Nanocellulose composite wound dressings for real-time pH wound monitoring.

The skin is the largest organ of the human body. Wounds disrupt the functions of the skin and can have catastrophic consequences for an individual resulting in significant morbidity and mortality. Wound infections are common and can substantially delay healing and can result in non-healing wounds and sepsis. Early diagnosis and treatment of infection reduce risk of complications and support wound healing. Methods for monitoring of wound pH can facilitate early detection of infection. Here we show a novel strategy for integrating pH sensing capabilities in state-of-the-art hydrogel-based wound dressings fabricated from bacterial nanocellulose (BC). A high surface area material was developed by self-assembly of mesoporous silica nanoparticles (MSNs) in BC. By encapsulating a pH-responsive dye in the MSNs, wound dressings for continuous pH sensing with spatiotemporal resolution were developed. The pH responsive BC-based nanocomposites demonstrated excellent wound dressing properties, with respect to conformability, mechanical properties, and water vapor transmission rate. In addition to facilitating rapid colorimetric assessment of wound pH, this strategy for generating functional BC-MSN nanocomposites can be further be adapted for encapsulation and release of bioactive compounds for treatment of hard-to-heal wounds, enabling development of novel wound care materials.

Efficacy of topical honey compared to systemic gentamicin for treatment of infected war wounds in a porcine model: A non-inferiority experimental pilot study.

BACKGROUND: In armed conflicts, infected wounds constitute a large portion of the surgical workload. Treatment consists of debridements, change of dressings, and antibiotics. Many surgeons advocate for the use of honey as an adjunct with the rationale that honey has bactericidal and hyperosmotic properties. However, according to a Cochrane review from 2015 there is insufficient data to draw any conclusions regarding the efficacy of honey in treatment of wounds. We, therefore, decided to evaluate if honey is non-inferior to gentamicin in the treatment of infected wounds in a highly translatable porcine wound model. MATERIAL AND METHODS: 50 standardized wounds on two pigs were infected with S. aureus and separately treated with either topically applied Manuka honey or intramuscular gentamicin for eight days. Treatment efficacy was evaluated with quantitative cultures, wound area measurements, histological, immunohistochemical assays, and inflammatory response. RESULTS: Topically applied Manuka honey did not reduce bacterial count or wound area for the duration of treatment. Intramuscular gentamicin initially reduced bacterial count (geometric mean 5.59*¸0.37 - 4.27*¸0.80 log10 (GSD) CFU/g), but this was not sustained for the duration of the treatment. However, wound area was significantly reduced with intramuscular gentamicin at the end of treatment (mean 112.8 ± 30.0-67.7 ± 13.2 (SD) mm2). ANOVA-analysis demonstrated no variation in bacterial count for the two treatments but significant variation in wound area (p<0.0001). The inflammatory response was more persistent in the pig with wounds treated with topically applied Manuka honey than in the pig treated with intramuscular gentamicin. CONCLUSION: At the end of treatment S. aureus count was the same with topically applied Manuka honey and intramuscular gentamicin. The wound area was unchanged with topically applied Manuka honey and decreased with intramuscular gentamicin. Topically applied Manuka honey could consequently be non-inferior to intramuscular gentamicin in reducing S. aureus colonization on the wound's surface, but not in reducing wound size. The use of Manuka honey dressings to prevent further progression of a wound infection may therefore be of value in armed conflicts, where definite care is not immediately available.

Effects of amniotic fluid on human keratinocyte gene expression: Implications for wound healing.

Cutaneous wounds can lead to huge suffering for patients. Early fetal wounds have the capacity to regenerate without scar formation. Amniotic fluid (AF), containing hyaluronic acid (HA), may contribute to this regenerative environment. We aimed to analyse changes in gene expression when human keratinocytes are exposed to AF or HA. Human keratinocytes were cultured to subconfluence, starved for 12 h and then randomised to be maintained in (1) Dulbecco's modified Eagle's medium (DMEM), (2) DMEM with 50% AF, or (3) DMEM with 50% fetal calf serum (FCS). Transcriptional changes were analysed using microarray and enriched with WebGestalt and Enrichr. Additionally, eight diagnostic genes were analysed using semiquantitative real-time PCR to investigate epidermal differentiation and cellular stress after HA exposure as an alternative for AF exposure. The AF and FCS treatments resulted in enrichment of genes relating to varied aspects of epidermal and keratinocyte biology. In particular, p63-, AP1- and NFE2L2- (Nrf2) associated genes were found significantly regulated in both treatments. More genes regulated by FCS treatment were associated with inflammatory signalling, whilst AF treatment was dominantly associated with molecular establishment of epidermis and lipid metabolic activity. HA exposure mostly resulted in gene regulation that was congruent with the AF microarray group, with increased expression of ITGA6 and LOR. We conclude that AF exposure enhances keratinocyte differentiation in vitro, which suggests that AF constituents can be beneficial for wound-healing applications.

