Reversal of endothelial progenitor cell dysfunction in patients with type 2 diabetes using a conditioned medium of human embryonic stem cell-derived endothelial cells.

BACKGROUND: The potential clinical application of bone marrow or peripheral blood-derived progenitor cells for cardiovascular regeneration in patients with diabetes mellitus (DM) is limited by their functional impairment. We sought to determine the mechanisms of impaired therapeutic efficacy of peripheral blood-derived progenitor cells in type 2 DM patients and evaluated the use of cell-free conditioned medium obtained from human embryonic stem cell-derived endothelial-like cells (ESC-ECs) to reverse their functional impairment. METHODS: The angiogenic potential of late outgrowth endothelial cells (OECs) and cytokine profile of the conditional medium of proangiogenic cells (PACs) derived from peripheral blood-mononuclear cells of healthy control and DM patients and ESC-ECs was compared by in vitro tube formation assay and a multiplex bead-based immunoassay kit, respectively. The in vivo angiogenic potential of ESC-ECs derived conditioned medium in rescuing the functional impairment of PB-PACs in DM patients was investigated using a hindlimb ischemia model. RESULTS: Human ESC-ECs had similar functional and phenotypic characteristics as OECs in healthy controls. Cytokine profiling showed that vascular endothelial growth factor, stromal cell-derived factor 1 and placental growth factor were down-regulated in PACs from DM patients. Tube formation assay that revealed functional impairment of OECs from DM patients could be rescued by ESC-ECs conditioned medium. Administration of ESC-ECs conditioned medium restored the therapeutic efficacy of PB-PACs from DM patients in a mouse model of hindlimb ischemia. CONCLUSIONS: Our results showed that peripheral blood-derived progenitor cells from DM patients have impaired function because of defective secretion of angiogenic cytokines, which could be restored by supplementation of ESC-ECs conditioned medium.

Substance P and glutamate receptor antagonists improve the anti-arthritic actions of dexamethasone in rats.

BACKGROUND AND PURPOSE: Current single drug treatments for rheumatoid arthritis have problems of limited efficacy and/or high toxicity. This study investigates the benefits of individual and combined treatments with dexamethasone and substance P and glutamate receptor antagonists in a rat model of arthritis. EXPERIMENTAL APPROACH: Arthritis was induced in rats by unilateral intra-articular injection of Freund's complete adjuvant. Separate groups of rats were subjected to the following treatments 15 min before induction of arthritis: (i) control with no drug treatment; (ii) single intra-articular injection of a NK(1) receptor antagonist RP67580; (iii) single intra-articular injection of a NMDA receptor antagonist AP7 plus a non-NMDA receptor antagonist CNQX; (iv) daily oral dexamethasone; and (v) combined treatment with dexamethasone and all of the above receptor antagonists. Knee joint allodynia, swelling, hyperaemia and histological changes were examined over a period of 7 days. KEY RESULTS: Treatment with dexamethasone suppressed joint swelling, hyperaemia and histological changes that include polymorphonuclear cell infiltration, synovial tissue proliferation and cartilage erosion in the arthritic rat knees. Treatment with RP67580 or AP7 plus CNQX did not attenuate hyperaemia or histological changes, but reduced joint allodynia and swelling. Co-administration of dexamethasone with these receptor antagonists produced greater inhibition on joint allodynia and swelling than their individual effects. CONCLUSIONS AND IMPLICATIONS: The data suggest substance P and glutamate contribute to arthritic pain and joint swelling. The efficacy of dexamethasone in reducing arthritic pain and joint swelling can be improved by co-administration of substance P and glutamate receptor antagonists.

Pharmacological characterization of receptor types mediating the dilator action of anandamide on blood vessels of the rat knee joint.

