Since their physiological niche contains low oxygen levels, we investigated whether cultivation of WJ-MSCs at 3% O2 affects their main features. Methods: WJ-MSCs were cultured under 21% and 3% O2 . Proliferation rate was followed by short and long term proliferation assays, clonogenic capacity by CFU-F assay and cell cycle and death by flow cytometry. Differentiation capacity was investigated by histochemical staining after induced differentiation. Pluripotency and differentiation markers' expression was determined by RT-PCR. Migration capacity was followed by scratch assay and mobilization from collagen, and the activity of proteolytic enzymes by zymography. Specific inhibitors of MAPK and Wnt/β-catenin pathways were used to investigate underlying molecular mechanisms. Results: Compared to standard 21% O2, cultivation of WJ-MSCs at 3% O2 did not influence their immunophenotype, while it modulated their differentiation process and enhanced their clonogenic and expansion capacity. 3% O2 induced transient change in cell cycle and prevented cell death. The expression of NANOG, OCT4A, OCT4B and SOX2 was increased at 3% O2 . Both cultivation and preculturing of WJ-MSCs at 3% O2 increased their in vitro migratory capacity and enhanced the activity of proteolytic enzymes. ERK1/2 mediated WJ-MSCs' mobilization from collagen regardless of oxygen levels, while Wnt/β-catenin pathway was activated during migration and mobilization at standard conditions. Conclusion: Culturing of WJ-MSCs under 3% O2 should be considered a credible condition when investigating their properties and potential use. Highlights: 3% O2 enhances WJ-MSCs clonogenic potential and stemness. 3% O2 stimulates WJ-MSC proliferation and protects cells from cell death. 3% O2 stimulates WJ-MSC migration as well as mobilization from collagen. 3% O2 enhances uPA and MMP-2 activity in migrating WJ-MSCs. MAPK and Wnt/β-catenin pathways mediate WJ-MSCs motility and uPA activity.