miR-709 exerts an angiogenic effect through a FGF2 upregulation induced by a GSK3B downregulation.

The aim of this study was to identify angiogenic microRNAs (miRNAs) that could be used in the treatment of hindlimb ischemic tissues. miRNAs contained in extracellular vesicles (EVs) deriving from the plasma were analyzed in C57BL/6 mice, which have ischemia tolerance, and in BALB/c mice without ischemia tolerance as part of a hindlimb ischemia model; as a result 43 angiogenic miRNA candidates were identified. An aortic ring assay was employed by using femoral arteries isolated from BALC/c mice and EVs containing miRNA; as a result, the angiogenic miRNA candidates were limited to 14. The blood flow recovery was assessed after injecting EVs containing miRNA into BALB/c mice with hindlimb ischemia, and miR-709 was identified as a promising angiogenic miRNA. miR-709-encapsulating EVs were found to increase the expression levels of the fibroblast growth factor 2 (FGF2) mRNA in the thigh tissues of hindlimb ischemia model BALB/c mice. miR-709 was also found to bind to the 3'UTR of glycogen synthase kinase 3 beta (GSK3B) in three places. GSK3B-knockdown human artery-derived endothelial cells were found to express high levels of FGF2, and were characterized by increased cell proliferation. These findings indicate that miR-709 induces an upregulation of FGF2 through the downregulation of GSK3B.

Allogenic multilayered fibroblast sheets promote anastomotic site healing in a rat model of esophageal reconstruction.

OBJECTIVE: Anastomotic leakage is a common and severe complication of esophageal reconstruction. Accordingly, there is a clinical need for novel methods to prevent it. We developed multilayered, growth factor-secreting fibroblast sheets that promote wound healing and angiogenesis. The present study aimed to assess the utility of allogenic multilayered fibroblast sheets in preventing esophageal anastomotic leakage in a rat model of esophageal reconstruction. METHODS: Allogenic multilayered fibroblast sheets prepared from oral mucosal tissues were implanted at esophageal anastomotic sites. RESULTS: The allogenic multilayered fibroblast sheet group had significantly higher burst pressure and collagen deposition compared to a control group five days postoperatively. The expression levels of collagen type I and III mRNAs around esophageal suture sites were higher in the allogenic multilayered fibroblast sheet group compared to the control group on postoperative days 0, 3, and 5. There was a trend toward lower anastomotic leakage and lower abscess scores in the allogenic multilayered fibroblast sheet group compared to the control group; however, these differences did not reach statistical significance. Allogenic multilayered fibroblast sheets completely disappeared at ten days after implantation. Further, no inflammation was observed at suture sites with implanted allogenic multilayered fibroblast sheets at five days after surgery. CONCLUSION: Allogenic multilayered fibroblast sheets may represent a promising method of preventing esophageal anastomotic leakage.

Postoperative changes in a bronchial stump following covering with free fat tissue in a rat model.

OBJECTIVES: Covering the bronchial stump with free fat tissue has been used as minimally invasive prophylaxis against bronchial stump fistulas; however, postoperative changes in the bronchial stump have not been well validated. Our goal was to examine changes in the bronchial stump in response to covering with free fat tissue in a rat model. METHODS: A left pneumonectomy was performed on 16 Wistar/ST rats, 12 of which had a bronchial stump covered with free subcutaneous fat tissue. Four rats that underwent a left pneumonectomy alone were sacrificed on postoperative day 7, and the 12 rats whose bronchial stumps were additionally covered with fat tissue were sacrificed on postoperative days 7, 14 and 56. Macroscopic and histological changes and pressure resistance of the bronchial stumps due to coverage with free fat tissue were examined. RESULTS: None of the rats showed macroscopic infection or necrosis in the thoracic cavity at the time of the rethoracotomy. The normal bronchial stumps remained mostly exposed, whereas the bronchial stumps covered with fat tissue were well-coated with tissue mass. Histologically, fibrous connective tissue containing microvessels gradually formed around the bronchial stump covered with fat tissue, and some of the tissue masses still had normal fat structures 56 days postoperatively. Covering with fat tissue significantly increased the pressure resistance of the bronchial stump 7 days postoperatively and further increased with time. CONCLUSIONS: Covering the bronchial stump with free fat tissue formed fibrous connective tissue around the bronchial stump and reinforced its closure.

