Chiara Botti

A Phase II Trial of Autologous Transplantation of Bone Marrow Stem Cells for Critical Limb Ischemia: Results of the Naples and Pietra Ligure Evaluation of Stem Cells Study

Critical limb ischemia (CLI) is a vascular disease affecting lower limbs, which is going to become a demanding challenge because of the aging of the population. Despite advances in endovascular therapies, CLI is associated with high morbidity and mortality. Patients without direct revascularization options have the worst outcomes. To date, 25%–40% of CLI patients are not candidates for surgical or endovascular approaches, ultimately facing the possibility of a major amputation. This study aimed to assess the safety and efficacy of autologous bone marrow (BM) transplantation performed in “no‐option” patients, in terms of restoring blood perfusion by collateral flow and limb salvage. A multicenter, prospective, not‐controlled phase II study for no‐option CLI patients was performed. Patients were subjected to intra‐arterial infusion of autologous bone marrow and followed for 12 months after the treatment. Variation of blood perfusion parameters, evaluated by laser Doppler flowmetry or transcutaneous oximetry, was set as the primary endpoint at 12 months after treatment and amputation‐free survival as the secondary endpoint. Sixty patients were enrolled and treated with BM transplantation, showing improvement in objective and subjective measures of perfusion. Furthermore, survival analysis demonstrated improved amputation‐free survival rates (75.2%) at 12 months after the treatment. This study provides further evidence that autologous bone marrow transplantation is well tolerated by CLI patients without adverse effects, demonstrating trends toward improvement in perfusion and reduced amputation rate, confirming the feasibility and safety of the procedure.

Cooperation between Myc and YY1 provides novel silencing transcriptional targets of alpha3beta1-integrin in tumour cells

We show that human osteosarcoma cells (Saos-2) have downregulation of α3β1-integrin compared to normal bone cells; this was further described in human osteosarcomas and in a primary murine sarcoma. The α3 gene was silenced in Saos-2 cells causing a low expression of α3β1-integrin and reduction in collagen attachment with increasing migratory capacity. Chromatin immunoprecipitation assay performed on α3 promoter established that Myc and Yin Yang protein (YY1) cooperate in tandem to downregulate the α3 gene. This silencing mechanism involves the binding of Myc and YY1 to DNA and formation of complexes among Myc/Max, YY1, CREB-binding protein and deacetylation activity. The promoter containing deletions of E-boxes or YY1 cassettes failed to downregulate the transcription of a reporter gene as well as the inhibition of deacetylation activity. Overexpression of both Myc and YY1 was necessary to determine the α3-integrin promoter downregulation in normal osteoblasts. This downregulation of α3β1-integrin can contribute to the acquisition of a more aggressive phenotype. YY1 regulated negatively the Myc activity through a direct interaction with the Myc/Max and deacetylase complexes. This represents a novel silencing mechanism with broad implications in the transcription machinery of tumours.

Beneficial effects of VEGF secreted from stromal cells in supporting endothelial cell functions: therapeutic implications for critical limb ischemia.

Critical limb ischemia (CLI) is the end stage of peripheral vascular disease (PVD). One third of CLI patients progresses to leg amputation with high associated morbidity and mortality. In no-option patients with end-stage critical limb ischemia, bone marrow cell transplantation has shown promising results, improving leg perfusion to the level of reducing major amputations and allowing limb salvage. We recently reported the successful application of an innovative protocol based on repeated autologous bone marrow cell transplantation, which resulted in an effective and feasible strategy for achieving long-term revascularization in patients with severe CLI. In an effort to understand the clinical benefit provided by stem cells therapy in patients with CLI, we characterized the marrow-derived stromal cells of CLI patients and we provided a correlation between the in vitro features of these cells and the clinical follow up at 12 months. We showed that cells derived from CLI patients had a reduced capacity to proliferate, adhere, and migrate, but that they stimulated proliferation and migration of endothelial cells through the release of VEGF-A, supporting the idea that the paracrine mechanisms underpinned the biological effects of long-term angiogenesis in CLI patients.

