Oxygenated Environment Enhances Both Stem Cell Survival and Osteogenic Differentiation

Abstract

Osteogenesis of mesenchymal stem cells (MSCs) is highly dependent on oxygen supply. We have shown that perfluorotributylamine (PFTBA), a synthetic oxygen carrier, enhances MSC-based bone formation in vivo. Exploring this phenomenon's mechanism, we hypothesize that a transient increase in oxygen levels using PFTBA will affect MSC survival, proliferation, and differentiation, thus increasing bone formation. To test this hypothesis, MSCs overexpressing bone morphogenetic protein 2 were encapsulated in alginate beads that had been supplemented with an emulsion of PFTBA or phosphate-buffered saline. Oxygen measurements showed that supplementation of PFTBA significantly increased the available oxygen level during a 96-h period. PFTBA-containing beads displayed an elevation in cell viability, which was preserved throughout 2 weeks, and a significantly lower ratio of dead cells throughout the experiment. Furthermore, the cells from the control group expressed significantly more hypoxia-related genes such as VEGF, DDIT3, and PKG1. Additionally, PFTBA supplementation led to an increase in the osteogenic differentiation and to a decrease in chondrogenic differentiation of MSCs. In conclusion, PFTBA increases the oxygen availability in the vicinity of the MSCs, which suffer oxygen exhaustion shortly after encapsulation in alginate beads. Consequently, cell survival is increased, and hypoxia-related genes are downregulated. In addition, PFTBA promotes osteogenic differentiation over chondrogeneic differentiation, and thereby can accelerate MSC-based bone regeneration.

Synergistic Effects of Hypoxia and Morphogenetic Factors on Early Chondrogenic Commitment of Human Embryonic Stem Cells in Embryoid Body Culture

“…These data indicate that both CCM and transient hypoxia stimulate chondrogenic commitment of hESCs in EB culture (Fig. 2ab), and that lineage specific differentiation depends not only on cell-secreted factors, but also on oxygen levels as previously reported for osteogenic differentiation [35, 36]. The transient hypoxia had stronger effect on priming the chondrogenic progenitors in EBs when maintained for 2 weeks compared to only 1 week (Fig.…”

Hypoxia Inhibits De Novo Vascular Assembly of Adipose-Derived Stromal/Stem Cell Populations, but Promotes Growth of Preformed Vessels

“…This may be achieved by preassembly of vascular networks before implantation or through oxygen delivery strategies in situ. [34][35][36][37] The in vivo tissue environment is certainly much more complex, with inflammation, cellular invasion, and other biological signaling occurring after implantation of a cell-seeded graft. Ongoing in vivo studies are necessary to completely understand the impact of this complex postimplantation environment on the ability of ASCs to functionally vascularize a graft in situ.…”

Strategies to engineer tendon/ligament-to-bone interface: Biomaterials, cells and growth factors

“…In addition, oxygen concentration has been shown to affect MSC differentiation and ECM production in vitro and in vivo. High oxygen concentration promotes osteogenic differentiation and induces bone formation and mineralization [156,157]. Low oxygen concentration favors chondrogenic differentiation, upregulates collagen type II and type X expression, and downregulates collagen I expression [150,158,159].…”