Recruitment Of Endothelial Cells Research Articles

Kidney Decellularized Extracellular Matrix Enhanced the Vascularization and Maturation of Human Kidney Organoids.

Kidney organoids derived from human pluripotent stem cells (hPSCs) have extensive potential for disease modelling and regenerative medicine. However, the limited vascularization and immaturity of kidney organoids have been still remained to overcome. Extracellular matrix (ECM) can provide mechanical support and a biochemical microenvironment for cell growth and differentiation. Here in vitro methods using a kidney decellularized extracellular matrix (dECM) hydrogel to culture hPSC‐derived kidney organoids, which have extensive vascular network and their own endothelial cells, are reported. Single‐cell transcriptomics reveal that the vascularized kidney organoids cultured using the kidney dECM have more mature patterns of glomerular development and higher similarity to human kidney than those cultured without the kidney dECM. Differentiation of α‐galactosidase A (GLA)‐knock‐out hPSCs generated using CRISPR/Cas9 into kidney organoids by the culture method using kidney dECM efficiently recapitulate Fabry nephropathy with vasculopathy. Transplantation of kidney organoids with kidney dECM into kidney of mouse accelerates the recruitment of endothelial cells from the host mouse kidney and maintains vascular integrity with the more organized slit diaphragm‐like structures than those without kidney dECM. The kidney dECM methodology for inducing extensive vascularization and maturation of kidney organoids can be applied to studies for kidney development, disease modeling, and regenerative medicine.

SDF-1α loaded bioengineered human amniotic membrane-derived scaffold transplantation in combination with hyperbaric oxygen improved diabetic wound healing

Based on its multifactorial nature, successful treatment of diabetic wounds requires combinatorial approach. In this regard, we hypothesized that engraftment of a bioengineered micro-porous three-dimensional human amniotic membrane-scaffold (HAMS) loaded by SDF-1α (SHAMS) in combination with hyperbaric oxygen (HBO), throughout mobilization and recruitment of endothelial progenitor cells (EPCs), could accelerate wound healing in rats with type 1 diabetes mellitus. To test this hypothesis, 30 days after inducting diabetes, an ischemic wound was created in rat skin and treatments were performed for 21 days. In addition to wounded non-diabetic (ND) group, diabetic animals were randomly divided into non-treated (NT-D), HBO-treated (HBO-D), HBO-treated plus HAMS transplantation (HBO+HAMS-D) or HBO-treated in combination with SHAMS transplantation (HBO+SHAMS-D) groups. Our results on post-wounding days 7, 14 and 21 showed that the wound closure, volume of new dermis and epidermis, numerical density of basal cells of epidermis, fibroblasts and blood vessels, number of proliferating cells, deposition of collagen and biomechanical properties of healed wound were considerably higher in both HBO+HAMS-D and HBO+SHAMS-D groups in comparison to those of the NT-D and HBO-D groups, and were the highest in HBO+SHAMS-D ones. The transcripts for Vegf, bFgf, and Tgf-β genes were significantly upregulated in all treatment regimens compared to NT-D group and were the highest for HBO+SHAMS-D group. This is while expression of Tnf-α and Il-1β as well as cell density of neutrophil and macrophage decreased more significantly in HBO+SHAMS-D group as compared with NT-D or HBO-D groups. Overall, it was found that using both HAMS transplantation and HBO treatment has more impact on diabetic wound healing. Moreover, SDF-1α loading on HAMS could transiently improve the wound healing process, as compared with the HBO+HAMS-D group on day 7 only.

A0085 - Bladder cancer-derived TSP4 advances lymphangiogenesis through lymphatic endothelial cell recruitment

A0085 - Bladder cancer-derived TSP4 advances lymphangiogenesis through lymphatic endothelial cell recruitment

Endothelial Cells Promote Osteogenesis by Establishing a Functional and Metabolic Coupling With Human Mesenchymal Stem Cells.

