Stromal Cell-Derived Factor-1α (SDF-1α) Promotes Growth and Migration of Bone Marrow Stromal Cells (BMSCs) and Gastric Cancer Cells Through Phosphatidylinositol 3-Kinase/AKT (PI3K/Akt) Pathway

SDF-1α activity is closely related to information transmission and cell migration when contributing to lymphatic metastasis in various tumors. Herein, we explored the interaction among SDF-1α, CXCR4 and PI3K/Akt signaling pathway in gastric cancer (GC) and their roles in this disorder. Human GC cells KATO-III and BMSCs were co-cultured without contact. GC cells were transfected with SDF-1α, CXCR4 inhibitor, and PI3K inhibitor. After examining the efficiency of transfection, cell migration was evaluated using Transwell chamber, and expression SDF-1α, CD133, and CXCR4 was determined by RT-qPCR. With transfection rate of 98%, the number of migrated cells reduced upon inhibition of CXCR4 and PI3K. Luciferase activity in 565 nm are high than CXCR4 inhibition group. (p < 0.05). Likewise, up-regulation of SDF-1α increased the expression of SDF-1 (0.825±0.061), CD133 (0.875±0.058), CXCR4 (0.801±0.052), and Akt (0.852±0.062), compared to the blank group, CXCR4 inhibition group and PI3K inhibition group (p < 0.05). Down-regulation of CXCR4 and PI3K, however, decreased the expression insignificantly (p > 0.05). Collectively, up-regulation of SDF-1α activates CXCR4 signaling pathway of BMSCs and stimulates its downstream PI3K/Akt signaling pathway and and increases the expression of CD133, thereby promoting malignant behaviors of GC cells.

CAF promotes chemoresistance through NRP2 in gastric cancer

Background Fibroblasts are the predominant cell type in the stroma of tumor, and cancer-associated fibroblasts (CAFs) promote cancer chemoresistance by secreting various bioactive molecules. However, the differential expression between CAFs and normal fibroblasts (NFs) and how can CAFs uniquely impact cancer cells are still unexplored. Methods Primary CAFs and NFs were cultured from gastric cancer specimens, and their variant expression was analyzed by RNA-sequencing. Chemoresistance was evaluated by measuring cell viability, apoptosis, and 3D-coculture techniques. Results CAFs were isolated from gastric cancers and defined by specific cell-surface markers. CAFs decreased the sensitivity of gastric cancer cells to 5-FU. RNA-sequencing showed that CAFs expressed a higher level of NRP2 than NFs. And the high expression of NRP2 was correlated with worse oncological outcomes in gastric cancer patients. Further study showed that the knockdown of NRP2 eradicated the resistance to 5-FU. And the secretion of stromal cell-derived factor-1 (SDF-1) was reduced following NRP2 knockdown. Furthermore, we found that the increased sensitivity to 5-FU was induced by DNA damage. And this process was mediated by predominant effectors of the Hippo pathway, YAP/TAZ. Conclusions The present study indicated that CAFs within gastric cancers promote chemoresistance through the expression of NRP2. The secretion of SDF-1 that mediated by VEGF/NRP2 signaling in CAFs and the activation of Hippo pathway in cancer cells in large part participated in this project.

Biomarker Signatures in Cancer Patients With and Without Venous Thromboembolism Events: A Substudy of CASSINI

Cancer is associated with an increased risk of venous thromboembolism (VTE). In the CASSINI study, ambulatory cancer patients with a Khorana risk score ≥2 had a reduced risk of VTE while receiving rivaroxaban. This analysis used blood samples from CASSINI to compare biomarker levels between patients with and without VTE. VTE occurred in 62 patients during the 6 months of CASSINI (cases), and they were matched by age, sex, cancer type, tumor stage, and Khorana score to 62 controls. Baseline blood samples were analyzed for 280 biomarkers, and biomarker distribution was compared using the Wilcoxon rank sum test between groups defined by VTE occurrence and vital status. Sparse Bayesian regression modeling was used to select a joint panel of potential VTE biomarkers. Biomarkers with the largest differences in baseline distribution among cancer patients with and without VTE included decreases in stromal cell-derived factor-1 (SDF-1), thyroid-stimulating hormone (TSH), and monocyte chemotactic protein 4 and increases in growth hormone (GH) and interleukin-1 receptor type 1 (IL-1R1). Between survivors and those who died, significantly different biomarkers included ST2, IL-8, and C-reactive protein. Regression analyses also identified decreases in SDF-1 and TSH. Pathway analysis indicated enrichment of cytokine and chemokine activity with IL-1R1, SDF-1, and GH, which are the strongest predictors of VTE or death. Our analyses highlight the interactions between hemostatic and inflammatory processes and identify candidate biomarkers of cancer-associated VTE. Prospective studies will determine clinical relevance of these biomarkers. This trial was registered at www.clinicaltrials.gov as #NCT02555878.

