Magnus S. Ågren

Bioactivity and stability of endogenous fibrogenic factors in platelet-rich fibrin

Platelet‐rich fibrin (PRF®) is an autologous fibrin sealant (FS) enriched with a platelet concentrate (>1,000,000 platelets/μL) produced by the automated Vivostat® system and used to enhance wound healing. The effects of PRF were compared with supernatant from thrombin‐activated platelet concentrate, recombinant human platelet‐derived growth factor (rhPDGF) isoforms, and a homologous FS in cultured normal human dermal fibroblasts. Also, the release of selected endogenous growth factors from PRF and their stability against proteolytic degradation were studied. The proliferative effect of PRF exceeded that of FS and rhPDGF‐BB, although it was lower than thrombin‐activated platelet concentrate possibly due to sustained growth factor release from platelets in PRF. Anti‐PDGF antibody blocked the mitogenic effect of rhPDGF‐BB but not that of PRF in growth‐arrested fibroblasts. PRF promoted secretion of carboxyterminal propeptide of type I collagen into conditioned medium while rhPDGF‐AB had no significant effect on collagen biosynthesis. Limited proteolysis of PDGF‐AB and no proteolysis of transforming growth factor‐β1 (TGF‐β1) in PRF were observed with trypsin treatment, whereas rhPDGF‐AB and rhTGF‐β1 in bovine serum albumin, matching the total protein concentration of PRF, were almost completely degraded after 24 hours at 37 °C. To conclude, PRF provides sustained release and protection against proteolytic degradation of endogenous fibrogenic factors important for wound healing.

Matrix metalloproteinase inhibition delays wound healing and blocks the latent transforming growth factor‐β1‐promoted myofibroblast formation and function

The ability to regulate wound contraction is critical for wound healing as well as for pathological contractures. Matrix metalloproteinases (MMPs) have been demonstrated to be obligatory for normal wound healing. This study examined the effect that the broad‐spectrum MMP inhibitor BB‐94 has when applied topically to full‐thickness skin excisional wounds in rats and its ability to inhibit the promotion of myofibroblast formation and function by the latent transforming‐growth factor‐β1 (TGF‐β1). BB‐94 delayed wound contraction, as well as all other associated aspects of wound healing examined, including myofibroblast formation, stromal cell proliferation, blood vessel formation, and epithelial wound coverage. Interestingly, BB‐94 dramatically increased the level of latent and active MMP‐9. The increased levels of active MMP‐9 may eventually overcome the ability of BB‐94 to inhibit this MMP and may explain why wound contraction and other associated events of wound healing were only delayed and not completely inhibited. BB‐94 was also found to inhibit the ability of latent TGF‐β1 to promote the formation and function of myofibroblasts. These results suggest that BB‐94 could delay wound closure through a twofold mechanism; by blocking keratinocyte migration and thereby blocking the necessary keratinocyte–fibroblast interactions needed for myofibroblast formation and by inhibiting the activation of latent TGF‐β1.

S100A8/A9 deficiency in nonhealing venous leg ulcers uncovered by multiplexed antibody microarray profiling

Background  Knowledge on the underlying mechanisms for nonhealing chronic wounds is fragmentary.

Evaluation of a near-senescent human dermal fibroblast cell line and effect of amelogenin

Background  Fibroblast senescence may delay healing of chronic wounds.

Ulcer bed infection

We report a case of ulcer bed infection in an enlarging venous leg ulcer without clinical signs of cellulitis in the surrounding tissues. Signs of infection in the leg ulcer were: 1) cocci‐like structures and bacteria‐like rods around vessel walls in the viable ulcer bed, 2) vasculitis‐like inflammation of deeply situated vessels of the viable tissue, 3) Pseudomonas aeruginosa‐specific antibodies in the serum (other than against exotoxin A), 4) extensive epidermolysis of normal human skin by the wound exudate in vitro, and 5) P. aeruginosa exotoxin A in the wound exudate (23 ng/ml). In an in vitro cell assay, the wound exudate was cytotoxic and rabbit antibodies to exotoxin A, but not a serine proteinase inhibitor, inhibited this cytotoxicity. P. aeruginosa exotoxin A might contribute to the pathogenesis of the ulcer enlargement. The ulcer improved after the third skin graft, probably mainly due to effective treatment with a long‐stretch compression bandage.

