**Conflict of interest**

Pluripotent stem cell maintenance and differentiation are new and difficult cell culture techniques. These involve monolayer or three-dimensional/cell suspension culture as well. Pluripotent stem cell may be cultured on feeder layer of feeder-free surface on biomatrices. The pluripotent stem cells themselves have excellent viability and proliferative capacity in normal oxygen circumstances [72]. Additionally, they are immortal and can continuously proliferate in pluripotent state. Reasonably, most study protocols emphasize the importance of altered oxygen levels, once differentiation steps are in progress. After differentiation, steps are initiated altered oxygen levels usually increase the yield of developed cells and increase functional activity, for example, insulin secretion of beta cells, derived from plu-

78 Hyperbaric Oxygen Treatment in Research and Clinical Practice - Mechanisms of Action in Focus

Pluripotent stem cells proliferate in low-oxygen levels in utero. It is also agreed that MSC have low oxygen circumstances *in vivo* in the bone marrow niche. Taking these into consideration, *in vitro* culture of the cells in normal oxygen circumstances is out of their normal niche. Interestingly, all of these cell types improved performance in therapeutic potential when cultured in hypoxic environment [45]. MSC improved angiogenesis-related gene expressions and protein expressions in hypoxia, furthermore implanting them into various *in vivo* models

HBOT would have a significant role in tissue engineering and preconditioning the engineered construct *in vitro*, before *in vivo* transplantation. As an example, tissue engineered mucosa were further developed in HBOT. The mucosal cells enhanced expression of angiogenesisrelated factor (e.g., VEGF, FGF and HGF) [74]. Enhanced angiogenesis by mucosal tissue may

Wide range of differentiation protocols exist, which aim improving the number of cardiovascular derivatives after the differentiation steps. These are increasing in endothelial cell and cardiovascular cells as well. With endothelial cells, recent protocols reached about 50% differentiation yield. Latest studies aim hypoxia as a diver to mesodermal and then to endothelial

In conclusion, HBOT is an interesting novel medical tool with wide range of therapeutic

*In vitro* cellular models utilize different HBOT protocols and need to be standardized to bring

This chapter outlined that HBOT increases endothelial and fibroblast viability and proliferation *in vitro*. Furthermore, tube formation and wound healing assay improved in response to HBOT. HBOT has significant effects on endothelial-related blot-clotting and platelet mechanisms as well. Furthermore, HBOT decreases ROS-related harm in not-healing wound model and improves blood-brain barrier after ischemic event in *in vitro* model. In new therapeutic promises, the stem cells would also benefit from HBOT in maintenance, proliferation and tis-

ripotent cells [14].

of ischemia resulted in better outcomes [73].

be beneficial for graft homing and retention.

lineage specification [75].

translatable data to clinicians.

sue engineering aspects as well.

**3. Conclusion**

potential.

The author declares no conflict of interest.
