Kinetics changes in total cholesterol predict HBeAg seroconversion in chronic hepatitis B patients treated with pegylated interferon-alfa.

There is no satisfactory standard for predicting HBeAg seroconversion during Pegylated interferon alpha (PegIFNα) treatment. Studies have shown that IFNα therapy in chronic hepatitis C patients could alter serum lipid profiles. However, there have been no studies on lipid changes that predict the outcome of PegIFNα monotherapy in treated-naive chronic hepatitis B (CHB) patients. This retrospective study included 130 treated-naive HBeAg-positive CHB patients receiving PegIFNα monotherapy. The relationship between serum lipid changes and HBeAg seroconversion was analysed. The TC-ALT-HBsAg-HBeAg-Genotype-Age (CASEGA) model was established to predict HBeAg seroconversion after PegIFN-α monotherapy. Among 130 patients, 33 achieved HBeAg seroconversion (SR) and 97 did not achieve HBeAg seroconversion (NR). The decrease in serum total cholesterol (TC) in the NR group was significantly higher than in the SR group at Week 24 (-9.59% vs. -0.31%, p < 0.001). Multivariate logistic regression analysis showed that the change in TC at Week 24 (odds ratio = 1.065, p = 0.009) was an independent predictor of HBeAg seroconversion. The area under the receiver operating characteristic curve for the CASEGA model was 0.883. The model score at the maximum Youden index was 90, and the specificity, sensitivity, positive predictive value and negative predictive value were 0.727, 0.794, 0.546 and 0.895, respectively. The HBeAg seroconversion rate at Week 72 in patients with scores >90 was significantly higher than that in patients with scores <90 (54.55% vs. 10.47%, p < 0.001). This study indicated that the change in the TC level at 24 weeks in CHB patients treated with PegIFNα was associated with HBeAg seroconversion. The CASEGA prediction model based on the TC change rate of 24 weeks has good predictive efficiency for HBeAg seroconversion.

Thyroid dysfunction incidence and risk factors in Chinese chronic hepatitis B patients treated with pegylated interferon alpha: A long-term follow-up study.

The long-term impact, incidence and risk factors of thyroid dysfunction in chronic hepatitis B (CHB) patients receiving pegylated interferon (IFN) alpha (PegIFN-alpha) therapy remain unclear. We aim to investigate the long-term safety of thyroid dysfunction in CHB patients receiving PegIFN-alpha. A retrospective observational study of 425 CHB patients with normal baseline thyroid function was carried out. Patients were followed up over 10 years to assess thyroid function after receiving IFN. At the end of the IFN therapy, 67 patients (15.8%) had developed thyroid dysfunction, 31 patients (46.3%) had hyperthyroidism and 64.4% presented with subclinical thyroid dysfunction. In follow-up of thyroid dysfunction patients, 37 patients (74.0%) spontaneously regained normal thyroid function. Pretreatment thyroid-stimulating hormone (TSH) level, thyroid peroxidase antibody (TPOAb) positivity and free thyroxine (FT4) were independent risk factors associated with thyroid dysfunction incidence. High TSH level (OR = 9.866, 95%CI, 3.245-29.998) was associated with a greater likelihood of hypothyroidism. High FT4 levels (OR = 0.464, 95%CI, 0.248-0.868) indicate a low likelihood of thyroid dysfunction. Thyroid dysfunction is a common but acceptable side effect of IFN therapy for CHB. Most thyroid dysfunction is reversible. Pretreatment TSH level and TPOAb positivity are risk factors for thyroid dysfunction development during IFN therapy. A high TSH level predicts an increased incidence of hypothyroidism. Moreover, FT4 may be a protective factor for thyroid dysfunction.

STAT4 genetic polymorphism significantly affected HBeAg seroconversion in HBeAg-positive chronic hepatitis B patients receiving Peginterferon-α therapy: A prospective cohort study in China.