Dry preserved multilayered fibroblast cell sheets are a new manageable tool for regenerative medicine to promote wound healing.

This study investigated the therapeutic effects of dry-preserved multi-layered fibroblast cell sheets (dry sheets) on cutaneous ulcers. Dry sheets were prepared by air-drying multi-layered fibroblast cell sheets (living sheets) to cease their life activities. Before in vivo application, we tested the release of growth factors into the medium to examine the mechanisms of dry sheets in wound healing. Vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) were released from both dry and living sheets, while high levels of fibroblast growth factor-2 (FGF-2) and high mobility group box 1 (HMGB1) protein were only from dry sheets. An in vitro fibroblast proliferation assay revealed that the dry sheet eluate significantly enhanced cell proliferation and VEGF and HGF production compared with living sheet eluate. FGF-2-neutralizing antibodies significantly blocked this proliferative response. In wounds created on diabetic mice, the dry sheet-treatment groups using autologous or allogeneic cells showed significantly accelerated wound closure compared with that in the no-treatment group. The storage stability of the dry sheet was better at refrigeration temperature than at room temperature and remained stable for at least 4 weeks. Our data indicated that allogeneic dry sheets represent a promising new tool for regenerative medicine that promotes wound healing.

Autologous Multilayered Fibroblast Sheets Can Reinforce Bronchial Stump in a Rat Model.

Bronchopleural fistula is one of the most serious postoperative complications caused by the incomplete healing of a bronchial stump. Fibroblasts play an important role in wound healing by facilitating connective tissue formation and inducing angiogenesis. We developed a method for production of multilayered fibroblast sheets that secreted some growth factors and promoted wound healing. The present study aimed to assess the treatment effect of multilayered fibroblast sheets on bronchial stump healing. In this rat model, left pneumonectomy was performed, and multilayered fibroblast sheets derived from autologous oral mucosal tissues were transplanted to the bronchial stump. The changes in the bronchial stump were examined macroscopically, histologically, and mechanically. The fibroblast sheets promoted the formation of thick connective tissues around the bronchial stump. The formed connective tissues were accompanied by new blood vessels, and fibrosis was observed over time. Then, 7 days after the transplantation of the fibroblast sheets, the bronchial wall became significantly thicker, and the area of the blood vessels for the bronchial wall tissues was significantly larger in the experimental group than in the control group. In addition, the burst pressure in the bronchial stump was significantly higher in the experimental group than in the control group. Bronchial stumps were reinforced by the transplantation of multilayered fibroblast sheets derived from autologous oral mucosal tissues.

Novel bone microenvironment model of castration-resistant prostate cancer with chitosan fiber matrix and osteoblasts.

The interaction between prostate cancer cells and osteoblasts is essential for the development of bone metastasis. Previously, novel androgen receptor axis-targeted agents (ARATs) were approved for metastatic castration-naïve and non-metastatic castration-resistant prostate cancer (CRPC); both of which are pivotal for investigating the association between the bone microenvironment and tumors. The present study established a novel in vitro 3D microenvironment model that simulated the bone microenvironment of CRPC, and evaluated the drug susceptibility of ARATs and the efficacy of the combination of abiraterone and dutasteride. Green fluorescent protein-transferred C4-2 cells (a CRPC cell line) and red fluorescent protein-transferred human osteoblasts differentiated from human mesenchymal stem cells were co-cultured in chitosan nanofiber matrix-coated culture plates to simulate the 3D scaffold of the bone microenvironment. The growth of C4-2 was quantified using live-cell imaging and the Cell3 iMager duos analysis system. The growth of C4-2 colonies were quantified for a maximum of 30 days. The expression of TGF-ß increased and promoted EMT in C4-2 cells co-cultured with osteoblasts, indicating resistance to ARATs. The IC50 of each drug and the combination effect of abiraterone and dutasteride were evaluated using this model. Combination treatment with abiraterone and dutasteride synergistically inhibited the growth of C2-4 colonies compared with individual investigational agents. This could be attributed to the reduction of 3-keto-5α-abiraterone, an androgen receptor agonist. The bone microenvironment model of the present study is unique and useful for evaluating new drug susceptibility testing in prostate cancer cells. This model may help to reveal the unknown mechanisms underlying micro- to clinical bone metastasis in prostate cancer.

