Acceleration of Angiogenesis after Paravasal Injection of Mesenchymal Stem Cells at the Site of Modeled Venous Thrombosis

Manipulating HGF signaling reshapes the cirrhotic liver niche and fills a therapeutic gap in regeneration mediated by transplanted stem cells

Long-term stem cell survival in the cirrhotic liver niche to maintain therapeutic efficacy has not been achieved. In a well-defined diethylnitrosamine (DEN)-induced liver fibrosis/cirrhosis animal model, we previously showed that liver-resident stem/progenitor cells (MLpvNG2+ cells) or immune cells have improved survival in the fibrotic liver environment but died via apoptosis in the cirrhotic liver environment, and increased levels of hepatocyte growth factor (HGF) mediated this cell death. We tested the hypothesis that inhibiting HGF signaling during the cirrhotic phase could keep the cells alive. We used adeno-associated virus (AAV) vectors designed to silence the c-Met (HGF-only receptor) gene or a neutralizing antibody (anti-cMet-Ab) to block the c-Met protein in the DEN-induced liver cirrhosis mouse model transplanted with MLpvNG2+ cells between weeks 6 and 7 after DEN administration, which is the junction of liver fibrosis and cirrhosis at the site where most intrahepatic stem cells move toward apoptosis. After 4 weeks of treatment, the transplanted MLpvNG2+ cells survived better in c-Met-deficient mice than in wild-type mice, and cell activity was similar to that of the mice that received MLpvNG2+ cells at 5 weeks after DEN administration (liver fibrosis phase when most of these cells proliferated). Mechanistically, a lack of c-Met signaling remodeled the cirrhotic environment, which favored transplanted MLpvNG2+ cell expansion to differentiation into mature hepatocytes and initiate endogenous regeneration by promoting mature host hepatocyte generation and mediating functional improvements. Therapeutically, c-Met-mediated regeneration can be mimicked by anti-cMet-Ab to interfere functions, which is a potential drug for cell-based treatment of liver fibrosis/cirrhosis.

Resistance exercise promotes the resolution and recanalization of deep venous thrombosis in a mouse model via SIRT1 upregulation

BACKGROUND

Early exercise for acute deep venous thrombosis (DVT) improves the patient's symptoms and does not increase the risk of pulmonary embolism. However, information about its effect on thrombus resolution is limited. The aim of this study was to investigate the role of resistance exercise (RE) in thrombus resolution and recanalization and determine its underlying mechanisms.  METHODS: Ninety-six C57BL/6 J mice were randomly divided into four groups: Control group (C, n = 24); DVT group (D, n = 24); RE + DVT group (ED, n = 24); and inhibitor + RE + DVT group (IED, n = 24). A DVT model was induced by stenosis of the inferior vena cava (IVC). After undergoing IVC ultrasound within 24 h post-operation to confirm DVT formation, mice without thrombosis were excluded. Other mice were sacrificed and specimens were obtained 14 or 28 days after operation. Thrombus-containing IVC was weighed, and the thrombus area and recanalization rate were calculated using HE staining. Masson's trichrome staining was used to analyze the collagen content. RT-PCR and ELISA were performed to examine IL-6, TNF-α, IL-10, and VEGF expression levels. SIRT1 expression was assessed using immunohistochemistry staining and RT-PCR. VEGF-A protein expression and CD-31-positive microvascular density (MVD) in the thrombus were observed using immunohistochemistry.  RESULTS: RE did not increase the incidence of pulmonary embolism. It reduced the weight and size of the thrombus and the collagen content. Conversely, it increased the recanalization rate. It also decreased the levels of the pro-inflammatory factors IL-6 and TNF-α and increased the expression levels of the anti-inflammatory factor IL-10. RE enhanced VEGF and SIRT1 expression levels and increased the MVD in the thrombosis area. After EX527 (SIRT1 inhibitor) was applied, the positive effects of exercise were suppressed.

CONCLUSIONS

RE can inhibit inflammatory responses, reduce collagen deposition, and increase angiogenesis in DVT mice, thereby promoting thrombus resolution and recanalization. Its underlying mechanism may be associated with the upregulation of SIRT1 expression.

