Global remodeling of the vascular stem cell niche in bone marrow of diabetic patients: implication of the microRNA-155/FOXO3a signaling pathway

Clinical outcomes of patients with acute myeloid leukemia and cardiovascular disease

Incidence of both acute myeloid leukemia (AML) and cardiovascular disease (CVD) increases with age. We evaluated whether pre-existing CVD impacts clinical outcomes in AML. We retrospectively evaluated 291 consecutive adult AML patients treated at our institution, 2014-2020. Pretreatment comorbidities were identified by chart review. Outcomes included complete remission (CR) and CR with incomplete count recovery (CRi) rates, disease-free survival (DFS), overall survival (OS) and incidence of cardiovascular adverse events. CVD was present in 34% of patients at AML diagnosis. CVD patients had worse performance status (p=0.03) and more commonly had secondary AML (p=0.03) and received hypomethylating (HMA) agent-based therapy (72% vs 38%, p< 0.001). CVD (0.45 vs 0.71, p<0.001) and diabetes mellitus (HR= 0.24, 95% CI: 0.08 - 0.8, p= 0.01) were associated with lower probability of achieving CR/CRi. Accounting for age, performance status (PS), complex karyotype, secondary disease and treatment, CVD patients had shorter OS (HR=1.5, 95% CI: 1.1-2.2, p=0.002), with 1- and 3-year OS 44% vs 67% and 25% vs 40%, respectively, but there was no difference in cumulative incidence of relapse between patients with vs without CVD. Thus, CVD is an independent risk factor for lower response rate and shorter survival in AML patients.

Diabetes and the Microvasculature of the Bone and Marrow

PURPOSE OF REVIEW

The purpose of this review is to highlight the evidence of microvascular dysfunction in bone and marrow and its relation to poor skeletal outcomes in diabetes mellitus.

RECENT FINDINGS

Diabetes mellitus is characterized by chronic hyperglycemia, which may lead to microangiopathy and macroangiopathy. Micro- and macroangiopathy have been diagnosed in Type 1 and Type 2 diabetes, coinciding with osteopenia, osteoporosis, enhanced fracture risk and delayed fracture healing. Microangiopathy has been reported in the skeleton, correlating with reduced blood flow and perfusion, vasomotor dysfunction, microvascular rarefaction, reduced angiogenic capabilities, and augmented vascular permeability. Microangiopathy within the skeleton may be detrimental to bone and manifest as, among other clinical abnormalities, reduced mass, enhanced fracture risk, and delayed fracture healing. More investigations are required to elucidate the various mechanisms by which diabetic microvascular dysfunction impacts the skeleton.

Endothelial heterogeneity and their relevance in cardiac development and coronary artery disease

Micro- and macrovascular endothelial cells (ECs) are characterized by structural and functional heterogeneity, which is also reflected in their secretory activity. The root of this heterogeneity and related regulatory mechanisms are still poorly understood. During embryogenesis, microvascular ECs participate in organogenesis prior to the development of the fetal circulation, suggesting that ECs are capable of releasing paracrine trophogens, termed angiocrine factors (AFs). These are angiocrine growth factors, adhesion molecules, and chemokines, which are intended to promote morphogenesis and repair of the adjacent parenchyma/stroma where the vessels are located. There is a tissue and organ-specificity of AFs that traces the heterogeneity of ECs. This AF heterogeneity also traces how ECs respond to pathological conditions or exposure to cardiovascular risk factors. The study of the mechanisms that regulate endothelial and paracrine heterogeneity and that contribute to endotheliopathy represents a broad and as yet understudied area of research. A better understanding of the cellular and molecular mechanisms that regulate this heterogeneity, leading to endotheliopathy is an exciting challenge. In this brief review we will discuss experimental advances in the heterogeneity of ECs and their AF, with a focus on their involvement in the pathogenesis of coronary artery disease.

Diabetic microvascular disease in non-classical beds: the hidden impact beyond the retina, the kidney, and the peripheral nerves

Diabetes microangiopathy, a hallmark complication of diabetes, is characterised by structural and functional abnormalities within the intricate network of microvessels beyond well-known and documented target organs, i.e., the retina, kidney, and peripheral nerves. Indeed, an intact microvascular bed is crucial for preserving each organ's specific functions and achieving physiological balance to meet their respective metabolic demands. Therefore, diabetes-related microvascular dysfunction leads to widespread multiorgan consequences in still-overlooked non-traditional target organs such as the brain, the lung, the bone tissue, the skin, the arterial wall, the heart, or the musculoskeletal system. All these organs are vulnerable to the physiopathological mechanisms that cause microvascular damage in diabetes (i.e., hyperglycaemia-induced oxidative stress, inflammation, and endothelial dysfunction) and collectively contribute to abnormalities in the microvessels' structure and function, compromising blood flow and tissue perfusion. However, the microcirculatory networks differ between organs due to variations in haemodynamic, vascular architecture, and affected cells, resulting in a spectrum of clinical presentations. The aim of this review is to focus on the multifaceted nature of microvascular impairment in diabetes through available evidence of specific consequences in often overlooked organs. A better understanding of diabetes microangiopathy in non-target organs provides a broader perspective on the systemic nature of the disease, underscoring the importance of recognising the comprehensive range of complications beyond the classic target sites.

Pathological roles of bone marrow adipocyte-derived monocyte chemotactic protein-1 in type 2 diabetic mice

Type 2 diabetes mellitus (T2DM) has become a prevalent public health concern, with beta-cell dysfunction involved in its pathogenesis. Bone marrow adipose tissue (BMAT) increases in both the quantity and area in individuals with T2DM along with heightened monocyte chemotactic protein-1 (MCP-1) secretion. This study aims to investigate the influence and underlying mechanisms of MCP-1 originating from bone marrow adipocytes (BMAs) on systemic glucose homeostasis in T2DM. Initially, a substantial decrease in the proliferation and glucose-stimulated insulin secretion (GSIS) of islet cells was observed. Moreover, a comparative analysis between the control (Ctrl) group and db/db mice revealed significant alterations in the gene expression profiles of whole bone marrow cells, with a noteworthy upregulation of Mcp-1. And the primary enriched pathways included chemokine signaling pathway and AGE-RAGE signaling pathway in diabetic complications. In addition, the level of MCP-1 was distinctly elevated in BMA-derived conditional media (CM), leading to a substantial inhibition of proliferation, GSIS and the protein level of phosphorylated Akt (p-Akt) in Min6 cells. After blocking MCP-1 pathway, we observed a restoration of p-Akt and the proliferation of islet cells, resulting in a marked improvement in disordered glucose homeostasis. In summary, there is an accumulation of BMAs in T2DM, which secrete excessive MCP-1, exacerbating the abnormal accumulation of BMAs in the bone marrow cavity through paracrine signaling. The upregulated MCP-1, in turn, worsens glucose metabolism disorder by inhibiting the proliferation and insulin secretion of islet cells through an endocrine pathway. Inhibiting MCP-1 signaling can partially restore the proliferation and insulin secretion of islet cells, ultimately ameliorating glucose metabolism disorder. It's worth noting that to delve deeper into the impact of MCP-1 derived from BMAs on islet cells and its potential mechanisms, it is imperative to develop genetically engineered mice with conditional Mcp-1 knockout from BMAs.

Endothelial progenitor cells as biomarkers of diabetes-related cardiovascular complications

Diabetes mellitus (DM) constitutes a chronic metabolic disease characterized by elevated levels of blood glucose which can also lead to the so-called diabetic vascular complications (DVCs), responsible for most of the morbidity, hospitalizations and death registered in these patients. Currently, different approaches to prevent or reduce DM and its DVCs have focused on reducing blood sugar levels, cholesterol management or even changes in lifestyle habits. However, even the strictest glycaemic control strategies are not always sufficient to prevent the development of DVCs, which reflects the need to identify reliable biomarkers capable of predicting further vascular complications in diabetic patients. Endothelial progenitor cells (EPCs), widely known for their potential applications in cell therapy due to their regenerative properties, may be used as differential markers in DVCs, considering that the number and functionality of these cells are affected under the pathological environments related to DM. Besides, drugs commonly used with DM patients may influence the level or behaviour of EPCs as a pleiotropic effect that could finally be decisive in the prognosis of the disease. In the current review, we have analysed the relationship between diabetes and DVCs, focusing on the potential use of EPCs as biomarkers of diabetes progression towards the development of major vascular complications. Moreover, the effects of different drugs on the number and function of EPCs have been also addressed.

