The role of cardiac pericytes in health and disease: therapeutic targets for myocardial infarction.

Millions of cardiomyocytes die immediately after myocardial infarction, regardless of whether the culprit coronary artery undergoes prompt revascularization. Residual ischaemia in the peri-infarct border zone causes further cardiomyocyte damage, resulting in a progressive decline in contractile function. To date, no treatment has succeeded in increasing the vascularization of the infarcted heart. In the past decade, new approaches that can target the heart's highly plastic perivascular niche have been proposed. The perivascular environment is populated by mesenchymal progenitor cells, fibroblasts, myofibroblasts and pericytes, which can together mount a healing response to the ischaemic damage. In the infarcted heart, pericytes have crucial roles in angiogenesis, scar formation and stabilization, and control of the inflammatory response. Persistent ischaemia and accrual of age-related risk factors can lead to pericyte depletion and dysfunction. In this Review, we describe the phenotypic changes that characterize the response of cardiac pericytes to ischaemia and the potential of pericyte-based therapy for restoring the perivascular niche after myocardial infarction. Pericyte-related therapies that can salvage the area at risk of an ischaemic injury include exogenously administered pericytes, pericyte-derived exosomes, pericyte-engineered biomaterials, and pharmacological approaches that can stimulate the differentiation of constitutively resident pericytes towards an arteriogenic phenotype. Promising preclinical results from in vitro and in vivo studies indicate that pericytes have crucial roles in the treatment of coronary artery disease and the prevention of post-ischaemic heart failure.

The Manufacturing Conditions for the Direct and Reproducible Formation of Electrospun PCL/Gelatine 3D Structures for Tissue Regeneration.

Electrospinning is a versatile technique for fabricating nanofibrous scaffolds for tissue engineering applications. However, the direct formation of 3D sponges through electrospinning has previously not been reproducible. We used a Taguchi experimental design approach to optimise the electrospinning parameters for forming PCL and PCL/gelatine 3D sponges. The following parameters were investigated to improve sponge formation: solution concentration, humidity, and solution conductivity. Pure PCL sponges were achievable. However, a much fluffier sponge formed by increasing the solution conductivity with gelatine. The optimal conditions for sponge formation 24 w/v% 80:20 PCL:gelatine on aluminium foil at ≥70% humidity, 15 cm, 22 kV and 1500 µL/h. The resulting sponge had a highly porous structure with a fibre diameter of ~1 µm. They also supported significantly higher cell viability than 2D electrospun mats, dropcast films of the same material and even the TCP positive control. Our study demonstrates that the direct formation of PCL/gelatine 3D sponges through electrospinning is feasible and promising for tissue engineering applications. The sponges have a highly porous structure and support cell viability, which are essential properties for tissue engineering scaffolds. Further studies are needed to optimise the manufacturing process and evaluate the sponges' long-term performance in vivo.

Ex Vivo Perfusion Culture of Large Blood Vessels in a 3D Printed Bioreactor.

Vascular disease forms the basis of most cardiovascular diseases (CVDs), which remain the primary cause of mortality and morbidity worldwide. Efficacious surgical and pharmacological interventions to prevent and treat vascular disease are urgently needed. In part, the shortage of translational models limits the understanding of the cellular and molecular processes involved in vascular disease. Ex vivo perfusion culture bioreactors provide an ideal platform for the study of large animal vessels (including humans) in a controlled dynamic environment, combining the ease of in vitro culture and the complexity of the live tissue. Most bioreactors are, however, custom manufactured and therefore difficult to adopt, limiting the reproducibility of the results. This paper presents a 3D printed system that can be easily produced and applied in any biological lab, and provides a detailed protocol for its setup, enabling users' operation. This innovative and reproducible ex vivo perfusion culture system enables the culture of blood vessels for up to 7 days in physiological conditions. We expect that adopting a standardized perfusion bioreactor will support a better understanding of physiological and pathological processes in large animal blood vessels and accelerate the discovery of new therapeutics.

Age-Dependent Decline in Common Femoral Artery Flow-Mediated Dilation and Wall Shear Stress in Healthy Subjects.

