Topical phenytoin administration accelerates the healing of acetic acid-induced colitis in rats: evaluation of transforming growth factor-beta, platelet-derived growth factor, and vascular endothelial growth factor.

Ulcerative colitis (UC), limited to the colon's innermost lining, has become a global health problem. Immunomodulatory and monoclonal antibodies are used to treat UC despite their side effects and limitations. Phenytoin is used to heal wounds owing to its effects on growth factors, collagen, and extracellular matrix synthesis. This study aimed to evaluate the effect of topical phenytoin administration in UC. Phenytoin was administered in two doses during the treatment. Eighty male Wistar rats (230-280 g) were divided randomly into ten groups of sham, control, hydrocortisone, phenytoin 1%, and 3% groups in 6- or 12-day treatment protocols. The UC model was induced by the administration of acetic acid 4% into the colon. Animals were killed on the 7th and 13th postoperative days. The main outcome measures included body weight loss, microscopic score, and ulcer index measured using specific criteria. Growth factors were measured by western blotting. Results illustrated that body weight loss was reversed in the treatment groups. Ulcer index had decreased on 6- and 12-day treatment protocols. Microscopic scores in 6-day enema treatment significantly decreased compared to the control groups. Transforming growth factor-beta (TGFß) significantly increased in a time-dependent manner and platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) significantly increased in a time- and dose-dependent manner in phenytoin 1% and 3% in the 6- and 12-day protocols. Phenytoin dose- and time-dependently reversed weight loss. In addition, histopathological parameters included microscopic scores, and the ulcer index was decreased through the induction of growth factors TGFß, PDGF, and VEGF and consequently accelerated ulcer healing.

Carnosine Impedes PDGF-Stimulated Proliferation and Migration of Vascular Smooth Muscle Cells In Vitro and Sprout Outgrowth Ex Vivo.

Carnosine, a naturally producing dipeptide, exhibits various beneficial effects. However, the possible role of carnosine in vascular disorders associated with pathological conditions, including proliferation and migration of vascular smooth muscle cells (VSMCs), largely remains unrevealed. Here, we investigated the regulatory role and mechanism of carnosine in platelet-derived growth factor (PDGF)-induced VSMCs. Carnosine inhibited the proliferation of PDGF-induced VSMCs without any cytotoxic effects. Carnosine treatment also induced G1-phase cell cycle arrest by causing a p21WAF1-mediated reduction in the expression of both cyclin-dependent kinases (CDKs) and cyclins in PDGF-treated VSMCs. Carnosine treatment suppressed c-Jun N-terminal kinase (JNK) phosphorylation in PDGF-stimulated signaling. Additionally, carnosine significantly prevented the migration of VSMCs exposed to PDGF. Carnosine abolished matrix metalloproteinase (MMP)-9 activity via reduced transcriptional binding activity of NF-κB, Sp-1, and AP-1 motifs in PDGF-treated VSMCs. Moreover, using aortic assay ex vivo, it was observed that carnosine addition attenuated PDGF-stimulated sprout outgrowth of VSMCs. Taken together, these results demonstrated that carnosine impeded the proliferation and migration of PDGF-stimulated VSMCs by regulating cell cycle machinery, JNK signaling, and transcription factor-mediated MMP-9 activity as well as prevented ex vivo sprout outgrowth of blood vessels. Thus, carnosine may be a potential candidate for preventing vascular proliferative disease.

Efficacy of topical recombinant human platelet-derived growth factor for treatment of diabetic lower-extremity ulcers: Systematic review and meta-analysis.

OBJECTIVE: Recombinant human platelet-derived growth factor (rhPDGF) is used topically in the treatment of diabetic lower-extremity ulcers. There have been few meta-analyses of the efficacy of rhPDGF in this treatment context. The aim of this study was to perform an updated systematic review and meta-analysis to assess the clinical efficacy of rhPDGF in the treatment of diabetic lower-extremity ulcers. METHODS: We searched the MEDLINE, Cochrane Library, EMBASE and Web of Knowledge databases up to April 30, 2014. Studies were identified and selected, and data were extracted by two independent reviewers. The primary efficacy outcome was complete healing rate. Adverse events were also assessed. The studies were evaluated for quality and publication bias. RESULTS: A total of 6 randomized controlled trials including 992 patients were selected from 173 identified studies. The studies compared rhPDGF treatment in the context of standard of care (SOC) to placebo or SOC alone. In the absence of study heterogeneity, a fixed-effects model was performed, and the combined odds ratio (OR) indicated a significantly greater complete healing rate in patients treated with rhPDGF compared to placebo or SOC alone. The ORs ranged from 0.58 to 2.77, with a combined OR of 1.53 (95% CI = 1.14 to 2.04, p = 0.004). A sensitivity analysis (leave-one-out method) indicated good study reliability, and a funnel plot with Egger test showed no publication bias. CONCLUSION: These results indicate that rhPDGF is efficacious in the treatment of diabetic lower-extremity ulcers.

