[Show abstract][Hide abstract] ABSTRACT: There is a need to develop economical, efficient and widely available therapeutic approaches to enhance the rate of skin wound healing. The optimal outcome of wound healing is restoration to the pre-wound quality of health. In this study we investigate the cellular response to biological stimuli using functionalized nanofibers from the self-assembling peptide, RADA16. We demonstrate that adding different functional motifs to the RADA16 base peptide can influence the rate of proliferation and migration of keratinocytes and dermal fibroblasts. Relative to unmodified RADA16; the Collagen I motif significantly promotes cell migration, and reduces proliferation.
[Show abstract][Hide abstract] ABSTRACT: To investigate the risk of cancer and potential gender effects in persons hospitalised with burn injury.
Population-based retrospective cohort study using record-linkage systems in Scotland and Western Australia.
Records of 37 890 and 23 450 persons admitted with a burn injury in Scotland and Western Australia, respectively, from 1983 to 2008. Deidentified extraction of all linked hospital morbidity records, mortality and cancer records were provided by the Information Service Division Scotland and the Western Australian Data Linkage Service.
Total and gender-specific number of observed and expected cases of total ('all sites') and site-specific cancers and standardised incidence ratios (SIRs).
From 1983 to 2008, for female burn survivors, there was a greater number of observed versus expected notifications of total cancer with 1011 (SIR, 95% CI 1.3, 1.2 to 1.4) and 244 (SIR, 95% CI 1.12, 1.05 to 1.30), respectively, for Scotland and Western Australia. No statistically significant difference in total cancer risk was found for males. Significant excesses in observed cancers among burn survivors (combined gender) in Scotland and Western Australian were found for buccal cavity, liver, larynx and respiratory tract and for cancers of the female genital tract.
Results from the Scotland data confirmed the increased risk of total ('all sites') cancer previously observed among female burn survivors in Western Australia. The gender dimorphism observed in this study may be related to the role of gender in the immune response to burn injury. More research is required to understand the underlying mechanism(s) that may link burn injury with an increased risk of some cancers.
BMJ Open 01/2014; 4(1):e003845. · 2.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Large full thickness skin defects caused by trauma or surgery require skin grafting, often in conjunction with dermal scaffolds such as INTEGRA(®). Due to the size and severity of these procedures, complications such as infection may occur. This can lead to poor healing outcomes. OBJECTIVE: To identify early biomarkers of complications during INTEGRA(®) healing. METHODS: Levels of EGF, TGF-β1, FGF-2, VEGF, IFN-α, GM-CSF, IL-4 and IL-8 were measured pre-surgery and at days 1, 7 and 25 post-surgery in peripheral blood of 15 pediatric patients treated with INTEGRA(®) for reconstructive procedures. The levels of these molecules were analysed with respect to the occurrence of complications. RESULTS: Complications (local infection) occurred in a group of 4 patients. This resulted in a reduced INTEGRA(®) take rate comparing to the group without complications (71.5±5.4% vs. 98.1±0.7%). In cases with complications there were significantly higher plasma concentrations of IL-4 and FGF-2 on day 7 (p=0.037 and p=0.008 respectively). Other markers were not significantly different between groups or at very low level at all time-points. WCC and CRP remained within normal ranges at all time-points. CONCLUSIONS: This data suggests that elevated levels of IL-4 and FGF-2 at early time-points after surgery may predict the development of complications in patients with INTEGRA(®). This may enable early interventions to prevent complications in procedures involving the use of INTEGRA(®).
Burns: journal of the International Society for Burn Injuries 09/2012; · 1.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: All patients with primary cutaneous malignant melanoma undergo surgical excision to remove the tumour, resulting in scar formation. There is marked variation in the aesthetic appearance of scars following surgery but limited knowledge about the genetic factors affecting non-keloid, surgical scar outcomes. This study aimed to investigate the role of known clinical factors and genetic polymorphisms in pigmentation and wound repair genes in non-keloid scar outcome, following melanoma excision. Participants were 202 cases who underwent a standardized scar assessment following surgical melanoma excision and provided a DNA sample. Genetic association analyses between single nucleotide polymorphisms (SNPs) from 24 candidate genes and scar outcome data were performed, controlling for relevant clinical factors. Following adjustment for multiple testing, SNP rs8110090 in TGFβ1 was significantly associated with both the primary scar outcome (a combination score reflecting vascularity, height and pliability, p = 0.0002, q = 0.01) and the secondary scar outcome (a combination score reflecting vascularity, height, pliability and pigmentation, p = 0.0002, q = 0.006). The minor allele G was associated with a poorer scar outcome. Younger age, time elapsed since excision, absence of kidney failure and eczema, presence of thyroid problems and infection were also associated with poorer scar outcome and were adjusted for in the final model, along with scar site. Results from this study suggest that genes involved in wound healing may play a role in determining scar outcome. Associations observed between scar outcome and clinical factors reinforce current clinical knowledge regarding factors affecting scarring. Replication studies in larger samples are warranted and will improve our understanding of the underlying mechanisms of scarring, potentially help to identify patients at risk of poor scar outcomes.
