Effects Of Hypoxia in Long‐Term In Vitro Expansion of Human Bone Marrow Derived Mesenchymal Stem Cells

Abstract

Mesenchymal stem cells (MSC) are considered multipotent stromal, non-hematopoietic cells with properties of self-renovation and differentiation. Optimal conditions for culture of MSC have been under investigation. The oxygen tension used for cultivation has been studied and appears to play an important role in biological behavior of mesenchymal cells. The aim is characterize MSC in hypoxia and normoxia conditions comparing their morphological and functional characteristics. Bone marrow-derived mesenchymal stem cells obtained from 15 healthy donors and cultured. MSC obtained from each donor were separated into two cultivation conditions normoxia (21% O ) and hypoxia (three donors at 1%, three donors at 2%, five donors at 3%, and four donors at 4% O ) up to second passage. MSC were evaluated for proliferation, differentiation, immunophenotyping, size and cell complexity, oxidative stress, mitochondrial activity, and autophagy. Culture conditions applied did not seem to affect immunophenotypic features and cellular plasticity. However, cells subjected to hypoxia showed smaller size and greater cellular complexity, besides lower proliferation (P < 0.002). Furthermore, cells cultured in low O tension had lower mitochondrial activity (P < 0.03) and a reduced tendency to autophagy, although oxidative stress did not vary among groups (P < 0.39). Oxygen tension seems to be a key regulator of cellular adaptation in vitro, and metabolic effects underlying this variable remain undescribed. Heterogeneity or even lack of results on the impact of oxygen concentration used for expanding MSC highlights the need for further research, in order to optimize conditions of cultivation and expansion and achieve greater safety and therapeutic efficacy. J. Cell. Biochem. 118: 3072-3079, 2017. © 2017 Wiley Periodicals, Inc.

Improved therapeutics of modified mesenchymal stem cells: an update

“…The suppression of NK activation is through prostaglandin-E2 secretion in a contact-independent manner, and IFN-γ-stimulated MSCs are less susceptible to NK killing [93]. It is also documented that hypoxic preconditioning at oxygen tensions of 1%, 2%, 3% and 4% show greater MSCs cellular complexity and decreased tendency to autophagy, enhancing their survival [95].…”

Regulation of the mitochondrial reactive oxygen species: Strategies to control mesenchymal stem cell fates ex vivo and in vivo

“…In contrast, hypoxic conditions may also protect MSCs from injury, promoting proliferation, differentiation, and survival in a ROS‐mediated manner. A paradoxical discovery was that compared with normoxia, MSCs cultured under hypoxia showed a smaller size and greater cellular complexity, lower proliferation and mitochondrial activity, and reduced autophagy . It also moderately increases ROS production and promotes the proliferative capacity and differentiation potency of MSCs via phosphorylation of the AKT and mTOR pathways .…”

“…A paradoxical discovery was that compared with normoxia, MSCs cultured under hypoxia showed a smaller size and greater cellular complexity, lower proliferation and mitochondrial activity, and reduced autophagy. 42 It also moderately increases ROS production and promotes the proliferative capacity and differentiation potency of MSCs via phosphorylation of the AKT and mTOR pathways. 43,44 Intriguingly, long-term hypoxic conditions upregulated the expression of HIF-1α, and the hypoxia MSCs showed greater cell viability, decreased ROS levels and increased resistance to oxidative stress for alleviating both early radiation-induced pneumonia and late pulmonary fibrosis when compared to normoxia MSCs.…”

Mathematical Modeling Reveals the Role of Hypoxia in the Promotion of Human Mesenchymal Stem Cell Long-Term Expansion

“…Human mesenchymal stem cells (MSCs) are multipotent stromal cells that are capable of self-renewal and differentiation into various lineages mainly including osteoblasts, chondrocytes, and adipocytes. Their major source in vivo is the bone marrow, and they have also been found in many other adult tissues such as the adipose tissue, dental pulp, and umbilical cord [ 1 , 2 ]. In recent years, MSCs have drawn a lot of biomedical research interest for their great potential in regenerative medicine due to their high proliferative ability and lineage plasticity [ 3 ].…”

“…Consequently, it is impossible to collect the large number of MSCs required for clinical trials purely from a single donor, which is one of the major limitations in the medical use of MSCs [ 9 , 10 ]. Therefore, ex vivo expansion is a necessary step for the acquisition of sufficient MSCs [ 2 , 4 ], and many research efforts have been devoted to the optimization of MSCs culture protocols, including the composition of the basal culture medium, the addition of specific growth factors, the seeding density, and the biophysical environment [ 11 ]. In this study, we focus on the effects of oxygen tension on MSC expansion, which has been investigated by plentiful experimental studies [ 2 , 7 , 8 , 12 – 15 ].…”