A variant in signal transducer and activator of transcription 4 (STAT4) was reported to correlate with the response of interferon-α (IFN-α) in a retrospective study in hepatitis B e antigen (HBeAg)-positive chronic hepatitis B virus (CHB) patients. Here, we conducted a prospective study to analyze the effect of STAT4 genetic polymorphism on the response of pegylated interferon-α-2a (PegIFN-α-2a) in HBeAg-positive patients. A prospective, multicenter, open-label, parallel cohort study was performed. One hundred and fifty treatment-naïve and 156 nucleos(t)ide analog (NA)-experienced HBeAg-positive CHB patients were enrolled, respectively. All patients received PegIFN-α-2a treatment for 48 weeks and 24-week follow-up post PegIFN-α-2a treatment. Before treatment, STAT4 genetic polymorphism was determined by PCR and DNA sequencing. Serological markers, serum HBV DNA levels, and adverse events were collected at each visit. We observed a larger reduction of HBV DNA load and a significantly higher HBeAg seroconversion rate in the GT/TT group than in the GG group at week 72 (p = 0.002 and p = 0.023) in treatment-naïve patients. In NA-experienced patients, the HBeAg seroconversion rate in the GT/TT group was higher than that in the GG group at week 72 (p = 0.005). STAT4 rs7574865 gene polymorphism was the strongest independent predictor of HBeAg seroconversion in both paralleled cohorts. Also, patients in the GT/TT group had a higher hepatitis B surface antigen loss rate than in the GG group in the study. There was no significant difference in adverse events between GG and GT/TT groups. This prospective cohort study confirmed that STAT4 rs7574865 gene polymorphism is associated with HBeAg seroconversion and HBsAg loss irrespective of naïve and NA-experienced HBeAg-positive CHB patients treated with PegIFN-α-2a.

Baseline serum exosome-derived miRNAs predict HBeAg seroconversion in chronic hepatitis B patients treated with peginterferon.

This study aimed to explore the value of baseline serum exosome-derived miRNAs for predicting HBeAg seroconversion in chronic hepatitis B (CHB) patients treated with peginterferon (Peg-IFN). A total of 120 treatment-naïve HBeAg-positive CHB patients who received Peg-IFN therapy (48 weeks) were enrolled. Next-generation sequencing was performed to screen the serum exosomal miRNAs that were associated with Peg-IFN treatment outcome, and qRT-PCR was used to validate them. The area under the receiver operating characteristic curve (AUROC) was used to evaluate the predictive efficacy of biomarkers. Thirty-three patients (27.5%) achieved HBeAg seroconversion (response group), and 87 patients (72.5%) did not achieve HBeAg seroconversion (nonresponse group). In the identification cohort, 40 serum exosome-derived miRNAs were differentially expressed between the response group (four patients) and the nonresponse group (four patients). In the confirmation cohort, the expression levels of serum exosomal miR-194-5p (p < .001) and miR-22-3p (p < .001) were significantly downregulated in the response group (29 patients) compared to the nonresponse group (83 patients). Multivariate analysis identified baseline serum exosomal miR-194-5p, miR-22-3p, alanine aminotransferase (ALT), and HBV DNA as independent predictors of HBeAg seroconversion (all p < .05). The AUROCs of serum exosomal miRNAs (0.77 and 0.75 for miR-194-5p and miR-22-3p, respectively) were higher than that of ALT (0.70) and HBV DNA (0.69). The combination of exosomal miR-194-5p and miR-22-3p further improved the predictive performance with an AUROC of 0.82. Baseline serum exosomal miR-194-5p and miR-22-3p may serve as novel biomarkers to predict HBeAg seroconversion in CHB patients treated with Peg-IFN.

Serum hepatitis B virus RNA levels as a predictor of HBeAg seroconversion during treatment with peginterferon alfa-2a.

BACKGROUND: Hepatitis B e antigen (HBeAg) seroconversion represents an endpoint of treatment of chronic hepatitis B virus (HBV) infections. METHODS: We have studied whether levels of serum hepatitis B virus ribonucleic acid (HBV RNA) during pegylated interferon alfa-2a treatment might be helpful for predicting HBeAg seroconversion. 61 HBeAg-positive chronic hepatitis B (CHB) patients treated with pegylated interferon alfa-2a alone or in combination with adefovir (10 mg/day) for 48 weeks were included in this retrospective analysis. Response was defined as HBeAg seroconversion at 24 weeks posttreatment. Receiver operating characteristic analyses were used to identify baseline and on-treatment HBV RNA levels associated with response. RESULTS: Twenty-two of 61 (36.1%) patients achieved a response. Baseline HBV RNA levels were lower in responders than in nonresponders (4.55 ± 1.19 and 5.90 ± 1.13 copies/mL, respectively, P = 0.001). Baseline HBV RNA cut off level (200,000 copies/mL) provided a positive predictive value (PPV) of 56.0% and a negative predictive value (NPV) of 77.8%. HBV RNA level (3000 copies/mL) at week 12 provide a PPV of 75.0% and a NPV of 82.8%. Moreover, HBeAg seroconversion rates at 24 weeks posttreatment were significantly higher in patients with HBV RNA ≤ 200,000 copies/mL at baseline and HBV RNA ≤ 3000 copies/mL at week 12 (92.9%) versus others (12.5%) (All P < 0.05). CONCLUSIONS: In Conclusions, serum HBV RNA levels may serve as a novel tool for prediction of HBeAg seroconversion during therapy with pegylated interferon alfa-2a in HBeAg-positive CHB patients.