Archives for Dermatological Research 05/2012; 304(5):343-51. · 2.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Burn injury can lead to abnormal sensory function at both the injury and at distant uninjured sites. Here, we used a mouse model to investigate return of nociceptive function and reinnervation of the skin at the wound and uninjured distant sites following a 3% total burn surface area full-thickness burn injury. We have previously shown that topical application of zinc-metallothionein-IIA (Zn(7) -MT-IIA) accelerates healing following burn injury, and here, we investigated the potential of Zn(7) -MT-IIA to enhance reinnervation and sensory recovery. In all burn-injured animals, there was a significant reduction in nociceptive responses (Semmes-Weinstein filaments) at locations near and distant to the wound up to 8 weeks following injury. Cutaneous nerve reinnervation (assessed using protein gene product 9.5 immunohistochemistry) of the wound center was slow in the epidermis but rapid in the dermis. In the dermis, nerves subsequently degenerated both at the wound center and in distant uninjured areas. In contrast, epidermal nerve densities in the distant uninjured areas returned to normal, uninjured levels. Zn(7) -MT-IIA did not influence return of nociceptive function nor reinnervation. We conclude that burn injury compromises nociceptive function and nerve regeneration both at the injury site and systemically; thus, therapies in addition to Zn(7) -MT-IIA should be explored to return normal sensory function.
Wound Repair and Regeneration 04/2012; 20(3):367-77. · 2.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Topographic modulation of tissue response is an important consideration in the design and manufacture of a biomaterial. In developing new tissue therapies for skin, all levels of architecture, including the nanoscale need to be considered. Here we show that keratinocyte phenotype is affected by nanoscale changes in topography with cell morphology, proliferation, and migration influenced by the pore size in anodic aluminum oxide membranes. A membrane with a pore size of 300 nm, which enhanced cell phenotype in vitro, was used as a dressing to cover a partial thickness burn injury in the pig. Wounds dressed with the membrane showed evidence of advanced healing with significantly less organizing granulation tissue and more mature epidermal layers than control wounds dressed with a standard burns dressing. The results demonstrate the importance of nanoscale topography in modulating keratinocyte phenotype and skin wound healing.
Tissue Engineering Part A 12/2011; 18(7-8):703-14. · 4.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The use of non-cultured autologous cells to promote wound healing and in reconstructive procedures is increasing. One common method for preparing these cells is the use of the ReCell(®) device. However, despite its current clinical use, no characterisation of the cell suspension produced using a ReCell(®) device has been published.
To characterise the ReCell suspension that is applied to wounds for cell type, viability, yield, stability and proliferative potential.
The ReCell(®) device was used to harvest cells from a 2 cm(2) piece of split-thickness skin isolated using a dermatome. The resulting cell suspension was analysed for cell yield, cell type, viability over time, proliferative potential and reproducibility.
Average viable cell yield was 1.7×10(6)/cm(2) of tissue, with 75.5% of the total cell isolate viable. Total viable cell number was not significantly reduced after 4 h storage at 22°C or 4°C, and was stable for 24 h at 4°C. Proliferative potential was assessed using a colony forming assay, with 0.3% of viable cells isolated forming keratinocyte colonies. Predominantly the suspension contained keratinocytes (64.3±28.8%) and fibroblasts (30.3±14.0%), with a small population of melanocytes also identified (3.5±0.5%). Finally, the supernatant contained low total protein (0.92 mg/ml) and the supernatant had no significant effects on cell viability or growth when applied ex vivo.
These results suggest the ReCell(®) device provides a method for the preparation of a cell suspension with high viability and proliferative potential, containing viable melanocytes and no apparent toxic cell debris. Further work on the sustained viability of these cells in vivo, and in particular after application to the wound, will be important to better understand the potential of the ReCell(®) device in the clinic.