Transplantation of autologous cells and porous gelatin microcarriers to promote wound healing.

Definitive treatment to achieve wound healing in major burns frequently include skin transplantation, where split-thickness skin grafts is considered gold standard. This method is associated with several drawbacks. To overcome these hurdles, efforts have been made to develop tissue engineered skin substitutes, often comprised of a combination of cells and biomaterials. In the present study, we aimed to investigate transplantation of autologous keratinocytes and fibroblasts seeded on porous gelatin microcarriers using a porcine wound model. Pre-seeded microcarriers were transplanted to a total of 168 surgical full-thickness wounds (2cm diameter) on eight adult female pigs and covered with occlusive dressings. The experimental groups included wounds transplanted with microcarriers seeded with the combination of keratinocytes and fibroblasts, microcarriers seeded with each cell type individually, microcarriers without cells, each cell type in suspension, and NaCl control. Wounds were allowed to heal for one, two, four or eight weeks before being excised and fixated for subsequent histological and immunohistochemical analysis. In vitro, we confirmed that viable cells populate the surface and the pores of the microcarriers. In vivo, the microcarriers were to a large extent degraded after two weeks. After one week, all treatment groups, with the exception of microcarriers alone, displayed significantly thicker neo-epidermis compared to controls. After two weeks, wounds transplanted with microcarriers seeded with cells displayed significantly thicker neo-epidermis compared to controls. After four weeks there was no difference in the thickness of neo-epidermis. In conclusion, the experiments performed illustrate that autologous cells seeded on porous gelatin microcarriers stimulates the re-epithelialization of wounds. This method could be a promising candidate for skin transplantation. Future studies will focus on additional outcome parameters to evaluate long-term quality of healing following transplantation.

Utilizing the Natural Composition of Brown Seaweed for the Preparation of Hybrid Ink for 3D Printing of Hydrogels.

This study aims to utilize the natural composition of brown seaweed by deriving alginate and cellulose concurrently from the stipe (stem-like) and blade (leaf-like) structures of the seaweed; further, this is followed by fibrillation for the direct and resource-efficient preparation of alginate/cellulose nanofiber (CNF) hybrid inks for three-dimensional (3D) printing of hydrogels. The efficiency of the fibrillation process was evaluated, and the obtained gels were further studied with regard to their rheological behavior. As a proof of concept, the inks were 3D printed into discs, followed by cross-linking with CaCl2 to form biomimetic hydrogels. It was shown that the nanofibrillation process from both seaweed structures is very energy-efficient, with an energy demand lower than 1.5 kW h/kg, and with CNF dimensions below 15 nm. The inks displayed excellent shear-thinning behavior and cytocompatibility and were successfully printed into 3D discs that, after cross-linking, exhibited an interconnected network structure with favorable mechanical properties, and a cell viability of 71%. The designed 3D biomimetic hydrogels offers an environmentally benign, cost-efficient, and biocompatible material platform with a favorable structure for the development of biomedical devices, such as 3D bio printing of soft tissues.

Tracking keratinocytes and melanocytes using carboxyfluorescein hydroxysuccinimidyl ester staining.

INTRODUCTION: The treatment of burn wounds and hypopigmentation conditions often require autologous transplantation of keratinocytes and melanocytes. Tracking transplanted cells to ascertain their contribution to tissue recapitulation presents a challenge. This study demonstrates a methodology based on passive staining with carboxyfluorescein hydroxysuccinimidyl ester (CFSE) that enables localization of cells in tissue sections to investigate the fate of transplanted cells in wound re-epithelialisation. METHODS: Viability and migration of CFSE-stained keratinocytes and melanocytes were investigated using viability staining and scratch assays, while proliferation of cells was measured using flow cytometry. In addition, CFSE-stained keratinocytes and melanocytes were transplanted to a human ex vivo wound model, either in suspension, or with the aid of macroporous gelatine microcarriers. Wounds were analysed seven, 14 and 21 days post transplantation using cryosectioning and fluorescence microscopy. Sections from wounds with transplanted co-cultured keratinocytes and melanocytes were stained for pancytokeratin to distinguish keratinocytes. RESULTS: CFSE-staining of keratinocytes and melanocytes did not affect the viability, migration or proliferation of the cells. Transplanted cells were tracked in ex vivo wounds for 21 days, illustrating that the staining had no effect on wound re-epithelialisation. In conclusion, this study presents a novel application of CFSE-staining for tacking transplanted primary human keratinocytes and melanocytes.

