Cellular and molecular mechanisms in vascular repair after traumatic brain injury: a narrative review

Traumatic brain injury (TBI) disrupts normal brain function and is associated with high morbidity and fatality rates. TBI is characterized as mild, moderate or severe depending on its severity. The damage may be transient and limited to the dura matter, with only subtle changes in cerebral parenchyma, or life-threatening with obvious focal contusions, hematomas and edema. Blood vessels are often injured in TBI. Even in mild TBI, dysfunctional cerebral vascular repair may result in prolonged symptoms and poor outcomes. Various distinct types of cells participate in vascular repair after TBI. A better understanding of the cellular response and function in vascular repair can facilitate the development of new therapeutic strategies. In this review, we analyzed the mechanism of cerebrovascular impairment and the repercussions following various forms of TBI. We then discussed the role of distinct cell types in the repair of meningeal and parenchyma vasculature following TBI, including endothelial cells, endothelial progenitor cells, pericytes, glial cells (astrocytes and microglia), neurons, myeloid cells (macrophages and monocytes) and meningeal lymphatic endothelial cells. Finally, possible treatment techniques targeting these unique cell types for vascular repair after TBI are discussed.

Penetrating carotid artery injury by air rifle: a case report

BACKGROUND

Air rifle injuries can cause significant vascular injuries. This air rifle injury has resulted in a penetrating neck trauma traversing the common carotid artery. There is debate around the need for radiological investigation, the most appropriate investigational modality, and the need for surgical exploration versus a conservative approach. This case report aims to exemplify a successful approach to managing Penetrating Carotid Injuries (PCI) while shedding light on the rationale behind the management decisions.

PRESENTATION

An 18-year-old Caucasian man arrived at the hospital following an air rifle injury to the right side of the neck, with active bleeding and a moderate haematoma displacing the trachea. He was haemodynamically stable, with a Glasgow Coma Scale (GCS) of 15 and no evidence of bruit. Computed Tomography Angiography (CTA) showed Right common carotid (CCA) artery injury with associated post-traumatic pseudoaneurysm. The pellet trajectory traverses the right superior thyroid gland. A duplex ultrasound scan (USS) confirmed two areas of arterial blush at the right CCA. Management involved neck exploration under General Anaesthesia (G.A.), repair of right CCA, bullet extraction, and wound washout. He received antibiotics for ten days and a single agent of antiplatelets for three months and was discharged two days postoperatively with no complications. He was followed up for eight months with no evidence of any trauma sequelae.

CONCLUSION

Penetrating carotid artery injuries are a serious concern. The small-sized pellets carry the risk of embolization. Therefore, neck exploration remains the gold standard treatment for PCI. Appropriate operative planning is crucial and can be optimised using radiological diagnostic modalities in haemodynamically stable patients. CTA is a non-invasive, swift, and adequate alternative to arteriography, providing valuable diagnostic information on vascular and aerodigestive injuries and bullet trajectory. This enables appropriate preparedness to achieve excellent outcomes in such critical cases.

Chronic social defeat alters brain vascular-associated cell gene expression patterns leading to vascular dysfunction and immune system activation

Brain vascular integrity is critical for brain health, and its disruption is implicated in many brain pathologies, including psychiatric disorders. Brain-vascular barriers are a complex cellular landscape composed of endothelial, glial, mural, and immune cells. Yet currently, little is known about these brain vascular-associated cells (BVACs) in health and disease. Previously, we demonstrated that 14 days of chronic social defeat (CSD), a mouse paradigm that produces anxiety and depressive-like behaviors, causes cerebrovascular damage in the form of scattered microbleeds. Here, we developed a technique to isolate barrier-related cells from the mouse brain and subjected the isolated cells to single-cell RNA sequencing. Using this isolation technique, we found an enrichment in BVAC populations, including distinct subsets of endothelial and microglial cells. In CSD compared to non-stress, home-cage control, differential gene expression patterns disclosed biological pathways involving vascular dysfunction, vascular healing, and immune system activation. Overall, our work demonstrates a unique technique to study BVAC populations from fresh brain tissue and suggests that neurovascular dysfunction is a key driver of psychosocial stress-induced brain pathology.

CCR2 monocytes repair cerebrovascular damage caused by chronic social defeat stress

Immune surveillance of the brain plays an important role in health and disease. Peripheral leukocytes patrol blood-brain barrier interfaces, and after injury, monocytes cross the cerebrovasculature and follow a pattern of pro- and anti-inflammatory activity leading to tissue repair. We have shown that chronic social defeat (CSD) causes scattered vasculature disruptions. Here, we assessed CCR2⁺ monocyte trafficking to the vascular injury sites in Ccr2^wt/rfp reporter mice both during CSD and one week following CSD cessation. We found that CSD for 14 days induced microhemorrhages where plasma fibrinogen leaked into perivascular spaces, but it did not affect the distribution or density of CCR2^rfp+ monocytes in the brain. However, after recovery from CSD, many vascularly adhered CCR2⁺ cells were detected, and gene expression of the CCR2 chemokine receptor ligands CCL7 and CCL12, but not CCL2, was elevated in endothelial cells. Adhered CCR2⁺ cells were mostly the non-classical, anti-inflammatory Ly6C^lo type, and they phagocytosed fibrinogen in perivascular spaces. In CCR2-deficient Ccr2^rfp/rfp mice, fibrinogen levels remained elevated in recovery. Fibrinogen infused intracerebroventricularly induced CCR2⁺ cells to adhere to the vasculature and phagocytose perivascular fibrinogen in Ccr2^wt/rfp but not Ccr2^rfp/rfp mice. Depletion of monocytes with clodronate liposomes during CSD recovery prevented fibrinogen clearance and blocked behavioral recovery. We hypothesize that peripheral CCR2⁺ monocytes are not elevated in the brain on day 14 at the end of CSD and do not contribute to its behavioral effects at that time, but in recovery following cessation of stress, they enter the brain and exert restorative functions mediating vascular repair and normalization of behavior.