Femoral artery (FA) endothelial function is a promising biomarker of lower extremity vascular health for peripheral artery disease (PAD) prevention and treatment; however, the impact of age on FA endothelial function has not been reported in healthy adults. Therefore, we evaluated the reproducibility and acceptability of flow-mediated dilation (FMD) in the FA and brachial artery (BA) (n = 20) and performed cross-sectional FA- and BA-FMD measurements in healthy non-smokers aged 22−76 years (n = 50). FMD protocols demonstrated similar good reproducibility. Leg occlusion was deemed more uncomfortable than arm occlusion; thigh occlusion was less tolerated than forearm and calf occlusion. FA-FMD with calf occlusion was lower than BA-FMD (6.0 ± 1.1% vs 6.4 ± 1.3%, p = 0.030). Multivariate linear regression analysis indicated that age (−0.4%/decade) was a significant independent predictor of FA-FMD (R2 = 0.35, p = 0.002). The age-dependent decline in FMD did not significantly differ between FA and BA (pinteraction agexlocation = 0.388). In older participants, 40% of baseline FA wall shear stress (WSS) values were <5 dyne/cm2, which is regarded as pro-atherogenic. In conclusion, endothelial function declines similarly with age in the FA and the BA in healthy adults. The age-dependent FA enlargement results in a critical decrease in WSS that may explain part of the age-dependent predisposition for PAD.

Cocoa flavanol consumption improves lower extremity endothelial function in healthy individuals and people with type 2 diabetes.

Background: diabetes and age are major risk factors for the development of lower extremity peripheral artery disease (PAD). Cocoa flavanol (CF) consumption is associated with lower risk for PAD and improves brachial artery (BA) endothelial function. Objectives: to assess if femoral artery (FA) endothelial function and dermal microcirculation are impaired in individuals with type 2 diabetes mellitus (T2DM) and evaluate the acute effect of CF consumption on FA endothelial function. Methods: in a randomised, controlled, double-blind, cross-over study, 22 individuals (n = 11 healthy, n = 11 T2DM) without cardiovascular disease were recruited. Participants received either 1350 mg CF or placebo capsules on 2 separate days in random order. Endothelial function was measured as flow-mediated dilation (FMD) using ultrasound of the common FA and the BA before and 2 hours after interventions. The cutaneous microvasculature was assessed using optical coherence tomography angiography. Results: baseline FA-FMD and BA-FMD were significantly lower in T2DM (FA: 3.2 ± 1.1% [SD], BA: 4.8 ± 0.8%) compared to healthy (FA: 5.5 ± 0.7%, BA: 6.0 ± 0.8%); each p < 0.001. Whereas in healthy individuals FA-FMD did not significantly differ from BA-FMD (p = 0.144), FA-FMD was significantly lower than BA-FMD in T2DM (p = 0.003) indicating pronounced and additional endothelial dysfunction of lower limb arteries (FA-FMD/BA-FMD: 94 ± 14% [healthy] vs. 68 ± 22% [T2DM], p = 0.007). The baseline FA blood flow rate (0.42 ± 0.23 vs. 0.73 ± 0.35 l min-1, p = 0.037) and microvascular dilation in response to occlusion in hands and feet were significantly lower in T2DM subjects than in healthy ones. CF increased both FA- and BA-FMD at 2 hours, compared to placebo, in both healthy and T2DM subgroups (FA-FMD effect: 2.9 ± 1.4%, BA-FMD effect 3.0 ± 3.5%, each pintervention< 0.001). In parallel, baseline FA blood flow and microvascular diameter significantly increased in feet (3.5 ± 3.5 µm, pintervention< 0.001) but not hands. Systolic blood pressure and pulse wave velocity significantly decreased after CF in both subgroups (-7.2 ± 9.6 mmHg, pintervention = 0.004; -1.3 ± 1.3 m s-1, pintervention = 0.002). Conclusions: individuals with T2DM exhibit decreased endothelial function that is more pronounced in the femoral than in the brachial artery. CFs increase endothelial function not only in the BA but also the FA both in healthy individuals and in those with T2DM who are at increased risk of developing lower extremity PAD and foot ulcers.

Porcine Organotypic Epicardial Slice Protocol: A Tool for the Study of Epicardium in Cardiovascular Research.

