Efficacy and safety of a fibrin sealant for adherence of autologous skin grafts to burn wounds: results of a phase 3 clinical study.

The objective of this phase 3, multicentered, prospective, randomized, evaluator-blinded, clinical study was to compare skin graft adherence utilizing a fibrin sealant containing 4 IU/ml thrombin (FS 4IU VH S/D [FS 4IU VH S/D will be marketed under the trade name ARTISS upon licensure in the United States]) to graft adherence utilizing staples in burn patients requiring wound excision and skin grafting. FS 4IU VH S/D was compared with staples in 138 patients. Patients had burn wounds measuring < or =40% of total body surface area with two comparable test sites measuring between 1 and 4% total body surface area each. Wound closure at day 28 was assessed using test site planimetry and review of day 28 photographs by three independent blinded evaluators (primary endpoint analysis). Secondary efficacy measures included hematoma/seroma on day 1, engraftment on day 5, and wound closure on day 14. Investigator and patient-reported outcomes were also assessed. The proportion of test sites with complete wound closure at day 28 was 70.3% in FS 4IU VH S/D treated sites and 65.8% in stapled sites, as assessed by planimetry. Blinded review of day 28 photographs confirmed that the rate of complete wound closure was similar between the two treatments, although the overall assessed rates of closure were lower than those determined by planimetry: FS 4IU VH S/D (43.3%) and staples (37.0%). The lower limit of the 97.5% confidence interval of the difference between FS 4IU VH S/D and staples was -0.029, which is above the predefined noninferiority margin of -0.1. Therefore, FS 4IU VH S/D is at least as efficacious as staples at the 97.5% one-sided level for complete wound closure by day 28. Hematoma/seroma on day 1 occurred at significantly (P < .0001) fewer FS 4IU VH S/D-treated sites (29.7% [95% CI 22.2-38.1%]) compared with stapled sites (62.3% [95% CI 53.7-70.4%]). Engraftment on day 5 was deemed to be 100% in 62.3% (95% CI 53.7-70.4%) of the FS 4IU VH S/D-treated sites and 55.1% (95% CI 46.4-63.5%) of the stapled sites (P = .0890). Complete wound closure by day 14 occurred in 48.8% (95% CI 39.9-57.8%) of the FS 4IU VH S/D treated sites and 42.6% (95% CI 34.0-51.6%) of the stapled sites (P = .2299). FS 4IU VH S/D scored significantly better than staples for all investigator-assessed outcomes, namely quality of graft adherence (P < .0001), preference for method of fixation (P < .0001), satisfaction with graft fixation (P < .0001), and overall quality of healing (P < .0001). Likewise, FS 4IU VH S/D scored significantly better than staples for all patient-assessed outcomes, namely anxiety about pain (P < .0001) and treatment preference (P <.0001). The safety profile of FS 4IU VH S/D was excellent as indicated by the lack of any related serious adverse experiences. These findings demonstrate that FS 4IU VH S/D is safe and effective for attachment of skin grafts, with outcomes at least as good as or better than staple fixation.

Comparison of fibrin sealant and staples for attaching split-thickness autologous sheet grafts in patients with deep partial- or full-thickness burn wounds: a phase 1/2 clinical study.

We undertook a multicenter, randomized, controlled, phase 1/2 clinical study to investigate the safety and efficacy of a fibrin sealant containing 4 IU/ml thrombin (FS 4IU) for the attachment of autologous sheet grafts in patients with deep partial-thickness or full-thickness burn wounds. Fibrin sealant (FS 4IU) was compared with staples for adherence of sheet grafts in 40 patients. Patients had to have burn wounds measuring 40% TBSA or less with two comparable test sites measuring between 1% and 4% TBSA each. Wound beds were prepared before treatment assignment, which was randomized. Percent area of hematoma/seroma at Day 1 (P = .0138) and questionable viability at Day 5 (P = .0182) were significantly less for FS 4IU-treated sites. Median percent area of graft survival on Day 14 was 100% for both treatments (P = .3525). The percentage of completely closed sites generally was greater for FS 4IU-sites on Days 5 to 91; the maximum difference occurred at Day 28 (79.5% vs 59%; P = .0215). The safety profile of FS 4IU was excellent as indicated by the lack of any related serious adverse experiences. These findings indicate that FS 4IU is safe and effective for fixation of skin grafts, with outcomes similar to or better than staple fixation. The data suggest that FS 4IU is a promising candidate for further clinical studies focusing on skin graft adhesion and burn wound healing.

Dual functionality of the anti-beta1 integrin antibody, 12G10, exemplifies agonistic signalling from the ligand binding pocket of integrin adhesion receptors.

Although integrins are known to mediate connections between extracellular adhesion molecules and the intracellular actin cytoskeleton, the mechanisms that are responsible for coupling ligand binding to intracellular signaling, for generating diversity in signaling, and for determining the efficacy of integrin signaling in response to ligand engagement are largely unknown. By characterizing the class of anti-integrin monoclonal antibodies (mAbs) that stimulate integrin activation and ligand binding, we have identified integrin-ligand-mAb complexes that exhibit differential signaling properties. Specifically, addition of 12G10 mAb to cells adhering via integrin alpha4beta1 was found to trigger disruption of the actin cytoskeleton and prevent cell attachment and spreading, whereas mAb addition to cells adhering via alpha5beta1 stimulated all of these processes. In contrast, soluble ligand binding to either alpha4beta1 or alpha5beta1 was augmented or unaffected by 12G10. The regions of the integrin responsible for differential signaling were then mapped using chimeras. Surprisingly, a chimeric alpha5 integrin containing the beta-propeller domain from the ligand binding pocket of alpha4 exhibited the same signaling properties as the full-length alpha4 integrin, whereas exchanging or removing cytoplasmic domains had no effect. Thus the mAb 12G10 demonstrates dual functionality, inhibiting cell adhesion and spreading while augmenting soluble ligand binding, via a mechanism that is determined by the extracellular beta-propeller domain of the associating alpha-subunit. These findings therefore demonstrate a direct and variable agonistic link between the ligand binding pocket of integrins and the cell interior that is independent of the alpha cytoplasmic domains. We propose that either ligand-specific transmembrane conformational changes or ligand-specific differences in the kinetics of transmembrane domain separation underlie integrin agonism.