Role of Stromal Cell-Derived Factor-1 in Endothelial Progenitor Cell-Mediated Vascular Repair and Regeneration

Endothelial progenitor cells (EPCs) are immature endothelial cells that participate in vascular repair and postnatal neovascularization and provide a novel and promising therapy for the treatment of vascular disease. Studies in different animal models have shown that EPC mobilization through pharmacological agents and autologous EPC transplantation contribute to restoring blood supply and tissue regeneration after ischemic injury. However, these effects of the progenitor cells in clinical studies exhibit mixed results. The therapeutic efficacy of EPCs is closely associated with the number of the progenitor cells recruited into ischemic regions and their functional abilities and survival in injury tissues. In this review, we discussed the regulating role of stromal cell-derived factor-1 (also known CXCL12, SDF-1) in EPC mobilization, recruitment, homing, vascular repair and neovascularization, and analyzed the underlying machemisms of these functions. Application of SDF-1 to improve the regenerative function of EPCs following vascular injury was also discussed. SDF-1 plays a crucial role in mobilizing EPC from bone marrow into peripheral circulation, recruiting the progenitor cells to target tissue and protecting against cell death under pathological conditions; thus improve EPC regenerative capacity. SDF-1 are crucial for regulating EPC regenerative function, and provide a potential target for improve therapeutic efficacy of the progenitor cells in treatment of vascular disease.

Irisin in atherosclerosis

Irisin, a novel exercise-induced myokine, has been shown to play important roles in increasing white adipose tissue browning, regulating energy metabolism and improving insulin resistance. Growing evidence suggests a direct role for irisin in preventing atherosclerosis (AS) by inhibiting oxidative stress, improving dyslipidemia, facilitating anti-inflammation, reducing cellular damage and recovering endothelial function. In addition, some studies have noted that serum irisin levels play an essential role in cardiovascular diseases (CVDs) risk prediction, highlighting that irisin has the potential to be a useful predictive marker and therapeutic target of AS, especially in monitoring therapeutic efficacy. This review summarizes the understanding of irisin-mediated regulation in essential biological pathways and functions in atherosclerosis and prompts further exploitation of the biological properties of irisin in the pathogenesis of atherosclerosis.

Major vascular injury during gynecologic cancer surgery

OBJECTIVE

Vascular injury during major gynecologic cancer surgery is a rare but potentially fatal complication. The purpose of this study was to review our experience with major vascular injury during gynecologic cancer surgery.

METHODS

This was a retrospective chart review of women undergoing surgery by our gynecologic oncology department from 7/1/99 to 6/30/20 who had a major vascular injury. We identified women who sustained a vascular injury by a combination of CPT code and medical record searches, fellow case logs and a list maintained for an ongoing quality assurance program. Data were expressed as median and range for continuous variables and as frequency and percentage for categorical variables. Fisher's exact test was used to analyze differences in complication rates between groups.

RESULTS

Major vascular injury was identified in 52 patients and procedures. The inferior vena cava was the most common site of injury, 32.7% (17/52), followed by the external iliac vein, 23.1% (12/52). Lymph node dissection was the most common time for a vascular injury to occur 51.9% (27/52). The majority of injuries required suture repair, 80.8% (42/52). Estimated blood loss in cases with vascular injury ranged from 100 mL to massive unquantifiable blood loss in the case of an aortic injury. Patients required a median of 2units of packed red blood cells. Postoperative complications included anemia requiring blood transfusion, 19.6% (9/46) and venous thromboembolism, 19.6% (9/46).

CONCLUSIONS

Vascular injury remains a rare but potentially morbid complication of gynecologic oncologic surgery. Prompt recognition and management are imperative in minimizing persistent bleeding and complications.

Subclavian artery injury secondary to blunt trauma successfully managed by median sternotomy with supraclavicular extension: A case report and literature review

INTRODUCTION

Subclavian artery injury secondary to blunt trauma is rare and only a few cases have been documented in the literature. Subclavian arteries are protected by the clavicles, ribs, and chest wall. Clinical management and surgical approach vary depending on the specific injury. We present the case of a 50 year old male with blunt right subclavian transection.

CASE PRESENTATION

A 50-year-old male presented after being struck by a train. On exam, the patient had open injuries to the right upper chest/extremity. CTA showed a transection of the mid right subclavian artery along with a long traumatic occlusion distal to the defect. The patient was taken to the operating room where median sternotomy with supraclavicular extension was used to expose the transected ends of the subclavian artery and successfully perform a bypass graft. After a long hospital stay, he had a near-full functional recovery.

DISCUSSION

Blunt subclavian injury is rare and carries a high mortality. Adequate intervention requires prompt identification and proper surgical approach for repair. Median sternotomy offers the best approach to visualize the proximal right subclavian artery. Extension with a supraclavicular incision can be necessary for distal control. This approach offered timely intervention, which ultimately saved his life and allowed for return of pre-trauma functional status.

CONCLUSION

Prompt identification of subclavian artery injury is paramount as such injuries carry a high mortality. Median sternotomy with supraclavicular extension is an appropriate open surgical approach to successfully manage proximal right subclavian artery injuries.

Vascular repairs in gynecologic operations are uncommon but predict major morbidity and mortality

OBJECTIVE

Gynecologic surgery has potential for adjunct vascular interventions, given the proximity of major intra-abdominal and pelvic blood vessels. Our goal was to determine contemporary incidence, associations, and outcomes of vascular repairs in gynecologic operations.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database (2005-2017) was queried for patients undergoing elective gynecologic operations. Vascular repairs were performed concurrently or during reoperation. Univariable and multivariable analyses evaluated associations with vascular repairs and 30-day morbidity.

