Ceramide kinase regulates the migration of bone marrow-derived mesenchymal stem cells

Endogenous bone marrow-derived mesenchymal stem cells (BM-MSCs) are mobilized into peripheral blood and injured tissues by various growth factors and cytokines that are expressed in the injured tissues, such as substance P (SP), stromal cell derived factor-1 (SDF-1), and transforming growth factor-beta (TGF-β). Extracellular bioactive lipid metabolites such as ceramide-1-phosphate and sphingosine-1-phosphate also modulate BM-MSC migration as SP, SDF-1, and TGF-β. However, the roles of intrinsic lipid kinases of BM-MSCs in the stem cell migration are unclear. Here, we demonstrated that ceramide kinase mediates the chemotactic migration of BM-MSCs in response to SP, SDF-1, or TGF-β. Furthermore, a specific inhibitor of ceramide kinase inhibited TGF-β-induced migration of BM-MSCs and N-cadherin that is necessary for BM-MSCs migration in response to TGF-β. Therefore, these results suggest that the intracellular ceramide kinase is required for the BM-MSCs migration and the roles of the intrinsic ceramide kinase in the migration are associated with N-cadherin regulation.     

Identification of chemoattractive factors involved in the migration of bone marrow-derived mesenchymal stem cells to brain lesions caused by prions

Bone marrow-derived mesenchymal stem cells (MSCs) have been reported to migrate to brain lesions of neurodegenerative diseases; however, the precise mechanisms by which MSCs migrate remain to be elucidated. In this study, we carried out an in vitro migration assay to investigate the chemoattractive factors for MSCs in the brains of prion-infected mice. The migration of immortalized human MSCs (hMSCs) was reduced by their pretreatment with antibodies against the chemokine receptors, CCR3, CCR5, CXCR3, and CXCR4 and by pretreatment of brain extracts of prion-infected mice with antibodies against the corresponding ligands, suggesting the involvement of these receptors, and their ligands in the migration of hMSCs. In agreement with the results of an in vitro migration assay, hMSCs in the corpus callosum, which are considered to be migrating from the transplanted area toward brain lesions of prion-infected mice, expressed CCR3, CCR5, CXCR3, and CXCR4. The combined in vitro and in vivo analyses suggest that CCR3, CCR5, CXCR3, and CXCR4, and their corresponding ligands are involved in the migration of hMSCs to the brain lesions caused by prion propagation. In addition, hMSCs that had migrated to the right hippocampus of prion-infected mice expressed CCR1, CX3CR1, and CXCR4, implying the involvement of these chemokine receptors in hMSC functions after chemotactic migration. Further elucidation of the mechanisms that underlie the migration of MSCs may provide useful information regarding application of MSCs to the treatment of prion diseases.     

Paracrine effects of mesenchymal stem cells in cisplatin-induced renal injury require heme oxygenase-1

Multipotent mesenchymal stem cells (MSC) have become a popular and promising therapeutic approach in many clinical conditions. MSC are beneficial in animal models of acute kidney injury (AKI), by mediating differentiation-independent paracrine properties, and have prompted ongoing clinical trials to evaluate the safety and efficacy of MSC. Heme oxygenase-1 (HO-1) is induced in response to stress including AKI and has important anti-apoptotic, anti-inflammatory, and proangiogenic properties in these settings. We therefore examined whether HO-1 plays a role in the beneficial effects of MSC in AKI. We isolated MSC from bone marrow of age-matched HO-1+/+ and HO-1-/- mice. Our studies indicate that while differentiation of MSC into osteo- and adipocytic lineages did not differ between cells isolated from HO-1+/+ and HO-1-/- mice, MSC from HO-1-/- mice had significantly lower angiogenic potential. Moreover, HO-1-/- MSC demonstrated reduced expression and secretion of several important growth and proangiogenic factors (stromal cell-derived factor-1, vascular endothelial growth factor-A, and hepatocyte growth factor) compared with MSC derived from HO-1+/+ mice. In addition, conditioned medium of HO-1+/+ MSC rescued functional and morphological changes associated with cisplatin-induced AKI, while the HO-1-/--conditioned medium was ineffectual. Our studies indicate that HO-1 plays an important role in MSC-mediated protection. The results expand understanding of the renoprotective effects of MSC and may provide novel strategies to better utilize MSC in various disease models.     