Burns: journal of the International Society for Burn Injuries 11/2011; 38(1):44-51. · 1.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chronic pain is a common occurrence for burn patients and has significant impact on quality of life. However, the etiology is not well understood. Understanding the mechanisms underlying the restoration of sensory function and the development of chronic pain after burn is critical to improving long-term outcomes.
To determine whether cutaneous innervation in burn patients with chronic pain is altered when compared to patients without chronic pain.
Twelve patients with unilateral injury and who reported chronic pain were recruited. Each patient underwent sensory function testing and both scar and matched site uninjured skin biopsy. Biopsies were analyzed for total nerve density and nociceptive C-fiber density using immunohistochemistry. Results were compared to a control group of 33 patients with unilateral injury and no reported long-term pain.
Sensory function was significantly diminished in scar compared to uninjured tissue in both study groups, but chronic pain patients did not have significantly diminished function when compared to control. Total nerve density was not significantly different between scar and uninjured sites in either group, or between groups. However, the density of nociceptive nerve fibers was significantly elevated in both uninjured (p=0.0193) and scar sites (p=0.0316) of the patients with chronic pain when compared to the control group.
This data suggests that differences in cutaneous innervation may contribute to chronic pain after burn. There also appears to be a systemic difference in cutaneous innervation extending to distal uninjured sites. Therefore efforts to affect cutaneous reinnervation after burn may lead to less patients experiencing chronic pain.
Burns: journal of the International Society for Burn Injuries 06/2011; 37(4):631-7. · 1.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Loss of sensory function in scar after burn is common, although the basis for this loss is not clear. Additionally, little is known about the effects of different treatment modalities on sensory function and neuroanatomical outcomes in burn patients. Here, we investigated the effects of the use of the INTEGRA(®) dermal scaffold on neuroanatomy and sensory function in acute burn patients.
We hypothesized that the use of artificial dermal templates would inhibit or reduce reinnervation after excision, since regrowth of nerves requires complex molecular interactions. Therefore the primary objective of this study was to identify whether there is regrowth of nerve fibres in the INTEGRA(®) dermal scaffold. The secondary objective was to identify whether the INTEGRA(®) dermal scaffold reduced nerve regrowth or limited sensory function outcomes in acute burn patients.
Five patients treated with INTEGRA(®), cultured epithelial autograft spray (prepared using ReCell(®) (CEA)) and split skin graft (SSG) were assessed for sensory function in scar and uninjured contralateral control skin. Neuroanatomy of scar and control sites was assessed using immunohistochemistry for PGP9.5, CGRP and substance P neuronal markers. Nerve density and sensory function was also assessed in a comparative group (n=8) treated with CEA and SSG only.
Neuroanatomy was not significantly different in the INTEGRA(®) patients when compared to the CEA/SSG group only. The patients treated with INTEGRA(®) had worse sensory function than those with CEA/SSG only.
Peripheral nerves do reinnervate the INTEGRA(®) dermal scaffold. There is no statistically significant reduction in reinnervation observed when compared to a control group. It is possible that the use of artificial dermal constructs, while permissive for nerve regrowth, limit functionality when compared to nerves that regrow through dermal tissue. Further research to understand the causes of this, and into enhancing reinnervation in dermal scaffolds may improve sensory outcome in the most severely burned patients.
Burns: journal of the International Society for Burn Injuries 05/2011; 37(7):1101-8. · 1.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A letter to the Editor of the Journal of Investigative Dermatology
Innervation of the skin is important in order to maintain functional sensation and enable appropriate response to environmental stimuli. Injury to the skin may involve peripheral nerve damage. Previous studies have shown an initial loss of nerve fibers followed by an increase above normal fiber density, which is followed by apoptosis and ultimately reduced innervation and sensory function in scar tissue (Hermanson et al., 1987; Stella et al., Supp.(767) 1994; Altun et al., 2001; Ward et al., 2004; Nedelec et al., 2005). Although some studies have found an association between reduced nerve density and sensation (Stella et al., 1994; Ward et al., 2004), other studies have not (Griffin et al., 2001; Nedelec et al., 2005). The contradictory nature of these findings is at least in part due to small sample numbers, incomplete functional and anatomical assessment, and the variable timeframes between injury and analysis. Herein, to better understand the changes in cutaneous innervation and sensory function, we have analyzed neuroanatomy in a rat model of burn injury, and assessed neuroanatomy in patients with unilateral burn injuries at least 18 months post-injury, which is commonly defined as the end point for scar maturity (Nedelec et al., 2005). All animal experiments were approved by the institutional animal ethics committee and were performed in accordance with the NHMRC Australian code of practice for the care and use of animals for scientific purposes. The human study was carried out in accordance with the regulations outlined in the national statement on ethical conduct in research involving humans issued by the NHMRC and was approved by the Royal Perth Hospital ethics committee.