RESULTS

A total of 201,224 gynecologic operations were identified: hysterectomy (88.3%), myomectomy (5.9%), adnexal surgery (3.5%), vulvovaginectomy/other (1.1%), nonadnexal tumor or cyst excision (0.5%), ectopic pregnancy treatment (0.4%), and pelvic lymphadenectomy (0.3%). There were 187 vascular repairs in 176 (0.09%) patients. Repairs were typically concurrent (89.8%) and most commonly included open abdominal blood vessel repair (51.8%), major abdominal artery ligation (25%), vena cava reconstruction/ligation (6%), common iliac vein ligation (4.2%), and aorta/great vessel repair (4.2%). A minority were performed endovascularly (1.7%). Patients undergoing vascular repairs were older (56 vs 46 years), were more likely to have an open vs minimally invasive/vaginal operation (71.6% vs 28.4%), and were more likely to have a hysterectomy (85.2%; P < .001 for all). In multivariable analysis, vascular repairs were observed more often with hysterectomy (odds ratio [OR]; 7.63, 95% confidence interval [CI], 2.28-25.55; P = .001) and open vs minimally invasive/vaginal operations (OR, 5.24; 95% CI, 2.64-10.42; P < .001). Vascular repairs were also more common for patients with malignant disease (OR, 2.84; 95% CI, 1.78-4.53; P < .001), patients assigned to American Society of Anesthesiologists class 3 or class 4 (OR, 1.85; CI, 1.36-2.53; P = .002), and patients without obesity (OR, 1.45; 95% CI, 1.08-1.96; P = .014). Vascular repairs independently predicted major morbidity and mortality (OR, 7.26; 95% CI, 5.26-10.03; P < .001) after adjustment for open operative approach, American Society of Anesthesiologists class 3 or class 4, and hysterectomy.

CONCLUSIONS

Whereas vascular repairs during gynecologic operations are rare, they are associated with morbidity and mortality. These findings provide an evidence base for risk assessment and informed consent.

Mechanoresponse of stem cells for vascular repair

Stem cells have shown great potential in vascular repair. Numerous evidence indicates that mechanical forces such as shear stress and cyclic strain can regulate the adhesion, proliferation, migration, and differentiation of stem cells via serious signaling pathways. The enrichment and differentiation of stem cells play an important role in the angiogenesis and maintenance of vascular homeostasis. In normal tissues, blood flow directly affects the microenvironment of vascular endothelial cells (ECs); in pathological status, the abnormal interactions between blood flow and vessels contribute to the injury of vessels. Next, the altered mechanical forces are transduced into cells by mechanosensors to trigger the reformation of vessels. This process occurs when signaling pathways related to EC differentiation are initiated. Hence, a deep understanding of the responses of stem cells to mechanical stresses and the underlying mechanisms involved in this process is essential for clinical translation. In this the review, we provide an overview of the role of stem cells in vascular repair, outline the performance of stem cells under the mechanical stress stimulation, and describe the related signaling pathways.

Perforator artery repair in revascularization of extremity degloving injuries

INTRODUCTION

This article aims to expand the microsurgical treatment options for extremity degloving injuries with perforator artery repairs of the specific degloved angiosomes in upper and lower extremity.

METHODS

Fourteen perforator arteries were repaired in seven patients. Four of them had circumferential degloving and 3 of them have non circumferential degloving injury. All had repair of the perforator arteries of the specific degloved segments. Four patients had additional vein repairs but none of the patients had AV shunts.

RESULTS

All perforators provided adequate arterial supply to their specific angiosomes with some necrotic areas in neighboring angiosomes.

CONCLUSIONS

Perforator artery repair within the degloved tissues provides a direct arterial supply successfully even if one could not find an intact venous plexus.

[Management of carotid-jugular fistula: Case report and review of the literature]

We report here the management of an acquired left carotid-jugular fistula in a 29-year-old man. This patient was referred to us for a ballistic wound of the left cheek evolving since one month with the diagnosis of a carotid pseudo-aneurysm discovered on Doppler ultrasound. The clinical presentation was marked by cervical thrill in favor of an arteriovenous fistula confirmed by computed tomography angiography. The surgical exploration by cervicotomy revealed a communication between common carotid artery and internal jugular vein that were repaired using a saphenous vein patch and a lateral suture respectively without complication. The control at five months found an asymptomatic patient with good patency of the repaired vessels.

Danhong injection mobilizes endothelial progenitor cells to repair vascular endothelium injury via upregulating the expression of Akt, eNOS and MMP-9

BACKGROUD

Endothelial progenitor cells (EPCs) have been characterized as one of the key effectors of endothelial healing. The effect of Danhong injection (DHI), the most widely prescribed Chinese medicine for coronary heart disease (CHD), on EPCs mobilization remains unclear.

PURPOSE

We aimed to assess the effect of DHI on EPCs mobilization to repair percutaneous coronary intervention (PCI) induced vascular injury, and to investigate the characteristics and potential mechanism of DHI on EPCs mobilization.

METHOD

Forty-two patients with CHD underwent PCI and received stent implantation were enrolled in a Phase II clinical trials. All patients received routine western medical treatment after PCI, patients of DHI group received DHI in addition. The levels of CECs, cytokines (vWF, IL-6, CRP) and EPCs were analyzed at baseline, post-PCI and after treatment. To investigate the characteristics of DHI on EPCs mobilization, 12 healthy volunteers received intravenous infusion of DHI once and the other 12 received for 7 days. EPCs enumeration were done at a series of time points. At last we tested the effect of DHI and three chemical constituents of DHI (danshensu; lithospermic acid, LA; salvianolic acid D, SaD) on EPCs level and expression of Akt, eNOS and MMP-9 in bone marrow cells of myocardial infarction (MI) mice.

RESULTS

In the DHI group the angina symptoms were improved, the levels of cytokines and CECs were reduced; while EPCs population was increased after treatment. In the phase I clinical trials, EPCs counts reached a plateau phase in 9 h and maintained for more than 10 h after a single dose. After continuous administration, EPCs levels plateaued on the 3rd or 4th day, and maintain till 1 day after the withdrawal, then its levels gradually declined. DHI treatment induced a timely dependent mobilization of EPCs. DHI promoted EPCs mobilization via upregulating the expression of Akt, eNOS and MMP-9 in BM. LA and SaD have played a valuable role in EPCs mobilization.

