Discrepancies on the Role of Oxygen Gradient and Culture Condition on Mesenchymal Stem Cell Fate

Abstract

Over the past few years, mesenchymal stem (or stromal) cells (MSCs) have garnered enormous interest due to their therapeutic value especially for their multilineage differentiation potential leading to regenerative medicine applications. MSCs undergo physiological changes upon in vitro expansion resulting in expression of different receptors, thereby inducing high variabilities in therapeutic efficacy. Therefore, understanding the biochemical cues that influence the native local signals on differentiation or proliferation of these cells is very important. There have been several reports that in vitro culture of MSCs in low oxygen gradient (or hypoxic conditions) upregulates the stemness markers and promotes cell proliferation in an undifferentiated state, as hypoxia mimics the conditions the progenitor cells experience within the tissue. However, different studies report different oxygen gradients and culture conditions causing ambiguity in their interpretation of the results. In this progress report, it is aimed to summarize recent studies in the field with specific focus on conflicting results reported during the application of hypoxic conditions for improving the proliferation or differentiation of MSCs. Further, it is tried to decipher the factors that can affect characteristics of MSC under hypoxia and suggest a few techniques that could be combined with hypoxic cell culture to better recapitulate the MSC tissue niche.

Bioinspired porous microspheres for sustained hypoxic exosomes release and vascularized bone regeneration

“…, 1–6% in the bone marrow). A large body studies have demonstrated that hypoxia culture of MSCs leads to enhanced secretion of various growth factors (GFs), as well as exosome cargo with improved therapeutic potential [ 16 , 17 ]. Recent works proved that the hypoxic condition of 1% O 2 induced the release of sEVs from various MSCs (e.g., bone marrow MSCs [ 18 ], and human umbilical cord MSCs [ 19 ]), hence enhancing the therapeutic efficacy of MSCs exosomes for treating multiple defects.…”

A Small-Molecule Cocktails-Based Strategy in Culture of Mesenchymal Stem Cells

“…In an ACY (-) group, MSCs were cultured as previously described ( Henrionnet et al, 2017 ; Samal et al, 2021 ). In brief, the culture medium contained low glucose DMEM (Gibco) supplemented with FBS (10%, Hyclone), fibroblast growth factor-basic (bFGF, 1 ng/ml, PeproTech), and penicillin/streptomycin (1%, Gibco).…”

Insight into Hypoxia Stemness Control

“…The potential application of stem cells for tissue regeneration represents an important challenge but it is necessary to optimize cell culture conditions to preserve the desired stem cell properties. As reported, some in vitro parameters can influence stem cell characteristics and reduce cellular proliferation supporting senescence [170]. One prominent characteristic of stem cells is their natural aptitude to reside in low O 2 condition niches.…”

“…In literature, there are evidence supporting complex link connecting hypoxia, metabolism, HIFs, and several molecules with crucial roles in the regulation of stemness or differentiation (Figure 6). Low O 2 tension can upregulate proliferation and the expression of pluripotency-related genes, probably by mimicking the conditions that stem cells experience in vivo [170]. In turn, these stemness factors can regulate other subordinate genes involved in the metabolic control of stemness [204] allowing the preservation of a more undifferentiated state and genetic stability (Figure 6).…”