Dual roles of myeloid-derived suppressor cells in various diseases: a review.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that originate from bone marrow stem cells. In pathological conditions, such as autoimmune disorders, allergies, infections, and cancer, normal myelopoiesis is altered to facilitate the formation of MDSCs. MDSCs were first shown to promote cancer initiation and progression by immunosuppression with the assistance of various chemokines and cytokines. Recently, various studies have demonstrated that MDSCs play two distinct roles depending on the physiological and pathological conditions. MDSCs have protective roles in autoimmune disorders (such as uveoretinitis, multiple sclerosis, rheumatoid arthritis, ankylosing spondylitis, type 1 diabetes, autoimmune hepatitis, inflammatory bowel disease, alopecia areata, and systemic lupus erythematosus), allergies, and organ transplantation. However, they play negative roles in infections and various cancers. Several immunosuppressive functions and mechanisms of MDSCs have been determined in different disease conditions. This review comprehensively discusses the associations between MDSCs and various pathological conditions and briefly describes therapeutic approaches.

Incidence and predictors of dorsal comminution in older adults with low-energy distal radius fracture.

PURPOSE: To identify the incidence of dorsal comminution using computed tomography (CT) images and identify predictors of this phenomenon in older adults with low-energy distal radius fractures (DRFs). METHODS: A total of 150 patients aged > 50 years with fall-induced dorsally angulated DRFs were enrolled in this study. Patients were divided into two groups based on the presence of dorsal comminution, defined as a metaphyseal void of greater than one-third of the maximum posterior to anterior depth of the bone on at least three cuts in the sagittal plane on post-reduction CT images. Data on participants' basic demographics, including age, sex, body mass index (BMI), and AO classification of DRFs, were collected. Bone mineral density (BMD) was assessed using T-scores of the femoral neck, and cortical thickness of the distal radius was determined from plain post-reduction radiographs. Radiological parameters and combined ulnar fractures were measured on plain pre-reduction radiographs. RESULTS: Among study participants, 91 (61%) had dorsal comminution, whereas 59 (39%) had no dorsal comminution on CT images. Both patient groups were compared based on presence of dorsal comminution, and showed no significant differences in age, sex, BMI, BMD, or cortical thickness on radiographs. However, all radiological parameters were better in the no dorsal comminution group than in the dorsal comminution group, and the proportion of patients with combined ulnar fractures was higher in the dorsal comminution group. In the multivariate analysis, the presence of combined ulnar fractures was the only significant predictor of dorsal comminution (p = 0.029, odds ratio = 2.267, 95% confidence interval: 1.085-4.736). CONCLUSION: The incidence of dorsal comminution is relatively high in patients with low-energy DRFs aged > 50 years. In particular, the presence of combined ulnar fractures is closely associated with dorsal comminution of DRFs. Thus, surgeons should exercise caution when evaluating this phenomenon.

Effects of Abdominal Massage for Preventing Acute Postoperative Constipation in Hip Fractures: A Prospective Interventional Study.

Background: This prospective randomized controlled study aimed to determine the effects of abdominal massage on constipation management in elderly patients with hip fractures. Methods: From August 2017 to December 2018, patients aged above 65 years with hip fractures (n = 88) were randomly assigned to a massage group that received a bowel massage (n = 48) or a control group that did not receive a bowel massage (n = 40). Patients in the bowel massage group received a bowel massage from a trained caregiver after breakfast at approximately 9:00 AM for an hour. On admission, 5 days after surgery, and on the day of discharge, the patient's normal and actual defecation pattern, stool consistency, and any problems with defecation were assessed through a structured interview. The questionnaire comprising the Bristol Stool Scale, patient assessment of constipation, time to defecation, medication for defecations, failure to defecate, cause of admission, admission period, and date of surgery were recorded. Statistical analyses were performed 5 days after surgery and on the day of discharge. Results: The mean age of the study cohort was 81.4 years (range, 65-99 years). The number of constipation remedies was significantly lower in the massage group than in the control group on postoperative day (POD) 5 and at discharge (9 vs. 15, p = 0.049 and 6 vs. 11, p = 0.039, respectively). The number of defecation failures was significantly lower in the massage group than in the control group (10 vs. 17, p = 0.028) on POD 5. However, the number of defecation failures at discharge was not significantly different between the two groups (p = 0.131). The development of postoperative ileus (p = 0.271) and length of hospital stay (p = 0.576) were not different between the groups. Conclusions: The number of constipation remedies was significantly lower in the massage group than in the control group on POD 5 and discharge, and the number of defecation failures was significantly lower in the massage group than in the control group on POD 5. Therefore, abdominal massage may be considered as an independent nursing initiative for constipation management.