CONCLUSION

These initial results demonstrated that DHI is effective in alleviating endothelial injury and promoting endothelial repair through enhancing EPCs mobilization and revealed the effect feature and possible mechanisms of DHI in mobilizing EPCs.

[Neurovascular complications in fractures of the extremities, part 1 : Vascular lesions]

Neurovascular injuries in fractures threaten at least the function of extremities. The timely interaction between diagnosis and treatment of vascular injuries helps to avoid a poor outcome or even fatal complications. An important parameter is to "think about it" for injuries under strain. An ankle-brachial index (ABI) of <0.9 is an indicator. Massive bleeding, manifest and long-lasting peripheral ischemia and a rapidly expanding hematoma necessitate an immediate surgical intervention. Endovascular techniques are recommended on the extremities of stable patients with circumscribed vascular lesions. The debate about the sequence of repair (vascular vs. osseous) has to be decided on an individual basis; however, when in doubt vascular repair should be given priority. Vessel reconstructions should be performed without tension and must be covered by vital soft tissues, the indications for fasciotomy should be liberally interpreted. The prognosis with respect to preservation of the extremity and long-term functional outcome substantially depends on the quality of treatment of accompanying injuries.

Repair of damaged cortical artery by direct micro-suture in surgical treatment of acute subdural hematoma: technical note

BACKGROUND

In surgical treatment of acute subdural hematoma (ASDH), neurosurgeons frequently encounter bleeding from cortical arteries, which is usually controlled with bipolar coagulation. However, bipolar coagulation is associated with a risk of sacrificing the cortical artery, which may affect the prognosis of neurological symptoms when these cortical arteries supply critical areas. In this article, we describe microsurgical repair of damaged cortical arteries using a 10-0 nylon micro-suture in patients with arterial-origin ASDH.

METHODS

After removal of the subdural hematoma, the exact bleeding point of the cortical artery was identified, and the 10-0 nylon suture stitches were placed on the arterial tear under a microscope. After completion of the micro-suture, vascular patency was confirmed by indocyanine green (ICG) videoangiography.

RESULTS

From June 2015 through February 2017, microsurgical repair was performed for seven cortical arteries in six patients. All damaged arteries were located near the Sylvian fissure, and all tears were pinhole tears. The average blood flow occlusion time was 8 min (range, 0-15 min). The patency of all seven repaired arteries was successfully confirmed by ICG videoangiography. Postoperative cerebral infarction was not observed except in one patient with cerebral contusion and a history of severe head trauma.

CONCLUSIONS

The present report demonstrates that repair of a cortical artery by the 10-0 nylon micro-suture is a simple and safe method with a low risk of sacrificing the artery. This technique may be a good option in the surgical treatment of arterial-origin ASDH, especially when the accompanying cerebral contusion is minimal.

Oleuropein attenuates hydrogen peroxide-induced autophagic cell death in human adipose-derived stem cells

Mesenchymal stem cells (MSCs) are multipotent progenitor cells with self-renewing properties; thus, transplanting functionally enhanced MSCs might be a promising strategy for cell therapy against ischemic diseases. However, extensive oxidative damage in ischemic tissue affects the cell fate of transplanted MSCs, eventually resulting in cell damage and autophagic cell death. Oleuropein (OLP) is a bioactive compound isolated from olives and olive oil that harbors antioxidant properties. This study aimed to investigate the potential cytoprotective effects of OLP against oxidative stress and autophagic cell death in MSCs. We found that short-term priming with OLP attenuated H₂O₂-induced apoptosis by regulating the pro-apoptotic marker Bax and the anti-apoptotic markers Bcl-2 and Mcl-1. Notably, OLP inhibits H₂O₂ -induced autophagic cell death by modulating autophagy-related death signals, including mTOR (mammalian target of rapamycin), ULK1 (unc-51 like autophagy activating kinase 1), Beclin-1, AMPK (AMP-activated protein kinase), and LC3 (microtubule-associated protein 1a/1b-light chain 3). Our data suggest that OLP might reduce H₂O₂-induced autophagy and cell apoptosis in MSCs by regulating both the AMPK-ULK axis and the Bcl-2-Mcl-1 axis. Consequently, short-term cell priming with OLP might enhance the therapeutic effect of MSCs against ischemic vascular diseases, which provides an important potential improvement for emerging therapeutic strategies.

Possible Muscle Repair in the Human Cardiovascular System

The regenerative potential of tissues and organs could promote survival, extended lifespan and healthy life in multicellular organisms. Niches of adult stemness are widely distributed and lead to the anatomical and functional regeneration of the damaged organ. Conversely, muscular regeneration in mammals, and humans in particular, is very limited and not a single piece of muscle can fully regrow after a severe injury. Therefore, muscle repair after myocardial infarction is still a chimera. Recently, it has been recognized that epigenetics could play a role in tissue regrowth since it guarantees the maintenance of cellular identity in differentiated cells and, therefore, the stability of organs and tissues. The removal of these locks can shift a specific cell identity back to the stem-like one. Given the gradual loss of tissue renewal potential in the course of evolution, in the last few years many different attempts to retrieve such potential by means of cell therapy approaches have been performed in experimental models. Here we review pathways and mechanisms involved in the in vivo repair of cardiovascular muscle tissues in humans. Moreover, we address the ongoing research on mammalian cardiac muscle repair based on adult stem cell transplantation and pro-regenerative factor delivery. This latter issue, involving genetic manipulations of adult cells, paves the way for developing possible therapeutic strategies in the field of cardiovascular muscle repair.

VEGF promotes endothelial progenitor cell differentiation and vascular repair through connexin 43

Background

Endothelial progenitor cell (EPC) differentiation is considered crucial for vascular repair. Vascular endothelial growth factor (VEGF) induces EPC differentiation, but the underlying mechanism of this phenomenon remains unclear. Connexin 43 (Cx43) is reported to be involved in the regulation of stem cell differentiation. Therefore, we sought to determine whether Cx43 is involved in VEGF-induced EPC differentiation and vascular repair.