Bone marrow vasculature advanced in vitro models for cancer and cardiovascular research

Cardiometabolic diseases and cancer are among the most common diseases worldwide and are a serious concern to the healthcare system. These conditions, apparently distant, share common molecular and cellular determinants, that can represent targets for preventive and therapeutic approaches. The bone marrow plays an important role in this context as it is the main source of cells involved in cardiovascular regeneration, and one of the main sites of liquid and solid tumor metastasis, both characterized by the cellular trafficking across the bone marrow vasculature. The bone marrow vasculature has been widely studied in animal models, however, it is clear the need for human-specific in vitro models, that resemble the bone vasculature lined by endothelial cells to study the molecular mechanisms governing cell trafficking. In this review, we summarized the current knowledge on in vitro models of bone marrow vasculature developed for cardiovascular and cancer research.

Vascular deficits contributing to skeletal fragility in type 1 diabetes

Over 1 million Americans are currently living with T1D and improvements in diabetes management have increased the number of adults with T1D living into later decades of life. This growing population of older adults with diabetes is more susceptible to aging comorbidities, including both vascular disease and osteoporosis. Indeed, adults with T1D have a 2- to 3- fold higher risk of any fracture and up to 7-fold higher risk of hip fracture compared to those without diabetes. Recently, diabetes-related vascular deficits have emerged as potential risks factors for impaired bone blood flow and poor bone health and it has been hypothesized that there is a direct pathophysiologic link between vascular disease and skeletal outcomes in T1D. Indeed, microvascular disease (MVD), one of the most serious consequences of diabetes, has been linked to worse bone microarchitecture in older adults with T1D compared to their counterparts without MVD. The association between the presence of microvascular complications and compromised bone microarchitecture indicates the potential direct deleterious effect of vascular compromise, leading to abnormal skeletal blood flow, altered bone remodeling, and deficits in bone structure. In addition, vascular diabetic complications are characterized by increased vascular calcification, decreased arterial distensibility, and vascular remodeling with increased arterial stiffness and thickness of the vessel walls. These extensive alterations in vascular structure lead to impaired myogenic control and reduced nitric-oxide mediated vasodilation, compromising regulation of blood flow across almost all vascular beds and significantly restricting skeletal muscle blood flow seen in those with T1D. Vascular deficits in T1D may very well extend to bone, compromising skeletal blood flow control, and resulting in reduced blood flow to bone, thus negatively impacting bone health. Indeed, several animal and ex vivo human studies report that diabetes induces microvascular damage within bone are strongly correlated with diabetes disease severity and duration. In this review article, we will discuss the contribution of diabetes-induced vascular deficits to bone density, bone microarchitecture, and bone blood flow regulation, and review the potential contribution of vascular disease to skeletal fragility in T1D.

Cardiovascular complications of diabetes: role of non-coding RNAs in the crosstalk between immune and cardiovascular systems

Diabetes mellitus, a group of metabolic disorders characterized by high levels of blood glucose caused by insulin defect or impairment, is a major risk factor for cardiovascular diseases and related mortality. Patients with diabetes experience a state of chronic or intermittent hyperglycemia resulting in damage to the vasculature, leading to micro- and macro-vascular diseases. These conditions are associated with low-grade chronic inflammation and accelerated atherosclerosis. Several classes of leukocytes have been implicated in diabetic cardiovascular impairment. Although the molecular pathways through which diabetes elicits an inflammatory response have attracted significant attention, how they contribute to altering cardiovascular homeostasis is still incompletely understood. In this respect, non-coding RNAs (ncRNAs) are a still largely under-investigated class of transcripts that may play a fundamental role. This review article gathers the current knowledge on the function of ncRNAs in the crosstalk between immune and cardiovascular cells in the context of diabetic complications, highlighting the influence of biological sex in such mechanisms and exploring the potential role of ncRNAs as biomarkers and targets for treatments. The discussion closes by offering an overview of the ncRNAs involved in the increased cardiovascular risk suffered by patients with diabetes facing Sars-CoV-2 infection.

Circulating progenitor cells and outcomes in patients with coronary artery disease

BACKGROUND

Low quantities of circulating progenitor cells (CPCs), specifically CD34+ populations, reflect impairment of intrinsic regenerative capacity. This study investigates the relationship between subsets of CPCs and adverse outcomes.

METHODS

1366 individuals undergoing angiography for evaluation of coronary artery disease (CAD) were enrolled into the Emory Cardiovascular Biobank. Flow cytometry identified CPCs as CD45med blood mononuclear cells expressing the CD34 epitope, with further enumeration of hematopoietic CPCs as CD133+/CXCR4+ cells and endothelial CPCs as vascular endothelial growth factor receptor-2 (VEGFR2+) cells. Adjusted Cox or Fine and Gray's sub-distribution hazard regression models analyzed the relationship between CPCs and 1) all-cause death and 2) a composite of cardiovascular death and non-fatal myocardial infarction (MI).

RESULTS

Over a median 3.1-year follow-up period (IQR 1.3-4.9), there were 221 (16.6%) all-cause deaths and 172 (12.9%) cardiovascular deaths/MIs. Hematopoietic CPCs were highly correlated, and the CD34+/CXCR4+ subset was the best independent predictor. Lower counts (≤median) of CD34+/CXCR4+ and CD34+/VEGFR2+ cells independently predicted all-cause mortality (HR 1.46 [95% CI 1.06-2.01], p = 0.02 and 1.59 [95% CI 1.15-2.18], p = 0.004) and cardiovascular death/MI (HR 1.50 [95% CI 1.04-2.17], p = 0.03 and 1.47 [95% CI 1.01-2.03], p = 0.04). A combination of low CD34+/CXCR4+ and CD34+/VEGFR2+ CPCs predicted all-cause death (HR 2.1, 95% CI 1.4-3.0; p = 0.0002) and cardiovascular death/MI (HR 2.0, 95% CI 1.3-3.2; p = 0.002) compared to those with both lineages above the cut-offs.

CONCLUSIONS

Lower levels of hematopoietic and endothelial CPCs indicate diminished endogenous regenerative capacity and independently correlate with greater mortality and cardiovascular risk in patients with CAD.

A cohort study of circulating progenitor cells after ST-segment elevation and non-ST segment elevation myocardial infarction in non-diabetic and diabetic patients

Background

Myocardial infarction induces elevation of progenitor cells in the circulation, a reparative response inhibited by type-2 diabetes.

Objectives

Determine if myocardial infarct severity and diabetes interactively influence the migratory activity of CD34+/CXCR4+ progenitor cells and if the migratory test predicts cardiac outcomes.

Materials and methods

A longitudinal study was conducted on patients with or without diabetes with a STEMI or NSTEMI. CD34+/CXCR4+ cells were measured in the peripheral blood using flow cytometry, and migratory activity was tested in vitro on cells isolated from samples collected on days 0 and 4 post-infarct. Cardiac function was assessed at three months using cardiac MRI.

Results

Of 1,149 patients screened, 71 (6.3%) were eligible and consented. Fifty had STEMI (16 with diabetes) and 21 NSTEMI (8 with diabetes). The proportion of CD34+/CXCR4+ cells within blood mononuclear cells was 1.96 times higher after STEMI compared with NSTEMI (GMR = 1.96, 95% CI 0.87, 4.37) and 1.55 times higher in patients with diabetes compared to patients without diabetes (GMR = 1.55, 95% CI 0.77, 3.13). In the latter, STEMI was associated with a 2.42-times higher proportion of migrated CD34 + /CXCR4 + cells compared with NSTEMI (GMR = 2.42, 95% CI 0.66, 8.81). In patients with diabetes, the association was the opposite, with a 55% reduction in the proportion of migrated CD34+/CXCR4+ cells. No statistically significant associations were observed between the frequency in peripheral blood or in vitro migration capacity of CD34+/CXCR4+ cells and MRI outcomes.

Conclusion

We document the interaction between infarct and diabetes on the migratory activity of CD34+/CXCR4+ cells. The test did not predict functional outcomes in the studied cohort.

Dysregulated transforming growth factor-beta mediates early bone marrow dysfunction in diabetes

Diabetes affects select organs such as the eyes, kidney, heart, and brain. Our recent studies show that diabetes also enhances adipogenesis in the bone marrow and reduces the number of marrow-resident vascular regenerative stem cells. In the current study, we have performed a detailed spatio-temporal examination to identify the early changes that are induced by diabetes in the bone marrow. Here we show that short-term diabetes causes structural and molecular changes in the marrow, including enhanced adipogenesis in tibiae of mice, prior to stem cell depletion. This enhanced adipogenesis was associated with suppressed transforming growth factor-beta (TGFB) signaling. Using human bone marrow-derived mesenchymal progenitor cells, we show that TGFB pathway suppresses adipogenic differentiation through TGFB-activated kinase 1 (TAK1). These findings may inform the development of novel therapeutic targets for patients with diabetes to restore regenerative stem cell function.

