The GLUT1-mTORC1 axis affects odontogenic differentiation of human dental pulp stem cells

Potent antitumor efficacy of human dental pulp stem cells armed with YSCH-01 oncolytic adenovirus

BACKGROUND

Systemic administration of oncolytic adenovirus for cancer therapy is still a challenge. Mesenchymal stem cells as cell carriers have gained increasing attention in drug delivery due to their excellent tumor tropism, immunosuppressive modulatory effects, and paracrine effects. However, the potential of human dental pulp stem cells (hDPSCs) loaded with oncolytic adenovirus for cancer biotherapy has not been investigated yet.

METHODS

The stemness of hDPSCs was characterized by FACS analysis and Alizarin red staining, Oil Red O staining, and immunofluorescence assays. The biological fitness of hDPSCs loaded with oncolytic adenovirus YSCH-01 was confirmed by virus infection with different dosages and cell viability CCK-8 assays. Additionally, the expression of CAR receptor in hDPSCs was detected by qPCR assay. Tumor tropism of hDPSC loaded with YSCH-01 in vitro and in vivo was investigated by Transwell assays and living tumor-bearing mice imaging technology and immunohistochemistry, Panoramic scanning of frozen section slices assay analysis. Furthermore, the antitumor efficacy was observed through the different routes of YSCH-01/hPDSCs administration in SW780 and SCC152 xenograft models. The direct tumor cell-killing effect of YSCH-01/hDPSCs in the co-culture system was studied, and the supernatant of YSCH-01/hDPSCs inhibited cell growth was further analyzed by CCK-8 assays.

RESULTS

hDPSCs were found to be susceptible to infection by a novel oncolytic adenovirus named YSCH-01 and were capable of transporting this virus to tumor sites at 1000 VP/cell infectious dosage in vitro and in vivo. Moreover, it was discovered that intraperitoneal injection of hDPSCs loaded with oncolytic adenovirus YSCH-01 exhibited potential anti-tumor effects in both SW780 and SCC152 xenograft models. The crucial role played by the supernatant secretome derived from hDPSCs loaded with YSCH-01 significantly exerted a specific anti-tumor effect without toxicity for normal cells, in both an active oncolytic virus and an exogenous protein-independent manner. Furthermore, the use of hDPSCs as a cell carrier significantly reduced the required dosage of virus delivery in vivo compared to other methods.

CONCLUSIONS

These findings highlight the promising clinical potential of hDPSCs as a novel cell carrier in the field of oncolytic virus-based anti-cancer therapy.

Forskolin enhanced the osteogenic differentiation of human dental pulp stem cells in vitro and in vivo

Background/purpose

Human dental pulp stem cells (hDPSCs) are multipotent adult stem cells that can differentiate into various lineages such as odontoblasts, osteoblasts, and chondrocytes. Regulation of hDPSCs differentiation with small-molecule compounds can be a useful tool for tissue engineering and regenerative therapy. Forskolin is an agonist of adenylate cyclase that promotes cyclic adenosine monophosphate production. However, the role of Forskolin in regulating the osteogenic differentiation of hDPSCs is still unknown.

Materials and methods

A cell counting kit-8 (CCK-8) assay was performed to screen out the safety concentrations of Forskolin. Following, quantitative polymerase chain reaction (qPCR) and alizarin red staining were performed to detect bone-related gene expression and mineralized deposit formation. Furthermore, we prepared cell sheets which were followed by a 3D culture for cell pellet formation. Finally, the hDPSC cell pellets were transplanted into immunodeficient mice.

Results

CCK-8 assay showed 5 μM and 10 μM Forskolin had no significant inhibition on the proliferation of hDPSCs. The qPCR indicated Forskolin (5, 10 μM) enhanced osteogenic differentiation of hDPSCs by upregulating bone-related genes. Alizarin red staining and its quantification analysis demonstrated Forskolin in 5 μM and 10 μM similarly enhanced the mineralized deposit formation of hDPSCs in vitro. After six weeks of transplantation, immunohistochemical stains showed that osteopontin expression and bone formation were significantly boosted in the Forskolin-treated group than in the normal osteogenic inducing group.

Conclusion

Our results indicate Forskolin enhances osteogenic differentiation of hDPSCs in vitro and boosts bone formation in vivo.

Allosteric links between the hydrophilic N-terminus and transmembrane core of human Na+ /H+ antiporter NHA2

The human Na+ /H+ antiporter NHA2 (SLC9B2) transports Na+ or Li+ across the plasma membrane in exchange for protons, and is implicated in various pathologies. It is a 537 amino acids protein with an 82 residues long hydrophilic cytoplasmic N-terminus followed by a transmembrane part comprising 14 transmembrane helices. We optimized the functional expression of HsNHA2 in the plasma membrane of a salt-sensitive Saccharomyces cerevisiae strain and characterized in vivo a set of mutated or truncated versions of HsNHA2 in terms of their substrate specificity, transport activity, localization, and protein stability. We identified a highly conserved proline 246, located in the core of the protein, as being crucial for ion selectivity. The replacement of P246 with serine or threonine resulted in antiporters with altered substrate specificity that were not only highly active at acidic pH 4.0 (like the native antiporter), but also at neutral pH. P246T/S versions also exhibited increased resistance to the HsNHA2-specific inhibitor phloretin. We experimentally proved that a putative salt bridge between E215 and R432 is important for antiporter function, but also structural integrity. Truncations of the first 50-70 residues of the N-terminus doubled the transport activity of HsNHA2, while changes in the charge at positions E47, E56, K57, or K58 decreased the antiporter's transport activity. Thus, the hydrophilic N-terminal part of the protein appears to allosterically auto-inhibit cation transport of HsNHA2. Our data also show this in vivo approach to be useful for a rapid screening of SNP's effect on HsNHA2 activity.