Bone formation involves a complex crosstalk between endothelial cells (EC) and osteodifferentiating stem cells. This functional interplay is greatly mediated by the paracrine and autocrine action of soluble factors released at the vasculature-bone interface. This study elucidates the molecular and functional responses triggered by this intimate interaction. In this study, we showed that human dermal microvascular endothelial cells (HMEC) induced the expression of pro-angiogenic factors in stem cells from human exfoliated deciduous teeth (SHED) and sustain their osteo-differentiation at the same time. In contrast, osteodifferentiating SHED increased EC recruitment and promoted the formation of complex vascular networks. Moreover, HMEC enhanced anaerobic glycolysis in proliferating SHED without compromising their ability to undergo the oxidative metabolic shift required for adequate osteo-differentiation. Taken together, these findings provide novel insights into the molecular mechanism underlying the synergistic cooperation between EC and stem cells during bone tissue renewal.

Astragaloside IV promotes the angiogenic capacity of adipose-derived mesenchymal stem cells in a hindlimb ischemia model by FAK phosphorylation via CXCR2

BackgroundTherapeutic angiogenesis by transplantation of autologous/allogeneic adipose stem cells (ADSCs) is a potential method for the treatment of critical limb ischemia (CLI). However, the therapeutic efficiency is limited by poor viability, adhesion, migration and differentiation after cell transplantation into the target area. Astragaloside IV (AS-IV), one of the main active components of Astragalus, has been widely used in the treatment of ischemic diseases and can promote cell proliferation and angiogenesis. However, there is no report on the effect of AS-IV on ADSCs and its effect on hindlimb ischemia through cell transplantation. PurposeThe purpose of this study was to elucidate that AS-IV pretreatment enhances the therapeutic effect of ADSC on critical limb ischemia, and to characterize the underlying molecular mechanisms. MethodsADSCs were obtained and pretreated with the different concentration of AS-IV. In vitro, we analyzed the influence of AS-IV on ADSC proliferation, migration, angiogenesis and recruitment of human umbilical vein endothelial cells (HUVECs) and analyzed the relevant molecular mechanism. In vivo, we injected drug-pretreated ADSCs into a Matrigel or hindlimb ischemia model and evaluated the therapeutic effect by the laser Doppler perfusion index, immunofluorescence, and histopathology. ResultsIn vitro experiments showed that AS-IV improved ADSC migration, angiogenesis and endothelial recruitment. The molecular mechanism may be related to the upregulation of CXC receptor 2 (CXCR2) to promote the phosphorylation of focal adhesion kinase (FAK). In vivo, Matrigel plug assay showed that ADSCs pretreated with AS-IV have stronger angiogenic potential. The laser Doppler perfusion index of the hindlimbs of mice in the ADSC/AS-IV group was significantly higher than the laser Doppler perfusion index of the hindlimbs of mice of the ADSC group and the control group, and the microvessel density was significantly increased. ConclusionOur results demonstrate that AS-IV pretreatment of ADSC improves their therapeutic efficacy in ameliorating severe limb exclusion symptomology through CXCR2 induced FAK phosphorylation, which will bring new insights into the treatment of severe limb ischemia.

Three-dimensional printing of bioceramic-induced macrophage exosomes: immunomodulation and osteogenesis/angiogenesis

Exosomes have attracted increasing attention in tissue regeneration and repair due to their roles in intercellular communication. Developing a customized delivery system is key to exosome-based regenerative therapeutics. Bioceramics play an important role in the immunomodulation of macrophages. Here, three-dimensional (3D) printing was applied to construct porous scaffolds with β-tricalcium phosphate (β-TCP) bioceramic-induced macrophage exosomes (BC-Exos). The three-dimensional-printed BC-Exo scaffolds, exhibiting a predefined structure and persistent release of exosomes, displayed distinct immunomodulatory effects and improved osteogenesis/angiogenesis. The BC-Exos in the printed scaffolds modulated macrophage polarization and the expression of chemokines for the recruitment of bone marrow mesenchymal stem cells (BMSCs) and endothelial cells. Scaffolds with BC-Exos from macrophages with a mixed phenotype significantly enhanced the osteogenic differentiation and immunosuppression of BMSCs and improved the angiogenic activity of human umbilical vein endothelial cells in vitro. For the potential mechanism, β-TCP bioceramics have an important effect on the immunomodulation of macrophages by regulating gene expression, increasing exosome production, and altering exosomal miRNA cargos, thereby affecting the paracrine effects of BC-Exos on immunomodulation and osteogenesis/angiogenesis. This study suggests that 3D printing of bioceramic-induced macrophage exosomes may be a useful strategy for tissue engineering and regenerative medicine.