Autologous transplantation of multilayered fibroblast sheets prevents postoperative pancreatic fistula by regulating fibrosis and angiogenesis.

INTRODUCTION: Postoperative pancreatic fistula (POPF) is a serious complication after gastrointestinal or pancreatic surgery. Despite intensive investigations, the occurrence has not significantly decreased in the past decades. The aims of this study were to clarify the pathophysiology of POPF and establish the preventive measures using multilayered fibroblast sheets. METHODS: We developed a pancreatic fistula (PF) model of rat with transection of the splenic duct and surrounding pancreatic parenchyma. Multilayered fibroblast sheets prepared from tails were autologously transplanted to this model. The preventive effect was biochemically and histologically evaluated by measuring the ascitic levels of pancreatic enzymes and conducting immunohistochemistry and real-time polymerase chain reaction analyses of pancreatic tissue. Findings were compared to those obtained with acellular materials simply sealing the wound. RESULTS: In the PF model, the ascitic levels of pancreatic enzymes were transiently up-regulated. Inflammation and necrosis were histologically observed in a wide range. Islets were damaged even in remote areas. Transplantation of multilayered fibroblast sheets dramatically reduced the ascitic leakage of enzymes, suppressed inflammation, and broadly preserved the islets. Compared with acellular materials, these sheets offered superior prevention of cellular activity through the spaciotemporal regulation of fibrosis and angiogenesis. Notably, the leakage hole appeared to have been plugged with the fibrotic matrix, which might have been the most crucial mechanism minimizing pancreatic damage. CONCLUSIONS: The autologous transplantation of multilayered fibroblast sheets significantly prevented PF and protected the pancreas, underscoring the potential utility of this approach for POPF prevention.

ARHGAP29 expression may be a novel prognostic factor of cell proliferation and invasion in prostate cancer.

Yes­associated protein (YAP) is a transcription­coupling factor that plays a central role in the Hippo pathway, and its activation regulates cell proliferation and carcinogenesis. YAP activation has been reported in various malignancies, conferring tumors with migratory and invasive abilities. Several studies have suggested that YAP expression is closely associated with prostate cancer. Furthermore, YAP has been revealed to regulate destabilization of F­actin associated with the cytoskeleton via Rho GTPase­activating protein 29 (ARHGAP29), suggesting that ARHGAP29 is associated with cancer metastasis. In the present study, the functions of ARHGAP29 were examined in four prostate cancer cell lines (22Rv1, LNCaP, DU145 and PC­3) and it was revealed that upregulation of ARHGAP29 in LNCaP and DU145 cells with the lowest expression of ARHGAP29 promoted cell proliferation and invasion. Conversely, ARHGAP29 knockdown in PC­3 cells with its highest expression level significantly reduced cell proliferation and invasion. In addition, immunohistochemistry of specimens from 133 patients who underwent radical prostatectomy was performed to investigate the clinical association between ARHGAP29 expression and prognosis in prostate cancer patients. Multivariate analysis demonstrated that ARHGAP29 was an independent prognostic factor for biochemical progression­free survival (P=0.0123). These findings indicated that ARHGAP29 in prostate cancer may be a potential prognostic biomarker and therapeutic target.

Hypoxic-conditioned cardiosphere-derived cell sheet transplantation for chronic myocardial infarction.