Methods

Rat spleen-derived EPCs were cultured and treated with various concentrations of VEGF (0, 10, or 50 ng/mL), and the relationship between EPC differentiation and Cx43 expression was evaluated. Thereafter, fluorescence redistribution after photobleaching was performed to assess the relationship between adjacent EPC differentiation and Cx43-induced gap junction intercellular communication (GJIC). After carotid artery injury, EPCs pretreated with VEGF were injected into the tail veins, and the effects of Cx43 on vascular repair were evaluated.

Results

EPCs cultured with VEGF exhibited accelerated differentiation and increased expression of Cx43. However, inhibition of Cx43 expression using short interfering RNA (siRNA) attenuated EPC GJIC and consequent EPC differentiation. VEGF-pretreated EPC transplantation promoted EPC homing and reendothelialization, and inhibited neointimal formation. These effects were attenuated by siRNA inhibition of Cx43.

Conclusions

Our results from in vivo and in vitro experiments indicated that VEGF promotes EPC differentiation and vascular repair through Cx43.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0684-1) contains supplementary material, which is available to authorized users.

Circulating endothelial progenitors in vascular repair

Endothelial Colony Forming Cells (ECFCs) are obtained in culture from Circulating Endothelial Progenitor Cells. They display all characteristics of endothelial cells and they display stem cells features. Cord blood-derived ECFCs (CB-ECFCs) have a high clonogenic and proliferative potentials, and exhibit vascular repair capabilities useful for the treatment of ischemic diseases. However, the link between immaturity and functional properties of CB-ECFCs is still poorly defined. We showed that these cells have a high clonogenic potential and are capable to be efficiently reprogrammed into induced pluripotent stem cells. Moreover, we analyzed the expression of a broad panel of genes involved in embryonic stem cell properties. We define a novel stem cell transcriptional signature for CB-ECFCs fora better characterization and stratification according to their stem cell profile. We then improved the yield of CB-ECFC production for obtaining cells more functional in fewer passages. We used Glycosaminoglycans (GAG), components from the extracellular matrix which potentiate heparin binding growth factor activities. GAG mimetics were designed, having the capacity to increase the yield of ECFC during the isolation process, to increase the number of colonies, improve adhesion, proliferation, migration and self-renewal. GAG mimetics have thus great interest for vascular regeneration in combination with ECFC. Our results show that CB-ECFC are immature cells harboring specific functions such as formation of colonies, proliferation and formation of vascular structures in vitro and in vivo.

Endothelial cell-derived pentraxin 3 limits the vasoreparative therapeutic potential of circulating angiogenic cells

Aims

Circulating angiogenic cells (CACs) promote revascularization of ischaemic tissues although their underlying mechanism of action and the consequences of delivering varying number of these cells for therapy remain unknown. This study investigates molecular mechanisms underpinning CAC modulation of blood vessel formation.

Methods and results

CACs at low (2 × 10⁵ cells/mL) and mid (2 × 10⁶ cells/mL) cellular densities significantly enhanced endothelial cell tube formation in vitro, while high density (HD) CACs (2 × 10⁷ cells/mL) significantly inhibited this angiogenic process. In vivo, Matrigel-based angiogenesis assays confirmed mid-density CACs as pro-angiogenic and HD CACs as anti-angiogenic. Secretome characterization of CAC-EC conditioned media identified pentraxin 3 (PTX3) as only present in the HD CAC-EC co-culture. Recombinant PTX3 inhibited endothelial tube formation in vitro and in vivo. Importantly, our data revealed that the anti-angiogenic effect observed in HD CAC-EC co-cultures was significantly abrogated when PTX3 bioactivity was blocked using neutralizing antibodies or PTX3 siRNA in endothelial cells. We show evidence for an endothelial source of PTX3, triggered by exposure to HD CACs. In addition, we confirmed that PTX3 inhibits fibroblast growth factor (FGF) 2-mediated angiogenesis, and that the PTX3 N-terminus, containing the FGF-binding site, is responsible for such anti-angiogenic effects.

Conclusion

Endothelium, when exposed to HD CACs, releases PTX3 which markedly impairs the vascular regenerative response in an autocrine manner. Therefore, CAC density and accompanying release of angiocrine PTX3 are critical considerations when using these cells as a cell therapy for ischaemic disease.

[EFFECT OF MACROPHAGE MIGRATION INHIBITORY FACTOR ON VASCULAR REPAIR OF STEROID-INDUCED AVASCULAR NECROSIS OF FEMORAL HEAD IN VITRO]

OBJECTIVE

To interpret the mechanisms of vascular repair disorders in steroid-induced avascular necrosis of the femoral head (SANFH) via detection of the changes of proliferation, migration, and macrophage migration inhibitory factor (MIF)/vascular endothelial growth factor (VEGF) expressions of endothelial cells (ECs) under hypoxia/glucocorticoid.

METHODS

According to culture conditions, human umbilical vein ECs (HUVECs) at passage 3 were divided into group A (normal), group B (1.0×10^-6 mol/L dexamethasone), group C (hypoxia), and group D (hypoxia+1.0×10^-6 mol/L dexamethasone). The cell activity was detected by AlamarBlue; the number of viable cells was detected in live/dead cell staining; the cell morphology was observed after cytoskeleton staining; cell migration ability was compared by scratch test; and the levels of MIF and VEGF expressions were detected by ELISA.

RESULTS

At 24 hours after culture, the cell activity and the number of living cells in group C were significantly higher than those in the other 3 groups, showing significant difference between groups (P<0.05), and group D had the worst cell activity and least living cells. Cytoskeleton staining showed that cells had normal morphology in groups A and B; cells had rich cytoskeleton and secretion granules in group C; cytoskeleton form disorder and nucleus pyknosis were observed in group D. Scratch test showed that the cell migration ability of group C was strongest while cell migration ability of group D was weakest. Accumulated concentration of MIF and VEGF in 4 groups significantly increased with time extending. Accumulated concentration of MIF in group C were significantly higher than that in other 3 groups at each time point (P<0.05). Within 24 hours after intervention, stage concentration of MIF during 1-8 hours was significantly lower than that during 0-1 hour and 8-24 hours in every group (P<0.05). Stage concentration of MIF in group C was significantly higher than other groups during 0-1 hour and 8-24 hours (P<0.05). Within 2 hours after intervention, stage concentration of MIF in 4 groups during 0.5-1 hour was significantly higher than that during other stages (P<0.05). Accumulated concentration of VEGF in group C was significantly higher than that in other groups at 8 and 24 hours (P<0.05). The stage concentration of VEGF in groups C and D during 8-24 hours was significantly higher than that during 0-1 hour and 1-8 hours (P<0.05). There was no significant difference in the stage concentration of VEGF within and among group A, B, C, and D at every stage within 2 hours after intervention (P>0.05).