Dysfunction of macrophages leads to diabetic bone regeneration deficiency

Insufficient bone matrix formation caused by diabetic chronic inflammation can result in bone nonunion, which is perceived as a worldwide epidemic, with a substantial socioeconomic and public health burden. Macrophages in microenvironment orchestrate the inflammation and launch the process of bone remodeling and repair, but aberrant activation of macrophages can drive drastic inflammatory responses during diabetic bone regeneration. In diabetes mellitus, the proliferation of resident macrophages in bone microenvironment is limited, while enhanced myeloid differentiation of hematopoietic stem cells (HSCs) leads to increased and constant monocyte recruitment and thus macrophages shift toward the classic pro-inflammatory phenotype, which leads to the deficiency of bone regeneration. In this review, we systematically summarized the anomalous origin of macrophages under diabetic conditions. Moreover, we evaluated the deficit of pro-regeneration macrophages in the diabetic inflammatory microenvironment. Finally, we further discussed the latest developments on strategies based on targeting macrophages to promote diabetic bone regeneration. Briefly, this review aimed to provide a basis for modulating the biological functions of macrophages to accelerate bone regeneration and rescue diabetic fracture healing in the future.

Results of a prospective observational study of autologous peripheral blood mononuclear cell therapy for no-option critical limb-threatening ischemia and severe diabetic foot ulcers

Background

Cell therapy with autologous peripheral blood mononuclear cells (PB-MNCs) may help restore limb perfusion in patients with diabetes mellitus and critical limb-threatening ischemia (CLTI) deemed not eligible for revascularization procedures and consequently at risk for major amputation (no-option). Fundamental is to establish its clinical value and to identify candidates with a greater benefit over time. Assessing the frequency of PB circulating angiogenic cells and extracellular vesicles (EVs) may help in guiding candidate selection.

Methods

We conducted a prospective, non-controlled, observational study on no-option CLTI diabetic patients that underwent intramuscular PB-MNCs therapy, which consisted of more cell treatments repeated a maximum of three times. The primary endpoint was amputation rate at 1 year following the first treatment with PB-MNCs. We evaluated ulcer healing, walking capability, and mortality during the follow-up period. We assessed angiogenic cells and EVs at baseline and after each cell treatment, according to primary outcome and tissue perfusion at the last treatment [measured as transcutaneous oxygen pressure (TcPO₂)].

Results

50 patients were consecutively enrolled and the primary endpoint was 16%. TcPO₂ increased after PB-MNCs therapy (17.2 ± 11.6 vs 39.1 ± 21.8 mmHg, p < .0001), and ulcers healed with back-to-walk were observed in 60% of the study population (88% of survivors) during follow-up (median 1.5 years). Patients with a high level of TcPO₂ (≥ 40 mmHg) after the last treatment showed a high frequency of small EVs at enrollment.

Conclusions

In no-option CLTI diabetic patients, PB-MNCs therapy led to an improvement in tissue perfusion, a high rate of healing, and back-to-walk. Coupling circulating cellular markers of angiogenesis could help in the identification of patients with a better clinical benefit over time.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01629-y.

Impaired haematopoietic stem / progenitor cell traffic and multi-organ damage in diabetes

During antenatal development, hematopoietic stem/progenitor cells (HSPCs) arise from a specialized endothelium and migrate from the extraembryonic mesoderm to the fetal liver before establishing hematopoiesis in the bone marrow (BM). It is still debated whether, in adulthood, HSPCs display such ontologic overlap with vascular cells and capacity for endothelial differentiation. Yet, adult HSPCs retain a prominent migratory activity and traffic in the bloodstream to secondary lymphoid organs and all peripheral tissues, before eventually returning to the BM. While patrolling parenchymatous organs, HSPCs locate close to the vasculature, where they establish local hematopoietic islands and contribute to tissue homeostasis by paracrine signals. Solid evidence shows that diabetes mellitus jeopardizes the traffic of HSPCs from BM to the circulation and peripheral tissues, a condition called “mobilopathy.” A reduction in the levels of circulating HSPCs is the most immediate and apparent consequence, which has been consistently observed in human diabetes, and is strongly associated with future risk for multi-organ damage, including micro- and macro-angiopathy. But the shortage of HSPCs in the blood is only the visible tip of the iceberg. Abnormal HSPC traffic results from a complex interplay among metabolism, innate immunity, and hematopoiesis. Notably, mobilopathy is mechanistically connected with diabetes-induced myelopoiesis. Impaired traffic of HSPCs and enhanced generation of pro-inflammatory cells synergize for tissue damage and impair the resolution of inflammation. We herein summarize the current evidence that diabetes affects HSPC traffic, which are the causes and consequences of such alteration, and how it contributes to the overall disease burden.

TCRP1 activated by mutant p53 promotes NSCLC proliferation via inhibiting FOXO3a

Previously, our lab explored that tongue cancer resistance-associated protein (TCRP1) plays a central role in cancer chemo-resistance and progression. Absolutely, TCRP1 was significantly increased in lung cancer. But the mechanism is far from elucidated. Here, we found that TCRP1 was increased in p53-mutant non-small-cell lung cancer (NSCLC), comparing to that in NSCLC with wild type p53. Further study showed that mutant p53 couldn't bind to the promoter of TCRP1 to inhibit its expression. While the wild type p53 did so. Next, loss-and gain-of-function assays demonstrated that TCRP1 promoted cell proliferation and tumor growth in NSCLC. Regarding the mechanism, TCRP1 encouraged AKT phosphorylation and blocked FOXO3a nuclear localization through favoring FOXO3a ubiquitination in cytoplasm, thus, promoted cell cycle progression. Conclusionly, TCRP1 was upregulated in NSCLC cells with mutant p53. TCRP1 promoted NSCLC progression via regulating cell cycle.

Phase I/IIa Feasibility Trial of Autologous Quality- and Quantity-Cultured Peripheral Blood Mononuclear Cell Therapy for Non-Healing Extremity Ulcers

Non-healing wounds are among the main causes of morbidity and mortality. We recently described a novel, serum-free ex vivo expansion system, the quantity and quality culture system (QQc), which uses peripheral blood mononuclear cells (PBMNCs) for effective and noninvasive regeneration of tissue and vasculature in murine and porcine models. In this prospective clinical study, we investigated the safety and efficacy of QQ-cultured peripheral blood mononuclear cell (MNC-QQ) therapy for chronic non-healing ischemic extremity wounds. Peripheral blood was collected from 9 patients with 10 chronic (>1 month) non-healing wounds (8 males, 1 female; 64-74 years) corresponding to ischemic extremity ulcers. PBMNCs were isolated and cultured using QQc. Within a 20-cm area surrounding the ulcer, 2 × 107 cells were injected under local anesthesia. Wound healing was monitored photometrically every 2 weeks. The primary endpoint was safety, whereas the secondary endpoint was efficacy at 12-week post-injection. All patients remained ambulant, and no deaths, other serious adverse events, or major amputations were observed for 12 weeks after cell transplantation. Six of the 10 cases showed complete wound closure with an average wound closure rate of 73.2% ± 40.1% at 12 weeks. MNC-QQ therapy increased vascular perfusion, skin perfusion pressure, and decreased pain intensity in all patients. These results indicate the feasibility and safety of MNC-QQ therapy in patients with chronic non-healing ischemic extremity wounds. As the therapy involves transplanting highly vasculogenic cells obtained from a small blood sample, it may be an effective and highly vasculogenic strategy for limb salvage.

Hematopoietic progenitor cell liabilities and alarmins S100A8/A9-related inflammaging associate with frailty and predict poor cardiovascular outcomes in older adults

Frailty affects the physical, cognitive, and social domains exposing older adults to an increased risk of cardiovascular disease and death. The mechanisms linking frailty and cardiovascular outcomes are mostly unknown. Here, we studied the association of abundance (flow cytometry) and gene expression profile (RNAseq) of stem/progenitor cells (HSPCs) and molecular markers of inflammaging (ELISA) with the cardiorespiratory phenotype and prospective adverse events of individuals classified according to levels of frailty. Two cohorts of older adults were enrolled in the study. In a cohort of pre-frail 35 individuals (average age: 75 years), a physical frailty score above the median identified subjects with initial alterations in cardiorespiratory function. RNA sequencing revealed S100A8/A9 upregulation in HSPCs from the bone marrow (>10-fold) and peripheral blood (>200-fold) of individuals with greater physical frailty. Moreover higher frailty was associated with increased alarmins S100A8/A9 and inflammatory cytokines in peripheral blood. We then studied a cohort of 104 more frail individuals (average age: 81 years) with multidomain health deficits. Reduced levels of circulating HSPCs and increased S100A8/A9 concentrations were independently associated with the frailty index. Remarkably, low HSPCs and high S100A8/A9 simultaneously predicted major adverse cardiovascular events at 1-year follow-up after adjustment for age and frailty index. In conclusion, inflammaging characterized by alarmin and pro-inflammatory cytokines in pre-frail individuals is mirrored by the pauperization of HSPCs in frail older people with comorbidities. S100A8/A9 is upregulated within HSPCs, identifying a phenotype that associates with poor cardiovascular outcomes.