Interrod spacing dependent angiogenesis and osseointegration of Na2TiO3 nanorods-patterned arrays via immunoregulation

Nanorods-arrayed coatings show topographical parameters-dependent immunomodulation that plays a key role in angiogenesis and consequent osseoinegration, while immunomodulation by interrod spacing, as a solely altered topographic parameter of an array, has not been clarified yet. In this context, four kinds of nanorods-arrayed coatings, appearing similar surface roughness and hydrophilia, were hydrothermally grown on Ti. The coatings comprise a bilayer structure with compact nanogranular Na2TiO3 as an inner layer and Na2TiO3 nanorods-patterned array as an outer layer. The nanorods in the coatings exhibit identical rod diameter and length but different interrod spacing values of ~ 45, 75, 140, and 245 nm, respectively. Compared to Ti, the arrayed coatings promote adhesion and filopodia formation of macrophages to accelarate their transformation from pro-inflammatory M1 phenotype to anti-inflammatory M2 phenotype. Moreover, the accelaration is more pronounced by the coatings with nanoscale interrod spacing (especially ~ 75 nm) compared to those with submicro-scale spacing. The rapid phenotypic switch of macrophages on the arrayed coatings trigers the increase in their secretion of pro-angiogenic factors, including PDGF-BB, ANG1 and SDF-1, to enhance recruitment and angiogenesis of human umbilical vein endothelial cells (HUVECs) in co-culture condition, and the enhancment is the most pronounced for HUVECs in response to macrophages on ~ 75 nm spaced nanorods-arrayed coating. Owing to the favorable immune microenvironment induced by the coating and consequently enhanced angiogenesis, ~ 75 nm spaced nanorods-arrayed coating exhibits the best osseoinetegration in rat femoral condyles. Our work provides insights into the surface structural design of an orthopedic implant favoring osseointegration.

English

Thalassemia, derived from Thalassa [Greek: Sea] refers to a cluster of hereditary haemoglobinopathies initially reported in areas of Sub-Saharan Africa, the Indian subcontinent, Southeast Asia, and the Mediterranean where malaria was (or is) endemic. Currently, it is the most frequently recognized haemoglobinopathy, and has been correlated with a plethora of immune system changes such as neutropenia, natural killer cell dysfunctions, increased activity of CD8 suppressor cells, along with disturbances in macrophage function, chemotaxis, phagocytosis, and interferons INFγ production.1 The reduction in the alpha or beta chain that leads to the production of haemoglobin is the key pathophysiology behind thalassemia. Therefore, weakened red blood cells can contribute to inadequate erythropoiesis and haemolytic anaemia. Thalassemia diseases are known as transfusion-dependent or non-dependent according to either their beta-globin chain genotype or their clinical path. The most serious type of thalassemia is beta-thalassemia major, and it is transfusiondependent, presenting in early infancy.2 A diagnosis of β-thalassemia major (BTM) means lifelong, regular transfusions, supplemented with adequate iron chelation therapy for the patient.3 This also means that unless adequate blood screening and hygiene procedures are in place, patients with BTM are at a risk of transfusion transmitted infections (TTI).4 Many countries have been prompted by the spread of Covid-19 infection to shutter routine outpatient coronary health care units before the pandemic is over, which also extends to people with thalassemia, who require regular follow-ups. While Covid-19 infection rates remain high, patients with thalassemia with planned cardiovascular examinations are advised to delay their medical appointments for a minimum of 3 months.1 In addition, according to the statement published by the Thalassemia International Foundation on the 13th of July, 2020, patients with hemoglobinopathies are at a greater risk in acquiring the Covid-19 infection, posing an additional challenge to the patients, families, and medical staff managing these disorders.5 Thalassaemic patients have reduced levels of protein S and protein C; elevated aggregation of platelets; and recruitment of monocytes, granulocytes, and endothelial cells. Patients of thalassemia also show elevated markers of platelet and coagulation activation, even in the absence of major thromboembolic events. An increase in D-Dimer levels is also seen in most Covid-19 patients who are hospitalised, attributable to the underlying inflammatory process.1 A variety of questions have been raised during the ongoing Covid-19 pandemic with respect to diagnostic and clinical approaches towards this particular population. The precise path of infection with Covid-19 in those patients has yet to be elucidated.2 The progression of Covid-19 infection in patients with hemoglobinopathy in general and thalassemia in particular is not fully known and is still an area of discussion and under review. We report a case of a 30-year-old male patient, a known case of beta thalassemia major on maintenance transfusion and iron chelation therapy who acquired Covid-19 infection.