Pegylated Interferon Alfa-2b Add-on Treatment in Hepatitis B Virus Envelope Antigen-Positive Chronic Hepatitis B Patients Treated with Nucleos(t)ide Analogue: A Randomized, Controlled Trial (PEGON).

Background: We studied whether 48 weeks of pegylated interferon alfa-2b (peginterferon) add-on therapy increases serological response in hepatitis B virus (HBV) envelope antigen (HBeAg)-positive patients receiving nucleos(t)ide analogue (NA) therapy, compared with continued NA monotherapy. Methods: This randomized trial included HBeAg-positive patients with compensated liver disease who were treated with entecavir/tenofovir for >12 months and had an HBV DNA load of <2000 IU/mL. Patients were randomly assigned in a 1:1 ratio to 48 weeks of peginterferon add-on therapy (n = 39) or continued NA monotherapy (n = 38). Response (defined as HBeAg seroconversion with an HBV DNA load of <200 IU/mL) was assessed at week 48, with responders discontinuing NA therapy at week 72. Results: The primary end point (response at week 96) was achieved in 18% of patients who were assigned peginterferon add-on therapy versus 8% of patients assigned NA monotherapy (P = .31). Among 58 interferon-naive patients, add-on therapy led to a greater frequency of HBeAg seroconversion (30% vs 7%; P = .034) and response (26% vs 7%; P = .068) at week 96, compared with monotherapy. Among 8 responders at week 48 who discontinued NA therapy at week 72, 6 patients (75%) maintained a response until week 96 (4 of 6 [67%] in the add-on therapy group vs 2 of 2 [100%] in the monotherapy group; P = 1.00). Adverse events were mainly related to peginterferon. Conclusion: The primary end point was negative, but peginterferon add-on therapy appeared to result in a greater frequency of HBeAg seroconversion, compared with NA monotherapy, in interferon-naive patients receiving NA therapy. Clinical Trials Registration: NCT01532843.

Reduction of Hepatitis B Surface Antigen May Be More Significant in PEGylated Interferon-Alpha Therapy Combined with Nucleotide Analogues than Combined with Nucleoside Analogues in Chronic Hepatitis B Patients: A Propensity Score Matching Study.

Background: Nucleotide analogues (NTs) monotherapy may have a more significant effect on reducing hepatitis B surface antigen (HBsAg) than nucleoside analogues (NSs) due to their immunomodulatory function. However, this superiority remains unknown when combined with PEGylated interferon α (PegIFNα). Therefore, this study aimed to explore whether NTs have more significant antiviral effects than NSs in combination therapy with PegIFNα. Methods: Chronic hepatitis B (CHB) patients treated with PegIFNα plus nucleos(t)ide analogues (NAs) were retrospectively recruited. Efficacy and the predictors of hepatitis B surface antigen (HBsAg) reduction >1 log10 IU/mL after 48 weeks were analyzed. Results: A total of 95 patients were included and divided into the PegIFNα + NTs group and the PegIFNα + NSs group. Propensity score matching (PSM) was performed. The PegIFNα + NTs group had a greater reduction of HBsAg (-3.52 vs. -2.33 log10 IU/mL, P=0.032) and a higher proportion of patients with HBsAg reduction >1 log10 IU/mL (100.0% vs. 72.2%, P=0.003) even after PSM. However, HBsAg and hepatitis B e-antigen (HBeAg) loss rates, HBeAg seroconversion rates, degree of HBeAg and hepatitis B virus (HBV) DNA decline, HBV DNA undetectable rates, and alanine aminotransferase (ALT) normalization rates showed no significant differences. Subgroup analyses showed the difference in the reduction of HBsAg was particularly evident in HBeAg-positive and the "add-on" subgroups. PegIFNα plus NTs (OR = 36.667, 95% CI = 3.837-350.384) was an independent predictor for HBsAg reduction >1 log10 IU/mL after 48 weeks. Conclusion: This study suggests that PegIFNα plus NTs may lead to more HBsAg reduction, especially in HBeAg-positive and "add-on" patients.

