Roles of bone-marrow-derived cells and inflammatory cytokines in neointimal hyperplasia after vascular injury

Animal Models of Neointimal Hyperplasia and Restenosis: Species-Specific Differences and Implications for Translational Research

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Neointimal hyperplasia is the major factor contributing to restenosis after angioplasty procedures.

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Multiple animal models exist to study basic and translational aspects of restenosis formation.

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Animal models differ substantially, and species-specific differences have major impact on the pathophysiology of the model.

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Genetic, dietary, and mechanical interventions determine the translational potential of the animal model used and have to be considered when choosing the model.

The process of restenosis is based on the interplay of various mechanical and biological processes triggered by angioplasty-induced vascular trauma. Early arterial recoil, negative vascular remodeling, and neointimal formation therefore limit the long-term patency of interventional recanalization procedures. The most serious of these processes is neointimal hyperplasia, which can be traced back to 4 main mechanisms: endothelial damage and activation; monocyte accumulation in the subintimal space; fibroblast migration; and the transformation of vascular smooth muscle cells. A wide variety of animal models exists to investigate the underlying pathophysiology. Although mouse models, with their ease of genetic manipulation, enable cell- and molecular-focused fundamental research, and rats provide the opportunity to use stent and balloon models with high throughput, both rodents lack a lipid metabolism comparable to humans. Rabbits instead build a bridge to close the gap between basic and clinical research due to their human-like lipid metabolism, as well as their size being accessible for clinical angioplasty procedures. Every different combination of animal, dietary, and injury model has various advantages and disadvantages, and the decision for a proper model requires awareness of species-specific biological properties reaching from vessel morphology to distinct cellular and molecular features.

Bone Marrow-Derived IL-1Ra Increases TNF Levels Poststroke

Tumor necrosis factor (TNF) and interleukin-1 receptor antagonist (IL-1Ra) are key players in stroke, a disease in which cell-based therapies have shown great potential. Having shown an infarct-reducing effect of bone marrow (BM) cells, especially cells with high IL-1Ra expression, we here investigated the effect of BM cells on TNF and other stroke-related mediators in mice after transient middle cerebral artery occlusion (tMCAo) and in vitro using adult microglial cultures. We analyzed stroke-related genes and inflammatory mediators using qPCR stroke Tier panels, electrochemiluminescence, or enzyme-linked immunosorbent assays. We found a significant correlation and cellular colocalization between microglial-derived TNF and IL-1Ra, though IL-1Ra production was TNF independent. BM treatment significantly increased TNF, interleukin (IL)-10, and IL-4 levels, while C-X-C motif ligand 1 (CXCL1), IL-12p70, and Toll-like receptor 2 (TLR2) decreased, suggesting that BM treatment favors an anti-inflammatory environment. Hierarchical clustering identified Tnf and IL-1rn within the same gene cluster, and subsequent STRING analysis identified TLR2 as a shared receptor. Although IL-1Ra producing BM cells specifically modulated TNF levels, this was TLR2 independent. These results demonstrate BM cells as modulators of poststroke inflammation with beneficial effects on poststroke outcomes and place TNF and IL-1Ra as key players of the defense response after tMCAo.

Comparative Proteomic Analysis of the Mesenchymal Stem Cells Secretome from Adipose, Bone Marrow, Placenta and Wharton's Jelly

Mesenchymal stem cells (MSCs) have the potential to be a viable therapy against various diseases due to their paracrine effects, such as secretion of immunomodulatory, trophic and protective factors. These cells are known to be distributed within various organs and tissues. Although they possess the same characteristics, MSCs from different sources are believed to have different secretion potentials and patterns, which may influence their therapeutic effects in disease environments. We characterized the protein secretome of adipose (AD), bone marrow (BM), placenta (PL), and Wharton’s jelly (WJ)-derived human MSCs by using conditioned media and analyzing the secretome by mass spectrometry and follow-up bioinformatics. Each MSC secretome profile had distinct characteristics depending on the source. However, the functional analyses of the secretome from different sources showed that they share similar characteristics, such as cell migration and negative regulation of programmed cell death, even though differences in the composition of the secretome exist. This study shows that the secretome of fetal-derived MSCs, such as PL and WJ, had a more diverse composition than that of AD and BM-derived MSCs, and it was assumed that their therapeutic potential was greater because of these properties.