MUC1 is involved in trophoblast transendothelial migration

The factors that regulate trophoblast invasion of the uterine vasculature are incompletely understood. In this paper we show that macaque trophoblasts express the mucin, MUC1, and that it is involved in trophoblast-endothelial interaction. Immunocytochemistry, Western blotting and RT-PCR analyses confirmed that MUC1 was expressed by isolated early gestation macaque trophoblasts. MUC1 was also detected in endovascular trophoblasts in sections of placental-decidual tissue during early gestation. A blocking antibody against MUC1 reduced trophoblast adhesion to uterine endothelial cells and also blocked trophoblast transendothelial migration. MUC1 is known to bind to Intercellular Adhesion Molecule-1 (ICAM-1) in other systems. Incubation in the presence of a blocking antibody against Intercellular Adhesion Molecule-1 (ICAM-1) or recombinant ICAM-1 modestly, but significantly, reduced transendothelial trophoblast migration. These results are consistent with the idea that MUC1 is involved in trophoblast adhesion to uterine endothelial cells and in trophoblast transendothelial migration.     

Increased stemness and migration of human mesenchymal stem cells in hypoxia is associated with altered integrin expression

Human mesenchymal stem cells (hMSCs) are regularly cultured and characterised under normoxic (21% O(2)) conditions, although the physiological oxygen tension in the stem cell niche is known to be as low as 1-2%. Oxygen itself is an important signalling molecule, but the distinct impact on various stem cell characteristics is still unclear. Therefore, the aim of this study was to evaluate the influence of oxygen concentration on the hMSC subpopulation composition, cell morphology and migration on different surfaces (polystyrene, collagen I, fibronectin, laminin) as well as on the expression of integrin receptors. Bone marrow-derived hMSCs were cultured either in normoxic (21% O(2)) or hypoxic (2% O(2)) conditions. The hMSC subpopulations were assessed by aspect ratio and cell area. Hypoxia promoted a more homogeneous cell population with a significantly higher fraction of rapidly self-renewing cells which are believed to be the true stem cells. Under hypoxic conditions hMSC volume and height were significantly decreased on all surfaces as measured by white light confocal microscopy. Furthermore, low oxygen tension led to a significant increase in cell velocity and Euclidian distance on all matrixes, which was evaluated by time-lapse microscopy. With regard to cell-matrix contacts, expression of several integrin subunits was evaluated by semi-quantitative RT-PCR. Increased expression of the subunits α(1), α(3), α(5,) α(6), α(11), α(v), β(1) and β(3) was observed in hypoxic conditions, while α(2) was higher expressed in normoxic cultured hMSCs. Taken together, our results indicate that hypoxic conditions promote stemness and migration of hMSC along with altering their integrin expression.     

Activation of CD74 inhibits migration of human mesenchymal stem cells

Therapeutic administration of mesenchymal stem cells (MSCs) by systemic delivery utilizes the innate ability of the cells to home to damaged tissues, but it can be an inefficient process due to a limited knowledge of cellular cues that regulate migration and homing. Our lab recently discovered that a potent pro-inflammatory cytokine, macrophage migration inhibitory factor (MIF), inhibits MSC migration. Because MIF may act on multiple cellular targets, an activating antibody (CD74Ab) was employed in this study to examine the effect of one MIF receptor, CD74 (major histocompatibility complex class II-associated invariant chain), on MSC motility. CD74 activation inhibits in a dose-dependent manner up to 90% of in vitro migration of MSCs at 40 μg/ml CD74Ab (p?<?0.001), with consistent effects observed among three MSC donor preparations. A blocking peptide from the C-terminus of CD74 eliminates the effect of CD74Ab on MSCs. This suggests that MIF may act on MSCs, at least in part, through CD74. Late-passage MSCs exhibit less chemokinesis than those at passage 2. However, MSCs remain responsive to CD74 activation during ex vivo expansion: MSC migration is inhibited ～2-fold in the presence of 5 µg/ml CD74Ab at passage 9 vs. ～3-fold at passage 2 (p?<?0.001). Consistent with this result, there were no significant differences in CD74 expression at all tested passages or after CD74Ab exposure. Targeting CD74 to regulate migration and homing potentially may be a useful strategy to improve the efficacy of a variety of MSC therapies, including those that require ex vivo expansion.     