OBJECTIVES: Cell therapy provides a suitable environment for regeneration through paracrine effects such as secretion of growth factors. Cardiosphere-derived cells (CDCs) have a high capacity for growth factor secretion and are an attractive target for clinical applications. In particular, a cell sheet technique was reported to have clinical advantages by covering a specific region. Here, we examined the effect of the hypoxic-conditioned (HC) autologous CDC sheet therapy on a rabbit chronic myocardial infarction model. METHODS: CDC sheet function was assessed by the enzyme-linked immunosorbent assay and quantified by polymerase chain reaction in vitro (days 1-3 of conditioning). The rabbit chronic myocardial infarction model was established by left coronary ligation. Autologous CDCs were isolated from the left atrial specimen; CDC sheets with or without 2-day HC were transplanted onto the infarcted hearts at 4 weeks. The cardiac function was assessed by an echocardiography at 0, 4 and 8 weeks. A histological analysis of the host hearts was performed by tomato lectin staining at 8 weeks. RESULTS: The optimal HC duration was 48 h. HC significantly increased the mRNA expression levels of VEGF and ANG2 on day 2 compared to the normoxic-conditioned (NC) group. The HC group showed significant improvement in the left ventricular ejection fraction (64.4% vs 58.8% and 53.4% in the NC and control) and a greater lectin-positive area in the ischaemic region (HC:NC:control = 13:8:2). CONCLUSIONS: HC enhances the paracrine effect of a CDC sheet on angiogenesis to improve cardiac function in the chronic myocardial infarction model, which is essential for cardiomyocyte proliferation during cardiac regeneration.

Dclk1 Inhibition Cancels 5-FU-induced Cell-cycle Arrest and Decreases Cell Survival in Colorectal Cancer.

BACKGROUND/AIM: 5-Fluorouracil (5-FU) is frequently used in colorectal cancer treatment, but with limited success. The aim of the present study was to explore the cytotoxic effects of 5-FU, in combination with inhibition of doublecortin-like kinase 1 (Dclk1), a tumor stem cell marker that regulates pro-survival signaling in colorectal cancer cells, in the human colon cancer cell line, COLO-320. MATERIALS AND METHODS: The effects of 5-FU treatment plus Dclk1 inhibition on the phosphorylation of checkpoint kinase 1 (Chk1), cell cycle, DNA damage, apoptosis, and cell survival in COLO-320 cells were evaluated. RESULTS: Combined treatment with 5-FU and a Dclk1 inhibitor, LRRK2-IN-1 (LRRK), decreased 5-FU-induced phosphorylation of Chk1 and canceled 5-FU-induced cell-cycle arrest at the S phase. Combined treatment with 5-FU and LRRK failed to induce poly (ADP-ribose) polymerase 1 (PARP-1) cleavage, but tended to decrease cell survival compared to individual treatment with 5-FU or LRRK. CONCLUSION: These results indicate that a combination of 5-FU and LRRK may be an effective, novel approach for colorectal cancer therapy.

TROY is a promising prognostic biomarker in patients with colorectal cancer.

Tumor necrosis factor receptor superfamily member 19 (TROY) is involved in the Wnt/ß-catenin signaling pathway and interacts with leucine-rich repeat containing G-protein-coupled receptor 5 (LGR5), which is a well-known biomarker of cancer stem cells and a prognostic marker of colorectal cancer (CRC). Because there have been no studies to evaluate the prognostic significance of TROY, we performed the present study to determine whether TROY can be a prognostic biomarker in CRC patients. We evaluated TROY expression levels in 100 CRC tissues by quantitative real-time PCR and investigated the association of TROY expression levels with clinicopathologic features. Cancer stage and TROY expression level were found to be independent prognostic factors of disease-free survival. Moreover, TROY overexpression was the sole independent prognostic factor of disease-free survival in patients with stage II and III CRC. These results suggest that analysis of TROY might help predict clinical outcome in patients with CRC. To support our findings, confirmatory studies using independent data sets are needed.

JAB1-STAT3 activation loop is associated with recurrence following 5-fluorouracil-based adjuvant chemotherapy in human colorectal cancer.

Jun activation domain-binding protein 1 (JAB1) has been shown to have multiple roles in tumorigenesis, including the degradation of tumor suppressor proteins such as p53, Smad7, Runx3 and the cyclin-dependent kinase inhibitor p27Kip1, and the activation of oncogenic transcription factors, such as c-Jun and hypoxia-inducible factor-1α. In addition, our previous study revealed that JAB1 positively regulates signal transducer and activator of transcription 3 (STAT3) DNA-binding activity in human colon cancer cells. In turn, the oncogenic transcription factor STAT3 positively regulates JAB1 expression, indicative of a positive feedback loop. Furthermore, high JAB1 expression is associated with a poor prognosis in numerous malignant carcinomas. However, the association between JAB1 expression and prognosis in colorectal cancer remains unclear. The aim of the present study was to elucidate the association between JAB1 and STAT3 expression and recurrence in colorectal cancer. In the present study, it was found that high JAB1 expression in primary colorectal cancer tissues is an independent predictor of recurrence following 5-fluorouracil (5-FU)-based adjuvant chemotherapy in colorectal cancer patients, and that high expression of both JAB1 and STAT3 in primary colorectal cancer tissues is associated with a lower recurrence-free survival rate following 5-FU-based adjuvant chemotherapy compared to high expression of only JAB1 or STAT3. Overall, these results suggest that JAB1 is a novel predictive marker of recurrence following 5-FU-based adjuvant chemotherapy in colorectal cancer patients, and that the JAB1-STAT3 activation loop may be a potential therapeutic target in recurrent colorectal cancer following 5-FU-based adjuvant chemotherapy.