The epicardium has recently gained interest in the cardiovascular field due to its capacity to support heart regeneration after ischemic injury. Models to study the epicardium of large animals in vitro are limited and mainly based on epicardial cell isolation/differentiation from stem cells, followed by 2D cells culture. In this method paper, we describe the procedure to obtain and culture 3D organotypic heart slices presenting an intact epicardium, as a novel model to study the epicardial physiology and activation. Epicardial slices are obtained from porcine hearts using a high-precision vibratome and retain a healthy epicardial layer embedded in its native extracellular environment and connected with other cardiac cells (cardiomyocytes, fibroblasts, vascular cells etc.). Epicardial slices can be cultured for 72 h, providing an ideal model for studying the epicardium physiology or perform pharmacological interventions/gene therapy approaches. We also report on methods to assesses the viability and composition of the epicardial slices, and evaluate their architecture in 3D through tissue decoloration. Finally, we present a potential application for a nanomaterial-based gene transfer method for tracking of epicardial cells within the slice. Crucially, given the similarity in morphology and physiology of porcine heart with its human counterpart, our system provides a platform for translational research while providing a clinically relevant and ethical alternative to the use of small animals in this type of research.

3D Printed Bioreactor Enabling the Pulsatile Culture of Native and Angioplastied Large Arteries.

Routine interventions such as balloon angioplasty, result in vascular activation and remodeling, often requiring re-intervention. 2D in vitro models and small animal experiments have enabled the discovery of important mechanisms involved in this process, however the clinical translation is often underwhelming. There is a critical need for an ex vivo model representative of the human vascular physiology and encompassing the complexity of the vascular wall and the physical forces regulating its function. Vascular bioreactors for ex vivo culture of large vessels are viable alternatives, but their custom-made design and insufficient characterization often hinders the reproducibility of the experiments. The objective of the study was to design and validate a novel 3D printed cost-efficient and versatile perfusion system, capable of sustaining the viability and functionality of large porcine arteries for 7 days and enabling early post-injury evaluations. MultiJet Fusion 3D printing was used to engineer the EasyFlow insert, converting a conventional 50 ml centrifuge tube into a mini bioreactor. Porcine carotid arteries either left untreated or injured with an angioplasty balloon, were cultured under pulsatile flow for up to 7 days. Pressure, heart rate, medium viscosity and shear conditions were adjusted to resemble arterial in vivo hemodynamics. Tissue viability, cell activation and matrix remodeling were analyzed by immunohistochemistry, and vascular function was monitored by duplex ultrasound. Culture conditions in the EasyFlow bioreactor preserved endothelial coverage and smooth muscle organization and extracellular matrix structure in the vessel wall, as compared to static culture. Injured arteries presented hallmarks of early remodeling, such as intimal denudation, smooth muscle cell disarray and media/adventitia activation in flow culture. Duplex ultrasound confirmed continuous pulsatile blood flow conditions, dose-dependent vasodilator response to nitroglycerin in untreated vessels and impaired dilator response in angioplastied vessels. The scope of this work is to validate a low-cost, robust and reproducible system to explore the culture of native and injured large arteries under pulsatile flow. While the study of vascular pathology is beyond the scope of the present paper, our system enables future investigations and provides a platform to test novel therapies and devices ex vivo, in a patient relevant system.

Mosquito saliva enhances virus infection through sialokinin-dependent vascular leakage.

Viruses transmitted by Aedes mosquitoes are an increasingly important global cause of disease. Defining common determinants of host susceptibility to this large group of heterogenous pathogens is key for informing the rational design of panviral medicines. Infection of the vertebrate host with these viruses is enhanced by mosquito saliva, a complex mixture of salivary-gland-derived factors and microbiota. We show that the enhancement of infection by saliva was dependent on vascular function and was independent of most antisaliva immune responses, including salivary microbiota. Instead, the Aedes gene product sialokinin mediated the enhancement of virus infection through a rapid reduction in endothelial barrier integrity. Sialokinin is unique within the insect world as having a vertebrate-like tachykinin sequence and is absent from Anopheles mosquitoes, which are incompetent for most arthropod-borne viruses, whose saliva was not proviral and did not induce similar vascular permeability. Therapeutic strategies targeting sialokinin have the potential to limit disease severity following infection with Aedes-mosquito-borne viruses.

Assessing Variability in Vascular Response to Cocoa With Personal Devices: A Series of Double-Blind Randomized Crossover n-of-1 Trials.