The evidence for the use of growth factors and active skin substitutes for the treatment of non-infected diabetic foot ulcers (DFU): a health technology assessment (HTA).

AIMS: Assessment of the safety, efficacy and effectiveness of growth factors alone or in combination with other technologies in the treatment of DFU including medical, economical, social, ethical and juridical aspects. METHODS: We systematically searched relevant data bases limited to English and German language and publications since 1990. Review and assessment of the quality of publications followed methods conforming to widely accepted standards for evidence-based medicine and health economics. RESULTS: We identified 25 studies comparing becaplermin, rhEGF, bFGF and the metabolically active skin grafts Dermagraft and Apligraf with standard wound care (SWC) alone or extracellular wound matrix. Study duration ranged from 12 to 20 weeks and the study population comprised between 17 and 382 patients. Treatment with becaplermin, rhEGF, Dermagraft and Apligraf resulted in a higher incidence of complete wound closure and shorter time to complete wound healing with statistically significant differences. Regarding the proportion of adverse events there was no difference between treatment groups. The methodological quality of the studies was affected by significant deficiencies. Economic evaluations showed becaplermin being cost-effective. CONCLUSIONS: Add-on therapy with growth factors and active skin substitutes for treating uncomplicated DFU could be an alternative to SWC alone. For explicit recommendations further studies with stronger evidence are necessary.

Prospective, randomized, multi-center feasibility trial of rhPDGF-BB versus autologous bone graft in a foot and ankle fusion model.

BACKGROUND: The increased morbidity and surgical time associated with harvesting autologous bone graft (ABG) have encouraged surgeons to develop synthetic orthobiologic alternatives. The recombinant form of platelet-derived growth factor (rhPDGF-BB), an angiogenic, mitogenic, and chemotactic cytokine, has been shown to significantly enhance bone formation in human periodontal osseous defects when combined with a tricalcium phosphate carrier (ß-TCP). The purpose of this prospective, controlled, randomized, multi-center feasibility clinical trial was to compare the safety and efficacy of this biosynthetic bone graft substitute (Augment™ Bone Graft) to ABG during ankle and hindfoot fusion. MATERIALS AND METHODS: Twenty adult subjects requiring ankle or hindfoot fusion from three U.S. centers were enrolled and randomized in a 2:1 ratio to receive Augment™ or ABG, respectively. Surgical approach and fixation techniques were standardized, and minimum followup was 9 months. The primary endpoint was radiographic osseous union, evaluated by a blinded independent radiologist. Secondary endpoints included assessment of clinical success, union rate by serial computed tomography (CT) examination, time to full weightbearing, AOFAS Ankle-Hindfoot Score (AOFAS), Foot Function Index (FFI), Short Form-12 (SF-12), and Visual Analog pain assessment Scale (Pain VAS). RESULTS: At 36 weeks, 77% (10/13) of the Augment™ and 50% (3/6) of the ABG patients were fused based on radiographic criteria. There were two nonunions in the Augment™ group (9%, 2/14). Healing rates based on 12 week CT scanning (50% osseous bridging) were 69% (9/13) in the Augment™ and 60% (3/5) in the ABG groups, respectively. All functional outcome measures (FFI, AOFAS, SF-12), as well as the VAS pain scores, improved in both groups over time. Surgical procedure times lasted an average 26 minutes longer for the ABG as compared to the Augment™ populations. There were no device related serious adverse events in this study. CONCLUSION: Based on the available data, the rate of radiographic union, time to full weightbearing, and outcomes scores between the Augment™ and ABG subjects appear comparable. Augment™ may represent a safe and efficacious treatment alternative to ABG during foot and ankle arthrodesis.

A matched cohort study of the risk of cancer in users of becaplermin.

