Task for Today: Complete the Puzzle of Circulating Stem Cells and the Atherosclerotic Burden

A Meta-Analysis of Randomized Controlled Trials on Therapeutic Efficacy and Safety of Autologous Cell Therapy for Atherosclerosis Obliterans

BACKGROUND

Atherosclerosis obliterans (ASO) is a chronic occlusive arterial disease and the most common type of peripheral arterial disease. Current treatment options like medication and vascularization have limited effects for "no-option" patients, and stem cell therapy is considered a viable option although its application and efficacy have not been standardized. The objective of this review was to assess the safety and efficacy of autologous stem cell therapy in patients with ASO.

METHODS

We performed a literature search of published RCTs for ASO patients receiving stem cell therapy without a revascularization option. PubMed, Embase, and the Cochrane Library were searched. This study was conducted by a pair of authors independently and audited by a third author. Data were synthesized with a random-effect model.

RESULTS

630 patients in 12 RCTs were included. The results showed that cell therapy significantly improved total amputation (RR: 0.64, p = 0.004, 95% CI: [0.47, 0.87]), major amputation (RR: 0.69, p = 0.02, 95% CI: [0.50, 0.94]), ankle-brachial index (ABI) (MD = 0.08, p = 0.004, 95% CI: [0.02, 0.13]), transcutaneous oxygen tension (TcO₂) (MD = 11.52, p = 0.004, 95% CI: [3.60, 19.43]) and rest pain score (MD = -0.64, p = 0.007, 95% CI: [-1.10, -0.17]) compared to placebo or standard care. However, current studies showed cell therapy was not superior to placebo or standard care in all-cause death (RR: 0.75, p = 0.34, 95% CI: [0.41, 1.36]) and ulcer size (MD = -8.85, p = 0.39, CI: [-29.05,11.36]).

LIMITATION

The number of trials included was limited. Moreover, most trials were designed for "no-option" patients and thus the results should be applied with caution to other PAD patients.

CONCLUSION

ASO patients can benefit from autologous cell therapy in limb salvage, limb blood perfusion, and rest pain alleviation.

Clinical approach to the inflammatory etiology of cardiovascular diseases

Inflammation is an obligatory marker of arterial disease, both stemming from the inflammatory activity of cholesterol itself and from well-established molecular mechanisms. Raised progenitor cell recruitment after major events and clonal hematopoiesis related mechanisms have provided an improved understanding of factors regulating inflammatory phenomena. Trials with inflammation antagonists have led to an extensive evaluation of biomarkers such as the high sensitivity C reactive protein (hsCRP), not exerting a causative role, but frequently indicative of the individual cardiovascular (CV) risk. Aim of this review is to provide indication on the anti-inflammatory profile of agents of general use in CV prevention, i.e. affecting lipids, blood pressure, diabetes as well nutraceuticals such as n-3 fatty acids. A crucial issue in the evaluation of the benefit of the anti-inflammatory activity is the frequent discordance between a beneficial activity on a major risk factor and associated changes of hsCRP, as in the case of statins vs PCSK9 antagonists. In hypertension, angiotensin converting enzyme inhibitors exert an optimal anti-inflammatory activity, vs the case of sartans. The remarkable preventive activity of SLGT-2 inhibitors in heart failure is not associated with a clear anti-inflammatory mechanism. Finally, icosapent ethyl has been shown to reduce the CV risk in hypertriglyceridemia, with a 27 % reduction of hsCRP. The inflammation-based approach to arterial disease has considerably gained from an improved understanding of the clinical diagnostic strategy and from a better knowledge on the mode of action of numerous agents, including nutraceuticals.

Bone, inflammation and the bone marrow niche in chronic kidney disease: what do we know?

Recent improvements in our understanding of physiology have altered the way in which bone is perceived: no longer is it considered as simply the repository of divalent ions, but rather as a sophisticated endocrine organ with potential extraskeletal effects. Indeed, a number of pathologic conditions involving bone in different ways can now be reconsidered from a bone-centred perspective. For example, in metabolic bone diseases like osteoporosis (OP) and renal osteodystrophy (ROD), the association with a worse cardiovascular outcome can be tentatively explained by the possible derangements of three recently discovered bone hormones (osteocalcin, fibroblast growth factor 23 and sclerostin) and a bone-specific enzyme (alkaline phosphatase). Further, in recent years the close link between bone and inflammation has been better appreciated and a wide range of chronic inflammatory states (from rheumatoid arthritis to ageing) are being explored to discover the biochemical changes that ultimately lead to bone loss and OP. Also, it has been acknowledged that the concept of the bone-vascular axis may explain, for example, the relationship between bone metabolism and vessel wall diseases like atherosclerosis and arteriosclerosis, with potential involvement of a number of cytokines and metabolic pathways. A very important discovery in bone physiology is the bone marrow (BM) niche, the functional unit where stem cells interact, exchanging signals that impact on their fate as bone-forming cells or immune-competent haematopoietic elements. This new element of bone physiology has been recognized to be dysfunctional in diabetes (so-called diabetic mobilopathy), with possible clinical implications. In our opinion, ROD, the metabolic bone disease of renal patients, will in the future probably be identified as a cause of BM niche dysfunction. An integrated view of bone, which includes the BM niche, now seems necessary in order to understand the complex clinical entity of chronic kidney disease-mineral and bone disorders and its cardiovascular burden. Bone is thus becoming a recurrently considered paradigm for different inter-organ communications that needs to be considered in patients with complex diseases.

The Key Role of Phosphate on Vascular Calcification

Vascular calcification (VC) is common in dialysis and non-dialysis chronic kidney disease (CKD) patients, even in the early stage of the disease. For this reason, it can be considered a CKD hallmark. VC contributes to cardiovascular disease (CVD) and increased mortality among CKD patients, although it has not been proven. There are more than one type of VC and every form represents a marker of systemic vascular disease and is associated with a higher prevalence of CVD in CKD patients, as shown by several clinical studies. Major risk factors for VC in CKD include: Increasing age, dialysis vintage, hyperphosphatemia (particularly in the setting of intermittent or persistent hypercalcemia), and a positive net calcium and phosphate balance. Excessive oral calcium intake, including calcium-containing phosphate binders, increases the risk for VC. Moreover, it has been demonstrated that there is less VC progression with non-calcium-containing phosphate binders. Unfortunately, until now, a specific therapy to prevent progression or to facilitate regression of VC has been found, beyond careful attention to calcium and phosphate balance.