Wound Conforming Matrix Containing Purified Homogenate of Dermal Collagen Promotes Healing of Diabetic Neuropathic Foot Ulcers: Comparative Analysis Versus Standard of Care.

Objective: To compare outcomes of diabetic foot ulcers (DFUs) treated with a collagen Wound Conforming Matrix (WCM) or standard of care (SOC). Approach: WCM, a highly purified homogenate of 2.6% fibrillar bovine dermal collagen that conforms to the wound surface, was evaluated in comparison to daily saline-moistened gauze dressing changes (SOC) as part of a retrospective subset analysis of a randomized controlled trial in DFU. Following a 2-week run-in period during which patients received SOC, patients whose wounds did not reduce in area by >30% during run-in were randomly assigned to receive WCM (one or two applications) or SOC. Results: Statistically significant acceleration of early healing rates was observed following a single application of WCM with weekly outer dressing changes compared with daily saline-moistened gauze dressing changes (SOC). Over a 4-week period, 50% of patients receiving a single application of WCM achieved ≥75% reduction in wound area compared with 13% for SOC. WCM appeared to be safe and well tolerated, with no adverse events related to treatment and no evidence of an immunologic reaction to bovine collagen. Innovation: WCM is unique in its intimate contact with the wound bed and its ability to progress a wound toward healing with a single application. Conclusion: WCM is a treatment modality to accelerate DFU healing rates, with the potential to reduce the likelihood of infection and other complications, and cost of care.

The First Approved Gene Therapy Product for Cancer Ad-p53 (Gendicine): 12 Years in the Clinic.

Gendicine (recombinant human p53 adenovirus), developed by Shenzhen SiBiono GeneTech Co. Ltd., was approved in 2003 by the China Food and Drug Administration (CFDA) as a first-in-class gene therapy product to treat head and neck cancer, and entered the commercial market in 2004. Gendicine is a biological therapy that is delivered via minimally invasive intratumoral injection, as well as by intracavity or intravascular infusion. The wild-type (wt) p53 protein expressed by Gendicine-transduced cells is a tumor suppressor that is activated by cellular stress, and mediates cell-cycle arrest and DNA repair, or induces apoptosis, senescence, and/or autophagy, depending upon cellular stress conditions. Based on 12 years of commercial use in >30,000 patients, and >30 published clinical studies, Gendicine has exhibited an exemplary safety record, and when combined with chemotherapy and radiotherapy has demonstrated significantly higher response rates than for standard therapies alone. In addition to head and neck cancer, Gendicine has been successfully applied to treat various other cancer types and different stages of disease. Thirteen published studies that include long-term survival data showed that Gendicine combination regimens yield progression-free survival times that are significantly longer than standard therapies alone. Although the p53 gene is mutated in >50% of all human cancers, p53 mutation status did not significantly influence efficacy outcomes and long-term survival rate for Ad-p53-treated patients. To date, Shenzhen SiBiono GeneTech has manufactured 41 batches of Gendicine in compliance with CFDA QC/QA requirements, and 169,571 vials (1.0 × 1012 vector particles per vial) have been used to treat patients. No serious adverse events have been reported, except for vector-associated transient fever, which occurred in 50-60% of patients and persisted for only a few hours. The manufacturing accomplishments and clinical experience with Gendicine, as well as the understanding of its cellular mechanisms of action and implications, could provide valuable insights for the international gene therapy community and add valuable data to promote further developments and advancements in the gene therapy field.

Intervention with Formulated Collagen Gel for Chronic Heel Pressure Ulcers in Older Adults with Diabetes.