Controlled clinical intervention studies have demonstrated that cocoa flavanols (CF) can decrease blood pressure and arterial stiffness in healthy humans, although a large variability in the effect size across trials has been reported. In this study, we evaluated the intra- and inter-individual variability of responses to CF in everyday life using a series of n-of-1 trials in healthy free-living individuals with normal blood pressure carrying personal devices. In total, eleven healthy young humans participated in a repeated crossover randomized controlled double-blind n-of-1 trial. On 8 consecutive days, each volunteer consumed on alternating days 6 CF capsules (862 mg CF) on 4 days and 6 matched placebo capsules (P, 0 mg CF/day) on another 4 days in one of the two randomized sequences (CF-P-CF-P-CF-P-CF-P or P-CF-P-CF-P-CF-P-CF). On each day, the capsules were taken at the same time in the morning with breakfast after baseline measurements. Each subject was provided with an upper arm blood pressure monitor and a finger clip that measures pulse wave velocity (PWV). Measurements of blood pressure, heart rate, and PWV were taken at least hourly over 12 h during the day by the participants. On the first 2 days, measurements were performed under supervision to provide training. The overall mixed model analysis showed that CF significantly decreased 12-h systolic blood pressure and PWV by -1.4 ± 0.3 mmHg and -0.11 ± 0.03 m/s, respectively. Peak effects were observed within the first 3 h (1.5 h SBP: -4.9 ± 2.2 mmHg, PWV: -0.32 ± 0.17 m/s) and again after 8 h post-ingestion. Large inter-individual variation in responses was found [intra-cluster correlation coefficients (ICC): 0.41, 0.41]. When analyzing single individuals' datasets, there was also considerable between-day variation in individual responses that varied greatly between subjects (ICC: 0-0.30, 0-0.22, 0-0.45). Effect sizes inversely correlated with baseline blood pressure values both between- and within-subjects. The data confirm that cocoa can decrease blood pressure and arterial stiffness in everyday life when elevated within the normal range. The large inter- and intra-individual variation in responses calls for more personalized nutritional intervention strategies.

Pericytes' Circadian Clock Affects Endothelial Cells' Synchronization and Angiogenesis in a 3D Tissue Engineered Scaffold.

Angiogenesis, the formation of new capillaries from existing ones, is a fundamental process in regenerative medicine and tissue engineering. While it is known to be affected by circadian rhythms in vivo, its peripheral regulation within the vasculature and the role it performs in regulating the interplay between vascular cells have not yet been investigated. Peripheral clocks within the vasculature have been described in the endothelium and in smooth muscle cells. However, to date, scarce evidence has been presented regarding pericytes, a perivascular cell population deeply involved in the regulation of angiogenesis and vessel maturation, as well as endothelial function and homeostasis. More crucially, pericytes are also a promising source of cells for cell therapy and tissue engineering. Here, we established that human primary pericytes express key circadian genes and proteins in a rhythmic fashion upon synchronization. Conversely, we did not detect the same patterns in cultured endothelial cells. In line with these results, pericytes' viability was disproportionately affected by circadian cycle disruption, as compared to endothelial cells. Interestingly, endothelial cells' rhythm could be induced following exposure to synchronized pericytes in a contact co-culture. We propose that this mechanism could be linked to the altered release/uptake pattern of lactate, a known mediator of cell-cell interaction which was specifically altered in pericytes by the knockout of the key circadian regulator Bmal1. In an angiogenesis assay, the maturation of vessel-like structures was affected only when both endothelial cells and pericytes did not express Bmal1, indicating a compensation system. In a 3D tissue engineering scaffold, a synchronized clock supported a more structured organization of cells around the scaffold pores, and a maturation of vascular structures. Our results demonstrate that pericytes play a critical role in regulating the circadian rhythms in endothelial cells, and that silencing this system disproportionately affects their pro-angiogenic function. Particularly, in the context of tissue engineering and regenerative medicine, considering the effect of circadian rhythms may be critical for the development of mature vascular structures and to obtain the maximal reparative effect.

OCTAVA: An open-source toolbox for quantitative analysis of optical coherence tomography angiography images.