Changes in Shoulder Trauma during the COVID-19 Pandemic: A South Korean Survey.

Background: This study aimed to investigate the changes in the incidence of shoulder trauma and surgery 1 year after the outbreak of coronavirus disease 2019 (COVID-19) with social restriction compared with 1 year before the pandemic. Methods: Patients managed in our orthopedic trauma center between February 18, 2020, and February 17, 2021 (COVID-19 period) for shoulder trauma were compared with patients managed for the same duration a year ago (non-COVID-19 period; February 18, 2019, to February 17, 2020). The incidence of shoulder trauma, surgery, and mechanism of injury were compared between these periods. Results: The total number of shoulder trauma cases was lower in the COVID-19 period than in the non-COVID-19 period, although the difference was not significant (160 vs. 180 cases, p = 0.278). In addition, traumatic shoulder surgeries decreased during the COVID-19 period (57 vs. 69 cases, p = 0.285). The incidence of shoulder trauma according to four diagnostic classifications (contusion, sprain/subluxation, fracture, and dislocation) and fracture/dislocation types did not differ between the periods. During the COVID-19 period, accidental falls outdoors (45 vs. 67, p = 0.038) and sports-related injuries (15 vs. 29, p = 0.035) significantly decreased, but accidental falls at home (52 vs. 37, p = 0.112) increased compared with those during the non-COVID-19 period, although the difference was not significant. The monthly incidence of shoulder trauma decreased 2 months after the first outbreak (significant in March, p = 0.019), then steadily increased and significantly decreased during the second outbreak (August, p = 0.012). However, the third outbreak (December, p = 0.077) had little effect on the incidence of shoulder trauma. The number of monthly traumatic shoulder surgeries showed a similar pattern to the monthly incidence of shoulder trauma. Conclusions: During the COVID-19 pandemic, annual shoulder trauma cases and surgeries decreased compared to those in the non-COVID-19 period, even though the difference was insignificant. The incidence of shoulder trauma and surgery was significantly reduced in the early COVID-19 period; however, the effect of the pandemic on orthopedic trauma practice was minimal after approximately half a year. Decreases in falls outdoors and sports-related injuries, but an increase in falls at home, were observed during the COVID-19 pandemic.

Age, Tear Size, Extent of Retraction, and Fatty Infiltration Associated With a High Chance of a Similar Rotator Cuff Tear in the Contralateral Shoulder Regardless of Symptoms in Patients Undergoing Cuff Repair in the Index Shoulder.

PURPOSE: To investigate the prevalence of a contralateral rotator cuff tear (RCT) in patients with a symptomatic RCT requiring repair and to determine whether findings from magnetic resonance imaging (MRI) of the affected shoulder can predict the presence of a contralateral tear. METHODS: Patients with atraumatic RCTs who had undergone arthroscopic repair between March 2019 and February 2021 were reviewed in this study. MRI of both shoulder joints was performed to evaluate the bilaterality of RCT. Demographic factors and MRI findings of index shoulders were assessed using logistic regression analysis to reveal any correlations with the presence of RCT in the contralateral shoulder. RESULTS: A total of 428 patients were enrolled in this study. When the affected shoulders had a posterosuperior rotator cuff (PSRC) or subscapularis tear including either an isolated or combined tear, 63.6% and 67.8% had the same tears on the contralateral side, respectively. A contralateral-side tear was found in 74.6% (185/248) of symptomatic cases and 44.8% (65/145) of asymptomatic cases, which represents a significant difference (P < .001). Logistic regression analysis revealed that age ≥67.5 years, tear size ≥17 mm, Goutallier grade ≥1.5, and Patte grade ≥1.5 were found to be indicative of potential contralateral PSRC tears. By contrast, the presence of a subscapularis tear in the affected shoulder was the only significant risk factor in predicting a potential subscapularis tear in the contralateral shoulder. CONCLUSIONS: Among patients with a symptomatic RCT requiring arthroscopic repair, 63.6% with a PSRC tear and 67.8% with a subscapularis tear in the affected shoulder were found to have a similar tear in the contralateral shoulder regardless of symptoms. Age, tear size, extent of retraction, fatty infiltration of PSRC tears, and the presence of subscapularis tears were identified as factors predictive of tears on the contralateral side. LEVEL OF EVIDENCE: Level IV, case series.