This study investigates the actions of N-(2-hydroxyethyl)-5Z,8Z,11Z,14Z-eicosatetraenamide (anandamide) on blood flow of the rat knee joint. Topical bolus administration of anandamide (10-1000 nmol) onto the exposed knee joint capsules produced dose-dependent increases in the knee joint blood flow. Various antagonists were tested on the vasodilator response to 100 nmol anandamide. Capsazepine (N-[2-(4-chlorophenyl)ethyl]-1,3,4,5-tetrahydro-7,8-dihydroxy-2H-2-benzazepine-2-carbothioamide), an antagonist of the transient receptor potential vanilloid type 1 (TRPV1) receptor, given at 10 and 100 nmol, suppressed the response by a maximum of 71%. A cannabinoid CB(1) receptor antagonist AM281 (10 nmol) and a CB(2) receptor antagonist AM630 (10 nmol) shortened its duration from 15 min to 5 min. O-1918 (1 nmol), an antagonist of the putative endothelial anandamide/abnormal-cannabidiol receptor, on its own or combined with capsazepine and the two cannabinoid receptor antagonists produced 38% and 24% inhibition on the peak vasodilator response to anandamide, respectively. URB597 (1 nmol), an inhibitor of fatty acid amide hydrolase (FAAH) suppressed the response by 40%, and an anandamide transporter inhibitor [N-(4-hydroxyphenyl)-5Z,8Z,11Z,14Z-eicosatetraenamide] (AM404; 1 nmol) or a cyclo-oxygenase (COX) inhibitor flurbiprofen (20 nmol) abolished the response. These findings suggest the vasodilator action of anandamide in the rat knee joint involved hydrolysis of the compound by FAAH, production of COX-derived eicosanoid(s), activation of TRPV1 receptors, and a small component involved activation of endothelial anandamide/abnormal-cannabidiol receptors; a minor delayed dilator response was mediated by activation of conventional cannabinoid receptors.

Time course and substance P effects on the vascular and morphological changes in adjuvant-induced monoarthritic rats.

The aim of this study is to characterize the time course of the vascular and morphological changes in arthritic rat knee joints induced by Freund's complete adjuvant (FCA), and to investigate the effects of substance P on these changes. Single unilateral intra-articular injections of 0.1 ml FCA produced swelling of the ipsilateral knees for 4 weeks, blood vessel permeability was increased for 1 week, but blood flow was unaffected except for minor bilateral increases on day 28. The ipsilateral knees also showed marked accumulation of immune cells from day 3 to day 28, minor synovial tissue proliferation on week 2, and some cartilage erosions on weeks 1 and 2. Another group of rats was given additional injection of 1 nmol substance P in their adjuvant-treated knees at 4 h prior to assessments of inflammatory parameters on each specified day. This produced further swelling in their ipsilateral knees on day 3 and day 14, blood vessel permeability was augmented in the first 2 weeks, and blood flow was increased throughout the 4 weeks except on day 7. Parallel but smaller increases in vascular permeability and blood flow were also observed in their contralateral knees. Substance P did not affect FCA-induced changes in immune cell infiltration, synovial tissue proliferation, and cartilage erosion. These findings confirm that intra-articular injection of a low dose of FCA could elicit discrete monoarthritis in rat knees, and substance P could exacerbate and spread the early signs of this disease to the contralateral knees.

Characterisation of somatostatin actions on knee joint blood vessels of the rat.

The effects of somatostatin on blood flow, plasma extravasation and knee joint sizes in the rat were investigated. Topical bolus administrations of somatostatin (10 pmol-100 nmol) onto the exposed rat knee joint capsules produced dose-dependent increases in knee joint blood flow with an ED(50) value of 1.7 nmol, and a maximum increase of 109.7%. The peak vasodilator response was observed at 1 min following drug administration, and it subsided at 5 min. Treatment of the rat knee with a somatostatin receptor antagonist cyclo(7-aminoheptanoul-Phe-D-Trp-Lys-Thr[Bzl] (cyclo-somatostatin; 2 x 20 nmol) significantly suppressed the somatostatin-induced vasodilator response, but treatment with the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME; 2 x 50 nmol) or the cyclo-oxygenase inhibitor flurbiprofen (2 x 10 nmol) had no effect. Unilateral intraarticular injections of somatostatin (10 nmol) produced no change on blood flow and sizes of the rat knee joints, but elicited marked ipsilateral Evans blue extravasation. Cyclo-somatostatin at doses of 2 x 20 and 2 x 50 nmol did not affect the plasma extravasation response to somatostatin. The present findings indicate the vasodilator effect of somatostatin is mediated by receptors sensitive to cyclo-somatostatin inhibition, but its plasma extravasation effect might be mediated by somatostatin receptor types that are resistant to inhibition by cyclo-somatostatin. There is no evidence that nitric oxide and prostaglandins are involved in the somatostatin-induced vasodilator response. It is suspected that the vascular effects of somatostatin demonstrated in this study would play a part in the innate response of an inflammatory reaction.