Fundamentals of randomized clinical trials in wound care: Design and conduct

The care for chronic and acute wounds is a substantial problem around the world. This has led to a plethora of products to accelerate healing. Unfortunately, the quality of studies evaluating the efficacy of such wound care products is frequently low. Randomized clinical trials are universally acknowledged as the study design of choice for comparing treatment effects, as they eliminate several sources of bias. We propose a framework for the design and conduct of future randomized clinical trials that will offer strong scientific evidence for the effectiveness of wound care interventions. While randomization is a necessary feature of a robust comparative study, it is not sufficient to ensure a study at low risk of bias. Randomized clinical trials should also ensure adequate allocation concealment and blinding of outcome assessors, apply intention‐to‐treat analysis, and use patient‐oriented outcomes. This article proposes strategies for improving the evidence base for wound care decision making.

Fundamentals of randomized clinical trials in wound care: Reporting standards

In wound care research, available high‐level evidence according to the evidence pyramid is rare, and is threatened by a poor study design and reporting. Without comprehensive and transparent reporting, readers will not be able to assess the strengths and limitations of the research performed. Randomized clinical trials (RCTs) are universally acknowledged as the study design of choice for comparing treatment effects. To give high‐level evidence the appreciation it deserves in wound care, we propose a step‐by‐step reporting standard for comprehensive and transparent reporting of RCTs in wound care. Critical reporting issues (e.g., wound care terminology, blinding, predefined outcome measures, and a priori sample size calculation) and wound‐specific barriers (e.g., large diversity of etiologies and comorbidities of patients with wounds) that may prevent uniform implementation of reporting standards in wound care research are addressed in this article. The proposed reporting standards can be used as guidance for authors who write their RCT, as well as for peer reviewers of journals. Endorsement and application of these reporting standards may help achieve a higher standard of evidence and allow meta‐analysis of reported wound care data. The ultimate goal is to help wound care professionals make better decisions for their patients in clinical practice.

Effects of isoniazid and niacin on experimental wound-healing

BACKGROUND There is a need for effective treatments of ischemic wounds. Our aim was to test the hypothesis that systemic administration of isoniazid or niacin can enhance wound healing in ischemic as well as nonischemic tissues. METHODS One 8-mm, full-thickness wound was made in a standardized, ischemic skin flap and 1 in adjacent nonischemic skin on the back of male Sprague-Dawley rats. Starting just after wounding, twice-daily intraperitoneal isoniazid (10 mg/kg b.i.d.), xanthinol nicotinate (30 mg/kg), or saline (control) were given for 14 days. Wound-healing was monitored by planimetry and oxygen tension in periphery of the wound using a microcatheter probe. Cellular proliferation in granulation tissue was assessed by immunohistochemical detection of proliferating cell nuclear antigen. The angiogenic activity of isoniazid and niacin was assessed using in vitro and ex vivo models. RESULTS Although wound ischemia was evident by decreased oxygen tension (26 +/- 10 mmHg; n = 9) compared with the adjacent nonischemic wounds (51 +/- 8 mmHg; n = 8), neither compound significantly influenced intracutaneous oxygen tension. Isoniazid (P < .0001), but not niacin, promoted ischemic wound-healing even though both compounds increased proliferation measured on day 14 (P < .01). In normal wounds, the cumulative change in relative wound area over 14 days was increased by niacin (P = .002), but not by isoniazid, although both niacin (P = .011) and isoniazid (P = .036) increased cellular proliferation. Neither isoniazid nor niacin showed activity in either an endothelial tube formation assay or organotypic angiogenic assay under normoxic conditions. CONCLUSION Isoniazid was capable of stimulating wound-healing in ischemic tissue to the level of nonischemic wounds and might offer a novel treatment option for wounds associated with arterial insufficiency. Although active in normal wounds, niacin did not promote ischemic wound-healing.