The efficacy and safety of adding on or switching to peginterferon α-2b in HBeAg-positive chronic hepatitis B patients with long-term entecavir treatment: a multicentre randomised controlled trial.

BACKGROUND & AIMS: The strategies of adding on or switching to peginterferon (PEG-IFN) improved the serological response rates in patients with chronic hepatitis B (CHB) who had previously experienced treatment with nucleos(t)ide analogues. However, robust data on which combination strategy is more effective remain lacking. METHODS: In this multicentre, parallel, open-label, randomised, controlled trial, patients with HBeAg-positive CHB who were treated with entecavir ≥2 years, and had hepatitis B surface antigen (HBsAg) <3000 IU/ml, HBeAg <200S/CO and HBV DNA <50 IU/ml were randomly assigned in a 1:1:1 ratio to add on PEG-IFN, switch to PEG-IFN or continue entecavir monotherapy for 48 weeks. The primary endpoint was HBeAg seroconversion at week 48. RESULTS: A total of 153 patients were randomised into three treatment arms (50 in add-on, 52 in switch-to and 51 in monotherapy). Compared with continuous entecavir monotherapy, both add-on and switch-to strategies achieved higher rates of HBeAg seroconversion (18.0% vs. 2.0%, p = 0.007; 19.2% vs. 2.0%, p = 0.005, respectively), HBeAg loss (24.0% vs. 5.9%, p = 0.010; 23.1% vs. 5.9%, p = 0.013, respectively), HBsAg < 100 IU/ml (30.0% vs. 0%, p < 0.001; 34.6% vs. 0%, p < 0.001, respectively), and higher HBsAg reduction (-0.90 vs. -0.06 log10 IU/ml, p < 0.001; -0.92 vs. -0.06 log10 IU/ml, p < 0.001, respectively) at week 48. The efficacy was comparable between add-on and switch-to arms (p > 0.05). Adverse events were mainly related to PEG-IFN but generally tolerable. CONCLUSION: In patients with CHB who achieved virological response with long-term entecavir, both adding on and switching to PEG-IFN are alternative strategies resulting in higher rates of HBeAg seroconversion and HBsAg reduction than continuous entecavir. CLINICAL TRIALS REGISTRATION: Chinese Clinical Trial Registry (www.chictr.org.cn, identifier: ChiCTR-IPR-17012055).

Efficacy of peg-interferon-nucleoside analog sequential optimization therapy in HBeAg-positive patients with CHB.

OBJECTIVE: This study aimed to evaluate the efficacy of Peg-interferon (Peg-IFN)-nucleoside analog (NA) sequential optimization therapy (SOT) in HBeAg-positive patients with chronic hepatitis B (CHB). METHODS: In this prospective two-center study, 132 CHB patients were assigned to receive Peg-IFN standard therapy for 48 weeks (65 patients) or Peg-IFN monotherapy for 12-24 weeks and NA add-on for those without early virological response (EVR) (67 patients). Both patient groups were monitored and followed for 24 weeks after treatments stop. RESULTS: At week 24 after treatments stop, the Peg-IFN-NA SOT group achieved more HBsAg levels drop (- 1.35 vs - 0.67 log10 IU/mL, p = 0.016), higher HBsAg ≤ 100 IU/mL (32.8% vs 9.2%, p = 0.001), HBV DNA undetectable (79.1% vs 49.2%, p < 0.001), and ALT normalization (80.6% vs 38.5%, p < 0.001) rates compared with Peg-IFN monotherapy. At week 24 after treatments stop, no significant difference was found in HBeAg seroconversion (35.8% vs 27.7%, p = 0.316), HBsAg loss (8.9% vs 4.6%, p = 0.323) and HBsAg seroconversion rates (4.5% vs 1.5%, p = 0.325) between Peg-IFN monotherapy group and Peg-IFN-NA SOT group. CONCLUSION: Starting with Peg-IFN followed by addition of NA achieved more HBsAg levels drop, and higher HBsAg ≤ 100 IU/mL, HBV DNA undetectable, and ALT normalization rates compared with Peg-IFN monotherapy.