BACKGROUND: Becaplermin is recombinant human platelet-derived growth factor for topical administration that might plausibly be related to cancer risk. Extended follow-up of patients from clinical trials of becaplermin compared with placebo identified a relative risk of cancer of 2.8 (95% confidence interval [CI], 0.6-12.8). The authors aimed to further investigate any association between becaplermin use and the occurrence of cancer by following a large cohort of patients in a clinical practice setting. METHODS: In a cohort of insured people, becaplermin initiators were matched to similar people who did not initiate becaplermin and were followed for up to 6 years for cancer incidence (up to 9 years for cancer mortality). Cancer incidence was identified from health insurance claims and validated by review of medical records. Cancer mortality was identified through linkage to the National Death Index. RESULTS: Among 1622 becaplermin initiators, there were 28 confirmed cancers and 9 cancer deaths, and among the 2809 matched comparators, there were 43 confirmed cancers and 16 cancer deaths. There was no increased risk of cancer with becaplermin (hazard ratio, 1.2; 95% CI, 0.7-1.9). Cancer mortality through 2003 was increased (rate ratio [RR] = 5.2; 95% CI, 1.7-17.6) among subjects with 3 or more dispensings. Additional follow-up through 2006 indicated no elevated cancer mortality risk overall (RR, 1.0; 95% CI, 0.5-2.3) and no statistically significant increase in the subgroup with more than 3 dispensings (RR, 2.4; 95% CI, 0.8-7.4). CONCLUSIONS: Becaplermin does not appear to increase the risk of cancer or cancer mortality.

Benefit-risk assessment of becaplermin in the treatment of diabetic foot ulcers.

Becaplermin is a recombinant platelet-derived growth factor composed of two B chains that is approved for the treatment of neuropathic diabetic foot ulcers extending into or beyond the subcutaneous tissue in patients with adequate arterial perfusion. The aim of this review is to assess the benefits and risks associated with the use of this agent. Randomized controlled trials have provided evidence for the efficacy of becaplermin in increasing healing rates, and cost analyses have repeatedly shown a favourable cost-effectiveness ratio. However, clinical experience has not met these high expectations and becaplermin is not widely used. Moreover, this agent has not been compared with other additional treatment modalities, notably bioengineered skin substitutes and extracellular matrix proteins, and such comparisons are eagerly awaited. Of particular note, increased cancer risk has been reported in patients treated with more than three tubes of becaplermin; thus, this agent should be used only when the anticipated benefits outweigh the potential harm, and with extreme caution in patients with diagnosed malignancy. Finally, longer follow-up data are necessary to shed more light on the potential risk of malignancy in connection with becaplermin use.

Platelet-derived growth factor-induced severe and chronic vasoconstriction of cerebral arteries: proposed growth factor explanation of cerebral vasospasm.

OBJECTIVE: After subarachnoid hemorrhage (SAH), platelet-derived growth factor-BB (PDGF-BB) is secreted in and around the cerebral arteries. To clarify the role of PDGF-BB in the development of vasospasm after SAH, we determined whether PDGF-BB alone can cause long-lasting vasoconstriction of a severity similar to that of vasospasm. In addition, the anti-vasospastic effect of trapidil, an antagonist of PDGF-BB function, was investigated. METHODS: We infused recombinant PDGF-BB (10 microg/mL saline as the vehicle) (n = 14) into the subarachnoid space of rabbits and analyzed alterations in the caliber of the basilar artery using repeated angiography. To study the role of PDGF-BB on the development of vasospasm, trapidil was administered continuously starting 1 hour after SAH, on day 0 (0.63-1.25 mg/kg /h or vehicle) for 47 hours (n = 24), or after the full development of cerebral vasospasm on day 2 (3.0 mg/kg/h or vehicle) for 0.5 hours (n = 17), and alterations in the caliber of the basilar artery were monitored. RESULTS: PDGF-BB caused long-lasting vasoconstriction, with maximum constriction of 56% (P < .001) of the control value (= 100%) on day 2, resembling vasospasm seen after SAH. Prolonged administration of intravenous trapidil, starting soon after SAH, prevented the development of vasospasm in a dose-dependent manner (P < .05, .01, or .001). Intravenous or intra-arterial administration of trapidil significantly dilated vasospasm (P < .01) on day 2, at least transiently. CONCLUSION: PDGF-BB, a growth factor synthesized in the subarachnoid space after SAH, can cause severe and long-lasting vasoconstriction. Significant prevention and resolution of vasospasm can be achieved by the PDGF-BB antagonist trapidil. We propose that excessive production of PDGF-BB, essentially aiming to repair injured arteries, causes cerebral vasospasm. Although the half-life of trapidil in serum may be shorter than that of PDGFG-BB-derived spasmogenic signaling, trapidil is a candidate drug for constructing a new therapeutic modality for preventing and resolving vasospasm.

Local controlled intramyocardial delivery of platelet-derived growth factor improves postinfarction ventricular function without pulmonary toxicity.