Therapeutic promises of ginkgolide A: A literature-based review

Ginkgolide A is a highly active platelet activating factor antagonist cage molecule which was isolated from the leaves of the Ginkgo biloba L. It is known for its inflammatory and immunological potentials. This review aims to sketch a current scenario on its therapeutic activities on the basis of scientific reports in the databases. A total 30 articles included in this review suggests that ginkgolide A has many important biological activities, including anti-inflammatory, anticancer, anxiolytic-like, anti-atherosclerosis and anti-atherombosis, neuro- and hepatoprotective effects. There is a lack of its toxicological (e.g. toxicity, cytotoxicity, genotoxicity and mutagenitcity) profile. In conclusion, ginkgolide A may be one of the potential therapeutic lead compounds, especially for the treatment of cardiovascular, hepatological, and neurological diseases and disorders. More studies are necessary on this hopeful therapeutic agent.

Effectiveness of umbilical cord mesenchymal stem cells in patients with critical limb ischemia

INTRODUCTION AND OBJECTIVE

Transplantation of umbilical cord mesenchymal stem cells (UC-MSCs) has been shown to be effective in treating critical limb ischemia (CLI). However, the mechanism of MSCs-mediated improvements, especially on the immune-inflammatory aspects of this disease, is still unknown. In this study, we investigated the changes in T-lymphocyte subpopulations and inflammatory mediators (such as IL-6, IL-10 and TNF-α) in PBMCs from CLI patients after UC-MSCs treatment and correlation between inflammatory mediators and EPCs.

PATIENTS AND METHODS

8 patients received UC-MSCs transplantation. Before the treatment, at 24h and 1 month thereafter, peripheral blood samples were collected from 8 patients and 8 healthy volunteers. Patients were evaluated for changes in IL-6, IL-10, TNF-α and levels of circulating EPCs.

RESULTS

TNF-α and IL-6 serum levels increased at 24h (p=0.017, p=0.099) after treatment and then decreased at 1 month (p=0.031, p=0.072) compared with those before treatment. The percentages of CD3+T, CD3+CD4+T-lymphocytes and NK cells decreased significantly after UC-MSCs treatment (p=0.002, p=0.012 and p=0.029, respectively). TNF-α (r=-0.602, p=0.038) was shown to be inversely correlated with the number of circulating EPCs.

CONCLUSIONS

This study demonstrates that UC-MSCs have anti-inflammatory and immunomodulation properties in CLI and suggests that UC-MSCs promote healing of non-healing wounds.

Blood level of CD45+ platelets and development of restenosis after drug-eluting stent implantation in patients with stable coronary artery disease

OBJECTIVE

The aim of this study was to assess CD45-positive platelets (CD45+ platelets) involvement in restenosis development after drug-eluting stent (DES) implantation in patients with stable coronary artery disease (CAD).

METHODS

The study comprised 126 male and female patients with stable angina pectoris, who underwent elective coronary stenting with DES and follow-up angiography within 6-12 months. The patients were assigned to the group with restenosis (n = 53) or group without restenosis (n = 73) according to the follow-up angiograms. In both groups we compared the level in blood of CD45+ platelets, the clinical, laboratory and angiographic variables, which may affect the development of restenosis. We have also constructed a logit regression model for prognosis of restenosis occurrence after DES implantation.

RESULTS

The blood count of CD45+ platelets was higher in patients with restenosis than in patients without: 0.82 % (0.58; 1.12) vs. 0.34 % (0.20; 0.68), p < 0.001, data are expressed as median (lower quartile; upper quartile). By binary comparisons of more than 35 different clinical, laboratory and angiographic variables we identified 8 significant risk factors for the development of stent restenosis after DES. In order to define the risk of the development of restenosis, we have built a logit regression model. The resulting logit regression equation included the level of CD45+ platelets, the neutrophil to lymphocyte ratio (NLR), small diameter arteries stenting and the number of simultaneously implanted stents in one patient. Receiver operating characteristic (ROC) curve analysis has demonstrated the high prognostic value of the resulting logit regression equation with an area under the curve (AUC) of 0.91 % (p < 0.001).

CONCLUSIONS

The acquired data indicate the presence of a close relationship between circulating CD45+ platelets and restenosis development after DES implantation in patients with stable CAD.

Effect of TGF-β1 on the Migration and Recruitment of Mesenchymal Stem Cells after Vascular Balloon Injury: Involvement of Matrix Metalloproteinase-14