Chronic pressure ulcers (PrUs), ulcers that fail to progress through the expected phases of wound healing in a timely fashion, are not only a concern for the patients afflicted with them, but are also a significant burden for the long-term-care facilities in which patients reside. The heel is the second most common location for PrUs. Morbidity and mortality rates for heel PrUs, particularly in the diabetic population, are alarming. Therefore, a consistently effective, cost-conscious, and user-friendly topical treatment for heel ulcers would be welcomed by patients and clinicians. This article describes a marked and rapid improvement in wound granulation in 3 older adult patients following weekly treatment for 8 weeks of chronic (≥1-year duration) heel ulcers with an easy-to-use, cost-effective, topical, formulated collagen gel.

Serial sharp debridement and formulated collagen gel to treat pressure ulcers in elderly long-term care patients: a case study.

Clinicians treating pressure ulcers in the elderly in long-term care often face psychosocial, financial, and patient quality-of-life challenges; as such, they seek to identify products that meet wound healing goals as expeditiously as possible. The purpose of this case series was to evaluate outcomes of serial sharp debridement and the application of a formulated collagen gel in patients with chronic, nonhealing pressure ulcers. Three patients (two women ages 82 and 74 years of age and one man 82 years old, all incontinent of bladder and bowel with numerous comorbidities) had wounds >18 months' duration on the buttocks or coccyx that failed to improve despite the use of a wide variety of treatments, including negative pressure wound therapy. All wounds were debrided at the start of treatment and weekly thereafter if necessary, followed by application of the collagen gel. The gel was covered with a sterile bordered gauze and, if needed, a semipermeable dressing. Dressings were left in place for up to 1 week. Two ulcers re-epithelialized completely after 4 to 5 weeks of care, and the wound bed of the third ulcer was ready for grafting after 6 weeks of care. No adverse events occurred. Nursing staff appreciated the reduced dressing change frequency, although dressing maintenance remains challenging in patients with frequent incontinence episodes. Randomized clinical trials to evaluate the efficacy of this treatment approach compared to the use of traditional moisture-retentive dressings are needed.

Formulated collagen gel accelerates healing rate immediately after application in patients with diabetic neuropathic foot ulcers.

We assessed the safety and efficacy of Formulated Collagen Gel (FCG) alone and with Ad5PDGF-B (GAM501) compared with Standard of Care (SOC) in patients with 1.5-10.0 cm(2) chronic diabetic neuropathic foot ulcers that healed <30% during Run-in. Wound size was assessed by planimetry of acetate tracings and photographs in 124 patients. Comparison of data sets revealed that acetate tracings frequently overestimated areas at some sites. For per-protocol analysis, 113 patients qualified using acetate tracings but only 82 qualified using photographs. Prior animal studies suggested that collagen alone would have little effect on healing and would serve as a negative control. Surprisingly trends for increased incidence of complete closure were observed for both GAM501 (41%) and FCG (45%) vs. Standard of Care (31%). By photographic data, Standard of Care had no significant effect on change in wound radius (mm/week) from during Run-in to Week 1 (-0.06 ± 0.32 to 0.78 ± 1.53, p=ns) but both FCG (-0.08 ± 0.61 to 1.97 ± 1.77, p<0.002) and GAM501 (-0.02 ± 0.58 to 1.46 ± 1.37, p<0.002) significantly increased healing rates that gradually declined over subsequent weeks. Both GAM501 and FCG appeared to be safe and well tolerated, and alternate dosing schedules hold promise to improve overall complete wound closure in adequately powered trials.

Treatment of nonhealing diabetic foot ulcers with a platelet-derived growth factor gene-activated matrix (GAM501): results of a phase 1/2 trial.