CONCLUSIONS

In hypoxia environment, the proliferation and migration of ECs is enhanced, and the secretion of VEGF and MIF is increased. High concentration of dexamethasone will suppress the process above, which induces vascular repair disorders and aggravating SANFH.

Transplantation of IL-10-transfected endothelial progenitor cells improves retinal vascular repair via suppressing inflammation in diabetic rats

PURPOSE

We aimed to evaluate the effect of IL-10 gene transfection on endothelial progenitor cells (EPCs) under inflammatory conditions, and explore the therapeutic potential of IL-10-transfected EPC transplantation on nonproliferative diabetic retinopathy (NPDR).

METHODS

Lentivirus vectors encoding IL-10 were constructed and introduced into EPCs isolated from rat bone marrow. After exposure to recombinant rat TNF-α, abilities of nontransfected EPCs (non-EPCs) and EPCs transfected with normal control lentivirus (EPCs-GFP) or IL-10 expressing lentivirus (EPCs-IL-10-GFP) were assessed, including migration, adhesion, and tube formation. IL-10 production by EPCs-IL-10-GFP was determined by ELISA. Following 12 weeks after establishment of diabetes, diabetic rats were randomly injected with non-EPCs, EPCs-GFP, or EPCs-IL-10-GFP via tail vein. Expression of inflammatory factors and factors associated with nuclear factor-kappa B (NF-kB) signal pathway, retinal histological analysis, and retinal vascular permeability were assessed 2 weeks after transplantation.

RESULTS

The detrimental effects of TNF-ɑ on the abilities of EPCs were significantly attenuated in EPCs-IL-10-GFP compared with non-EPCs and EPCs-GFP. The concentration of IL-10 in the EPCs-IL-10-GFP group was significantly higher than the non-EPCs and EPCs-GFP groups. Additionally, transplantation of EPCs-IL-10-GFP significantly inhibited inflammatory factors expression and activation of NF-kB signal pathway, improved retinal histological changes, and attenuated retinal vascular permeability.

CONCLUSION

In conclusion, transplantation of IL-10-transfected EPCs significantly improved EPCs-mediated retinal vascular repair and subsequently suppressed NPDR progression. This was associated with inflammation suppression, at least partly via inhibiting the NF-kB signal pathway. Transplantation of IL-10-transfected EPCs may be a new strategy for treatment of NPDR.

Use of Statins to Augment Progenitor Cell Function in Preclinical and Clinical Studies of Regenerative Therapy: a Systematic Review

BACKGROUND

Mesenchymal stromal cells (MSCs) and endothelial progenitor cells (EPCs) are used in cell-based regenerative therapy. HMG CoA reductase inhibitors (statins) appear promising in blocking apoptosis, prolonging progenitor cell survival and improving their capacity to repair organ function.

METHODS

We performed a systematic review of preclinical and clinical studies to clarify whether statins can improve cell-based repair of organ injury. MEDLINE, EMBASE, and PUBMED databases were searched (1947 to June 25, 2013). Controlled clinical and pre-clinical studies were included that evaluated statin therapy used alone or in combination with MSCs or EPCs in patients or animals with organ injury.

RESULTS

After screening 771 citations, 100 records underwent full eligibility screening of which 38 studies met eligibility and were included in the review: Studies were grouped into pre-clinical studies that involved statin treatment in combination with cell therapy (18 studies), preclinical studies of statin therapy alone (13 studies) and clinical studies of statin therapy (7 studies). Studies addressed cardiac injury (14 studies), vascular disorders (15 studies), neurologic conditions (8 studies) and bone fractures (1 study). Pre-clinical studies of statins in combination with MSC infusion (15 studies) or EPC therapy (3 studies) were described and despite marked heterogeneity in reporting outcomes of cellular analysis and organ function, all of these cell-based pre-clinical studies reported improved organ recovery with the addition of statin therapy. Moreover, 13 pre-clinical studies involved the administration of a statin drug alone to animals. An increase in EPC number and/or function (no studies of MSCs) was reported in 11 of these studies (85 %) and improved organ function in 12 studies (92 %). We also identified 7 clinical studies and none involved the administration of cells but described an increased number and/or function of EPCs (no studies of MSCs) and improved organ function with statin therapy (1.2-fold to 35-fold improvement over controls) in all 7 studies.

CONCLUSION

Our systematic review provides a foundation of encouraging results that support further study of statins in regenerative therapy to augment the number and/or function of MSCs used in cell-based repair and to augment the number and function of EPCs in vivo to repair damaged tissues. Larger studies are needed to ensure safety and confirm clinical benefits.