间充质干细胞移植治疗急性肺损伤的研究进展

急性肺损伤是一种临床常见的危重病症,临床上传统的治疗方法一般以尽早去除诱因、控制感染、机械通气及器官功能支持治疗为主。间充质干细胞属于成体干细胞的一种,能主动归巢至肺损伤部位,并通过向肺泡和支气管上皮细胞分化参与组织修复,同时间充质干细胞能够调节急性肺损伤时局部和全身炎症反应和免疫紊乱,从而发挥治疗作用,可能是治疗急性肺损伤的一个很有前景的方法。作者就间充质干细胞移植治疗急性肺损伤的研究进展进行综述。     

Cell-autonomous heparanase modulates self-renewal and migration in bone marrow-derived mesenchymal stem cells

Background

Stem cell-fate is highly regulated by stem cell niche, which is composed of a distinct microenvironment, including neighboring cells, signals and extracellular matrix. Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stem cells and are potentially applicable in wide variety of pathological conditions. However, the niche microenvironment for BM-MSCs maintenance has not been clearly characterized. Accumulating evidence indicated that heparan sulfate glycosaminoglycans (HS-GAGs) modulate the self-renewal and differentiation of BM-MSCs, while overexpression of heparanase (HPSE1) resulted in the change of histological profile of bone marrow. Here, we inhibited the enzymatic activity of cell-autonomous HPSE1 in BM-MSCs to clarify the physiological role of HPSE1 in BM-MSCs.

Results

Isolated mouse BM-MSCs express HPSE1 as indicated by the existence of its mRNA and protein, which includes latent form and enzymatically active HPSE1. During in vitro osteo-differentiations, although the expression levels of Hpse1 fluctuated, enzymatic inhibition did not affect osteogenic differentiation, which might due to increased expression level of matrix metalloproteinase 9 (Mmp9). However, cell proliferation and colony formation efficiency were decreased when HPSE1 was enzymatically inhibited. HPSE1 inhibition potentiated SDF-1/CXCR4 signaling axis and in turn augmented the migratory/anchoring behavior of BM-MSCs. We further demonstrated that inhibition of HPSE1 decreased the accumulation of acetylation marks on histone H4 lysine residues suggesting that HPSE1 also modulates the chromatin remodeling.

Conclusions

Our findings indicated cell-autonomous HPSE1 modulates clonogenicity, proliferative potential and migration of BM-MSCs and suggested the HS-GAGs may contribute to the niche microenvironment of BM-MSCs.     

Galanin is highly expressed in bone marrow mesenchymal stem cells and facilitates migration of cells both in vitro and in vivo

Galanin peptide has recently been found to be highly abundant in early embryonic mouse mesenchyme, while galanin and its receptors are expressed in embryonic mouse stem cells. Bone marrow mesenchymal stem cells (BMMSCs) represent the primary source for adult stem cell therapy. In this study we examined the abundance of galanin and its receptors in BMMSCs and evaluated its possible function. Galanin mRNA and protein were highly expressed in BMMSCs cultures up to four passages, while among the three galanin receptor subtypes (GalR1, GalR2, and GalR3) only GalR2 and to a lesser extent GalR3 were expressed. Using chemotaxis and wound assays we found that galanin protein increased the migration of BMMSCs. Furthermore, increased serum galanin levels in a galanin transgenic model enhanced the mobilization (homing) of injected BMMSCs in vivo. These data suggest a role for galanin in BMMSC migration, probably through activation of the GalR2 receptor.     

Involvement of cationic channels in proliferation and migration of human mesenchymal stem cells

Human mesenchymal stem cells (HMSCs) have been applied in various clinic settings. Ion channels play an important role in cellular physiology. However, the potential role of cationic channels in regulating the proliferation and migration properties of hMSCs remains to be determined. In the present study, the functional expression of ion channels in hMSCs was investigated by patch clamp. MTT assay and BrdU stainings were used to assess the proliferation of hMSCs. hMSC migration was evaluated by Transwell migration assays. The results show that sodium-, L-type calcium, potassium currents have been identified in hMSCs. TEA (K⁺ channel blocker), nifedipine (Ca²⁺ channel blocker) can inhibit both proliferation and migration of hMSCs. The increase of extracellular Ca²⁺ concentration promoted both proliferation and migration of hMSCs. TTX, a Na⁺ channel blocker, promoted cell proliferation but inhibited cell migration. Our data suggest that cationic channels (sodium, L-type calcium, potassium channels) play important roles in regulating proliferation and migration of hMSCs.