Restenosis or occlusion after vascular procedures is ascribed to intimal hyperplasia. Transforming growth factor (TGF)-β1 is involved in recruitment of mesenchymal stem cells (MSCs) following arterial injury, and its release from latent TGF-binding protein by matrix metalloproteinase (MMP)-14-induced proteolysis contributes to neointima formation. However, the relationship between MMP-14 and TGF-β1 activation in restenosis is unknown. This study investigated the relationship using a rat model of balloon-induced injury. Rats were assigned to vehicle-, SB431542 (SB)-, or recombinant human (rh)TGF-β1-treated groups and examined at various time points after balloon-induced injury for expression of TGF-β1/Smad signalling pathway components, MMP-14 and MSCs markers including Nestin, CD29, and Sca1⁺CD29⁺CD11b/c⁻CD45⁻. Intimal hyperplasia was reduced in SB- and rhTGF-β1-treated rats. The expression of TGF-β1, TGF-β1RI, and Smad2/3 was decreased, but the levels of phosphorylated Smad2/3 were higher in SB-treated rats than vehicle-treated after 7 days to 14 days. rhTGF-β1 administration decreased the expression of TGF-β1/Smad pathway proteins, except for TGF-β1RI. Nestin and CD29 expression and the number of Sca1⁺CD29⁺CD11b⁻CD45⁻ cells were reduced, whereas MMP-14 expression was increased after SB431542 and rhTGF-β1 administration. These results suggest that TGF-β1/Smad signalling and MMP-14 act to recruit MSCs which differentiate to vascular smooth muscle cells and mesenchymal-like cells that participate in arterial repair/remodelling.

Autologous bone marrow mesenchymal stem cells associated with tantalum rod implantation and vascularized iliac grafting for the treatment of end-stage osteonecrosis of the femoral head

Tantalum rod implantation with vascularized iliac grafting has been reported to be an effective method for the treatment of young patients with osteonecrosis of the femoral head (ONFH) to avert the need for total hip arthroplasty (THA). However, there have been unsatisfactory success rates for end-stage ONFH. The authors describe a modified technique using bone marrow mesenchymal stem cells (BMMSCs) associated with porous tantalum rod implantation combined with vascularized iliac grafting for the treatment of end-stage ONFH. A total of 24 patients (31 hips) with end-stage ONFH were treated with surgery; ARCO IIIc stage was observed in 19 hips and ARCO IV stage was observed in 12 hips. All patients were followed for a mean time of 64.35 ± 13.03 months (range 26–78). Operations on only five hips were converted to THA. The joint-preserving success rate of the entire group was 89.47% for ARCO stage IIIc and 75% for ARCO stage IV. The mean Harris hip score of the 31 hips improved significantly from 38.74 ± 5.88 points (range 22–50) to 77.23 ± 14.75 points (range 33–95). This intervention was safe and effective in delaying or avoiding total hip replacement for end-stage ONFH.

Mesenchymal Stem Cell Paracrine Factors in Vascular Repair and Regeneration

Mesenchymal stem cell therapy show great optimism in the treatment of several diseases. MSCs are attractive candidates for cell therapy because of easy isolation, high expansion potential giving unlimited pool of transplantable cells, low immunogenicity, amenability to ex vivo genetic modification, and multipotency. The stem cells orchestrate the repair process by various mechanisms such as transdifferentiation, cell fusion, microvesicles or exosomes and most importantly by secreting paracrine factors. The MSCs release several angiogenic, mitogenic, anti-apoptotic, anti-inflammatory and anti-oxidative factors that play fundamental role in regulating tissue repair in various vascular and cardiac diseases. The therapeutic release of these factors by the cells can be enhanced by several strategies like genetic modification, physiological and pharmacological preconditioning, improved cell culture and selection methods, and biomaterial based approaches. The current review describes the impact of paracrine factors released by MSCs on vascular repair and regeneration in myocardial infarction, restenosis and peripheral artery disease, and the various strategies adopted to enhance the release of these paracrine factors to enhance organ function.

TGF-β1/Smad signaling, MMP-14, and MSC markers in arterial injury: discovery of the molecular basis of restenosis

Transforming growth factor (TGF)-β1 has been suggested to be involved in the recruitment of mesenchymal stem cells (MSCs) following arterial injury, but the role of downstream signaling and the contribution of the recruited MSCs are still unknown. The release of latent TGF-β1 from latent TGF-binding protein (LTBP) by matrix metallopeptidase-14 (MMP-14) proteolysis was demonstrated, which contributed to neointima formation, but the relationship between MMP-14 and activated TGF-β1 in the process of restenosis has yet to be explored. In this study, we observed the change in expression and distribution of TGF-β1/Smad signaling pathway proteins, MMP-14, and MSC markers in the process of neointima formation using a rat model for balloon-induced carotid artery injury. We found that the increase in downstream Smad signaling was consistent with the elevation of TGF-β1 levels and MSCs accumulated at the lumen side of neointima. Furthermore, the activation of MMP-14 in the injured artery was preceded by the increase in TGF-β1 levels. Herein, we conclude that MMP-14 induces an elevation in the levels of TGF-β1/Smad signaling proteins in injured arteries, and that MSCs are recruited by TGF-β1/Smad signaling and MMP-14, possibly differentiating into vascular smooth muscle cell (VSMC)-like cells and VSMC via modulation of TGF-β1/Smads signaling and MMP-14.