Hematopoietic Progenitors and the Bone Marrow Niche Shape the Inflammatory Response and Contribute to Chronic Disease

It is now well understood that the bone marrow (BM) compartment can sense systemic inflammatory signals and adapt through increased proliferation and lineage skewing. These coordinated and dynamic alterations in responding hematopoietic stem and progenitor cells (HSPCs), as well as in cells of the bone marrow niche, are increasingly viewed as key contributors to the inflammatory response. Growth factors, cytokines, metabolites, microbial products, and other signals can cause dysregulation across the entire hematopoietic hierarchy, leading to lineage-skewing and even long-term functional adaptations in bone marrow progenitor cells. These alterations may play a central role in the chronicity of disease as well as the links between many common chronic disorders. The possible existence of a form of “memory” in bone marrow progenitor cells is thought to contribute to innate immune responses via the generation of trained immunity (also called innate immune memory). These findings highlight how hematopoietic progenitors dynamically adapt to meet the demand for innate immune cells and how this adaptive response may be beneficial or detrimental depending on the context. In this review, we will discuss the role of bone marrow progenitor cells and their microenvironment in shaping the scope and scale of the immune response in health and disease.

When a Friend Becomes Your Enemy: Natural Killer Cells in Atherosclerosis and Atherosclerosis-Associated Risk Factors

Atherosclerosis (ATS), the change in structure and function of arteries with associated lesion formation and altered blood flow, is the leading cause of cardiovascular disease, the number one killer worldwide. Beyond dyslipidemia, chronic inflammation, together with aberrant phenotype and function of cells of both the innate and adaptive immune system, are now recognized as relevant contributors to atherosclerosis onset and progression. While the role of macrophages and T cells in atherosclerosis has been addressed in several studies, Natural Killer cells (NKs) represent a poorly explored immune cell type, that deserves attention, due to NKs’ emerging contribution to vascular homeostasis. Furthermore, the possibility to re-polarize the immune system has emerged as a relevant tool to design new therapies, with some succesfull exmples in the field of cancer immunotherapy. Thus, a deeper knowledge of NK cell pathophysiology in the context of atherosclerosis and atherosclerosis-associated risk factors could help developing new preventive and treatment strategies, and decipher the complex scenario/history from “the risk factors for atherosclerosis” Here, we review the current knowledge about NK cell phenotype and activities in atherosclerosis and selected atherosclerosis risk factors, namely type-2 diabetes and obesity, and discuss the related NK-cell oriented environmental signals.

Unraveling and Targeting Myocardial Regeneration Deficit in Diabetes

Cardiomyopathy is a common complication in diabetic patients. Ventricular dysfunction without coronary atherosclerosis and hypertension is driven by hyperglycemia, hyperinsulinemia and impaired insulin signaling. Cardiomyocyte death, hypertrophy, fibrosis, and cell signaling defects underlie cardiomyopathy. Notably, detrimental effects of the diabetic milieu are not limited to cardiomyocytes and vascular cells. The diabetic heart acquires a senescent phenotype and also suffers from altered cellular homeostasis and the insufficient replacement of dying cells. Chronic inflammation, oxidative stress, and metabolic dysregulation damage the population of endogenous cardiac stem cells, which contribute to myocardial cell turnover and repair after injury. Therefore, deficient myocardial repair and the progressive senescence and dysfunction of stem cells in the diabetic heart can represent potential therapeutic targets. While our knowledge of the effects of diabetes on stem cells is growing, several strategies to preserve, activate or restore cardiac stem cell compartments await to be tested in diabetic cardiomyopathy.

The Fate Status of Stem Cells in Diabetes and its Role in the Occurrence of Diabetic Complications

Diabetes mellitus (DM) is becoming a growing risk factor for public health worldwide. It is a very common disease and is widely known for its susceptibility to multiple complications which do great harm to the life and health of patients, some even lead to death. To date, there are many mechanisms for the complications of diabetes, including the generation of reactive oxygen species (ROS) and the abnormal changes of gas transmitters, which ultimately lead to injuries of cells, tissues and organs. Normally, even if injured, the body can quickly repair and maintain its homeostasis. This is closely associated with the repair and regeneration ability of stem cells. However, many studies have demonstrated that stem cells happen to be damaged under DM, which may be a nonnegligible factor in the occurrence and progression of diabetic complications. Therefore, this review summarizes how diabetes causes the corresponding complications by affecting stem cells from two aspects: stem cells dysfunctions and stem cells quantity alteration. In addition, since mesenchymal stem cells (MSCs), especially bone marrow mesenchymal stem cells (BMMSCs), have the advantages of strong differentiation ability, large quantity and wide application, we mainly focus on the impact of diabetes on them. The review also puts forward the basis of using exogenous stem cells to treat diabetic complications. It is hoped that through this review, researchers can have a clearer understanding of the roles of stem cells in diabetic complications, thus promoting the process of using stem cells to treat diabetic complications.

Activation of Bone Marrow Adaptive Immunity in Type 2 Diabetes: Rescue by Co-stimulation Modulator Abatacept

Background: Chronic low-grade inflammation and alterations in innate and adaptive immunity were reported in Type 2 diabetes (T2D). Here, we investigated the abundance and activation of T cells in the bone marrow (BM) of patients with T2D. We then verified the human data in a murine model and tested if the activation of T cells can be rescued by treating mice with abatacept, an immunomodulatory drug employed for the treatment of rheumatoid arthritis. Clinical evidence indicated abatacept can slow the decline in beta-cell function.

Methods: A cohort of 24 patients (12 with T2D) undergoing hip replacement surgery was enrolled in the study. Flow cytometry and cytokine analyses were performed on BM leftovers from surgery. We next compared the immune profile of db/db and control wt/db mice. In an additional study, db/db mice were randomized to receive abatacept or vehicle for 4 weeks, with endpoints being immune cell profile, indices of insulin sensitivity, and heart performance.

Results: Patients with T2D showed increased frequencies of BM CD4⁺ (2.8-fold, p = 0.001) and CD8⁺ T cells (1.8-fold, p = 0.01), with the upregulation of the activation marker CD69 and the homing receptor CCR7 in CD4⁺ (1.64-fold, p = 0.003 and 2.27-fold, p = 0.01, respectively) and CD8⁺ fractions (1.79-fold, p = 0.05 and 1.69-fold, p = 0.02, respectively). These differences were confirmed in a multivariable regression model. CCL19 (CCR7 receptor ligand) and CXCL10/11 (CXCR3 receptor ligands), implicated in T-cell migration and activation, were the most differentially modulated chemokines. Studies in mice confirmed the activation of adaptive immunity in T2D. Abatacept reduced the activation of T cells and the levels of proinflammatory cytokines and improved cardiac function but not insulin sensitivity.

Conclusions: Results provide proof-of-concept evidence for the activation of BM adaptive immunity in T2D. In mice, treatment with abatacept dampens the activation of adaptive immunity and protects from cardiac damage.

Cell Therapy for Critical Limb Ischemia: Advantages, Limitations, and New Perspectives for Treatment of Patients with Critical Diabetic Vasculopathy

PURPOSE OF REVIEW

To provide a highlight of the current state of cell therapy for the treatment of critical limb ischemia in patients with diabetes.

RECENT FINDINGS

The global incidence of diabetes is constantly growing with consequent challenges for healthcare systems worldwide. In the UK only, NHS costs attributed to diabetic complications, such as peripheral vascular disease, amputation, blindness, renal failure, and stroke, average £10 billion each year, with cost pressure being estimated to get worse. Although giant leaps forward have been registered in the scope of early diagnosis and optimal glycaemic control, an effective treatment for critical limb ischemia is still lacking. The present review aims to provide an update of the ongoing work in the field of regenerative medicine. Recent advancements but also limitations imposed by diabetes on the potential of the approach are addressed. In particular, the review focuses on the perturbation of non-coding RNA networks in progenitor cells and the possibility of using emerging knowledge on molecular mechanisms to design refined protocols for personalized therapy. The field of cell therapy showed rapid progress but has limitations. Significant advances are foreseen in the upcoming years thanks to a better understanding of molecular bottlenecks associated with the metabolic disorders.

Mobilization of endothelial progenitor cells promotes angiogenesis after full thickness excision by AMD3100 combined with G-CSF in diabetic mice by SDF-1/CXCR4 axis

AIM

The aim of the present study was to investigate the effect of the mobilization of EPCs by AMD3100 combined with G-CSF on wound healing in diabetic mice.