Enhancement of cytotoxic effects of gemcitabine by Dclk1 inhibition through suppression of Chk1 phosphorylation in human pancreatic cancer cells.

Although gemcitabine (GEM) is frequently used in the treatment of pancreatic cancer, the effects are limited. To increase the inhibitory effect of GEM, the identification of a molecular target is needed. Recent studies have revealed that doublecortin-like kinase 1 (Dclk1) positively regulates tumor growth, invasion, metastasis, factors related to epithelial-mesenchymal transition (EMT), pluripotency, angiogenesis, and anti-apoptosis in pancreatic cancer cells. Therefore, Dclk1 is a potential therapeutic target for pancreatic cancer. However, the Dclk1-signaling pathway including its substrate proteins remains to be elucidated. To identify the candidate substrate proteins phosphorylated by Dclk1, we performed a cancer-related phosphorylated protein microarray using Dclk1-inhibited MIA Paca2 cells. Expression levels of phosphorylated cdc25A (p-cdc25A) and phosphorylated Chk1 (p-Chk1), belonging to the ATR pathway, were decreased by treatment with Dclk1 inhibitor LRRK2-IN-1 (LRRK), indicating Dclk1 involvement in the ATR pathway. Consistent with this finding, the GEM-induced p-Chk1 expression was significantly decreased by treatment with LRRK. Notably, combined treatment with GEM and LRRK allowed cell cycle progression without arresting at S phase, while individual treatment with GEM induced cell cycle arrest at S phase. In addition, combined treatment with GEM and LRRK increased the number of γ-H2AX-positive cells compared with that upon individual treatments. Moreover, LRRK alone, and combined treatment with GEM and LRRK, induced caspase-3 activation and PARP1 cleavage, in contrast to treatment with GEM alone. Finally, combined treatment with GEM and LRRK significantly reduced cell survival compared to individual treatment with GEM. These results indicate that Dclk1 inhibition in combination with GEM treatment offers a novel approach to treat pancreatic cancer cells.

Microgravity influences maintenance of the human muscle stem/progenitor cell pool.

Microgravity induces skeletal muscle atrophy; however, the underlying mechanism is not clarified. In particular, the influence of microgravity on human skeletal muscle stem/progenitor cells (SMPCs) is not well understood. In this study, we used induced pluripotent stem cell-derived human SMPCs to investigate the effect of microgravity on maintenance of the stem/progenitor cell pool. Human SMPCs were induced by free-floating spherical aggregation culture, and derivatized-SMPC spheres were maintained in a microgravity condition (10-3 G) for 2 weeks using a clinostat rotation system. Microgravity culture deformed the SMPC spheres, with no signs of apoptosis. The most obvious change from microgravity culture was a significant decrease in the expression level of Pax7 in the SMPC spheres, with reduced numbers of myotubes in adhesion culture. Pax7 expression also decreased in the presence of the proteasome inhibitor MG132, indicating that the proteasomal degradation of Pax7 protein is not critical for its reduced expression in microgravity culture. Moreover, microgravity culture decreased the expression level of tumor necrosis factor receptor-associated factor 6 (TRAF6) and phosphorylation of its downstream molecule extracellular-related kinase (ERK) in SMPC spheres. Therefore, microgravity negatively regulates Pax7 expression in human SMPCs possibly through inhibition of the TRAF6/ERK pathway to consequently dysregulate SMPC pool maintenance. Overall, these results suggest that skeletal muscle atrophy is caused by microgravity-induced exhaustion of the stem cell pool.