Fucoidan improves bioactivity and vasculogenic potential of mesenchymal stem cells in murine hind limb ischemia associated with chronic kidney disease

Chronic kidney disease (CKD) is a significant risk factor for cardiovascular and peripheral vascular disease. Although mesenchymal stem cell (MSC)-based therapy is a promising strategy for treatment of ischemic diseases associated with CKD, the associated pathophysiological conditions lead to low survival and proliferation of transplanted MSCs. To address these limitations, we investigated the effects of fucoidan, a sulfated polysaccharide, on the bioactivity of adipose tissue-derived MSCs and the potential of fucoidan-treated MSCs to improve neovascularization in ischemic tissues of CKD mice. Treatment of MSCs with fucoidan increased their proliferative potential and the expression of cell cycle-associated proteins, such as cyclin E, cyclin dependent kinase (CDK) 2, cyclin D1, and CDK4, via focal adhesion kinase and the phosphatidylinositol-4,5-bisphosphate 3-kinase-Akt axis. Moreover, fucoidan enhanced the immunomodulatory activity of MSCs through the ERK-IDO-1 signal cascade. Fucoidan was found to augment the proliferation, incorporation, and endothelial differentiation of transplanted MSCs at ischemic sites in CKD mice hind limbs. In addition, transplantation of fucoidan-treated MSCs enhanced the ratio of blood flow and limb salvage in CKD mice with hind limb ischemia. To our knowledge, our findings are the first to reveal that fucoidan enhances the bioactivity of MSCs and improves their neovascularization in ischemic injured tissues of CKD. In conclusion, fucoidan-treated MSCs may provide an important pathway toward therapeutic neovascularization in patients with CKD.

The sulfated polysaccharide fucoidan rescues senescence of endothelial colony-forming cells for ischemic repair

The efficacy of cell therapy using endothelial colony-forming cells (ECFCs) in the treatment of ischemia is limited by the replicative senescence of isolated ECFCs in vitro. Such senescence must therefore be overcome in order for such cell therapies to be clinically applicable. This study aimed to investigate the potential of sulfated polysaccharide fucoidan to rescue ECFCs from cellular senescence and to improve in vivo vascular repair by ECFCs. Fucoidan-preconditioning of senescent ECFCs was shown by flow cytometry to restore the expression of functional ECFC surface markers (CD34, c-Kit, VEGFR2, and CXCR4) and stimulate the in vitro tube formation capacity of ECFCs. Fucoidan also promoted the expression of cell cycle-associated proteins (cyclin E, Cdk2, cyclin D1, and Cdk4) in senescent ECFCs, significantly reversed cellular senescence, and increased the proliferation of ECFCs via the FAK, Akt, and ERK signaling pathways. Fucoidan was found to enhance the survival, proliferation, incorporation, and endothelial differentiation of senescent ECFCs transplanted in ischemic tissues in a murine hind limb ischemia model. Moreover, ECFC-induced functional recovery and limb salvage were markedly improved by fucoidan pretreatment of ECFCs. To our knowledge, the findings of our study are the first to demonstrate that fucoidan enhances the neovasculogenic potential of ECFCs by rescuing them from replicative cellular senescence. Pretreatment of ECFCs with fucoidan may thus provide a novel strategy for the application of senescent stem cells to therapeutic neovascularization.

IL-22 affects smooth muscle cell phenotype and plaque formation in apolipoprotein E knockout mice

OBJECTIVE

IL-22 is a recently discovered cytokine that belongs to the family of IL-10 related cytokines. It is produced by activated T-cells and innate lymphoid cells and has been suggested to be involved in tissue repair. As both inflammation and repair play important roles in atherosclerosis we investigated if IL-22 deficiency influences the disease process in Apoe(-/-) mice.

METHODS

We generated IL-22(-/-)Apoe(-/-) mice and fed them high-fat-diet for 14 weeks to characterize atherosclerosis development.

RESULTS

IL-22(-/-)Apoe(-/-) mice exhibited reduced plaque size both in the aorta (p = 0.0036) and the aortic root compared (p = 0.0012) with Apoe(-/-) controls. Moreover, plaque collagen was reduced in IL-22(-/-)Apoe(-/-) mice (p = 0.02) and this was associated with an increased expression of smooth muscle cell (SMC)-α-actin (p = 0.04) and caldesmon (p = 0.016) in the underlying media. Carotid arteries from IL-22(-/-)Apoe(-/-) mice displayed increased expression of genes associated with a contractile SMC phenotype e.g. α-actin (p = 0.004) and caldesmon (p = 0.03). Arterial SMCs were shown to express the IL-22 receptor and in vitro exposure to IL-22 resulted in a down-regulation of alpha actin and caldesmon gene expression in these cells.

CONCLUSION

Our observations demonstrate that IL-22 is involved in plaque formation and suggest that IL-22 released by immune cells is involved in activation of vascular repair by stimulating medial SMC dedifferentiation into a synthetic phenotype. This response contributes to plaque growth by enabling SMC migration into the intima but may also help to stabilize the plaque.

Fucoidan protects mesenchymal stem cells against oxidative stress and enhances vascular regeneration in a murine hindlimb ischemia model

BACKGROUND

Mesenchymal stem cells (MSCs) have the potential to differentiate into multiple cell lineages. Given this potential for tissue regeneration, MSC-based therapeutic applications have been considered in recent years. However, ischemia-induced apoptosis has been reported to be one of the main causes of MSC death following transplantation. The primary objective of this study was to determine whether a natural antioxidant, fucoidan, could protect MSCs from ischemia-induced apoptosis in vitro and in vivo. Furthermore, we investigated the mechanism of action of fucoidan's anti-ischemic effect in MSCs.

METHODS AND RESULT

Pre-treatment with fucoidan (10 μg/mL) suppressed the increase in H2O2-induced reactive oxygen species (ROS) levels and drastically reduced apoptotic cell death in MSCs. Fucoidan inhibited the activation of the pro-apoptotic proteins p38-mitogen-activated protein kinase (MAPK), Jun N-terminal kinase (JNK), and caspase-3, and augmented the expression of the anti-apoptosis protein cellular inhibitor of apoptosis (cIAP). Moreover, fucoidan significantly increased manganese superoxide dismutase (MnSOD) expression and decreased cellular ROS levels via the Akt pathway, resulting in enhanced cell survival. In a murine hindlimb ischemia model, transplanted fucoidan-treated MSCs showed significantly enhanced cell survival and proliferation in ischemic tissues. Functional recovery and limb salvage also remarkably improved in mice injected with fucoidan-stimulated MSCs compared with mice injected with non-stimulated MSCs.