The results from a Phase 1/2 study of a replication-defective adenovirus encoding human platelet-derived growth factor (PDGF)-B formulated in a bovine collagen (Ad-5PDGF-B; 2.6% collagen; GAM501) gel for nonhealing neuropathic diabetic foot ulcers is reported. The primary objectives of the study were to evaluate the safety, maximum-tolerated dose, and preliminary biological activity of GAM501. Fifteen patients enrolled into the study with chronic, nonhealing ulcers received either a single administration of GAM501 at one of three dose levels, or up to four administrations of GAM501 at 1-week intervals. All patients received standard of care treatment including debridement and were required to wear an off-loading shoe. GAM501 was found to be safe and well tolerated with no evidence of systemic or local toxicity at all doses so no maximum-tolerated dose was reached. Serum antibody titers to platelet-derived growth factor-B homodimer and collagen were negative and adenoviral DNA was not detected in the blood. In the 12 patients that completed the study, ulcer closure was observed by Month 3 in 10 patients, seven of whom received a single application of GAM501. In conclusion, GAM501 did not appear to have any toxicity at doses that showed biological activity. GAM501 holds promise as a potentially effective treatment for nonhealing diabetic foot ulcers.

Adenovirus encoding human platelet-derived growth factor-B delivered to alveolar bone defects exhibits safety and biodistribution profiles favorable for clinical use.

Platelet-derived growth factor (PDGF) gene therapy offers promise for tissue engineering of tooth-supporting alveolar bone defects. To date, limited information exists regarding the safety profile and systemic biodistribution of PDGF gene therapy vectors when delivered locally to periodontal osseous defects. The aim of this preclinical study was to determine the safety profile of adenovirus encoding the PDGF-B gene (AdPDGF-B) delivered in a collagen matrix to periodontal lesions. Standardized alveolar bone defects were created in rats, followed by delivery of matrix alone or containing AdPDGF-B at 5.5 x 10(8) or 5.5 x 10(9) plaque-forming units/ml. The regenerative response was confirmed histologically. Gross clinical observations, hematology, and blood chemistries were monitored to evaluate systemic involvement. Bioluminescence and quantitative polymerase chain reaction were used to assess vector biodistribution. No significant histopathological changes were noted during the investigation. Minor alterations in specific hematological and blood chemistries were seen; however, most parameters were within the normal range for all groups. Bioluminescence analysis revealed vector distribution at the axillary lymph nodes during the first 2 weeks with subsequent return to baseline levels. AdPDGF-B was well contained within the localized osseous defect area without viremia or distant organ involvement. These results indicate that AdPDGF-B delivered in a collagen matrix exhibits acceptable safety profiles for possible use in human clinical studies.

Adenovirus encoding human platelet-derived growth factor-B delivered in collagen exhibits safety, biodistribution, and immunogenicity profiles favorable for clinical use.

We have developed a therapeutic approach to wound repair involving immobilization of gene transfer vectors within biocompatible matrices (gene-activated matrix, or GAM). The matrix also serves as a scaffold for cellular in-growth and subsequent gene uptake and expression. An adenoviral vector encoding human platelet-derived growth factor-B delivered in collagen (AdPDGF-B/GAM) has demonstrated efficacy in models of wound repair. The safety, biodistribution, and immunogenicity profiles of AdPDGF-B/GAM were examined using a rabbit dermal wound model. Four weekly doses at 1 x 10(10) and 1 x 10(11) viral particles/cm2 of wound surface stimulated dose-related increases in granulation tissue formation and cell proliferation. In situ hybridization and immunostaining demonstrated concordant expression of human PDGF-B mRNA and protein. No treatment-related changes in hematology, serum chemistry, or histopathology were observed. Although AdPDGF-B DNA and PDGF-B mRNA were detected in wounds and axillary lymph nodes of treated animals, no AdPDGF-B was detected in blood or other organs. No immunologic responses against collagen were observed; however, as expected, IgG responses to AdPDGF-B and human PDGF-BB protein were detected. In adenovirus-preimmunized rats, attenuation of the wound healing response was modest (approximately 16%). Collectively, these observations indicate that repeat doses of AdPDGF-B/GAM are well tolerated and lead to robust, localized tissue repair.

Platelet-derived growth factor B, but not fibroblast growth factor 2, plasmid DNA improves survival of ischemic myocutaneous flaps.