METHODS

The full-thickness excisional wounds model of diabetic mice (db/db) was examined by hematoxylin and eosin staining, immunohistochemical staining, and western blotting to compare the wound healing and neovascularization among the combination, AMD3100 alone, G-CSF alone, and control groups.

RESULTS

The wounds reached the complete closure in the combination, AMD3100 alone, G-CSF alone, and control groups on days 17, 20, 21, 21 after surgery, respectively. In addition, the combination group promoted the inflammatory cell recruitment and glandular formation. On day 10 from injury, the protein expression of CD31 in the combination group was significantly higher compared with the other three groups (p < 0.001). The level of SDF-1 protein remained high in the combined group until on day 10 after surgery (p < 0.001).

CONCLUSION

The mobilization of endogenous EPCs by AMD3100 combine with G-CSF is able to enhance the complete healing of full-thickness wounds and neovascularization in db/db mice may by SDF-1/CXCR4 axis. These findings provided a novel method and indication of duration of mobilization on diabetic wound healing and tissue regeneration.

Experimental Type 2 Diabetes Differently Impacts on the Select Functions of Bone Marrow-Derived Multipotent Stromal Cells

Bone marrow-derived multipotent stromal cells (BMMSCs) represent an attractive therapeutic modality for cell therapy in type 2 diabetes mellitus (T2DM)-associated complications. T2DM changes the bone marrow environment; however, its effects on BMMSC properties remain unclear. The present study aimed at investigating select functions and differentiation of BMMSCs harvested from the T2DM microenvironment as potential candidates for regenerative medicine. BMMSCs were obtained from Zucker diabetic fatty (ZDF; an obese-T2DM model) rats and their lean littermates (ZL; controls), and cultured under normoglycemic conditions. The BMMSCs derived from ZDF animals were fewer in number, with limited clonogenicity (by 2-fold), adhesion (by 2.9-fold), proliferation (by 50%), migration capability (by 25%), and increased apoptosis rate (by 2.5-fold) compared to their ZL counterparts. Compared to the cultured ZL-BMMSCs, the ZDF-BMMSCs exhibited (i) enhanced adipogenic differentiation (increased number of lipid droplets by 2-fold; upregulation of the Pparg, AdipoQ, and Fabp genes), possibly due to having been primed to undergo such differentiation in vivo prior to cell isolation, and (ii) different angiogenesis-related gene expression in vitro and decreased proangiogenic potential after transplantation in nude mice. These results provided evidence that the T2DM environment impairs BMMSC expansion and select functions pertinent to their efficacy when used in autologous cell therapies.

Getting blood out of a stone: Identification and management of patients with poor hematopoietic cell mobilization

Hematopoietic cell transplantation (HCT) has become a primary treatment for many cancers. Nowadays, the primary source of hematopoietic cells is by leukapheresis collection of these cells from peripheral blood, after a forced egress of hematopoietic cells from marrow into blood circulation, a process known as "mobilization". In this process, mobilizing agents disrupt binding interactions between hematopoietic cells and marrow microenvironment to facilitate collection. As the first essential step of HCT, poor mobilization, i.e. failure to obtain a desired or required number of hematopoietic cell, is one of the major factors affecting engraftment or even precluding transplantation. This review summarizes the available mobilization regimens using granulocyte-colony stimulating factor (G-CSF) and plerixafor, as well as the current understanding of the factors that are associated with poor mobilization. Strategies to mobilize patients or healthy donors who failed previous mobilization are discussed. Multiple novel agents are under investigation and some of them have shown the potential to enhance the mobilization response to G-CSF and/or plerixafor. Further investigation of the risk factors including genetic factors will offer an opportunity to better understand the molecular mechanism of mobilization and help develop new therapeutic strategies for successful mobilizations.

Considering Cause and Effect of Immune Cell Aging on Cardiac Repair after Myocardial Infarction

The importance of the immune system for cardiac repair following myocardial infarction is undeniable; however, the complex nature of immune cell behavior has limited the ability to develop effective therapeutics. This limitation highlights the need for a better understanding of the function of each immune cell population during the inflammatory and resolution phases of cardiac repair. The development of reliable therapies is further complicated by aging, which is associated with a decline in cell and organ function and the onset of cardiovascular and immunological diseases. Aging of the immune system has important consequences on heart function as both chronic cardiac inflammation and an impaired immune response to cardiac injury are observed in older individuals. Several studies have suggested that rejuvenating the aged immune system may be a valid therapeutic candidate to prevent or treat heart disease. Here, we review the basic patterns of immune cell behavior after myocardial infarction and discuss the autonomous and nonautonomous manners of hematopoietic stem cell and immune cell aging. Lastly, we identify prospective therapies that may rejuvenate the aged immune system to improve heart function such as anti-inflammatory and senolytic therapies, bone marrow transplant, niche remodeling and regulation of immune cell differentiation.

Bone marrow fat: friend or foe in people with diabetes mellitus?

Global trends in the prevalence of overweight and obesity put the adipocyte in the focus of huge medical interest. This review highlights a new topic in adipose tissue biology, namely the emerging pathogenic role of fat accumulation in bone marrow (BM). Specifically, we summarize current knowledge about the origin and function of BM adipose tissue (BMAT), provide evidence for the association of excess BMAT with diabetes and related cardiovascular complications, and discuss potential therapeutic approaches to correct BMAT dysfunction. There is still a significant uncertainty about the origins and function of BMAT, although several subpopulations of stromal cells have been suggested to have an adipogenic propensity. BM adipocytes are higly plastic and have a distinctive capacity to secrete adipokines that exert local and endocrine functions. BM adiposity is abundant in elderly people and has therefore been interpreted as a component of the whole-body ageing process. BM senescence and BMAT accumulation has been also reported in patients and animal models with Type 2 diabetes, being more pronounced in those with ischaemic complications. Understanding the mechanisms responsible for excess and altered function of BMAT could lead to new treatments able to preserve whole-body homeostasis.

Pharmacologic PPAR-γ Activation Reprograms Bone Marrow Macrophages and Partially Rescues HSPC Mobilization in Human and Murine Diabetes

Mobilization of hematopoietic stem/progenitor cells (HSPC) from the bone marrow (BM) is impaired in diabetes. Excess oncostatin M (OSM) produced by M1 macrophages in the diabetic BM signals through p66Shc to induce Cxcl12 in stromal cells and retain HSPC. BM adipocytes are another source of CXCL12 that blunts mobilization. We tested a strategy of pharmacologic macrophage reprogramming to rescue HSPC mobilization. In vitro, PPAR-γ activation with pioglitazone switched macrophages from M1 to M2, reduced Osm expression, and prevented transcellular induction of Cxcl12 In diabetic mice, pioglitazone treatment downregulated Osm, p66Shc, and Cxcl12 in the hematopoietic BM, restored the effects of granulocyte-colony stimulation factor (G-CSF), and partially rescued HSPC mobilization, but it increased BM adipocytes. Osm deletion recapitulated the effects of pioglitazone on adipogenesis, which was p66Shc independent, and double knockout of Osm and p66Shc completely rescued HSPC mobilization. In the absence of OSM, BM adipocytes produced less CXCL12, being arguably devoid of HSPC-retaining activity, whereas pioglitazone failed to downregulate Cxcl12 in BM adipocytes. In patients with diabetes on pioglitazone therapy, HSPC mobilization after G-CSF was partially rescued. In summary, pioglitazone reprogrammed BM macrophages and suppressed OSM signaling, but sustained Cxcl12 expression by BM adipocytes could limit full recovery of HSPC mobilization.

MicroRNA-21/PDCD4 Proapoptotic Signaling From Circulating CD34+ Cells to Vascular Endothelial Cells: A Potential Contributor to Adverse Cardiovascular Outcomes in Patients With Critical Limb Ischemia

OBJECTIVE

In patients with type 2 diabetes (T2D) and critical limb ischemia (CLI), migration of circulating CD34⁺ cells predicted cardiovascular mortality at 18 months after revascularization. This study aimed to provide long-term validation and mechanistic understanding of the biomarker.

RESEARCH DESIGN AND METHODS

The association between CD34⁺ cell migration and cardiovascular mortality was reassessed at 6 years after revascularization. In a new series of T2D-CLI and control subjects, immuno-sorted bone marrow CD34⁺ cells were profiled for miRNA expression and assessed for apoptosis and angiogenesis activity. The differentially regulated miRNA-21 and its proapoptotic target, PDCD4, were titrated to verify their contribution in transferring damaging signals from CD34⁺ cells to endothelial cells.