Perivascular cell-derived extracellular vesicles stimulate colorectal cancer revascularization after withdrawal of antiangiogenic drugs.

Antiangiogenic tyrosine kinase inhibitors (AA‐TKIs) have become a promising therapeutic strategy for colorectal cancer (CRC). In clinical practice, a significant proportion of cancer patients temporarily discontinue AA‐TKI treatment due to recurrent toxicities, economic burden or acquired resistance. However, AA‐TKI therapy withdrawal‐induced tumour revascularization frequently occurs, hampering the clinical application of AA‐TKIs. Here, this study demonstrates that tumour perivascular cells mediate tumour revascularization after withdrawal of AA‐TKI therapy. Pharmacological inhibition and genetic ablation of perivascular cells largely attenuate the rebound effect of CRC vascularization in the AA‐TKI cessation experimental settings. Mechanistically, tumour perivascular cell‐derived extracellular vehicles (TPC‐EVs) contain Gas6 that instigates the recruitment of endothelial progenitor cells (EPCs) for tumour revascularization via activating the Axl pathway. Gas6 silence and an Axl inhibitor markedly inhibit tumour revascularization by impairing EPC recruitment. Consequently, combination therapy of regorafenib with the Axl inhibitor improves overall survival in mice metastatic CRC model by inhibiting tumour growth. Together, these data shed new mechanistic insights into perivascular cells in off‐AA‐TKI‐induced tumour revascularization and indicate that blocking the Axl signalling may provide an attractive anticancer approach for sustaining long‐lasting angiostatic effects to improve the therapeutic outcomes of antiangiogenic drugs in CRC.

New insights into spatio-temporal dynamics of mesenchymal progenitor cell ingress during peri-implant wound healing: Provided by intravital imaging

Surface topography drives the success of orthopedic and dental implants placed in bone, by directing the biology occurring at the tissue-implant interface. Over the last few decades, striking advancements have been made in the development of novel implant surfaces that enhance bone anchorage to their surfaces through contact osteogenesis: the combination of the two phenomena of recruitment and migration of mesenchymal progenitor cells to the implant surface, and their differentiation into bone-forming cells. While the latter is generally understood, the mechanisms and dynamics underlying the migration and recruitment of such progenitor cells into the wound site have garnered little attention. To address this deficit, we surgically inserted metallic implants with two different surface topographies into the skulls of mice, and then employed real-time spatiotemporal microscopic monitoring of the peri-implant tissue healing to track the ingress of cells. Our results show that nano-topographically complex, in comparison to relatively smooth, implant surfaces profoundly affect recruitment of both endothelial cells, which are essential for angiogenesis, and the mesenchymal progenitor cells that give rise to the reparative tissue stroma. The latter appear concomitantly in the wound site with endothelial cells, from the vascularized areas of the periosteum, and demonstrate a proliferative “bloom” that diminishes with time, although some of these cells differentiate into important stromal cells, pericytes and osteocytes, of the reparative wound. In separate experiments we show, using trajectory plots, that the directionality of migration for both endothelial and perivascular cells can be explained by implant surface dependent release of local cytokine gradients from platelets that would become activated on the implant surfaces during initial blood contact. These findings provide new biological insights into the earliest stages of wound healing, and have broad implications in the application of putative nano-topographically complex biomaterials in many tissue types.

Melanoma Associated Chitinase 3-Like 1 Promoted Endothelial Cell Activation and Immune Cell Recruitment.