Potential benefits of triage for the trauma patient in a Kenyan emergency department.

BACKGROUND: Improved trauma management can reduce the time between injury and medical interventions, thus decreasing morbidity and mortality. Triage at the emergency department is essential to ensure prioritization and timely assessment of injured patients. The aim of the present study was to investigate how a lack of formal triage system impacts timely intervention and mortality in a sub-Saharan referral hospital. Further, the study attempts to assess potential benefits of triage towards efficient management of trauma patients in one middle income country. METHODS: A prospective descriptive study was conducted. Adult trauma patients admitted to the emergency department during an 8-month period at Moi Teaching and Referral Hospital in Eldoret, Kenya, were included. Mode of arrival and vital parameters were registered. Variables included in the analysis were Injury Severity Score, time before physician's assessment, length of hospital stay, and mortality. The patients were retrospectively categorized according to the Rapid Emergency Triage and Treatment System (RETTS) from patient records. RESULTS: A total of 571 patients were analyzed, with a mean Injury Severity Score of 12.2 (SD 7.7) with a mean length of stay of 11.6 (SD 18.3) days. The mortality rate was 1.8%. The results obtained in this study illustrate that trauma patients admitted to the emergency department at Eldoret are not assessed in a timely fashion, and the time frame recommendations postulated by RETTS are not adhered to. Assessment of patients according to the triage algorithm used revealed a significantly higher average Injury Severity Score in the red category than in the other color categories. CONCLUSION: The results from this study clearly illustrate a lack of correct prioritization of patients in relation to the need for timely assessment. This is further demonstrated by the retrospective triage classification of patients, which identified patients with high ISS as in urgent need of care. Since no significant difference in to time to assessment regardless of injury severity was observed, the need for a well-functioning triage system is apparent.

Topical Minocycline Effectively Decontaminates and Reduces Inflammation in Infected Porcine Wounds.

BACKGROUND: Wound infection can impair postoperative healing. Topical antibiotics have potential to treat wound infection and inflammation and minimize the adverse effects associated with systemic antibiotics. METHODS: Full-thickness porcine wounds were infected with Staphylococcus aureus. Using polyurethane wound enclosure devices, wounds were treated with topical 100 µg/ml minocycline, topical 1000 µg/ml minocycline, topical saline control, or 4 mg/kg intravenous minocycline. Bacteria were quantified in wound tissue and fluid obtained over 9 hours. Immunosorbent assays were used to analyze inflammatory marker concentrations. Minocycline's effect on in vitro migration and proliferation of human keratinocytes and fibroblasts was tested using scratch assays and metabolic assays, respectively. RESULTS: After 6 hours, 100 and 1000 µg/ml topical minocycline decreased bacteria in wound tissue to 3.5 ± 0.87 and 2.9 ± 2.3 log colony-forming units/g respectively, compared to 8.3 ± 0.9 log colony-forming units/g in control wounds (p < 0.001) and 6.9 ± 0.2 log colony-forming units/g in wounds treated with 4 mg/kg intravenous minocycline (p < 0.01). After 2 hours, topical minocycline reduced concentrations of the inflammatory cytokines interleukin-1ß, interleukin-6, and tumor necrosis factor-α (p < 0.01), and inflammatory cell counts in wound tissue (p < 0.05). In noninfected wounds, topical minocycline significantly reduced interleukin-1ß, interleukin-6, and inflammatory cell counts after 4 hours (p < 0.01). Matrix metalloproteinase-9 concentrations decreased after 1-hour treatment (p < 0.05). Keratinocyte and fibroblast in vitro functions were not adversely affected by 10 µg/ml minocycline or less. CONCLUSIONS: Topical minocycline significantly reduces bacterial burden and inflammation in infected wounds compared with wounds treated with intravenous minocycline or control wounds. Minocycline also decreases local inflammation independently of its antimicrobial effect.