The effect of cerclage wiring with intramedullary nail surgery in proximal femoral fracture: a systematic review and meta-analysis.

PURPOSE: The aim of this study was to evaluate the utility of cerclage wiring with intramedullary nail surgery in the treatment of proximal femoral fractures. METHODS: MEDLINE, Embase, and Cochrane Library were systematically searched for studies that evaluated the impact of cerclage wiring on proximal femoral fractures published up to September 20, 2021. Pooled analysis identified differences in the (1) fracture healing profile, (2) perioperative variables, (3) complications, and (4) clinical outcome score between cerclage wiring and non-cerclage wiring. RESULTS: Fourteen studies involving 1,718 patients with proximal femoral fractures who underwent cephalomedullary nailing surgeries were included. The pooled analysis revealed a longer fracture union time in the non-cerclage wiring group than in the cerclage wiring group (mean difference [MD] = - 1.03 months; 95% confidence interval [CI]: - 1.47 to - 0.59; P < 0.001), and there was no difference in the nonunion rate. The operation time was longer in the cerclage wiring group (MD = 14.32 min; 95% CI: 6.42-22.22; P < 0.001), but there were no differences in blood loss and the rate of poor quality of reduction. Superficial and deep infection rates showed no difference between the groups, and the readmission rate also showed no difference. The cerclage wiring group had a higher Harris hip score than the non-cerclage wiring group (MD = 2.13; 95% CI: 0.77-3.49; P = 0.002). CONCLUSIONS: Intramedullary nailing with cerclage wiring is considered a useful treatment method for proximal femoral fractures. It enables anatomic reduction and stable fixation, thereby reducing union time and facilitating rapid functional recovery.

Advanced Xenograft Model with Cotransplantation of Patient-Derived Organoids and Endothelial Colony-Forming Cells for Precision Medicine.

Preclinical evaluation models have been developed for precision medicine, with patient-derived xenograft models (PDXs) and patient-derived organoids (PDOs) attracting increasing attention. However, each of these models has application limitations. In this study, an advanced xenograft model was established and used for drug screening. PDO and endothelial colony-forming cells (ECFCs) were cotransplanted in NRGA mice (PDOXwE) to prepare the model, which could also be subcultured in Balb/c nude mice. Our DNA sequencing analysis and immunohistochemistry results indicated that PDOXwE maintained patient genetic information and tumor heterogeneity. Moreover, the model enhanced tumor growth more than the PDO-bearing xenograft model (PDOX). The PDO, PDOXwE, and clinical data were also compared in the liver metastasis of a colorectal cancer patient, demonstrating that the chemosensitivity of PDO and PDOXwE coincided with the clinical data. These results suggest that PDOXwE is an improvement of PDOX and is suitable as an evaluation model for precision medicine.

CCL8 mediates crosstalk between endothelial colony forming cells and triple-negative breast cancer cells through IL-8, aggravating invasion and tumorigenicity.

Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer with a poor prognosis for which no effective therapeutic measures are currently available. The present study aimed to investigate whether interactions with endothelial colony-forming cells (ECFCs) promote aggressive progression of TNBC cells. Herein, using an indirect co-culture system, we showed that co-culture increased the invasive and migratory phenotypes of both MDA-MB-231 TNBC cells and ECFCs. Through a cytokine antibody array and RT-PCR analysis, we revealed that co-culture markedly induced secretion of the chemokine C-C motif ligand (CCL)8 from ECFCs and that of interleukin (IL)-8 from MDA-MB-231 cells. CCL8 was crucial for ECFC-induced IL-8 secretion and invasion of MDA-MB-231 cells as well as for MDA-MB-231-enhanced MMP-2 secretion and angiogenesis of ECFCs. We suggest c-Jun as a transcription factor for CCL8-induced IL-8 expression in MDA-MB-231 cells. IL-8 was important for co-culture-induced CCL8 and MMP-2 upregulation and invasion of ECFCs. Notably, our findings reveal a positive feedback loop between CCL8 and IL-8, which contributes to the aggressive phenotypes of both ECFC and TNBC cells. Using an MDA-MB-231 cell-based xenograft model, we show that tumor growth and metastasis are increased by co-injected ECFCs in vivo. Increased expression of IL-8 was observed in tissues with bone metastases in mice injected with conditioned media from co-cultured cells. High IL-8 levels are correlated with poor recurrence-free survival in TNBC patients. Together, these results suggest that CCL8 and IL-8 mediate the crosstalk between ECFCs and TNBC, leading to aggravation of tumorigenicity in TNBC.

Differential Angiogenic Responses of Human Endothelial Colony-Forming Cells to Different Molecular Subtypes of Breast Cancer Cells.

OBJECTIVE: Triple negative breast cancer (TNBC) is one subtype of breast cancer. It is characterized by lack of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Compared with non-TNBC, TNBC is more aggressive, of higher grade, and frequently metastatic with poor prognosis, which is correlated with upregulated microvascular density. Endothelial colony-forming cells (ECFCs) mediate neovascularization, which is the crucial contributor to cancer growth and metastasis. The present study aimed to determine whether angiogenic responses of ECFCs are regulated differently by TNBC compared with non-TNBC. METHODS: MDA-MB-231 and MCF7 cells were utilized for TNBC and non-TNBC, respectively. Bone-marrow-derived human ECFCs were treated with a conditioned medium (CM) of cancer cells to investigate the paracrine effect on angiogenesis. Also, ECFCs were co-cultured with cancer cells to evaluate the angiogenic effect of direct cell-to-cell interaction. Angiogenic responses of ECFCs were evaluated by proliferation, migration, and tube formation. Gene expression profiles of pro-angiogenic factors were also analyzed. RESULTS: Migration and tube formation of ECFCs were increased by treatment with CM of MDA-MB-231, which correlated with a higher gene expression profile of pro-angiogenic factors in MDA-MB-231 compared to MCF7. Interestingly, ECFCs co-cultured with MDA-MB-231 showed further increase of tube formation, suggesting synergic mechanisms between the paracrine effect and direct interaction between the cells. CONCLUSION: The angiogenic potential of ECFCs was enhanced by TNBC through both direct and indirect mechanisms. Therefore, the investigation of signaling pathways to regulate ECFC-mediated angiogenesis will be important to the discovery of anti-angiogenic therapies to treat TNBC patients.

Three-dimensional Angiogenesis Assay System using Co-culture Spheroids Formed by Endothelial Colony Forming Cells and Mesenchymal Stem Cells.