RESULTS

Multivariable regression analysis confirmed that CD34⁺ cell migration forecasts long-term cardiovascular mortality. CD34⁺ cells from T2D-CLI patients were more apoptotic and less proangiogenic than those from control subjects and featured miRNA-21 downregulation, modulation of several long noncoding RNAs acting as miRNA-21 sponges, and upregulation of the miRNA-21 proapoptotic target PDCD4. Silencing miR-21 in control CD34⁺ cells phenocopied the T2D-CLI cell behavior. In coculture, T2D-CLI CD34⁺ cells imprinted naive endothelial cells, increasing apoptosis, reducing network formation, and modulating the TUG1 sponge/miRNA-21/PDCD4 axis. Silencing PDCD4 or scavenging reactive oxygen species protected endothelial cells from the negative influence of T2D-CLI CD34⁺ cells.

CONCLUSIONS

Migration of CD34⁺ cells predicts long-term cardiovascular mortality in T2D-CLI patients. An altered paracrine signaling conveys antiangiogenic and proapoptotic features from CD34⁺ cells to the endothelium. This damaging interaction may increase the risk for life-threatening complications.

Stem cell mobilization with plerixafor and healing of diabetic ischemic wounds: A phase IIa, randomized, double-blind, placebo-controlled trial

Bone marrow‐derived cells contribute to tissue repair, but traffic of hematopoietic stem/progenitor cells (HSPCs) is impaired in diabetes. We therefore tested whether HSPC mobilization with the CXCR4 antagonist plerixafor improved healing of ischemic diabetic wounds. This was a pilot, phase IIa, double‐blind, randomized, placebo‐controlled trial (NCT02790957). Patients with diabetes with ischemic wounds were randomized to receive a single subcutaneous injection of plerixafor or saline on top of standard medical and surgical therapy. The primary endpoint was complete healing at 6 months. Secondary endpoints were wound size, transcutaneous oxygen tension (TcO₂), ankle‐brachial index (ABI), amputations, and HSPC mobilization. Twenty‐six patients were enrolled: 13 received plerixafor and 13 received placebo. Patients were 84.6% males, with a mean age of 69 years. HSPC mobilization was successful in all patients who received plerixafor. The trial was terminated after a preplanned interim analysis of 50% of the target population showed a significantly lower healing rate in the plerixafor vs the placebo group. In the final analysis data set, the rate of complete healing was 38.5% in the plerixafor group vs 69.2% in the placebo group (chi‐square P = .115). Wound size tended to be larger in the plerixafor group for the entire duration of observation. No significant difference was noted for the change in TcO₂ and ABI or in amputation rates. No other safety concern emerged. In conclusion, successful HSPC mobilization with plerixafor did not improve healing of ischemic diabetic wounds. Contrary to what was expected, outside the context of hematological disorders, mobilization of diabetic HSPCs might exert adverse effects on wound healing.

Bone Marrow Endothelial Cells Regulate Myelopoiesis in Diabetes Mellitus

BACKGROUND

Diabetes mellitus is a prevalent public health problem that affects about one-third of the US population and leads to serious vascular complications with increased risk for coronary artery disease. How bone marrow hematopoiesis contributes to diabetes mellitus complications is incompletely understood. We investigated the role of bone marrow endothelial cells in diabetic regulation of inflammatory myeloid cell production.

METHODS

In 3 types of mouse diabetes mellitus, including streptozotocin, high-fat diet, and genetic induction using leptin-receptor-deficient db/db mice, we assayed leukocytes, hematopoietic stem and progenitor cells (HSPC). In addition, we investigated bone marrow endothelial cells with flow cytometry and expression profiling.

RESULTS

In diabetes mellitus, we observed enhanced proliferation of HSPC leading to augmented circulating myeloid cell numbers. Analysis of bone marrow niche cells revealed that endothelial cells in diabetic mice expressed less Cxcl12, a retention factor promoting HSPC quiescence. Transcriptome-wide analysis of bone marrow endothelial cells demonstrated enrichment of genes involved in epithelial growth factor receptor (Egfr) signaling in mice with diet-induced diabetes mellitus. To explore whether endothelial Egfr plays a functional role in myelopoiesis, we generated mice with endothelial-specific deletion of Egfr (Cdh5^Cre Egfr^fl/fl). We found enhanced HSPC proliferation and increased myeloid cell production in Cdh5^Cre Egfr^fl/fl mice compared with wild-type mice with diabetes mellitus. Disrupted Egfr signaling in endothelial cells decreased their expression of the HSPC retention factor angiopoietin-1. We tested the functional relevance of these findings for wound healing and atherosclerosis, both implicated in complications of diabetes mellitus. Inflammatory myeloid cells accumulated more in skin wounds of diabetic Cdh5^Cre Egfr^fl/fl mice, significantly delaying wound closure. Atherosclerosis was accelerated in Cdh5^Cre Egfr^fl/fl mice, leading to larger and more inflamed atherosclerotic lesions in the aorta.

CONCLUSIONS

In diabetes mellitus, bone marrow endothelial cells participate in the dysregulation of bone marrow hematopoiesis. Diabetes mellitus reduces endothelial production of Cxcl12, a quiescence-promoting niche factor that reduces stem cell proliferation. We describe a previously unknown counterregulatory pathway, in which protective endothelial Egfr signaling curbs HSPC proliferation and myeloid cell production.

MicroRNA Profile of Patients with Chronic Limb-Threatening Ischemia

Chronic limb-threatening ischemia (CLTI) results in devastating complications such as lower-limb amputations. In this study, a genome-wide plasma microRNAs (miRNA) sequencing was performed to identify miRNA(s) associated with CLTI. Blood samples were collected from early stage CLTI patients (ABI < 0.9) and non-PAD controls (ABI ≥ 0.9) for 3 experiments: discovery phase (n = 23), confirmatory phase (n = 52) and validation phase (n = 20). In the discovery phase, next generation sequencing (NGS) was used to identify miRNA circulating in the plasma CLTI (n = 13) patients, compared to non-PAD controls (n = 10). Two down-regulated miRNAs (miRNA-6843-3p and miRNA-6766-5p) and three upregulated miRNAs (miRNA-1827, miRNA-320 and miRNA-98-3p) were identified (≥2-fold change). In the confirmatory phase, these 5 deregulated miRNAs were further investigated in non-PAD (n = 21) and CTLI (n = 31) patients using qRT-PCR. Only miRNA-1827 was found to be significantly upregulated (≥3-fold, p-value < 0. 001) in the CLTI group. Lastly, to minimize the influence of confounding factors, miRNA-1827 plasma levels were validated in a third cohort of CLTI patients (n = 10) matched to non-PAD controls (n = 10). Our analysis demonstrated that miRNA-1827 expression was increased in the CLTI cohort (≥2-folds, p-value < 0.001). In summary, circulating miRNA-1827 is significantly elevated in patients with CLTI.

Bone marrow as a target and accomplice of vascular complications in diabetes

Peripheral vascular complications are common in diabetic patients. While pathogenic mechanisms have received much consideration, only recently regenerative processes captured attention. There is now a consensus that the bone marrow is a source of reparative cells and that this healing mechanism is lost in people with diabetes, especially in those suffering from ischemic complications. This failure was thought to occur due to a negative impact of diabetes on the mobilization of stem/progenitor cells with angiogenic properties from the bone marrow to the circulation. Moreover, those patients showing severely reduced bone marrow cell mobilization also bared a very high risk for adverse cardiovascular events. More recently, the structural integrity of the bone marrow was recognized to be altered because of the rarefaction of local microvasculature and innervation, thus mirroring anatomical features that typically occur in peripheral tissues. Ensuing hypoxia, nutrient starvation, and creation of an acidic and oxidative environment concur in causing the depletion of stem/progenitor cells in the endosteal niche and in forcing stromal cells to activate an adipogenesis program. Moreover, stem/progenitor cells acquire a pathogenic phenotype and, once mobilized, can pass harmful signalling molecules to vascular cells of peripheral tissues thereby contributing to ischemic complications. These new pieces of evidence indicate that the bone marrow should deserve more attention in the current care of critical limb ischemia and diabetic foot. Owing to powerful reserve capacities, the bone marrow integrity could be preserved and even rescued using rehabilitation programs and pharmacological treatments with consequent benefit for local and whole-organism homeostasis.