Full-thickness porcine burns infected with Staphylococcus aureus or Pseudomonas aeruginosa can be effectively treated with topical antibiotics.

Burn and blast injuries are frequently complicated by invasive infections, which lead to poor wound healing, delay in treatment, disability, or death. Traditional approach centers on early debridement, fluid resuscitation, and adjunct intravenous antibiotics. These modalities often prove inadequate in burns, where compromised local vasculature limits the tissue penetration of systemic antibiotics. Here, we demonstrate the treatment of infected burns with topical delivery of ultrahigh concentrations of antibiotics. Standardized burns were inoculated with Staphylococcus aureus or Pseudomonas aeruginosa. After debridement, burns were treated with either gentamicin (2 mg/mL) or minocycline (1 mg/mL) at concentrations greater than 1,000 times the minimum inhibitory concentration. Amount of bacteria was quantified in tissue biopsies and wound fluid following treatment. After six days of gentamicin or minocycline treatment, S. aureus counts decreased from 4.2 to 0.31 and 0.72 log CFU/g in tissue, respectively. Similarly, P. aeruginosa counts decreased from 2.5 to 0.0 and 1.5 log CFU/g in tissue, respectively. Counts of both S. aureus and P. aeruginosa remained at a baseline of 0.0 log CFU/mL in wound fluid for both treatment groups. The findings here demonstrate that super-therapeutic concentrations of antibiotics delivered topically can rapidly reduce bacterial counts in infected full-thickness porcine burns. This treatment approach may aid wound bed preparation and accelerate time to grafting.

Topical delivery of ultrahigh concentrations of gentamicin is highly effective in reducing bacterial levels in infected porcine full-thickness wounds.

BACKGROUND: Injury to the skin can predispose individuals to invasive infection. The standard of care for infected wounds is treatment with intravenous antibiotics. However, antibiotics delivered intravenously may have poor tissue penetration and be dose limited by systemic side effects. Topical delivery of antibiotics reduces systemic complications and delivers increased drug concentrations directly to the wound. METHODS: Porcine full-thickness wounds infected with Staphylococcus aureus were treated with ultrahigh concentrations (over 1000 times the minimum inhibitory concentration) of gentamicin using an incubator-like wound healing platform. The aim of the present study was to evaluate clearance of infection and reduction in inflammation following treatment. Gentamicin cytotoxicity was evaluated by in vitro assays. RESULTS: Application of 2000 µg/ml gentamicin decreased bacterial counts in wound tissue from 7.2 ± 0.3 log colony-forming units/g to 2.6 ± 0.6 log colony-forming units/g in 6 hours, with no reduction observed in saline controls (p < 0.005). Bacterial counts in wound fluid decreased from 5.7 ± 0.9 log colony-forming units/ml to 0.0 ± 0 log colony-forming units/ml in 1 hour, with no reduction observed in saline controls (p < 0.005). Levels of interleukin-1ß were significantly reduced in gentamicin-treated wounds compared with saline controls (p < 0.005). In vitro, keratinocyte migration and proliferation were reduced at gentamicin concentrations between 100 and 1000 µg/ml. CONCLUSIONS: Topical delivery of ultrahigh concentrations of gentamicin rapidly decontaminates acutely infected wounds and maintains safe systemic levels. Treatment of infected wounds using the proposed methodology protects the wound and establishes a favorable baseline for subsequent treatment.

Sustained release of amnion-derived cellular cytokine solution facilitates achilles tendon healing in rats.

OBJECTIVE: In the United States, around 50% of all musculoskeletal injuries are soft tissue injuries including ligaments and tendons. The objective of this study is to assess the role of amnion-derived cellular cytokine solution (ACCS) in carboxy-methyl cellulose (CMC) gel in the healing of Achilles tendon in a rat model, and to examine its effects on mechanical properties and collagen content. METHODS: Achilles tendons of Sprague-Dawley rats were exposed and transected. The distal and proximal ends were injected with either saline or ACCS in CMC, in a standardized fashion, and then sutured using a Kessler technique. Tendons from both groups were collected at 1, 2, 4, 6, and 8 weeks postoperatively and assessed for material properties. Collagen studies were performed, including collagen content, collagen cross-linking, tendon hydration, and immunohistochemistry. Tendons were also evaluated histologically for cross-sectional area. RESULTS: Mechanical testing demonstrated that treatment with ACCS in CMC significantly enhances breaking strength, ultimate tensile strength, yield strength, and Young's modulus in the tendon repair at early time points. In context, collagen content, as well as collagen cross-linking, was also significantly affected by the treatment. CONCLUSION: The application of ACCS in CMC has a positive effect on healing tendons by improving mechanical properties at early time points. Previous studies on onetime application of ACCS (not in CMC) did not show significant improvement on tendon healing at any time point. Therefore, the delivery in a slow release media like CMC seems to be essential for the effects of ACCS demonstrated in this study.