Age-related increase in Wnt inhibitor causes a senescence-like phenotype in human cardiac stem cells.

Aging of cardiac stem/progenitor cells (CSCs) impairs heart regeneration and leads to unsatisfactory outcomes of cell-based therapies. As the precise mechanisms underlying CSC aging remain unclear, the use of therapeutic strategies for elderly patients with heart failure is severely delayed. In this study, we used human cardiosphere-derived cells (CDCs), a subtype of CSC found in the postnatal heart, to identify secreted factor(s) associated with CSC aging. Human CDCs were isolated from heart failure patients of various ages (2-83 years old). Gene expression of key soluble factors was compared between CDCs derived from young and elderly patients. Among these factors, SFRP1, a gene encoding a Wnt antagonist, was significantly up-regulated in CDCs from elderly patients (≥65 years old). sFRP1 levels was increased significantly also in CDCs, whose senescent phenotype was induced by anti-cancer drug treatment. These results suggest the participation of sFRP1 in CSC aging. We show that the administration of recombinant sFRP1 induced cellular senescence in CDCs derived from young patients, as indicated by increased levels of markers such as p16, and a senescence-associated secretory phenotype. In addition, co-administration of recombinant sFRP1 could abrogate the accelerated CDC proliferation induced by Wnt3A. Taken together, our results suggest that canonical Wnt signaling and its antagonist, sFRP1, regulate proliferation of human CSCs. Furthermore, excess sFRP1 in elderly patients causes CSC aging.

Therapeutic strategies for cell-based neovascularization in critical limb ischemia.

Critical limb ischemia (CLI) causes severe ischemic rest pain, ulcer, and gangrene in the lower limbs. In spite of angioplasty and surgery, CLI patients without suitable artery inflow or enough vascular bed in the lesions are often forced to undergo amputation of a major limb. Cell-based therapeutic angiogenesis has the potential to treat ischemic lesions by promoting the formation of collateral vessel networks and the vascular bed. Peripheral blood mononuclear cells and bone marrow-derived mononuclear cells are the most frequently employed cell types in CLI clinical trials. However, the clinical outcomes of cell-based therapeutic angiogenesis using these cells have not provided the promised benefits for CLI patients, reinforcing the need for novel cell-based therapeutic angiogenesis strategies to cure untreatable CLI patients. Recent studies have demonstrated the possible enhancement of therapeutic efficacy in ischemic diseases by preconditioned graft cells. Moreover, judging from past clinical trials, the identification of adequate transplant timing and responders to cell-based therapy is important for improving therapeutic outcomes in CLI patients in clinical settings. Thus, to establish cell-based therapeutic angiogenesis as one of the most promising therapeutic strategies for CLI patients, its advantages and limitations should be taken into account.

Extracellular miR-224 as a prognostic marker for clear cell renal cell carcinoma.

Exosome-miRNAs (exo-miR) have recently been identified as modulators of cancer progression and distant metastasis. We previously found that intracellular miR-224 is up-regulated and significantly related to cancer invasion and metastasis in clear cell renal cell carcinoma (ccRCC). We therefore investigated the role of exosome miR-224 in ccRCC and explored the interaction between intra- and extracellular miR-224 in renal cell carcinoma. To validate the method for isolating exosomes from blood samples or cell culture media, we examined exosome morphology using transmission electron microscope (TEM). We investigated the relationship between exo-miR-224 expression and patient prognosis in 108 ccRCC patients. We isolated exosomes from a metastatic renal cancer cell line and tested their effects on a primary renal cancer cell line with several functional analyses. We found that the high expression level exo-miR-224 group has significantly shorter progression-free survival, cancer-specific survival, and overall survival compared with the low expression group. In multivariate analysis, a high level of exo-miR-224 was a significant risk factor related to all prognoses investigated. After adding exosomes from a metastatic RCC cell line to a primary RCC cell line, cell proliferation and invasion were increased while the percentage of apoptotic cells was significantly decreased. Intracellular levels of miR-224 were significantly up-regulated in the primary renal cancer cell line. Extracellular miR-224 in exosomes impacts on patient prognosis and is a potential prognostic biomarker for ccRCC patients.