Carbon black nanoparticles induce pulmonary fibrosis through NLRP3 inflammasome pathway modulated by miR-96 targeted FOXO3a

Carbon black nanoparticle (CBNP) is a core constituent of air pollutants like fine particulate matter (PM2.5) as well as a common manufactural material. It was proved to pose adverse effects on lung function and even provoke pulmonary fibrosis. However, the underlying mechanisms of CBNPs-induced pulmonary fibrosis remain unclear. The present study aimed to investigate the mechanism of fibrotic effects caused by CBNPs in rat lung and human bronchial epithelial (16HBE) cells. Forty-nine male rats were randomly subjected to 7 groups, means the 14-day exposure group (30 mg/m³), the 28-day exposure groups (5 mg/m³ and 30 mg/m³), the 90-day exposure group (30 mg/m³) and their respective controls. Rats were nose-only-inhaled CBNPs. 16HBE cells were treated with 0, 50, 100 and 200 μg/mL CBNPs respectively for 24 h. Besides, Forkhead transcription factor class O (FOXO)3a and miR-96 overexpression or suppression 16HBE cells were established to reveal relative mechanisms. Our results suggested CBNPs induced pulmonary fibrosis in time- and dose-dependent manners. CBNPs induced persisting inflammation in rat lung as observed by histopathology and cytology analyses in whole lung lavage fluid (WLL). Both in vivo and in vitro, CBNPs exposure significantly increased the expression of NLRP3 inflammasome, accompanied by the increased reactive oxygen species (ROS), decreased miR-96 and increased FOXO3a expressions dose -and time-dependently. MiR-96 overexpression or FOXO3a suppression could partially rescue the fibrotic effects through inhibiting NLRP3 inflammasome. Conclusively, our research show that CBNPs-induced pulmonary fibrosis was at least partially depended on activation of NLRP3 inflammasome which modulated by miR-96 targeting FOXO3a.

Angiogenic Abnormalities in Diabetes Mellitus: Mechanistic and Clinical Aspects

CONTEXT

Diabetes causes severe pathological changes to the microvasculature in many organs and tissues and is at the same time associated with an increased risk of coronary and peripheral macrovascular events. We herein review alterations in angiogenesis observed in human and experimental diabetes and how they contribute to diabetes onset and development of vascular complications.

EVIDENCE ACQUISITION

The English language medical literature was searched for articles reporting on angiogenesis/vasculogenesis abnormalities in diabetes and their clinical manifestations, mechanistic aspects, and possible therapeutic implications.

EVIDENCE SYNTHESIS

Angiogenesis is a complex process, driven by a multiplicity of molecular mechanisms and involved in several physiological and pathological conditions. Incompetent angiogenesis is pervasive in diabetic vascular complications, with both excessive and defective angiogenesis observed in various tissues. A striking different angiogenic response typically occurs in the retina vs the myocardium and peripheral circulation, but some commonalities in abnormal angiogenesis can explain the well-known association between microangiopathy and macroangiopathy. Impaired angiogenesis can also affect endocrine islet and adipose tissue function, providing a link to diabetes onset. Exposure to high glucose itself directly affects angiogenic/vasculogenic processes, and the mechanisms include defective responses to hypoxia and proangiogenic factors, impaired nitric oxide bioavailability, shortage of proangiogenic cells, and loss of pericytes.

CONCLUSIONS

Dissecting the molecular drivers of tissue-specific alterations of angiogenesis/vasculogenesis is an important challenge to devise new therapeutic approaches. Angiogenesis-modulating therapies should be carefully evaluated in view of their potential off-target effects. At present, glycemic control remains the most reasonable therapeutic strategy to normalize angiogenesis in diabetes.

Impact of Diabetes Mellitus on Bone Health

Long-term exposure to a diabetic environment leads to changes in bone metabolism and impaired bone micro-architecture through a variety of mechanisms on molecular and structural levels. These changes predispose the bone to an increased fracture risk and impaired osseus healing. In a clinical practice, adequate control of diabetes mellitus is essential for preventing detrimental effects on bone health. Alternative fracture risk assessment tools may be needed to accurately determine fracture risk in patients living with diabetes mellitus. Currently, there is no conclusive model explaining the mechanism of action of diabetes mellitus on bone health, particularly in view of progenitor cells. In this review, the best available literature on the impact of diabetes mellitus on bone health in vitro and in vivo is summarised with an emphasis on future translational research opportunities in this field.

Impaired Regeneration Contributes to Poor Outcomes in Diabetic Peripheral Artery Disease

Diabetes mellitus increases the risk and accelerates the course of peripheral artery disease, making patients more susceptible to ischemic events and infections and delaying tissue healing. Current understanding of pathogenic mechanisms is mainly based on the negative influence of diabetes mellitus on atherosclerotic disease and inflammation. In recent years, the novel concept that diabetes mellitus can impinge on endogenous regenerative processes has been introduced. Diabetes mellitus affects regeneration at the local level, disturbing proper angiogenesis, collateral artery formation, and muscle repair. Recent evidence indicates that an impairment in vascular mural cells, alias pericytes, may participate in diabetic peripheral vasculopathy. Moreover, the bone marrow undergoes a global remodeling, consisting of microvessels and sensory neurons rarefaction and fat accumulation, which creates a hostile microenvironment for resident stem cells. Bone marrow remodeling is also responsible for detrimental systemic effects. In particular, the aid of reparative cells from the bone marrow is compromised: these elements are released in an improper manner and become harmful vectors of inflammatory and antiangiogenic molecules and noncoding RNAs. This new understanding of impaired regeneration is inspiring new therapeutic options for the treatment of ischemic complications in people with diabetes mellitus.

Nerve growth factor gene therapy improves bone marrow sensory innervation and nociceptor-mediated stem cell release in a mouse model of type 1 diabetes with limb ischaemia

AIMS/HYPOTHESIS

Sensory neuropathy is common in people with diabetes; neuropathy can also affect the bone marrow of individuals with type 2 diabetes. However, no information exists on the state of bone marrow sensory innervation in type 1 diabetes. Sensory neurons are trophically dependent on nerve growth factor (NGF) for their survival. The aim of this investigation was twofold: (1) to determine if sensory neuropathy affects the bone marrow in a mouse model of type 1 diabetes, with consequences for stem cell liberation after tissue injury; and (2) to verify if a single systemic injection of the NGF gene exerts long-term beneficial effects on these phenomena.

METHODS

A mouse model of type 1 diabetes was generated in CD1 mice by administration of streptozotocin; vehicle was administered to non-diabetic control animals. Diabetic animals were randomised to receive systemic gene therapy with either human NGF or β-galactosidase. After 13 weeks, limb ischaemia was induced in both groups to study the recovery post injury. When the animals were killed, samples of tissue and peripheral blood were taken to assess stem cell mobilisation and homing, levels of substance P and muscle vascularisation. An in vitro cellular model was adopted to verify signalling downstream to human NGF and related neurotrophic or pro-apoptotic effects. Normally distributed variables were compared between groups using the unpaired Student's t test and non-normally distributed variables were assessed by the Wilcoxon-Mann-Whitney test. The Fisher's exact test was employed for categorical variables.

RESULTS

Immunohistochemistry indicated a 3.3-fold reduction in the number of substance P-positive nociceptive fibres in the bone marrow of type 1 diabetic mice (p < 0.001 vs non-diabetic). Moreover, diabetes abrogated the creation of a neurokinin gradient which, in non-diabetic mice, favoured the mobilisation and homing of bone-marrow-derived stem cells expressing the substance P receptor neurokinin 1 receptor (NK1R). Pre-emptive gene therapy with NGF prevented bone marrow denervation, contrasting with the inhibitory effect of diabetes on the mobilisation of NK1R-expressing stem cells, and restored blood flow recovery from limb ischaemia. In vitro hNGF induced neurite outgrowth and exerted anti-apoptotic actions on rat PC12 cells exposed to high glucose via activation of the canonical neurotrophic tyrosine kinase receptor type 1 (TrkA) signalling pathway.

CONCLUSIONS/INTERPRETATION

This study shows, for the first time, the occurrence of sensory neuropathy in the bone marrow of type 1 diabetic mice, which translates into an altered modulation of substance P and depressed release of substance P-responsive stem cells following ischaemia. NGF therapy improves bone marrow sensory innervation, with benefits for healing on the occurrence of peripheral ischaemia. Nociceptors may represent a new target for the treatment of ischaemic complications in diabetes.

Bone marrow pericyte dysfunction in individuals with type 2 diabetes

AIMS/HYPOTHESIS

Previous studies have shown that diabetes mellitus destabilises the integrity of the microvasculature in different organs by damaging the interaction between pericytes and endothelial cells. In bone marrow, pericytes exert trophic functions on endothelial cells and haematopoietic cells through paracrine mechanisms. However, whether bone marrow pericytes are a target of diabetes-induced damage remains unknown. Here, we investigated whether type 2 diabetes can affect the abundance and function of bone marrow pericytes.

METHODS

We conducted an observational clinical study comparing the abundance and molecular/functional characteristics of CD146⁺ pericytes isolated from the bone marrow of 25 individuals without diabetes and 14 individuals with uncomplicated type 2 diabetes, referring to our Musculoskeletal Research Unit for hip reconstructive surgery.