Journal of Investigative Dermatology 03/2010; 130(7):1948-51. · 6.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neuronal cell death caused by glutamate excitotoxicity is prevalent in various neurological disorders and has been associated with the transcriptional activation of activator protein-1 (AP-1). In this study, we tested 19 recently isolated AP-1 inhibitory peptides, fused to the cell penetrating peptide TAT, for their efficacy in preventing cell death in cortical neuronal cultures following glutamate excitotoxicity. Five peptides (PYC19D-TAT, PYC35D-TAT, PYC36D-TAT, PYC38D-TAT, PYC41D-TAT) displayed neuroprotective activity in concentration responses in both l- and retro-inverso d-isoforms with increasing levels of neuroprotection peaking at 83%. Interestingly, the D-TAT peptide displayed a neuroprotective effect increasing neuronal survival to 25%. Using an AP-1 luciferase reporter assay, we confirmed that the AP-1 inhibitory peptides reduce AP-1 transcriptional activation, and that c-Jun and c-Fos mRNA following glutamate exposure is reduced. In addition, following glutamate exposure the AP-1 inhibitory peptides decreased calpain-mediated alpha-fodrin cleavage, but not neuronal calcium influx. Finally, as neuronal death following glutamate excitotoxicity was transcriptionally independent (actinomycin D insensitive), our data indicate that activation of AP-1 proteins can induce cell death via non-transcriptional pathways. Thus, these peptides have potential application as therapeutics directly or for the rational design of small molecule inhibitors in both apoptotic and necrotic neuronal death associated with AP-1 activation.
Journal of Neurochemistry 10/2009; 112(1):258-70. · 4.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cells respond to changes in the environment by altering their phenotype. The ability to influence cell behavior by modifying their environment provides an opportunity for therapeutic application, for example, to promote faster wound healing in response to skin injury. Here, we have modified the preparation of an aluminium oxide template to generate large uniform membranes with differing nano-pore sizes. Epidermal cells (keratinocytes) and dermal cells (fibroblasts) readily adhere to these nanoporous membranes. The pore size appears to influence the rate of cell proliferation and migration, important aspects of cell behavior during wound healing. The suitability of the membrane to act as a dressing after a burn injury was assessed in vivo; application of the membrane demonstrated adherence and conformability to the skin surface of a pig, with no observed degradation or detrimental effect on the repair. Our results suggest that keratinocytes are sensitive to changes in topography at the nanoscale level and that this property may be exploited to improve wound repair after tissue injury.
Tissue Engineering Part A 07/2009; 15(12):3753-63. · 4.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The importance of vitamins for optimal metabolism is well established. However, currently little is known about the optimal vitamin levels required for burn patients. As a consequence, current practice both for macronutrient supplementation and vitamin supplementation varies widely between burn units. A better understanding of the effects of vitamins on metabolism may lead to better nutrition and subsequently improved outcomes for burn patients. Thiamine is an important co-factor required for multiple enzymes involved in carbohydrate metabolism. We have examined the levels of thiamine (B1) in burn patients as well as the effects of thiamine supplementation on the levels of serum thiamine, pyruvate and lactate. Twenty patients had blood samples taken on the day of admission, then on days 1, 3, and 7 post-admission and weekly thereafter until discharge. Of these, nine received enteral feeding. Six patients received thiamine supplementation. Serum thiamine, pyruvate and lactate levels were measured at each time point. Serum thiamine levels increased significantly with thiamine supplementation (p<0.001). Serum thiamine levels also increased with time of supplementation (p<0.001). Serum thiamine level was closely associated with pyruvate and lactate levels, with a decrease in both pyruvate and lactate associated with increased serum thiamine. Lastly, pyruvate and lactate levels appear closely associated in a linear relationship. This study suggests thiamine supplementation increases serum thiamine and that this increase is associated with a decrease in pyruvate and lactate levels. Further study of changes in metabolic flux associated with thiamine supplementation and a randomised control trial of thiamine supplementation are required to establish whether thiamine supplementation is beneficial to burn patients' metabolism and recovery.