Increased plasma VEGF levels following ischemic preconditioning are associated with downregulation of miRNA-762 and miR-3072-5p.

Ischemic preconditioning (IPC) has protective effects against ischemia-perfusion injury of organs. In the present study, we investigated the associated mechanisms after performing remote IPC (rIPC) of lower limbs by clamping abdominal aorta in mice. Subsequent experiments showed decreased damage and paralysis of lower limbs following spinal cord injury (SCI). Concomitantly, plasma vascular endothelial growth factor (VEGF) levels were increased 24 h after rIPC compared with those in sham-operated animals. In subsequent microRNA analyses, thirteen microRNAs were downregulated in exosomes 24 h after rIPC. Further studies of femoral CD34-positive bone marrow (BM) cells confirmed downregulation of these seven microRNAs 24 h after rIPC compared with those in sham-operated controls. Subsequent algorithm-based database searches suggested that two of the seven microRNAs bind to the 3' UTR of VEGF mRNA, and following transfection into CD34-positive BM cells, anti-miR-762, and anti-miR-3072-5p inhibitors led to increased VEGF concentrations. The present data suggest that rIPC transiently increases plasma VEGF levels by downregulating miR-762 and miR-3072-5p in CD34-positive BM cells, leading to protection against organ ischemia.

Treatment of refractory cutaneous ulcers with mixed sheets consisting of peripheral blood mononuclear cells and fibroblasts.

The purpose of this study was to confirm the therapeutic effects of mixed sheets consisting of peripheral blood mononuclear cells (PBMNCs) and fibroblasts on cutaneous skin ulcers. Vascular endothelial growth factor (VEGF) secretion in mixed cell sheets was much higher than in PBMNCs and fibroblasts. Concerning the mechanism, transforming growth factor beta 1 and platelet-derived growth factor BB secreted from PBMNCs enhanced VEGF production in fibroblasts. In wounds created on the backs of diabetic mice, the therapeutic effect of mixed cell sheets was similar to that of daily treatment with trafermin, a recombinant human basic fibroblast growth factor. Although abnormal granulation tissue and inflammatory cell infiltration were observed in trafermin-treated wounds, the transplantation of mixed cell sheets resulted in the natural anatomy of subcutaneous tissues. The expression patterns of identical wound-healing factors in wounds were different between mixed sheet-transfected and trafermin-treated animals. Because mixed cell sheets transplanted into full-thickness skin defects were eliminated in hosts by day 21 in syngeneic transplantation models, allogeneic transplantation was performed using mice with different genetic backgrounds. The wound-healing rates were similar between the mixed cell sheet and trafermin groups. Our data indicated that mixed cell sheets represent a promising therapeutic material for cutaneous ulcers.

Autologous preconditioned mesenchymal stem cell sheets improve left ventricular function in a rabbit old myocardial infarction model.

Mesenchymal stem cells (MSCs) constitute one of the most powerful tools for therapeutic angiogenesis in infarcted hearts. However, conventional MSC transplantation approaches result in insufficient therapeutic effects due to poor retention of graft cells in severe ischemic diseases. Cell sheet technology has been developed as a new method to prolong graft cell retention even in ischemic tissue. Recently, we demonstrated that hypoxic pretreatment enhances the therapeutic efficacy of cell sheet implantation in infarcted mouse hearts. In this study, we investigated whether hypoxic pretreatment activates the therapeutic functions of bone marrow-derived MSC (BM-MSC) sheets and improves cardiac function in rabbit infarcted hearts following autologous transplantation. Production of vascular endothelial growth factor (VEGF) was increased in BM-MSC monolayer sheets and it peaked at 48 h under hypoxic culture conditions (2% O2). To examine in vivo effects, preconditioned autologous BM-MSC sheets were implanted into a rabbit old myocardial infarction model. Implantation of preconditioned BM-MSC sheets accelerated angiogenesis in the peri-infarcted area and decreased the infarcted area, leading to improvement of the left ventricular function of the infarcted heart. Importantly, the therapeutic efficacy of the preconditioned BM-MSC sheets was higher than that of standardly cultured sheets. Thus, implantation of autologous preconditioned BM-MSC sheets is a feasible approach for enhancing therapeutic angiogenesis in chronically infarcted hearts.