Assessing quality of healing in skin: review of available methods and devices.

The process of wound healing is dynamic and takes place over months to years, during which there is a resolution of angiogenesis, continued wound contraction, and connective tissue remodeling. The outcome of this process is most commonly the formation of a scar, defined as a fibrous tissue replacing normal tissues destroyed by injury or disease. Scars often have a lowered or total loss of vital skin functions and imbue a large burden on both the patient and the health care system as a whole. Scar treatments are plentiful but are often unsatisfactory or inconsistent. No single treatment method has been universally adopted. To evaluate the clinical treatment as well as research focused on developing novel methods for scar management, objective studies of the progression of scar formation and the properties of mature scars are needed. Several parameters, including barrier function as well as mechanical and physiological properties, need to be taken into account when both categorizing and treating healing wounds and scars. To date, there is no available methodology that provides a comprehensive evaluation of a scar's properties. This review aims at presenting an overview of available scar assessment methods and devices, ranging from analysis of collagen properties in tissue biopsies to noninvasive methods for studies of mechanical parameters such as breaking strength and skin elasticity. In the cases where conclusive studies have been performed, the differences between normal skin and scar with respect to the above parameters are presented. Furthermore, this review highlights areas where the development of additional modalities are needed.

Moist dressing coverage supports proliferation and migration of transplanted skin micrografts in full-thickness porcine wounds.

Transplantation of skin micrografts in a 1:100 ratio regenerate the epidermis of full-thickness wounds in pigs within 14 days in a wet environment. The aim of the current study was to combine micrografts and commercially available moist dressings. We hypothesized that micrografts regenerate the epidermis when covered with a moist dressing. 5cm×5cm and 10cm×10cm full-thickness wounds were created on the backs of pigs. Wounds were transplanted with 0.8mm×0.8mm micrografts created from a split-thickness skin graft in a 1:100 ratio. 5cm×5cm wounds were treated with wound chambers, moist dressings or dry gauze (non-transplanted control group). 10cm×10cm wounds were compared to non-transplanted wounds, both covered with moist dressings. Reepithelialization was assessed in biopsies from day 10, 14 and 18 post-transplantation. 5cm×5cm transplanted wounds covered with moist dressings showed 69.5±20.6% reepithelialization by day 14 and 90.5±10.4% by day 18, similar to wounds covered with a wound chamber (63.9±16.7 and 86.2±11.9%, respectively). 18 days post-transplantation, 10cm×10cm transplanted wounds covered with moist dressings showed 66.1±10.3% reepithelialization, whereas nontransplanted wounds covered with moist dressings were 40.6±6.6% reepithelialized. We conclude that micrografts combined with clinically available moist dressings regenerate the epidermis of full-thickness wounds.

CCN2 is transiently expressed by keratinocytes during re-epithelialization and regulates keratinocyte migration in vitro by the ras-MEK-ERK signaling pathway.

BACKGROUND: CCN2 (previously known as connective tissue growth factor) is a multifunctional matricellular protein that has numerous effects on cell life and cell interactions with the connective tissue. Although the importance of CCN2 for the fibrotic process in wound healing has been well studied, the involvement of CCN2 in keratinocyte function has not yet been explored. Therefore, the aim of the present study was to investigate the role of CCN2 in the epidermis during wound healing. MATERIALS AND METHODS: Immunohistochemistry was done on sections from full-thickness porcine wounds. The effect of CCN2 on the migration of cultured human keratinocytes exposed to scratch wounds, the effect on phosphorylation of extracellular signal-related kinases (ERK), and the effect of adding inhibitors to the ERK/mitogen-activated protein kinase pathway to human keratinocytes were studied. RESULTS: The CCN2 protein was transiently expressed in vivo at the leading keratinocyte edge during re-epithelialization of full-thickness porcine wounds. In vitro, exogenous addition of CCN2 to human keratinocyte cultures regulated keratinocyte migration and resulted in phosphorylation of ERK. The addition of inhibitors of ERK/mitogen-activated protein kinase counteracted the effect of CCN2 on migration. CONCLUSIONS: CCN2 was transiently expressed at the leading keratinocyte edge in vivo. The biologic importance of this was supported in vitro, because CCN2 regulated human keratinocyte migration through activation of the Ras-mitogen-activated protein kinase kinase-ERK signal transduction pathway.