Optical coherence tomography angiography (OCTA) performs non-invasive visualization and characterization of microvasculature in research and clinical applications mainly in ophthalmology and dermatology. A wide variety of instruments, imaging protocols, processing methods and metrics have been used to describe the microvasculature, such that comparing different study outcomes is currently not feasible. With the goal of contributing to standardization of OCTA data analysis, we report a user-friendly, open-source toolbox, OCTAVA (OCTA Vascular Analyzer), to automate the pre-processing, segmentation, and quantitative analysis of en face OCTA maximum intensity projection images in a standardized workflow. We present each analysis step, including optimization of filtering and choice of segmentation algorithm, and definition of metrics. We perform quantitative analysis of OCTA images from different commercial and non-commercial instruments and samples and show OCTAVA can accurately and reproducibly determine metrics for characterization of microvasculature. Wide adoption could enable studies and aggregation of data on a scale sufficient to develop reliable microvascular biomarkers for early detection, and to guide treatment, of microvascular disease.

The emerging role of perivascular cells (pericytes) in viral pathogenesis.

Viruses may exploit the cardiovascular system to facilitate transmission or within-host dissemination, and the symptoms of many viral diseases stem at least in part from a loss of vascular integrity. The microvascular architecture is comprised of an endothelial cell barrier ensheathed by perivascular cells (pericytes). Pericytes are antigen-presenting cells (APCs) and play crucial roles in angiogenesis and the maintenance of microvascular integrity through complex reciprocal contact-mediated and paracrine crosstalk with endothelial cells. We here review the emerging ways that viruses interact with pericytes and pay consideration to how these interactions influence microvascular function and viral pathogenesis. Major outcomes of virus-pericyte interactions include vascular leakage or haemorrhage, organ tropism facilitated by barrier disruption, including viral penetration of the blood-brain barrier and placenta, as well as inflammatory, neurological, cognitive and developmental sequelae. The underlying pathogenic mechanisms may include direct infection of pericytes, pericyte modulation by secreted viral gene products and/or the dysregulation of paracrine signalling from or to pericytes. Viruses we cover include the herpesvirus human cytomegalovirus (HCMV, Human betaherpesvirus 5), the retrovirus human immunodeficiency virus (HIV; causative agent of acquired immunodeficiency syndrome, AIDS, and HIV-associated neurocognitive disorder, HAND), the flaviviruses dengue virus (DENV), Japanese encephalitis virus (JEV) and Zika virus (ZIKV), and the coronavirus severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2; causative agent of coronavirus disease 2019, COVID-19). We touch on promising pericyte-focussed therapies for treating the diseases caused by these important human pathogens, many of which are emerging viruses or are causing new or long-standing global pandemics.

A Critical Role for Perivascular Cells in Amplifying Vascular Leakage Induced by Dengue Virus Nonstructural Protein 1.

Dengue is the most prevalent arthropod-borne viral disease affecting humans, with severe dengue typified by potentially fatal microvascular leakage and hypovolemic shock. Blood vessels of the microvasculature are composed of a tubular structure of endothelial cells ensheathed by perivascular cells (pericytes). Pericytes support endothelial cell barrier formation and maintenance through paracrine and contact-mediated signaling and are critical to microvascular integrity. Pericyte dysfunction has been linked to vascular leakage in noncommunicable pathologies such as diabetic retinopathy but has never been linked to infection-related vascular leakage. Dengue vascular leakage has been shown to result in part from the direct action of the secreted dengue virus (DENV) nonstructural protein NS1 on endothelial cells. Using primary human vascular cells, we show here that NS1 also causes pericyte dysfunction and that NS1-induced endothelial hyperpermeability is more pronounced in the presence of pericytes. Notably, NS1 specifically disrupted the ability of pericytes to support endothelial cell function in a three-dimensional (3D) microvascular assay, with no effect on pericyte viability or physiology. These effects are mediated at least in part through contact-independent paracrine signals involved in endothelial barrier maintenance by pericytes. We therefore identify a role for pericytes in amplifying NS1-induced microvascular hyperpermeability in severe dengue and thus show that pericytes can play a critical role in the etiology of an infectious vascular leakage syndrome. These findings open new avenues of research for the development of drugs and diagnostic assays for combating infection-induced vascular leakage, such as severe dengue.IMPORTANCE The World Health Organization considers dengue one of the top 10 global public health problems. There is no specific antiviral therapy to treat dengue virus and no way of predicting which patients will develop potentially fatal severe dengue, typified by vascular leakage and circulatory shock. We show here that perivascular cells (pericytes) amplify the vascular leakage-inducing effects of the dengue viral protein NS1 through contact-independent signaling to endothelial cells. While pericytes are known to contribute to noncommunicable vascular leakage, this is the first time these cells have been implicated in the vascular effects of an infectious disease. Our findings could pave the way for new therapies and diagnostics to combat dengue and potentially other infectious vascular leakage syndromes.