Studies in the field of angiogenesis have been aggressively growing in the last few decades with the recognition that angiogenesis is a hallmark of more than 50 different pathological conditions, such as rheumatoid arthritis, oculopathy, cardiovascular diseases, and tumor metastasis. During angiogenesis drug development, it is crucial to use in vitro assay systems with appropriate cell types and proper conditions to reflect the physiologic angiogenesis process. To overcome limitations of current in vitro angiogenesis assay systems using mainly endothelial cells, we developed a 3-dimensional (3D) co-culture spheroid sprouting assay system. Co-culture spheroids were produced by two human vascular cell precursors, endothelial colony forming cells (ECFCs) and mesenchymal stem cells (MSCs) with a ratio of 5 to 1. ECFCs+MSCs spheroids were embedded into type I collagen matrix to mimic the in vivo extracellular environment. A real-time cell recorder was utilized to continuously observe the progression of angiogenic sprouting from spheroids for 24 h. Live cell fluorescent labeling technique was also applied to tract the localization of each cell type during sprout formation. Angiogenic potential was quantified by counting the number of sprouts and measuring the cumulative length of sprouts generated from the individual spheroids. Five randomly-selected spheroids were analyzed per experimental group. Comparison experiments demonstrated that ECFCs+MSCs spheroids showed greater sprout number and cumulative sprout length compared with ECFCs-only spheroids. Bevacizumab, an FDA-approved angiogenesis inhibitor, was tested with the newly-developed co-culture spheroid assay system to verify its potential to screen anti-angiogenic drugs. The IC50 value for ECFCs+MSCs spheroids compared to the ECFCs-only spheroids was closer to the effective plasma concentration of bevacizumab obtained from the xenograft tumor mouse model. The present study suggests that the 3D ECFCs+MSCs spheroid angiogenesis assay system is relevant to physiologic angiogenesis, and can predict an effective plasma concentration in advance of animal experiments.

Endothelial colony forming cells and mesenchymal progenitor cells form blood vessels and increase blood flow in ischemic muscle.

Here we investigated whether endothelial colony forming cells (ECFC) and mesenchymal progenitor cells (MPC) form vascular networks and restore blood flow in ischemic skeletal muscle, and whether host myeloid cells play a role. ECFC + MPC, ECFC alone, MPC alone, or vehicle alone were injected into the hind limb ischemic muscle one day after ligation of femoral artery and vein. At day 5, hind limbs injected with ECFC + MPC showed greater blood flow recovery compared with ECFC, MPC, or vehicle. Tail vein injection of human endothelial specific Ulex europaeus agglutinin-I demonstrated an increased number of perfused human vessels in ECFC + MPC compared with ECFC. In vivo bioluminescence imaging showed ECFC persisted for 14 days in ECFC + MPC-injected hind limbs. Flow cytometric analysis of ischemic muscles at day 2 revealed increased myeloid lineage cells in ECFC + MPC-injected muscles compared to vehicle-injected muscles. Neutrophils declined by day 7, while the number of myeloid cells, macrophages, and monocytes did not. Systemic myeloid cell depletion with anti-Gr-1 antibody blocked the improved blood flow observed with ECFC + MPC and reduced ECFC and MPC retention. Our data suggest that ECFC + MPC delivery could be used to reestablish blood flow in ischemic tissues, and this may be enhanced by coordinated recruitment of host myeloid cells.

Rapamycin improves TIE2-mutated venous malformation in murine model and human subjects.

Venous malformations (VMs) are composed of ectatic veins with scarce smooth muscle cell coverage. Activating mutations in the endothelial cell tyrosine kinase receptor TIE2 are a common cause of these lesions. VMs cause deformity, pain, and local intravascular coagulopathy, and they expand with time. Targeted pharmacological therapies are not available for this condition. Here, we generated a model of VMs by injecting HUVECs expressing the most frequent VM-causing TIE2 mutation, TIE2-L914F, into immune-deficient mice. TIE2-L914F-expressing HUVECs formed VMs with ectatic blood-filled channels that enlarged over time. We tested both rapamycin and a TIE2 tyrosine kinase inhibitor (TIE2-TKI) for their effects on murine VM expansion and for their ability to inhibit mutant TIE2 signaling. Rapamycin prevented VM growth, while TIE2-TKI had no effect. In cultured TIE2-L914F-expressing HUVECs, rapamycin effectively reduced mutant TIE2-induced AKT signaling and, though TIE2-TKI did target the WT receptor, it only weakly suppressed mutant-induced AKT signaling. In a prospective clinical pilot study, we analyzed the effects of rapamycin in 6 patients with difficult-to-treat venous anomalies. Rapamycin reduced pain, bleeding, lesion size, functional and esthetic impairment, and intravascular coagulopathy. This study provides a VM model that allows evaluation of potential therapeutic strategies and demonstrates that rapamycin provides clinical improvement in patients with venous malformation.