Spatiotemporal regulation of endogenous MSCs using a functional injectable hydrogel system for cartilage regeneration

Hydrogels have been extensively favored as drug and cell carriers for the repair of knee cartilage defects. Recruiting mesenchymal stem cells (MSCs) in situ to the defect region could reduce the risk of contamination during cell delivery, which is a highly promising strategy to enhance cartilage repair. Here, a cell-free cartilage tissue engineering (TE) system was developed by applying an injectable chitosan/silk fibroin hydrogel. The hydrogel system could release first stromal cell-derived factor-1 (SDF-1) and then kartogenin (KGN) in a unique sequential drug release mode, which could spatiotemporally promote the recruitment and chondrogenic differentiation of MSCs. This system showed good performance when formulated with SDF-1 (200 ng/mL) and PLGA microspheres loaded with KGN (10 μΜ). The results showed that the hydrogel had good injectability and a reticular porous structure. The microspheres were distributed uniformly in the hydrogel and permitted the sequential release of SDF-1 and KGN. The results of in vitro experiments showed that the hydrogel system had good cytocompatibility and promoted the migration and differentiation of MSCs into chondrocytes. In vivo experiments on articular cartilage defects in rabbits showed that the cell-free hydrogel system was beneficial for cartilage regeneration. Therefore, the composite hydrogel system shows potential for application in cell-free cartilage TE.

Protease-Triggered Release of Stabilized CXCL12 from Coated Scaffolds in an Ex Vivo Wound Model

Biomaterials are designed to improve impaired healing of injured tissue. To accomplish better cell integration, we suggest to coat biomaterial surfaces with bio-functional proteins. Here, a mussel-derived surface-binding peptide is used and coupled to CXCL12 (stromal cell-derived factor 1α), a chemokine that activates CXCR4 and consequently recruits tissue-specific stem and progenitor cells. CXCL12 variants with either non-releasable or protease-mediated-release properties were designed and compared. Whereas CXCL12 was stabilized at the N-terminus for protease resistance, a C-terminal linker was designed that allowed for specific cleavage-mediated release by matrix metalloproteinase 9 and 2, since both enzymes are frequently found in wound fluid. These surface adhesive CXCL12 derivatives were produced by expressed protein ligation. Functionality of the modified chemokines was assessed by inositol phosphate accumulation and cell migration assays. Increased migration of keratinocytes and primary mesenchymal stem cells was demonstrated. Immobilization and release were studied for bioresorbable PCL-co-LC scaffolds, and accelerated wound closure was demonstrated in an ex vivo wound healing assay on porcine skin grafts. After 24 h, a significantly improved CXCL12-specific growth stimulation of the epithelial tips was already observed. The presented data display a successful application of protein-coated biomaterials for skin regeneration.

Dental pulp stem cells as a therapy for congenital entero-neuropathy

Hirschsprung’s disease (HSCR) and its allied disorders are congenital entero-neuropathies with life-long implications in many cases. Here we report the effects of intravenous transplantation of cultured dental pulp stem cells derived from deciduous teeth (dDPSCs) into ‘Japanese fancy-1’ (JF1) mice with entero-neuropathy caused by Ednrb mutation. Intravenously injected dDPSCs (multipotent neural crest cells with low immunogenicity) migrated to affected regions of the intestine through interactions between stromal cell-derived factor-1α and C-X-C chemokine receptor type-4. Notably, transplanted dDPSCs differentiated into both enteric neurons and pacemaker interstitial cells to correct abnormalities in the electrical and mechanical activities of the proximal colon. dDPSC transplantation also led to repair of the small intestinal mucosa, changes in the gastrointestinal microbiota, improvements in nutritional status and prolongation of survival. We anticipate that dDPSC transplantation could be developed into a novel cell-based therapy for HSCR and its allied disorders.

Modifying strategies for SDF-1/CXCR4 interaction during mesenchymal stem cell transplantation

Mesenchymal stem cell (MSC) transplantation is regarded as a promising candidate for the treatment of ischaemic heart disease. The major hurdles for successful clinical translation of MSC therapy are poor survival, retention, and engraftment in the infarcted heart. Stromal cell-derived factor-1/chemokine receptor 4 (SDF-1/CXCR4) constitutes one of the most efficient chemokine/chemokine receptor pairs regarding cell homing. In this review, we mainly focused on previous studies on how to regulate the SDF-1/CXCR4 interaction through various priming strategies to maximize the efficacy of mesenchymal stem cell transplantation on ischaemic hearts or to facilitate the required effects. The strengthened measures for enhancing the therapeutic efficacy of the SDF-1/CXCR4 interaction for mesenchymal stem cell transplantation included the combination of chemokines and cytokines, hormones and drugs, biomaterials, gene engineering, and hypoxia. The priming strategies on recipients for stem cell transplantation included ischaemic conditioning and device techniques.