Autologous bone marrow cell therapy for peripheral arterial disease

Inadequate blood supply to tissues caused by obstruction of arterioles and/or capillaries results in ischemic injuries – these injuries can range from mild (eg, leg ischemia) to severe conditions (eg, myocardial infarction, stroke). Surgical and/or endovascular procedures provide cutting-edge treatment for patients with vascular disorders; however, a high percentage of patients are currently not treatable, owing to high operative risk or unfavorable vascular involvement. Therapeutic angiogenesis has recently emerged as a promising new therapy, promoting the formation of new blood vessels by the introduction of bone marrow–derived stem and progenitor cells. These cells participate in the development of new blood vessels, the enlargement of existing blood vessels, and sprouting new capillaries from existing blood vessels, providing evidence of the therapeutic utility of these cells in ischemic tissues. In this review, the authors describe peripheral arterial disease, an ischemic condition affecting the lower extremities, summarizing different aspects of vascular regeneration and discussing which and how stem cells restore the blood flow. The authors also present an overview of encouraging results from early-phase clinical trials using stem cells to treat peripheral arterial disease. The authors believe that additional research initiatives should be undertaken to better identify the nature of stem cells and that an intensive cooperation between laboratory and clinical investigators is needed to optimize the design of cell therapy trials and to maximize their scientific rigor. Only this will allow the results of these investigations to develop best clinical practices. Additionally, although a number of stem cell therapies exist, many treatments are performed outside international and national regulations and many clinical trials have been not registered on databases such as ClinicalTrials.gov or EudraCT. Therefore, more rigorous clinical trials are required to confirm the first hopeful results and to address the challenging issues.

The developmental environment and atherogenesis.

Introduction Crucial advances in our understanding of atherogenesis have been achieved during the past two decades. The historical hypothesis of pathogenesis (‘lipid accumulation’) has evolved to integrate several pathogenic mechanisms contributing to the initiation and evolution of atherogenesis. Vascular inflammation and apoptosis may play pivotal roles in its progression and onset. Endothelial dysfunction is considered to be one of the earliest events in atherogenesis. This chapter will discuss emerging concepts in the pathogenesis of, and therapeutic approaches to, atherosclerosis. Some novel risk factors, including impaired fasting glucose, triglycerides and triglyceride-rich lipoprotein remnants, lipoprotein (a), homocysteine, and high-sensitivity C-reactive protein, might contribute to an increased risk of atherosclerosis (Fruchart et al . 2004). Moreover, hypercholesterolaemia and hypertension have synergistic deleterious effects on coronary endothelial function (Rodriguez-Porcel et al . 2003). The pathogenesis of atherosclerosis has been related also to infiltration of immune cells, which are involved in systemic and local, innate as well as adaptive, immune responses (Zhou and Hansson 2004). As some inflammatory and autoimmune diseases could be treated by immunologically based therapy, it is of particular interest to consider whether such principles could also be applied to prevent or treat atherosclerosis. Atherosclerosis is ultimately responsible for myocardial infarction, peripheral arterial disease and ischaemic stroke, and is characterised by a long lag-time between onset and clinical manifestation. The prodromal stages of human atherosclerotic lesions are already formed during fetal development (Napoli et al . 1997a, 1999a, Palinski and Napoli 2002a). Intimal thickening is also observed in fetal coronary arteries (Ikari et al . 1999).

Pro-inflammatory cytokines activate hypoxia-inducible factor 3α via epigenetic changes in mesenchymal stromal/stem cells

Human mesenchymal stromal/stem cells (hMSCs) emerged as a promising therapeutic tool for ischemic disorders, due to their ability to regenerate damaged tissues, promote angiogenesis and reduce inflammation, leading to encouraging, but still limited results. The outcomes in clinical trials exploring hMSC therapy are influenced by low cell retention and survival in affected tissues, partially influenced by lesion’s microenvironment, where low oxygen conditions (i.e. hypoxia) and inflammation coexist. Hypoxia and inflammation are pathophysiological stresses, sharing common activators, such as hypoxia-inducible factors (HIFs) and NF-κB. HIF1α and HIF2α respond essentially to hypoxia, activating pathways involved in tissue repair. Little is known about the regulation of HIF3α. Here we investigated the role of HIF3α in vitro and in vivo. Human MSCs expressed HIF3α, differentially regulated by pro-inflammatory cytokines in an oxygen-independent manner, a novel and still uncharacterized mechanism, where NF-κB is critical for its expression. We investigated if epigenetic modifications are involved in HIF3α expression by methylation-specific PCR and histone modifications. Robust hypermethylation of histone H3 was observed across HIF3A locus driven by pro-inflammatory cytokines. Experiments in a murine model of arteriotomy highlighted the activation of Hif3α expression in infiltrated inflammatory cells, suggesting a new role for Hif3α in inflammation in vivo.