RESULTS

Immunohistochemistry revealed that diabetes causes capillary rarefaction and compression of arteriole size in bone marrow, without changing CD146⁺ pericyte counts. These data were confirmed by flow cytometry on freshly isolated bone marrow cells. We then performed an extensive functional and molecular characterisation of immunosorted CD146⁺ pericytes. Type 2 diabetes caused a reduction in pericyte proliferation, viability, migration and capacity to support in vitro angiogenesis, while inducing apoptosis. AKT is a key regulator of the above functions and its phosphorylation state is reportedly reduced in the bone marrow endothelium of individuals with diabetes. Surprisingly, we could not find a difference in AKT phosphorylation (at either Ser473 or Thr308) in bone marrow pericytes from individuals with and without diabetes. Nonetheless, the angiocrine signalling reportedly associated with AKT was found to be significantly downregulated, with lower levels of fibroblast growth factor-2 (FGF2) and C-X-C motif chemokine ligand 12 (CXCL12), and activation of the angiogenesis inhibitor angiopoietin 2 (ANGPT2). Transfection with the adenoviral vector carrying the coding sequence for constitutively active myristoylated AKT rescued functional defects and angiocrine signalling in bone marrow pericytes from diabetic individuals. Furthermore, an ANGPT2 blocking antibody restored the capacity of pericytes to promote endothelial networking.

CONCLUSIONS/INTERPRETATION

This is the first demonstration of pericyte dysfunction in bone marrow of people with type 2 diabetes. An altered angiocrine signalling from pericytes may participate in bone marrow microvascular remodelling in individuals with diabetes.

Diabetics show accelerated progression of knee cartilage and meniscal lesions: data from the osteoarthritis initiative

OBJECTIVE

To investigate whether subjects with diabetes show accelerated knee joint structural degeneration over 4 years compared to diabetes-free controls.

MATERIALS AND METHODS

Two hundred forty-four participants with diabetes were selected from the Osteoarthritis Initiative cohort and matched with 244 diabetes-free controls. 3.0-T MRI scans of the right knee were obtained at baseline and 4-year follow-up. Evaluation of structural knee abnormalities was performed using the Whole-Organ Resonance Imaging Scoring system (WORMS). Linear regression analysis was conducted to compare structural temporal changes in each compartment, as well as the mean across all compartments by diabetes status.

RESULTS

Study groups were similar in age (63.0 vs. 63.3 years, p = 0.73), body mass index (31.5 vs. 31.0 kg/m², p = 0.21), sex (female 52.0 vs. 52.9%, p = 0.85) and radiographic Kellgren/Lawrence score distribution (p = 0.99). Structural degeneration was significantly worse in the knees of diabetics with an increase in the overall WORMS sum score (delta WORMS [95% CI]: 4.87 [4.17, 5.57], vs. 3.23 [2.60, 3.85] p = 0.001). Moreover, diabetics showed a greater increase in cartilage lesions in the global knee (p < 0.001), but also separately in the patella, lateral tibia, and both femoral compartments (lowest p value; p = 0.001). Furthermore, diabetics showed also a greater increase in meniscus lesion score, in both the medial (p = 0.01) and lateral meniscus (p = 0.01).

CONCLUSIONS

Diabetics exhibited a significantly greater increase in cartilage and meniscus lesions when compared to diabetes-free controls over 4 years. Overall, our findings suggest that diabetics exhibit a stronger deterioration of knee structure and are therefore potentially at higher risk for developing knee OA.

Diabetes-Associated Myelopoiesis Drives Stem Cell Mobilopathy Through an OSM-p66Shc Signaling Pathway

Diabetes impairs the mobilization of hematopoietic stem/progenitor cells (HSPCs) from the bone marrow (BM), which can worsen the outcomes of HSPC transplantation and of diabetic complications. In this study, we examined the oncostatin M (OSM)-p66Shc pathway as a mechanistic link between HSPC mobilopathy and excessive myelopoiesis. We found that streptozotocin-induced diabetes in mice skewed hematopoiesis toward the myeloid lineage via hematopoietic-intrinsic p66Shc. The overexpression of Osm resulting from myelopoiesis prevented HSPC mobilization after granulocyte colony-stimulating factor (G-CSF) stimulation. The intimate link between myelopoiesis and impaired HSPC mobilization after G-CSF stimulation was confirmed in human diabetes. Using cross-transplantation experiments, we found that deletion of p66Shc in the hematopoietic or nonhematopoietic system partially rescued defective HSPC mobilization in diabetes. Additionally, p66Shc mediated the diabetes-induced BM microvasculature remodeling. Ubiquitous or hematopoietic restricted Osm deletion phenocopied p66Shc deletion in preventing diabetes-associated myelopoiesis and mobilopathy. Mechanistically, we discovered that OSM couples myelopoiesis to mobilopathy by inducing Cxcl12 in BM stromal cells via nonmitochondrial p66Shc. Altogether, these data indicate that cell-autonomous activation of the OSM-p66Shc pathway leads to diabetes-associated myelopoiesis, whereas its transcellular hematostromal activation links myelopoiesis to mobilopathy. Targeting the OSM-p66Shc pathway is a novel strategy to disconnect mobilopathy from myelopoiesis and restore normal HSPC mobilization.

Therapies for Type 1 Diabetes: Current Scenario and Future Perspectives

Type 1 diabetes (T1D) is caused by autoimmune destruction of insulin-producing β cells located in the endocrine pancreas in areas known as islets of Langerhans. The current standard-of-care for T1D is exogenous insulin replacement therapy. Recent developments in this field include the hybrid closed-loop system for regulated insulin delivery and long-acting insulins. Clinical studies on prediction and prevention of diabetes-associated complications have demonstrated the importance of early treatment and glucose control for reducing the risk of developing diabetic complications. Transplantation of primary islets offers an effective approach for treating patients with T1D. However, this strategy is hampered by challenges such as the limited availability of islets, extensive death of islet cells, and poor vascular engraftment of islets post-transplantation. Accordingly, there are considerable efforts currently underway for enhancing islet transplantation efficiency by harnessing the beneficial actions of stem cells. This review will provide an overview of currently available therapeutic options for T1D, and discuss the growing evidence that supports the use of stem cell approaches to enhance therapeutic outcomes.

MicroRNA‑93 regulates angiogenesis in peripheral arterial disease by targeting CDKN1A

MicroRNAs (miRNAs) are considered to be critical mediators of gene expression with respect to tumor progression, although their role in ischemia-induced angiogenesis is poorly characterized, including in peripheral arterial disease (PAD). Furthermore, the underlying mechanism of action of specific miRNAs in PAD remains unknown. Reverse transcription-quantitative polymerase chain reaction analysis revealed that microRNA-93 (miR-93) was significantly upregulated in patients with PAD and in the EA.hy926 endothelial cells in response to hypoxia. Additionally, miRNA (miR)-93 promoted angiogenesis by enhancing proliferation, migration and tube formation. Cyclin dependent kinase inhibitor 1A (CDKN1A), verified as a potential target gene of miR-93, was inhibited by overexpressed miR-93 at the protein and mRNA expression levels. Furthermore, a hind-limb ischemia model served to evaluate the role of miR-93 in angiogenesis in vivo, and the results demonstrated that miR-93 overexpression enhanced capillary density and perfusion recovery from hind-limb ischemia. Taken together, miR-93 was indicated to be a promising target for pharmacological regulation to promote angiogenesis, and the miR-93/CDKN1A pathway may function as a novel therapeutic approach in PAD.

Circulating microRNA-155 is associated with insulin resistance in chronic hepatitis C patients

BACKGROUND AND STUDY AIM

Hepatitis C represents a potential public health problem worldwide. Insulin resistance (IR) and type 2 diabetes (T2D) are among the serious metabolic complications for chronic hepatitis C virus (HCV) infection. MicroRNAs (miRNAs) are a group of small non-coding RNAs which are implicated in the modulation of almost all biological processes. The objective of this study was to investigate the levels of both miR-155 and miR-34a in sera of chronic HCV patients with or without T2D.

PATIENTS AND METHODS

In this study, we investigated the expression of both miR-155 and miR-34a in 80 subjects (20 HCV, 19 HCV/T2D, 21 T2D and 19 healthy controls), using quantitative real-time PCR.

RESULTS

Our results revealed significantly higher levels of both miR-155 and miR-34a in chronic HCV patients compared to healthy control subjects. However, only circulating miR-155 levels showed significant decline in diabetic HCV patients compared to non-diabetic HCV group. Intriguingly, the circulating levels of miR-155 were inversely correlated with HOMA-IR, fasting blood glucose and HbA1c levels.

CONCLUSION

Our findings indicate that the insulin resistance and T2D in HCV are strongly related to miR-155. This may suggest a role for miR-155 in the pathogenesis of IR caused by HCV. However, further large-scale studies are required to confirm our findings.