Rapid onset of perfused blood vessels after implantation of ECFCs and MPCs in collagen, PuraMatrix and fibrin provisional matrices.

We developed an in vivo vascularization model in which human endothelial colony-forming cells (ECFCs) and human mesenchymal progenitor cells (MPCs) form blood vessel networks when co-injected (ECFC + MPC) into nude mice in rat tail type I collagen, bovine fibrin or synthetic peptide PuraMatrix matrices. We used three approaches to determine the onset of functional vascularization when ECFC + MPC suspended in these matrices were implanted in vivo. The first was immunohistochemistry to detect vessels lined by human endothelial cells and filled with red blood cells. The second was in vivo vascular staining by tail vein injection of a mixture of Ulex europaeus agglutinin I (UEA-I), a lectin specific for human endothelium, and Griffonia simplicifolia isolectin B4 (GS-IB4 ), a lectin specific for rodent endothelium. The third approach employed contrast-enhanced ultrasound to measure the perfusion volumes of implants in individual animals over time. Human endothelial-lined tubular structures were detected in vivo on days 1 and 2 after implantation, with perfused human vessels detected on days 3 and 4. Contrast-enhanced ultrasound revealed significant perfusion of ECFC + MPC/collagen implants on days 1-4, at up to 14% perfused vascular volume. ECFC + MPC implanted in fibrin and PuraMatrix matrices also supported perfusion at day 1, as assessed by ultrasound (at 12% and 23% perfused vascular volume, respectively). This model demonstrates that ECFC + MPC suspended in any of the three matrices initiated a rapid onset of vascularization. We propose that ECFC + MPC delivered in vivo provide a means to achieve rapid perfusion of tissue-engineered organs or for in situ tissue repair.

Neuropilin-1 functions as a VEGFR2 co-receptor to guide developmental angiogenesis independent of ligand binding.

During development, tissue repair, and tumor growth, most blood vessel networks are generated through angiogenesis. Vascular endothelial growth factor (VEGF) is a key regulator of this process and currently both VEGF and its receptors, VEGFR1, VEGFR2, and Neuropilin1 (NRP1), are targeted in therapeutic strategies for vascular disease and cancer. NRP1 is essential for vascular morphogenesis, but how NRP1 functions to guide vascular development has not been completely elucidated. In this study, we generated a mouse line harboring a point mutation in the endogenous Nrp1 locus that selectively abolishes VEGF-NRP1 binding (Nrp1(VEGF-)). Nrp1(VEGF-) mutants survive to adulthood with normal vasculature revealing that NRP1 functions independent of VEGF-NRP1 binding during developmental angiogenesis. Moreover, we found that Nrp1-deficient vessels have reduced VEGFR2 surface expression in vivo demonstrating that NRP1 regulates its co-receptor, VEGFR2. Given the resources invested in NRP1-targeted anti-angiogenesis therapies, our results will be integral for developing strategies to re-build vasculature in disease.

Atmospheric-pressure plasma jet induces DNA double-strand breaks that require a Rad51-mediated homologous recombination for repair in Saccharomyces cerevisiae.

Non-thermal plasma generated under atmospheric pressure produces a mixture of chemically reactive molecules and has been developed for a number of biomedical applications. Recently, plasma jet has been proposed as novel cancer therapies based on the observation that free radicals generated by plasma jet induce mitochondria-mediated apoptotic cell death. We show here that air plasma jet induces DNA double-strand breaks (DSBs) in yeast chromosomes leading to genomic instability and loss of viability, which are alleviated by Rad51, the yeast homolog of Escherichiacoli RecA recombinase, through DNA damage repair by a homologous recombination (HR) process. Hypersensitivity of rad51 mutant to air plasma was not restored by antioxidant treatment unlike sod1 mutant that was highly sensitive to reactive oxygen species (ROS) challenge, suggesting that plasma jet induces DSB-mediated cell death independent of ROS generation. These results may provide a new insight into the mechanism of air plasma jet-induced cell death.