CONCLUSION

Taken together, these results show that fucoidan protects MSCs from ischemia-induced cell death by modulation of apoptosis-associated proteins and cellular ROS levels through regulation of the MnSOD and Akt pathways, suggesting that fucoidan could be powerful therapeutic adjuvant for MSC-based therapy in ischemic diseases.

Paediatric extremity vascular injuries - experience from a large urban trauma centre in India

INTRODUCTION

Paediatric extremity vascular injuries are infrequent, and management protocols draw significantly from adult vascular trauma experience necessitating a continuous review of evidence.

MATERIALS AND METHODS

A retrospective registry review of all consecutive patients younger than 18 years age treated for extremity vascular trauma from 2007 to 2012 was carried out. Diagnostic algorithm relied little on measurement of pressure indices. Data was collected about demographics, time since injury, pattern of injury, ISS, initial GCS and presence of shock, results of diagnostic modality and treatment given with associated complications. Patients completing 2 years follow up were assessed for functional disability and vascular patency. A multivariable regression model was used to evaluate effects of - ISS, presence of orthopaedic injury, soft tissue injury, neural injury and arterial patency at the end of 2 years - on outcome of functional disability.

RESULTS

Paediatric extremity vascular injuries accounted for 0.68% hospital admissions with a median delay of 8h from injury. 82 patients were included with 50 cases examined for long term outcome. Patient cohort was overwhelmingly male, with 'fall', 'road traffic injury' and 'glass cut' being most common injury mechanisms. CT angiography and duplex scan based diagnostic algorithm performed satisfactorily further identifying missed injuries and aiding complex orthopaedic reconstruction. Brachial and femoral vessels were most commonly injured. Lower extremity vascular injury was found associated with significantly higher ISS and requirement for fasciotomy. Upper extremity vascular injury was associated with higher odds of neural injury. Younger children were at higher risk of combined radial and ulnar vessel injury. No patient satisfactorily complied with post-operative anticoagulant/antithrombotic prophylaxis. 28 patients had good functional outcome with unsatisfactory functional outcome found associated with significantly higher ISS, presence of orthopaedic and neural injury, along with absence of arterial patency.

CONCLUSION

The epidemiology of paediatric peripheral vascular injury differs in India compared to west. Certain traditional management principles of extremity vascular trauma may stand uniquely challenged in the paediatric population.

Improving cardiovascular outcomes in rheumatic diseases: therapeutic potential of circulating endothelial progenitor cells

Patients with Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE) have a significantly increased risk of cardiovascular disease (CVD). The reason for this is unclear but may be due, at least in part, to the failure of endothelial repair mechanisms. Over the last 15 years there has been much interest in the mechanisms of endothelial renewal and its potential as a therapy for CVD. In the circulation there are two distinct populations of cells; myeloid angiogenic cells (MACs) which augment repair by the paracrine secretion of angiogenic factors, and outgrowth endothelial cells (OECs) which are true endothelial progenitor cells (EPCs) and promote vasculogenesis by differentiating into mature endothelium. There are marked abnormalities in the number and function of these cells in patients with RA and SLE. Inflammatory cytokines including interferon-alpha (IFNα) and tumour-necrosis factor alpha (TNFα) both impair MAC and OEC function ex vivo and may therefore contribute to the CVD risk in these patients. Whilst administration of mononuclear cells, MACs and other progenitors has improved cardiovascular outcomes in the acute setting, this is not a viable option in chronic disease. The pharmacological manipulation of MAC/OEC function in vivo however has the potential to significantly improve endothelial repair and thus reduce CVD in this high risk population.

The effects of stenting on shear stress: relevance to endothelial injury and repair

Stent deployment following balloon angioplasty is used routinely to treat coronary artery disease. These interventions cause damage and loss of endothelial cells (EC), and thus promote in-stent thrombosis and restenosis. Injured arteries are repaired (intrinsically) by locally derived EC and by circulating endothelial progenitor cells which migrate and proliferate to re-populate denuded regions. However, re-endothelialization is not always complete and often dysfunctional. Moreover, the molecular and biomechanical mechanisms that control EC repair and function in stented segments are poorly understood. Here, we propose that stents modify endothelial repair processes, in part, by altering fluid shear stress, a mechanical force that influences EC migration and proliferation. A more detailed understanding of the biomechanical processes that control endothelial healing would provide a platform for the development of novel therapeutic approaches to minimize damage and promote vascular repair in stented arteries.

Pulse oximetry for the diagnosis and prediction for surgical exploration in the pulseless perfused hand as a result of supracondylar fractures of the distal humerus

BACKGROUND

The management of the pulseless perfused hand in association with a supracondylar humerus fracture following operative stabilisation remains controversial. Previous authors have suggested the use of color-flow duplex monitoring, magnetic resonance angiography and segmental pressure monitoring as objective steps to ascertain blood flow following adequate internal fixation. We examine the use of the waveform of the pulse oximeter in objectively determining a perfused limb and in predicting the need for surgical exploration in patients who present with a pulseless perfused hand after operative stabilisation for supracondylar fracture of the humerus.

METHODS

A retrospective review of all supracondylar fractures over a 60 month duration (2005-2009) in our instituition was performed. Each electronic record was reviewed and limbs which had absent radial pulse following admission were identified. X-ray films of each of the patients were reviewed. A search using the Pubmed database was performed with the following keywords, supracondylar humerus fracture, pediatric, pulseless, vascular injury, arterial repair.

RESULTS

In this series of pulseless perfused hands following operative fixation of supracondylar fracture, a total of 26 patients were reviewed. All were Gartland grade III extension type fractures. Postoperative pulse oximeter waveforms were present in all but 4 patients. These patients subsequently had exploration of the brachial artery with significant findings. In the remaining 22 patients, waveforms were present and the child had return of the radial pulse soon after operative fixation without any further need for surgical exploration. At 24 months follow-up, all children were well with no neurovascular compromise.

CONCLUSIONS

The presence of a waveform on a pulse oximeter is a sensitive and easily available modality in determining vascular perfusion as compared to other more complex investigations. The high sensitivity of this test will allow surgeons to objectively determine the requirement for surgical exploration of the brachial artery.