BACKGROUND: Local delivery methods can target therapies to specific tissues and potentially avoid toxicity to other organs. Platelet-derived growth factor can protect the myocardium, but it also plays an important role in promoting pulmonary hypertension. It is not known whether local myocardial delivery of platelet-derived growth factor during myocardial infarction (MI) can lead to sustained cardiac benefit without causing pulmonary hypertension. METHODS AND RESULTS: We performed a randomized and blinded experiment of 127 rats that survived experimental MI or sham surgery. We delivered platelet-derived growth factor (PDGF)-BB with self-assembling peptide nanofibers (NFs) to provide controlled release within the myocardium. There were 6 groups with n > or = 20 in each group: sham, sham+NF, sham+NF/PDGF, MI, MI+NF, and MI+NF/PDGF. Serial echocardiography from 1 day to 3 months showed significant improvement of ventricular fractional shortening, end-systolic dimension, and end-diastolic dimension with local PDGF delivery (P < 0.05 for MI+NF/PDGF versus MI or MI+NF). Catheterization at 4 months revealed improved ventricular function in the controlled delivery group (left ventricular end-diastolic pressure, cardiac index, +dP/dt, -dP/dt, and time constant of exponential decay all P < 0.05 for MI+NF/P versus MI or MI+NF). Infarcted myocardial volume was reduced by NF/PDGF therapy (34.0 +/- 13.3% in MI, 28.9 +/- 12.9% in MI+NF, and 12.0 +/- 5.8% in MI+NF/PDGF; P < 0.001). There was no evidence of pulmonary toxicity from the therapy, with no differences in right ventricular end-systolic pressure, right ventricular dP/dt, bromodeoxyuridine staining, or pulmonary artery medial wall thickness. CONCLUSIONS: Intramyocardial delivery of PDGF by self-assembling peptide NFs leads to long-term improvement in cardiac performance after experimental infarction without apparent pulmonary toxicity. Local myocardial protection may allow prevention of heart failure without systemic toxicity.

Matrix immobilization enhances the tissue repair activity of growth factor gene therapy vectors.

Although growth factor proteins display potent tissue repair activities, difficulty in sustaining localized therapeutic concentrations limits their therapeutic activity. We reasoned that enhanced histogenesis might be achieved by combining growth factor genes with biocompatible matrices capable of immobilizing vectors at delivery sites. When delivered to subcutaneously implanted sponges, a platelet-derived growth factor B-encoding adenovirus (AdPDGF-B) formulated in a collagen matrix enhanced granulation tissue deposition 3- to 4-fold (p < or = 0.0002), whereas vectors encoding fibroblast growth factor 2 or vascular endothelial growth factor promoted primarily angiogenic responses. By day 8 posttreatment of ischemic excisional wounds, collagen-formulated AdPDGF-B enhanced granulation tissue and epithelial areas up to 13- and 6-fold (p < 0.009), respectively, and wound closure up to 2-fold (p < 0.05). At longer times, complete healing without excessive scar formation was achieved. Collagen matrices were shown to retain both vector and transgene products within delivery sites, enabling the transduction and stimulation of infiltrating repair cells. Quantitative PCR and RT-PCR demonstrated both vector DNA and transgene mRNA within wound beds as late as 28 days posttreatment. By contrast, aqueous formulations allowed vector seepage from application sites, leading to PDGF-induced hyperplasia in surrounding tissues but not wound beds. Finally, repeated applications of PDGF-BB protein were required for neotissue induction approaching equivalence to a single application of collagen-immobilized AdPDGF-B, confirming the utility of this gene transfer approach. Overall, these studies demonstrate that immobilizing matrices enable the controlled delivery and activity of tissue promoting genes for the effective regeneration of injured tissues.

Becaplermin and necrobiosis lipoidicum diabeticorum: results of a case control pilot study.

Necrobiosis lipoidica diabeticorum (NLD) is a rare skin condition associated with diabetes, which characteristically occurs in the pretibial region of the lower limbs (Boulton et al., 1988). The lesions generally appear as well-circumscribed reddish plaques, which are most often asymptomatic, resulting primarily in cosmetic disability. Currently, there is no reliable form of treatment for NLD, although many regimens have been tried (Shall et al., 1990)

Topical becaplermin: new preparation. A slight short-term help for some diabetic patients.

(1) The reference curative treatment for chronic ulcers in diabetic patients is to avoid pressure on the lesions, and to give appropriate local care. (2) A topical gel containing 0.01% becaplermin, a cell growth factor, is now marketed in Europe for the treatment of chronic neuropathic ulcers measuring less than 5 cm2 in diabetic patients. (3) The clinical file mainly comprises four trials, two of which were double-blind, testing two concentrations. In the largest trial, which gave the most favourable results, the lesions healed completely after 20 weeks in 50% of patients, compared with 35% of patients who used the excipient gel and received local care. (4) The optimal concentration of becaplermin gel is not known. Neither is its effect on lesions larger than 5 cm2 or its ability to prevent the need for amputation. (5) None of the clinical trials revealed any severe adverse effects (particularly tumour growth), but pharmacovigilance data are limited. (6) In practice, the very expensive topical becaplermin gel can help some patients, in whom it slightly accelerates ulcer healing.