Autologous Mesenchymal Stem Cell and Islet Cotransplantation: Safety and Efficacy

Islet engraftment after transplantation is impaired by high rates of islet/β cell death caused by cellular stressors and poor graft vascularization. We studied whether cotransplantation of ex vivo expanded autologous bone marrow-derived mesenchymal stem cells (MSCs) with islets is safe and beneficial in chronic pancreatitis patients undergoing total pancreatectomy with islet autotransplantation. MSCs were harvested from the bone marrow of three islet autotransplantation patients and expanded at our current Good Manufacturing Practices (cGMP) facility. On the day of islet transplantation, an average dose of 20.0 ± 2.6 ×106 MSCs was infused with islets via the portal vein. Adverse events and glycemic control at baseline, 6, and 12 months after transplantation were compared with data from 101 historical control patients. No adverse events directly related to the MSC infusions were observed. MSC patients required lower amounts of insulin during the peritransplantation period (p = .02 vs. controls) and had lower 12-month fasting blood glucose levels (p = .02 vs. controls), smaller C-peptide declines over 6 months (p = .01 vs. controls), and better quality of life compared with controls. In conclusion, our pilot study demonstrates that autologous MSC and islet cotransplantation may be a safe and potential strategy to improve islet engraftment after transplantation. (Clinicaltrials.gov registration number: NCT02384018). Stem Cells Translational Medicine 2018;7:11-19.

Results of Experimental Ligation of the Main Vein with the Use of Cell Technologies

Autologous multipotent mesenchymal stromal cells (MMSC) of bone marrow origin with transfected GFP gene and additionally stained cell membranes were injected to rats through the skin in the projection of ligated femoral vein. The results were evaluated by fluorescent microscopy. No signs of MMSC incorporation into the wall of ligated vessel or reorganized collaterals were detected. Angiogenesis processes involving MMSC were detected in experimental rats within just 4 days and progressed until week 2 postinjection, mainly in granulations at the site of surgical intervention and the cicatrix forming there. Injected MMSC completely formed all tunics of the new vessels and incorporated in the vessels forming from the recipient cells. MMSC and the objects created from them were gradually eliminated with participation of macrophages and replaced by structures formed from the recipient cells.

Possibility of Aggravation of Tissue Sclerosis after Injection of Multipotent Mesenchymal Stromal Cells Near the Forming Cicatrix in the Experiment

The peculiarities of tissue sclerosis after injection of autologous bone marrow multipotent mesenchymal stromal cells transfected with GFP gene and stained with Vybrant CM-Dil cell membrane dye were studied by light microscopy with luminescence. The surgical intervention consisting in ligation of the great vein was followed by tissue sclerotic transformation caused by direct damage and chronic inflammation caused by the presence of slowly resorbed ligature. Injection of stromal cells after this intervention led to formation of more extensive scar. This can attest to the possibility of stromal cells differentiation into connective tissue cells, fibroblasts, and stimulation of proliferation and collagen synthesis by host fibroblasts. A decrease in the volume of dense fibrous connective tissue due to scar reorganization at latter terms cannot not excluded.

Initial Stages of Angiogenesis after Acute Experimental Local Venous Outflow Disturbances and Application of Cell Technologies

The initial stages of angiogenesis in rats after transcutaneous injection of autologous bone marrow multipotent mesenchymal stromal cells transfected with GFP gene and stained cell membranes in the projection of ligated femoral vein were studied by fluorescent light and confocal laser microscopy. Large clusters of brightly fluorescing elongated fibroblast-like cells were seen in the paravasal tissue and in the postoperative scar and signs of angiogenesis were noted as soon as in 4 days. The injected cells not only formed new vessels, but also integrated into vessels formed by host cells. Some injected cells were phagocytizied by macrophages and the latter started to fluoresce due to the presence of the membrane dye. These macrophages within the specified period appeared in the regional inguinal lymph nodes where they formed clusters in the lymphoid parenchyma of the cortical substance.