Chitinase 3-like 1 (CHI3L1) is an enzymatically inactive mammalian chitinase that is associated with tumor inflammation. Previous research indicated that CHI3L1 is able to interact with different extracellular matrix components, such as heparan sulfate. In the present work, we investigated whether the interaction of CHI3L1 with the extracellular matrix of melanoma cells can trigger an inflammatory activation of endothelial cells. The analysis of the melanoma cell secretome indicated that CHI3L1 increases the abundance of various cytokines, such as CC-chemokine ligand 2 (CCL2), and growth factors, such as vascular endothelial growth factor A (VEGF-A). Using a solid-phase binding assay, we found that heparan sulfate-bound VEGF-A and CCL2 were displaced by recombinant CHI3L1 in a dose-dependent manner. Microfluidic experiments indicated that the CHI3L1 altered melanoma cell secretome promoted immune cell recruitment to the vascular endothelium. In line with the elevated VEGF-A levels, CHI3L1 was also able to promote angiogenesis through the release of extracellular matrix-bound pro-angiogenic factors. In conclusion, we showed that CHI3L1 is able to affect the tumor cell secretome, which in turn can regulate immune cell recruitment and blood vessel formation. Accordingly, our data suggest that the molecular targeting of CHI3L1 in the course of cancer immunotherapies can tune patients’ response and antitumoral inflammation.

Investigation of Vasculogenesis Inducing Biphasic Scaffolds for Bone Tissue Engineering.

Vascularization is the main obstacle for the bone tissue engineering strategies since the defect size is generally large. Incorporation of angiogenic factors is one of the strategies employed in order to accelerate vascularization and improve bone healing. In this study, a biphasic scaffold consisting of fibrous poly(lactide-co-glycolide) (PLGA) and poly(lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) hydrogel loaded with vascular endothelial growth factor-A (VEGF) inducer, GS4012, was constructed. Mesenchymal stem cells isolated from rat bone marrow (rBMSCs) were used for differentiation into osteogenic cells, and endothelial cells isolated from rat peripheral blood (rPBECs) were used to test the in vitro endothelial cell recruitment. The biphasic scaffold was tested for cell proliferation, ALP expression, VEGF induction, expression of osteogenic genes by rBMSCs, and recruitment of rPBECs in vitro and for improved bone healing and vascularization in vivo on critical size rat cranial defects. Endothelial migration through porous insert and VEGF induction were obtained in vitro in response to GS4012 as well as the upregulation of ALP, Runx2, Col I, and OC gene expressions. The biphasic scaffold was also shown to be effective in improving endothelial cell recruitment, vascularization, and bone healing in vivo. Thus, the proposed design has a great potential for the healing of critical size bone defect in tissue engineering studies according to both in vitro and in vivo investigations.

The Effect of Platelet-Rich Plasma on Endothelial Progenitor Cell Functionality.

Platelets mediate circulating endothelial progenitor cell (EPC) recruitment and maturation, participating in vascular repair, however the underlying mechanism(s) remain unclear. We investigated the effect of platelet-rich plasma (PRP) on the functionality of CD34+-derived late-outgrowth endothelial cells (OECs) in culture. Confluent OECs were coincubated with PRP under platelet aggregation (with adenosine diphosphate; ADP) and nonaggregation conditions, in the presence/absence of the reversible P2Y12 platelet receptor antagonist ticagrelor. Outgrowth endothelial cell activation was evaluated by determining prostacyclin (PGI2) and monocyte chemoattractant protein-1 (MCP-1) release and intercellular adhesion molecule-1 (ICAM-1) membrane expression. Similar experiments were performed using human umbilical vein endothelial cells (HUVECs). Platelet-rich plasma increased ICAM-1 expression and PGI2 and MCP-1 secretion compared with autologous platelet-poor plasma, whereas ADP-aggregated platelets in PRP did not exhibit any effect. Platelet-rich plasma pretreated with ticagrelor prior to activation with ADP increased all markers to a similar extent as PRP. Similar results were obtained using HUVECs. In conclusion, PRP induces OEC activation, a phenomenon not observed when platelets are aggregated with ADP. Platelet inhibition with ticagrelor restores the PRP capability to activate OECs. Since EPC activation is important for endothelial regeneration and angiogenesis, we suggest that agents inhibiting platelet aggregation, such as ticagrelor, may promote platelet-EPC interaction and EPC function.

Anti-Tumoral and Anti-Angiogenic Effects of Low-Diluted Phenacetinum on Melanoma.