Low hepatitis B surface antigen and HBV DNA levels predict response to the addition of pegylated interferon to entecavir in hepatitis B e antigen positive chronic hepatitis B.

BACKGROUND: Various treatment combinations of peginterferon (PEG-IFN) and nucleos(t)ide analogues have been evaluated for chronic hepatitis B (CHB), but the optimal regimen remains unclear. AIMS: To study whether PEG-IFN add-on increases response compared to entecavir (ETV) monotherapy, and whether the duration of ETV pretreatment influences response. METHODS: Response was evaluated in HBeAg positive patients previously treated in two randomized controlled trials. Patients received ETV pretreatment for at least 24 weeks and were then allocated to 24-48 weeks of ETV+PEG-IFN add-on, or continued ETV monotherapy. Response was defined as HBeAg loss combined with HBV DNA <200 IU/mL 48 weeks after discontinuing PEG-IFN. RESULTS: Of 234 patients, 118 were assigned PEG-IFN add-on and 116 continued ETV monotherapy. Response was observed in 38/118 (33%) patients treated with add-on therapy and in 23/116 (20%) with monotherapy (P = 0.03). The highest response to add-on therapy compared to monotherapy was observed in PEG-IFN naive patients with HBsAg levels below 4000 IU/mL and HBV DNA levels below 50 IU/mL at randomization (70% vs 34%; P = 0.01). Above the cut-off levels, response was low and not significantly different between treatment groups. Duration of ETV pretreatment was associated with HBsAg and HBV DNA levels (both P < 0.005), but not with response (P = 0.82). CONCLUSIONS: PEG-IFN add-on to ETV therapy was associated with higher response compared to ETV monotherapy in patients with HBeAg positive CHB. Response doubled in PEG-IFN naive patients with HBsAg below 4000 IU/mL and HBV DNA below 50 IU/mL, and therefore identifies them as the best candidates for PEG-IFN add-on (Identifiers: NCT00877760, NCT01532843).

In vitro study of stimulation effect on endothelialization by a copper bearing cobalt alloy.

Endothelialization is an important process after stenting in coronary artery. Recovery of the injured site timely can reduce the neointima formation and platelet absorbance, leading to a lower risk of in-stent restenosis. Copper is known to be critical in vascular construction. Thus a combination of copper with stent materials is a meaningful attempt. A copper bearing L605-Cu cobalt alloy was prepared and its effect on human umbilical vein endothelial cells (HUVECs) was evaluated in vitro in this study. It was found that HUVECs attached and stretched better on the surface of L605-Cu compared with L605, and the apoptosis of cells was decreased simultaneously. The migration and tube formation of HUVECs were also enhanced by the extract of L605-Cu. Furthermore, L605-Cu increased the mRNA expression of VEGF in HUVECs significantly. However it had no effect on the secretion of NO or mRNA expression of eNOS. The result of blood clotting test indicated that L605-Cu had better blood compatibility. These results above have demonstrated that the L605-Cu alloy is promising to be a new stent material with function of accelerating endothelialization. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 561-569, 2018.

Evaluation of promoting effect of a novel Cu-bearing metal stent on endothelialization process from in vitro and in vivo studies.

Drug eluting stents (DES) have been extensively applied nowadays and reduce the incidence of in-stent restenosis (ISR) greatly as compared with bare metal stents (BMS). However, the development of DES is hindered by the risk of late stent thrombosis (LST) due to delayed re-endothelialization, while endothelialization is an important process related to ISR and LST after implantation. 316L is a traditional stent material without bioactivity and have a high risk of ISR. Cu is recognized for angiogenesis stimulation in these years. Hence a copper bearing 316L stainless steel (316L-Cu) was prepared and evaluated about its effect on endothelialization in this paper. Compared with traditional 316L, it was proved that 316L-Cu increased the proliferation of co-cultured human umbilical vein endothelial cells (HUVECs) at first day. Moreover, HUVECs stretched better on the surface of 316L-Cu. It also improved the expression of angiogenesis related genes and tube formation ability in vitro. 316L-Cu-BMS, DES and 316L-BMS were implanted in swine to evaluate the re-endothelialization ability in vivo. And 316L-Cu-BMS showed the best effect on endothelialization with good biosafety. Consequently, 316L-Cu is a kind of promising BMS material for coronary field.

