Hypoxic preconditioning enhances bone marrow mesenchymal stem cell migration via Kv2.1 channel and FAK activation

Abstract

Transplantation using stem cells including bone marrow mesenchymal stem cells (BMSCs) is emerging as a potential regenerative therapy after ischemic attacks in the heart and brain. The migration capability of transplanted cells is a critical cellular function for tissue repair. Based on our recent observations that hypoxic preconditioning (HP) has multiple benefits in improving stem cell therapy and that the potassium Kv2.1 channel acts as a promoter for focal adhesion kinase (FAK) activation and cell motility, the present investigation tested the hypothesis that HP treatment can increase BMSC migration via the mechanism of increased Kv2.1 expression and FAK activities. BMSCs derived from green fluorescent protein-transgenic mice were treated under either normoxic (N-BMSC) or hypoxic (0.5% O2) (HP-BMSC) conditions for 24 h. Western blot analysis showed HP selectively upregulated Kv2.1 expression while leaving other K+ channels, such as Kv1.5 and Kv1.4, unaffected. Compared with normoxic controls, significantly larger outward delayed rectifier K+ currents were recorded in HP-BMSCs. HP enhanced BMSC migration/homing activities in vitro and after intravenous transplantation into rats subjected to permanent myocardial infarction (MI). The HP-promoted BMSC migration was inhibited by either blocking K+ channels or knocking down Kv2.1. Supporting a relationship among HP, Kv2.1, and FAK activation, HP increased phosphorylation of FAK397 and FAK576/577, and this effect was antagonized by blocking K+ channels. These findings provide novel evidence that HP enhances the ability of BMSCs to migrate and home to the injured region; this effect is mediated through a regulatory role of Kv2.1 on FAK phosphorylation/activation.

Hypoxic Preconditioning Increases the Neuroprotective Effects of Mesenchymal Stem Cells in a Rat Model of Spinal Cord Injury

“…Although previous studies have reported the hypoxic culture conditions for preconditioning of cell-based therapy [17][18][19], the optimal culture conditions remain unknown. In this study, Car9 and Vegf expression increased significantly in rMSCs under the 1% pO 2 hypoxic condition compared with that under the normoxic condition.…”

“…Culturing cells under hypoxic conditions is a less invasive, alternative method to pre-condition of transplanted cells [17][18][19]. Although MSCs are usually cultured under normoxic conditions, MSCs exist in low oxygen (hypoxic) conditions in vivo [20] and the oxygen tensions are an important factor during MSC culture because stem cells are particularly sensitive to their microenvironment [21].…”

Intranasal Delivery of Bone Marrow Mesenchymal Stem Cells Improved Neurovascular Regeneration and Rescued Neuropsychiatric Deficits after Neonatal Stroke in Rats

“…Pretreated or genetically modified BMSCs targeting the elevation of these factors showed increased cell viability and enhanced migration and homing capacity to lesion sites (21,24,48,50,53,69). BMSCs can stimulate endogenous neuronal differentiation and synaptic connection, thus improving neuronal activity (26).…”

The role of the microenvironment on the fate of adult stem cells

“…Hypoxic conditions can significantly promote the formation of the FAK-Kv2.1 complex, increasing focal adhesion kinase (FAK) phosphorylation and upregulating CXCR4 in MSCs. All of these hypoxic effects reinforce the migration capacity and the homing of transplanted cells to the lesion sites [73]. Maijenburg et al [76] investigated the process of MSC migration and found that nuclear receptors Nur77 and Nurr1 showed the highest expression in migratory MSCs.…”

“…These factors have been shown to share the same trophic mechanisms that are essential for the roles of grafted SCs, which are necessary for their survival. Upregulated factors may include angiopoietin-I, VEGF, hepatocyte growth factor (HGF), placental growth factor (PlGF), BDNF, and fibroblast growth factor-2 (FGF-2) [65,72,73]. Treatment using some of these recombinant proteins or the induced endogenous expression of these proteins to enhance the secretion effects can reduce neuronal death and promote angiogenesis and attenuate many pathophysiological changes.…”