HYPOTHESIS: Tissue flaps are commonly used for surgical reconstruction, especially to cover difficult wounds and in breast reconstruction following mastectomy. Complications due to inadequate flap perfusion are a source of morbidity and, in the lower extremity, can result in amputation. SETTING: Laboratory. INTERVENTIONS: We evaluated the ability of platelet-derived growth factor (PDGF) B and fibroblast growth factor 2 plasmid DNA, formulated in a type I collagen matrix, to promote tissue survival in a rat transverse rectus abdominis muscle flap model based on the inferior deep epigastric vascular supply. In the absence of any therapeutic agent, only about 24% of flap tissue survives in this model. The DNA/matrix formulations were delivered subcutaneously into the skin paddles 7 days before flap elevation, and tissues were harvested 7 days later. RESULTS: Our studies reveal dramatic increases in overall vascularity after treatment with PDGF-B and fibroblast growth factor 2 plasmid DNA; however, only PDGF-B increased flap survival (130% increase at 228 micro g/cm(2) of plasmid DNA vs controls; P<.01). Transdermal spectral imaging demonstrated an increase in patent vessels supporting blood flow in flaps treated with PDGF-B plasmid DNA vs the fibroblast growth factor 2 transgene. CONCLUSION: Matrix-enabled gene therapy may provide an effective nonsurgical approach for promoting flap survival and is well suited for surgical applications in which transient therapeutic transgene expression is desired.

Delivery of FGF genes to wound repair cells enhances arteriogenesis and myogenesis in skeletal muscle.

Tissue repair is driven by migratory macrophages and fibroblasts that infiltrate injury sites and secrete growth factors. We now report the enhancement of skeletal muscle repair by targeting transgene delivery to these repair cells using matrix-immobilized gene vectors. Plasmid and adenovirus vectors immobilized in collagen-gelatin admixtures were delivered to excisional muscle wounds, and when encoding either fibroblast growth factor-2 (FGF2) or FGF6 transgenes, produced early angiogenic responses that subsequently remodeled into arteriogenesis. FGF2 gene delivery enhanced the number of CD31(+) endothelial cells present at treatment sites > 6-fold by day 14, and muscular arteriole density up to 11-fold by day 21 (P<0.0001). Muscle repair was also enhanced, as FGF gene-treated wounds filled with regenerating myotubes expressing the marker CD56 (an average 20-fold increase in CD56 expression versus controls, P<0.0001). These responses required transfection of a threshold level of repair cells, achievable only in injured muscles, and were transgene-driven, as neither platelet-derived growth factor-B (PDGFB) gene nor FGF2 protein delivery produced equivalent responses. In conclusion, using biomatrices to direct gene delivery to repair cells allows for relatively complex regenerative processes such as arteriogenesis and myogenesis, and therefore represents a promising approach to treating injured and ischemic muscle.

Identification of FGF receptor-binding peptides for cancer gene therapy.

Linear FGF receptor-binding heptapeptides were identified by phage display using sequential rounds of biopanning against cells with displacement of phage by FGF2. The consensus motif MXXP was iterated after four to five rounds and the peptide MQLPLAT was studied in depth. Phage bearing MQLPLAT showed high levels of binding to FGF receptor positive cells, with over 90% of phage bound being eluted competitively by adding free FGF2. MQLPLAT phage showed only limited binding to Cos7 cells deficient in receptors for FGF. MQLPLAT phage bound to SKOV3 cells with a K(d) of 2.51 x 10(-10) M. Although binding could be blocked by preincubation with free FGF2, heparin could not displace the phage. Use of MQLPLAT to target polyelectrolyte gene delivery vectors in vitro in the presence of serum achieved up to 40-fold greater transgene transduction than nontargeted vectors. MQLPLAT phage were administered into gastric carcinomas via the tumor-feeding artery immediately following resection from patients. The phage showed up to 9-fold more accumulation in the tumor than in adjacent regions of normal tissue, whereas control phage showed less than 2-fold. These peptides should provide useful ligands for specific delivery of gene therapy vectors to clinically relevant targets.