Melanoma is the most aggressive form of skin cancer and the most rapidly expanding cancer in terms of worldwide incidence. If primary cutaneous melanoma is mostly treated with a curative wide local excision, malignant melanoma has a poor prognosis and needs other therapeutic approaches. Angiogenesis is a normal physiological process essential in growth and development, but it also plays a crucial role in crossing from benign to advanced state in cancer. In melanoma progression, angiogenesis is widely involved during the vertical growth phase. Currently, no anti-angiogenic agents are efficient on their own, and combination of treatments will probably be the key to success. In the past, phenacetin was used as an analgesic to relieve pain, causing side effects at large dose and tumor-inducing in humans and animals. By contrast, Phenacetinum low-dilution is often used in skin febrile exanthema, patches profusely scattered on limbs, headache, or flushed face without side effects. Herein are described the in vitro, in vivo, and ex vivo anti-angiogenic and anti-tumoral potentials of Phenacetinum low-dilution in a B16F1 tumor model and endothelial cells. We demonstrate that low-diluted Phenacetinum inhibits in vivo tumor growth and tumor vascularization and thus increases the survival time of B16F1 melanoma induced-C57BL/6 mice. Moreover, Phenacetinum modulates the lung metastasis in a B16F10 induced model. Ex vivo and in vitro, we evidence that low-diluted Phenacetinum inhibits the migration and the recruitment of endothelial cells and leads to an imbalance in the pro-tumoral macrophages and to a structural malformation of the vascular network. All together these results demonstrate highly hopeful anti-tumoral, anti-metastatic, and anti-angiogenic effects of Phenacetinum low-dilution on melanoma. Continued studies are needed to preclinically validate Phenacetinum low-dilution as a complementary or therapeutic strategy for melanoma treatment.

MiR-222-3p downregulation prompted the migration, invasion and recruitment of endothelial progenitor cells via ADIPOR1 expression increase-induced AMKP activation

BackgroundClinical data show that aneurysm rupture causes high mortality in aged men. MicroRNAs (miRNAs) were reported to regulate endothelial progenitor cells (EPCs) which play a vital role in repairing endothelial damage and maintaining vascular integrity. This study identified a novel miRNA regulator for the functions of EPCs in aneurysm repair. MethodsAbdominal aortic aneurysm (AAA) model was established on Sprague-Dawley rats which later underwent antagomiR-222 treatment. The histopathological changes of AAA rats were examined by hematoxylin-eosin staining. Flow cytometry was performed to quantify EPCs in peripheral blood and identify EPCs isolated from the rat femur. The potential target of miR-222-3p was predicted by TargetScan v7.2 and validated by Dual-luciferase reporter assay. The effects of miR-222-3p and ADIPOR1 on the migration, invasion and tube formation of EPCs were evaluated by wound healing, Transwell and tube formation assays. The expressions of miR-222-3p and ADIPOR1 in aortic aneurysm tissues and EPCs were assessed by qRT-PCR or Western blot. ResultsAAA exhibited histopathological abnormality, a decreased number of EPCs in the peripheral blood and an increased miR-222-3p expression. AntagomiR-222 injection reversed all these phenomena in AAA rats. Upregulating miR-222-3p expression inhibited the migration, invasion, and tube formation of EPCs, and the expressions of ADIPOR1 and phosphorylated-AMKP, while downregulating miR-222-3p expression exerted opposite effects in EPCs. ADIPOR1 was identified as a target gene of miR-222-3p. Overexpressing ADIPOR1 abrogated the effects of miR-222-3p upregulation on EPCs. ConclusionDownregulated miR-222-3p prompted the migration, invasion and recruitment of EPCs by targeting ADIPOR1-induced AMKP activation.

Crosstalk between Inflammation and the BBB in Stroke.