Angiogenesis in Tissue Engineering: As Nature Intended?

Despite the steady increase in the number of studies focusing on the development of tissue engineered constructs, solutions delivered to the clinic are still limited. Specifically, the lack of mature and functional vasculature greatly limits the size and complexity of vascular scaffold models. If tissue engineering aims to replace large portions of tissue with the intention of repairing significant defects, a more thorough understanding of the mechanisms and players regulating the angiogenic process is required in the field. This review will present the current material and technological advancements addressing the imperfect formation of mature blood vessels within tissue engineered structures.

Textile-based non-invasive lithium drug monitoring: A proof-of-concept study for wearable sensing.

Flexible wearable chemical sensors are emerging tools which target diagnosis and monitoring of medical conditions. One of the potential applications of wearable chemical sensors is therapeutic drug monitoring for drugs that have a narrow therapeutic range such as lithium. We have investigated the possibility of developing a fibre-based device for non-invasive lithium drug monitoring in interstitial fluid. A flexible cotton-based lithium sensor was coupled with a carbon fibre-based reference electrode to obtain a potentiometric device. In vitro reverse iontophoresis experiments were performed to extract Li+ from under porcine skin by applying a current density of 0.4 mA cm-2 via two electrodes. Carbon fibre-based reverse iontophoresis electrodes were fabricated and used instead of a conventional silver wire-based version and comparable results were obtained. The fibre-based Li+ sensor and reference electrodes were capable of determining the Li+ concentration in samples collected via reverse iontophoresis and the results compared well to those obtained by ion chromatography. Additionally, biocompatibility of the materials used have been tested. Promising results were obtained which confirm the possibility of monitoring lithium in interstitial fluid using a wearable sensor.

Scalable High-Affinity Stabilization of Magnetic Iron Oxide Nanostructures by a Biocompatible Antifouling Homopolymer.

Iron oxide nanostructures have been widely developed for biomedical applications because of their magnetic properties and biocompatibility. In clinical applications, stabilization of these nanostructures against aggregation and nonspecific interactions is typically achieved using weakly anchored polysaccharides, with better-defined and more strongly anchored synthetic polymers not commercially adopted because of their complexity of synthesis and use. Here, we show for the first time stabilization and biocompatibilization of iron oxide nanoparticles by a synthetic homopolymer with strong surface anchoring and a history of clinical use in other applications, poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)]. For the commercially important case of spherical particles, binding of poly(MPC) to iron oxide surfaces and highly effective individualization of magnetite nanoparticles (20 nm) are demonstrated. Next-generation high-aspect-ratio nanowires (both magnetite/maghemite and core-shell iron/iron oxide) are, furthermore, stabilized by poly(MPC) coating, with the nanowire cytotoxicity at large concentrations significantly reduced. The synthesis approach exploited to incorporate functionality into the poly(MPC) chain is demonstrated by random copolymerization with an alkyne-containing monomer for click chemistry. Taking these results together, poly(MPC) homopolymers and random copolymers offer a significant improvement over current iron oxide nanoformulations, combining straightforward synthesis, strong surface anchoring, and well-defined molecular weight.

Perivascular cells and tissue engineering: Current applications and untapped potential.

The recent development of tissue engineering provides exciting new perspectives for the replacement of failing organs and the repair of damaged tissues. Perivascular cells, including vascular smooth muscle cells, pericytes and other tissue specific populations residing around blood vessels, have been isolated from many organs and are known to participate to the in situ repair process and angiogenesis. Their potential has been harnessed for cell therapy of numerous pathologies; however, in this Review we will discuss the potential of perivascular cells in the development of tissue engineering solutions for healthcare. We will examine their application in the engineering of vascular grafts, cardiac patches and bone substitutes as well as other tissue engineering applications and we will focus on their extensive use in the vascularization of engineered constructs. Additionally, we will discuss the emerging potential of human pericytes for the development of efficient, vascularized and non-immunogenic engineered constructs.