Human vasculogenic cells form functional blood vessels and mitigate adverse remodeling after ischemia reperfusion injury in rats.

Cell-based therapies to restore heart function after infarction have been tested in pre-clinical models and clinical trials with mixed results, and will likely require both contractile cells and a vascular network to support them. We and others have shown that human endothelial colony forming cells (ECFC) combined with mesenchymal progenitor cells (MPC) can be used to "bio-engineer" functional human blood vessels. Here we investigated whether ECFC + MPC form functional vessels in ischemic myocardium and whether this affects cardiac function or remodeling. Myocardial ischemia/reperfusion injury (IRI) was induced in 12-week-old immunodeficient rats by ligation of the left anterior descending coronary artery. After 40 min, myocardium was reperfused and ECFC + MPC (2 × 10(6) cells, 2:3 ratio) or PBS was injected. Luciferase assays after injection of luciferase-labeled ECFC + MPC showed that 1,500 ECFC were present at day 14. Human ECFC-lined perfused vessels were directly visualized by femoral vein injection of a fluorescently-tagged human-specific lectin in hearts injected with ECFC + MPC but not PBS alone. While infarct size at day 1 was no different, LV dimensions and heart weight to tibia length ratios were lower in cell-treated hearts compared with PBS at 4 months, suggesting post-infarction remodeling was ameliorated by local cell injection. Fractional shortening, LV wall motion score, and fibrotic area were not different between groups at 4 months. However, pressure-volume loops demonstrated improved cardiac function and reduced volumes in cell-treated animals. These data suggest that myocardial delivery of ECFC + MPC at reperfusion may provide a therapeutic strategy to mitigate LV remodeling and cardiac dysfunction after IRI.

Bioengineered human vascular networks transplanted into secondary mice reconnect with the host vasculature and re-establish perfusion.

The ability to form anastomoses with the host circulation is essential for vascular networks incorporated within cell-seeded bioengineered tissues. Here, we tested whether and how rapidly human endothelial colony forming cell (ECFC)/mesenchymal progenitor cell (MPC)-derived bioengineered vessels, originally perfused in one mouse, could become reperfused in a secondary mouse. Using in vivo labeling with a systemically injected mixture of human- and murine-specific lectins, we demonstrate that ECFC/MPC blood vessels reconnect and are perfused at day 3 after transplantation. Furthermore, we quantified the longitudinal change in perfusion volume in the same implants before and after transplantation using contrast-enhanced micro-ultrasonic imaging. Perfusion was restored at day 3 after transplantation and increased with time, suggesting an important new feature of ECFC/MPC blood vessels: the bioengineered vessels can reconnect with the vasculature when transplanted to a new site. This feature extends the potential applications of this postnatal progenitor cell-based technology for transplantable large tissue-engineered constructs.

Rapamycin suppresses self-renewal and vasculogenic potential of stem cells isolated from infantile hemangioma.

Infantile hemangioma (IH) is a common childhood vascular tumor. Although benign, some hemangiomas cause deformation and destruction of features or endanger life. The current treatments, corticosteroid or propranolol, are administered for several months and can have adverse effects on the infant. We designed a high-throughput screen to identify the Food and Drug Administration-approved drugs that could be used to treat this tumor. Rapamycin, an mTOR (mammalian target of Rapamycin) inhibitor, was identified, based on its ability to inhibit proliferation of a hemangioma-derived stem cell population, human vasculogenic cells, which we had previously discovered. In vitro and in vivo studies show that Rapamycin reduces the self-renewal capacity of the hemangioma stem cells, diminishes differentiation potential, and inhibits the vasculogenic activity of these cells in vivo. Longitudinal in vivo imaging of blood flow through vessels formed with hemangioma stem cells shows that Rapamycin also leads to regression of hemangioma blood vessels, consistent with its known anti-angiogenic activity. Finally, we demonstrate that Rapamycin-induced loss of stemness can work in concert with corticosteroid, the current standard therapy for problematic hemangioma, to block hemangioma formation in vivo. Our studies reveal that Rapamycin targets the self-renewal and vascular differentiation potential in patient-derived hemangioma stem cells, and suggests a novel therapeutic strategy to prevent formation of this disfiguring and endangering childhood tumor.