Improved Efficacy of a pegylated interferon-α-2a stepwise optimization treatment strategy in the treatment of hepatitis B e antigen-positive chronic hepatitis B patients.

Current pegylated interferon-α (PEG-IFN) treatment for chronic hepatitis B (CHB) e-antigen (HBeAg)-positive patients are suboptimal, and effective ways of improving PEG-IFN treatment efficacy are needed.This retrospective cohort study compared the efficacy of a PEG-IFN stepwise optimization treatment (PEG-IFN SOT) strategy with that of a 48-week PEG-IFN standard therapy (PEG-IFN ST) in HBeAg-positive CHB patients.A total of 110 patients were included in our study. Of these, 70 received the PEG-IFN SOT and 40 received the PEG-IFN ST (control group). We based the decision whether to add adefovir and/or extend the PEG-IFN-based treatment to 96 weeks on the patients' 12-week or 24-week early virological response (12W EVR, at least a 2 log10 reduction in HBV DNA copies/mL at week 12; 24W EVR, at least 1 log10 reduction in HBsAg IU/mL or HBsAg <1500 IU/mL at week 24) and their 48-week partial response (48W PR, 1.0 ≤HBeAg ≤10.0 S/CO or HBeAg >10.0 S/CO but HBsAg <1000 IU/mL).The HBeAg seroconversion rate 24 weeks post-PEG-IFN treatment was significantly higher in the PEG-IFN SOT than the PEG-IFN ST group (50% vs 22.5%, P = 0.005). The HBsAg clearance rates in the PEG-IFN SOT and ST groups were 10% and 0% (P = 0.04), respectively. Receiving PEG-IFN SOT (OR = 0.26, P = 0.01), ALT × ULN at baseline (OR = 0.74, P = 0.003), and achieving 12 and 24W EVR (OR = 0.29, P = 0.03) were independent factors associated with HBeAg seroconversion.PEG-IFN SOT is a promising strategy for achieving high rates of serological response in HBeAg-positive CHB patients.

Sustained delivery of sphingosine-1-phosphate using poly(lactic-co-glycolic acid)-based microparticles stimulates Akt/ERK-eNOS mediated angiogenesis and vascular maturation restoring blood flow in ischemic limbs of mice.

Therapeutic angiogenesis is a promising strategy for treating ischemia. The lysophospholipid mediator sphingosine-1-phosphate (S1P) acts on vascular endothelial cells to stimulate migration and tube formation, and plays the critical role in developmental angiogenesis. We developed poly(lactic-co-glycolic-acid) (PLGA)-based S1P-containing microparticles (PLGA-S1P), which are biodegradable and continuously release S1P, and studied the effects of PLGA-S1P on neovascularization in murine ischemic hindlimbs. Intramuscular injections of PLGA-S1P stimulated blood flow in C57BL/6 mice dose-dependently, with repeated administrations at a 3-day interval, rather than a single bolus or 6-day interval, over 28 days conferring the optimal stimulating effect. In Balb/c mice that exhibit limb necrosis and dysfunction due to retarded blood flow recovery, injections of PLGA-S1P stimulated blood flow with alleviation of limb necrosis and dysfunction. PLGA-S1P alone did not induce edema in ischemic limbs, and rather blocked vascular endothelial growth factor-induced edema. PLGA-S1P not only increased the microvessel densities in ischemic muscle, but promoted coverage of vessels with smooth muscle cells and pericytes, thus stabilizing vessels. PLGA-S1P stimulated Akt and ERK with increased phosphorylation of endothelial nitric oxide synthase in ischemic muscle. The effects of the nitric oxide synthase inhibitor, Nomega-nitro-L-arginine methylester, showed that PLGA-S1P-induced blood flow stimulation was partially dependent on nitric oxide. Injections of PLGA-S1P also increased the expression of angiogenic factors and the recruitment of CD45-, CD11b- and Gr-1-positive myeloid cells, which are implicated in post-ischemic angiogenesis, into ischemic muscle. These results indicate that PLGA-based, sustained local delivery of S1P is a potentially useful therapeutic modality for stimulating post-ischemic angiogenesis.