The blood-brain barrier (BBB), which is located at the interface between the central nervous system (CNS) and the circulatory system, is instrumental in establishing and maintaining the microenvironmental homeostasis of the CNS. BBB disruption following stroke promotes inflammation by enabling leukocytes, T cells and other immune cells to migrate via both the paracellular and transcellular routes across the BBB and to infiltrate the CNS parenchyma. Leukocytes promote the removal of necrotic tissues and neuronal recovery, but they also aggravate BBB injury and exacerbate stroke outcomes, especially after late reperfusion. Moreover, the swelling of astrocyte endfeet is thought to contribute to the ‘no-reflow’ phenomenon observed after cerebral ischemia, that is, blood flow cannot return to capillaries after recanalization of large blood vessels. Pericyte recruitment and subsequent coverage of endothelial cells (ECs) alleviate BBB disruption, which causes the transmigration of inflammatory cells across the BBB to be a dynamic process. Furthermore, interneurons and perivascular microglia also make contacts with ECs, astrocytes and pericytes to establish the neurovascular unit. BBB-derived factors after cerebral ischemia triggered microglial activation. During the later stage of injury, microglia remain associated with brain ECs and contribute to repair mechanisms, including postinjury angiogenesis, by acquiring a protective phenotype, which possibly occurs through the release of microglia-derived soluble factors. Taken together, we reviewed dynamic and bidirectional crosstalk between inflammation and the BBB during stroke and revealed targeted interventions based on the crosstalk between inflammation and the BBB, which will provide novel insights for developing new therapeutic strategies.

An update to the advances in understanding distraction histogenesis: From biological mechanisms to novel clinical applications

Over the past 3 decades, Ilizarov technique namely distraction histogenesis (DH) technique has been widely accepted and applied in orthopaedics and traumatology with outstanding clinical outcomes and emerging novel applications. This review focuses on the recent advances in understanding the biological mechanisms of DH, new methods for promoting bone consolidation in DH procedures and novel clinical applications of DH techniques. Tension stress regulates many genes during DH, including signaling transduction molecules, BMPs, inflammatory and angiogenic factors as well as epigenetic factors. DH also triggers systemic responses such as recruitment of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs). These activities play important roles in regulating bone regeneration and remodeling during DH. To promote bone formation in DH is still a clinical challenge, and minimal or non-invasive means for promoting bone consolidation are preferable, such as weight-bearing exercise, ultrasound and electromagnetic stimuli; whereas systemic administration of anabolic agents and hormones may also achieve better outcomes. Local cell transplantation and application of various biological factors at the right time may also be the choices. With better understanding of the biological mechanisms, applications of DH technique have now been extended for managing skin wound, joint disorders and avascular diseases. However, more basic or clinical researches are still needed to unravel the “magic” of DH technique. DH technique awakens and promotes human body’s self-regeneration potentials and leads to many novel treatment strategies. A substantial number of methods have been found to promote bone consolidation in DH to shorten the treatment duration and make the application of DH easier. Novel clinical applications of DH technique have now been extended to management of soft-tissue repair disorders, avascular diseases and others, with many more new biological mechanisms yet to be defined. A full understanding of DH technique may facilitate its wider and more appropriate clinical applications.

The crosstalk between osteodifferentiating stem cells and endothelial cells promotes angiogenesis and bone formation

The synergistic crosstalk between osteodifferentiating stem cells and endothelial cells (ECs) gained the deserved consideration, shedding light on the role of angiogenesis for bone formation and healing. A deep understanding of the molecular basis underlying the mutual influence of Mesenchymal Stem Cells (MSCs) and ECs in the osteogenic process may help improve greatly bone regeneration. Here, the authors demonstrated that osteodifferentiating MSCs co-cultured with ECs, promote angiogenesis and ECs recruitment. Moreover, through the use of 3D co-culture systems, we showed that ECs are in turn able to further stimulate the osteodifferentiation of MSCs, thus enhancing bone production. These findings highlighted the existence of a virtuous loop between MSCs and ECs that is central to the osteogenic process. Unravelling the molecular mechanisms governing the functional interaction MSCs and ECs holds great potential in the field of regenerative medicine.

A hybrid vascular graft harnessing the superior mechanical properties of synthetic fibers and the biological performance of collagen filaments.