Burns: journal of the International Society for Burn Injuries 06/2009; 36(2):261-9. · 1.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Scarring after severe burn is a result of changes in collagen deposition and fibroblast activity that result in repaired but not regenerated tissue. Re-epithelialisation of wounds and dermal cell repopulation has been thought to be driven by cells in the periphery of the wound. However, recent research demonstrated that cells originating from the bone marrow contribute to healing wounds in other tissues and also after incisional injury. We investigated the contribution of bone marrow-derived cells to long-term cell populations in scar tissue (primarily fibroblasts and keratinocytes) after severe burn. Wild-type mice were lethally irradiated and then the bone marrow reconstituted by injection of chimeric bone marrow cells expressing EGFP marker protein. Mice with chimeric bone marrow were then given a burn, either an 1-cm diameter injury (to mimic minor injury) or 2-cm diameter (to mimic moderate injury). Wounds were analysed at days 1, 3, 7, 14, 21, 28, 56 and 120 using FACS and immunohistochemistry to identify the percentage and cell type within the wound originating from the bone marrow. The inflammatory cell infiltrate at the early time-points was bone marrow in origin. At later time-points, we noted that over half of the fibroblast population was bone marrow-derived; we also observed that a small percentage of keratinocytes appeared to be bone marrow in origin. These findings support the theory that the bone marrow plays an important role in providing cells not only for inflammation but also dermal and epidermal cells during burn wound healing. This increases our understanding of cell origins in the healing wound, and has the potential to impact on clinical practice providing a potential mechanism for intervention away from conventional topical treatments and directed instead to systemic treatments affecting the bone marrow response.
Burns: journal of the International Society for Burn Injuries 11/2008; 35(3):356-64. · 1.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The skin provides vital protection from infection and dehydration. Maintenance of the skin is through a constant program of proliferation, differentiation and apoptosis of epidermal cells, whereby proliferating cells in the basal layer differentiating to form the keratinized, anucleated stratum corneum. The WNT signalling pathway is known to be important in the skin. WNT signalling has been shown to be important both in epidermal development and in the maintenance and cycling of hair follicles and epidermal stem cells. However, the precise role for this pathway in epidermal differentiation remains unknown. We investigated the role of the WNT signalling inhibitor sFRP4 in epidermal differentiation. sFRP4 is expressed in both normal skin and keratinocytes in culture. Expression of sFRP4 mRNA and protein increases with keratinocyte differentiation and apoptosis, whilst exposure of keratinocytes to exogenous sFRP4 promotes apoptosis and expression of the terminal differentiation marker Involucrin. These data suggest sFRP4 promotes epidermal differentiation.
Biochemical and Biophysical Research Communications 11/2008; 377(2):606-11. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Severe injury to the epidermal barrier often results in scarring and life-long functional deficits, the outcome worsening with a number of factors including time taken to heal. We have investigated the potential of exogenous metallothionein IIA (Zn(7)-MT-IIA), a naturally occurring small cysteine-rich protein, to accelerate healing of burn wounds in a mouse model. Endogenous MT-I/II expression increased in basal keratinocytes concurrent with reepithelialization after a burn injury, indicating a role for MT-I/II in wound healing. In vitro assays of a human keratinocyte cell line indicated that, compared with saline controls, exogenous Zn(7)-MT-IIA significantly increased cell viability by up to 30% (p<0.05), decreased apoptosis by 13% (p<0.05) and promoted keratinocyte migration by up to 14% (p<0.05), all properties that may be desirable to promote rapid wound repair. Further in vitro assays using immortalized and primary fibroblasts indicated that Zn7-MT-IIA did not affect fibroblast motility or contraction (p>0.05). Topical administration of exogenous Zn(7)-MT-IIA (2 microg/mL) in vivo, immediately postburn accelerated healing, promoted faster reepithelialization (3 days: phosphate-buffered saline (PBS), 8.9+/-0.3 mm diameter vs. MT-I/II, 7.1+/-0.7 mm; 7 days: PBS 5.8+/-0.98 mm vs. MT-I/II, 3.6+/-1.0 mm, p<0.05) and reduced epidermal thickness (MT-I/II: 45+/-4 microm vs. PBS: 101+/-19 microm, p<0.05) compared with controls. Our data suggest that exogenous Zn(7)-MT-IIA may prove a valuable therapeutic for patients with burns and other skin injuries.
Wound Repair and Regeneration 09/2008; 16(5):682-90. · 2.77 Impact Factor