Effects of estradiol on renal cyclic guanosine monophosphate and oxidative stress in spontaneously hypertensive rats.

BACKGROUND: Evidence suggests that estradiol offers protection against the development of cardiovascular and renal pathologies, although the mechanisms involved are still under investigation. The nitric oxide (NO) pathway regulates blood pressure and kidney function, and estradiol is associated with increases in NO bioavailability. We hypothesized that in female spontaneously hypertensive rats (SHRs), estra-diol increases NO bioavailability, activates the NO synthase (NOS) pathway, and suppresses superoxide production compared with rats that underwent ovariectomy (OVX). OBJECTIVE: The goal of this study was to determine whether estradiol regulates the NO/cyclic guanosine monophosphate (cGMP) pathway and superoxide levels in the kidneys of female SHR. METHODS: Three types of SHRs were studied: gonad-intact females, OVX rats, and OVX rats with estra-diol replacement (OVX+E). Renal cortical cGMP levels were measured to assess NO bioavailability. NOS enzymatic activity, NOS protein expression, basal superoxide production, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity were measured in the renal cortex. RESULTS: Fifty-six SHRs were included in the study (17 intact females, 21 OVX rats, 18 OVX+E rats). Mean (SEM) cGMP levels were significantly lower in the renal cortex of OVX rats (0.03 [0.008] pmol/mg, n = 5) than in intact females (0.1 [0.02] pmol/mg, n = 6; P < 0.05), and estradiol restored cGMP levels to those seen in intact females (0.1 [0.01] pmol/mg, n = 5; P < 0.05). Despite a decrease in cGMP following OVX, renal cortical NOS activity, NOS1 and NOS3 protein expression, and the phosphorylation status of NOS3 were comparable among the 3 groups (n = 7-9 per group). However, mean basal superoxide production in the renal cortex was higher in OVX rats (3.2 [0.3] cpm/mg, n = 12) than in intact females (1.9 [0.3] cpm/mg, n = 8; P < 0.05) and lower in OVX+E rats (1.3 [0.3] cpm/mg, n = 9; P < 0.05). Mean NADPH oxidase activity was comparable in the renal cortex of intact females and OVX rats (81 [4] and 83 [12] cpm/35 microg, respectively [n = 5 per group]). OVX+E rats had significantly lower mean renal cortical NADPH oxidase activity than did rats in the other groups (45 [6] cpm/35 microg, n = 6; P < 0.05), and the decrease in activity was accompanied by a decrease in p22(phox) protein expression. CONCLUSIONS: In vivo manipulations of estradiol levels influenced renal cortical NO bioavailability, as assessed indirectly by cGMP measurements. The decrease in cGMP following OVX was not due to alterations in the activity or expression of NOS.

Enhancement of platelet aggregation and thrombus formation by arsenic in drinking water: a contributing factor to cardiovascular disease.

Arsenic in drinking water is a worldwide health problem that is associated with cardiovascular disease, but the cause is currently unknown. Arsenic effects on platelets, which are important in development of cardiovascular disease, were examined in vitro and in a drinking water study using a rat animal model. Trivalent inorganic arsenic (arsenite) induced in vitro aggregation when platelets were exposed to subthreshold challenge by thrombin and several other agonists in a concentration-dependent manner, with arsenite being the most potent form tested. Arsenite also induced significant increases in serotonin secretion, thromboxane A(2) formation, and adhesion protein expression in platelets. Consistent with the in vitro studies, 4-week ingestion of arsenite-contaminated drinking water resulted in enhanced arterial thrombosis. Human platelets showed similar responses, suggesting that the effects seen in animal experiments are applicable to humans. These results will provide new insights into the mechanism of arsenic-induced cardiovascular disease. They will also allow regulatory agencies to estimate risk from arsenic-induced cardiovascular disease and to determine if drinking water regulatory levels based on human cancer studies will protect against noncancer effects associated with cardiovascular disease.