Tissue-engineered small caliber vascular grafts have attracted much research attention as a viable alternative to traditional vascular grafts with their biocompatibility and potential to achieve complete healing. However, the major challenge is to fabricate a scaffold with both satisfactory mechanical properties and fast endothelialization. In this study, a hybrid tubular vascular tissue engineered scaffold has been circular-knitted using novel electrochemically aligned collagen (ELAC) filaments plied together with traditional poly(lactic acid) (PLA) yarn. The collagen component was able to promote the recruitment and proliferation of endothelial cells by increasing the initial cell adhesion 10-fold and the eventual cell population 3.2 times higher than the PLA scaffold alone. At the same time, the PLA yarn was able to provide sufficient mechanical strength and structural stability, as well as facilitate scaffold fabrication on high speed textile production equipment. The tubular hybrid scaffold exhibited excellent bursting strength (1.89±0.43MPa) and suture retention strength (10.86±0.49N), and had comparable compliance (3.98±1.94%/100mmHg) to that of the coronary artery (3.8±0.3%/100mmHg) under normotensive pressure. With its excellent mechanical and biological performance, this prototype hybrid scaffold is a promising candidate for the construction of a clinically successful and easily translatable tissue-engineered small caliber vascular graft.

Abstract 121: Mammary adipocytes drive breast tumor progression and angiogenesis via the VEGF/IL6/STAT3 signaling axis

Abstract Obesity is associated with a substantially increased risk (~50%) and a poor prognosis of breast cancer (BC) in postmenopausal (PM) women. The mechanism(s) underlying obesity-related BC are not clearly understood and, to date, most studies focus on the systemic effects of subcutaneous or visceral adipocytes on BC. We hypothesize that the increased local presence of ‘obese' mammary adipocytes within the breast microenvironment promotes the acquisition of an angiogenic and invasive breast tumor cell phenotype and thereby markedly accelerates tumor proliferation and progression. We first asked whether local interactions between mammary adipocytes and BC cells might promote tumor growth and if so, what the underlying mechanism(s) might be. Preadipocytes isolated from mammary adipose tissues of overweight/obese pre- (Pre-M; n=7) and post-menopausal (PM; n=9) women were differentiated into mature adipocytes using standard protocols. The effects of both normal (NA) and cancer-associated (CAA) mammary adipocyte secretome from Pre-M and PM obese women were tested on human and mouse BC cell lines respectively. BC cells (MDA-MB-436, MCF-7, M-Wnt), when treated with the secretome of mammary adipocytes from obese women (ObAd-CM), upregulated potent angiogenic factors, including VEGF-A, Angiopoietin-1, Jagged 1, HIF1-α and bFGF and significantly suppressed the angiogenesis inhibitor Tsp-1. ObAd-CM from both Pre-M and PM women significantly stimulated BC cell proliferation, migration and invasion. Importantly, compared to Pre-M patients, CAA Ad-CM from PM patients promoted higher levels of BC cell proliferation, migration and invasion. Pre-treatment with ObAd-CM resulted in increased endothelial cell (EC) recruitment by BC cells, an indispensable step in tumor angiogenesis. This effect was reversed by VEGF neutralization. In addition, ObAd-CM treatment significantly increased EC proliferation and capillary tube formation. Adipokines such as IL-6, IL-8, MCP-1, adiponectin and leptin were highly expressed in ObAd-CM. Of these, IL-6 neutralization alone inhibited the ObAd-CM-induced migratory and invasive phenotype of BC cells. Treatment with ObAd-CM also resulted in significant activation of pSTAT3, pAkt and pErk in BC cells. STAT3 inhibition reversed the ObAd-CM-mediated effects on BC cell proliferation and migration, suggesting that the pro-tumorigenic effects of Ob mammary adipocytes are mediated via IL-6/STAT3 signaling. Taken together, our results indicate that Ob mammary adipocytes promote migration, proliferation, invasion and the angiogenic phenotype in BC cells and suggest that targeting the VEGF/IL-6/STAT3 signaling axis may be a useful strategy in obesity-driven breast tumor growth and metastasis. [Supported by NIH RO1CA185530, the Karp Family Foundation and the Breast Cancer Research Foundation] Citation Format: Roopali Roy, Takaya Shimura, Lauren Merritt, Katherine Gonzalez, Emily Man, Margaret Lotz-Bousvaros, Susan Pories, Marsha A. Moses. Mammary adipocytes drive breast tumor progression and angiogenesis via the VEGF/IL6/STAT3 signaling axis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 121.