Amnion-derived multipotent progenitor cells improve achilles tendon repair in rats.

OBJECTIVE: Tendon injuries produce considerable morbidity, long-lasting disability, and remain a considerable challenge for clinicians and patients. The objective of the study was to assess the effect of amnion-derived multipotent progenitor (AMP) cells and amnion-derived cell cytokine solution on Achilles tendon healing by using a rat model. METHODS: Achilles tendons of Sprague-Dawley rats were exposed and transected. The distal and proximal ends were injected with either saline, amnion-derived cell cytokine solution, or AMP cells in a standardized fashion and then sutured by using a Kessler technique. Tendons from each group (n = 6-13) were collected at weeks 1, 2, and 4 postoperatively and assessed for material properties (ultimate tensile strength, Young modulus, yield strength, and breaking strength). Tendons were also evaluated histologically for cross-sectional area by using hematoxylin-eosin and trichrome stains. RESULTS: Mechanical testing showed that the Young modulus was significantly higher in AMP cells-treated tendons at week 4 compared with both saline-treated and amnion-derived cell cytokine solution-treated tendons. Yield strength was significantly higher in the AMP cells-treated group compared with saline-treated controls at week 4. No significant differences were observed between the study groups at weeks 1 and 2. DISCUSSION: Amnion-derived multipotent progenitor cells have a positive effect on healing tendons by improving mechanical strength and elastic modulus during the healing process. The presented findings suggest the clinical utility of AMP cells in facilitating the healing of ruptured tendons. Both the Young modulus and yield strengths of tendons increased significantly following treatment with AMP cells.

Differentiation of human dermal fibroblasts towards endothelial cells.

The ultimate goal of vascular tissue engineering is the production of functional grafts for clinical use. Difficulties acquiring autologous endothelial cells have motivated the search for alternative cell sources. Differentiation of dermal fibroblasts towards several mesenchymal lineages as well as endothelial cells has been proposed. The aim of the present study was to investigate the endothelial differentiation capacity of human dermal fibroblasts on a gene expression, protein expression and functional physiological level. Endothelial differentiation of fibroblasts was induced by culturing cells in 30% human serum, but not in fetal calf serum. Expression of proteins and genes relevant for endothelial function and differentiation was increased after induction. Furthermore, fibroblasts exposed to 30% human serum displayed increased uptake of low-density lipoprotein and formation of capillary-like networks. The results of this study may have an impact on cell sourcing for vascular tissue engineering, and the development of methods for vascularization of autologous tissue engineered constructs.

Osteogenically-induced human dermal fibroblasts as a tool to regenerate bone.

Engineering of bone tissue could help to overcome the need for extensive reconstruction and associated donor site morbidity, and it has been proposed that osteogenic biomaterials, which are scaffolds that contain osteocompetent cells, could be used to fill large bone defects. This study investigated the potential of osteogenically-induced human dermal fibroblasts cultured on gelatin microcarriers combined with platelet-rich plasma in a model of a femoral defect in athymic rats. Defects were transplanted with one of the following six combinations: 1 = sodium chloride, 2 = platelet-rich plasma, 3 = microcarriers + platelet-rich plasma, 4 = human dermal fibroblasts on microcarriers + platelet-rich plasma, 5 = human osteoblasts on microcarriers + platelet-rich plasma, and 6 = osteogenically induced human dermal fibroblasts on microcarriers + platelet-rich plasma. The femoral defects were assessed 4 weeks postoperatively with computed tomography (CT), routine histological staining, fluorescence in situ hybridisation, and polyclonal antibodies directed towards osteocalcin and osteonectin. Radiographs of all groups taken 4 weeks postoperatively showed unhealed defects. Femoral defects transplanted with osteogenically-induced human dermal fibroblasts on microcarriers (group 6) contained dense clusters of cells with large quantities of extracellular matrix. These clusters were exclusive to this group and stained strongly for osteocalcin and osteonectin. Fluorescence in situ hybridisation showed viable human cells in femoral defects that had been transplanted with microcarriers seeded with cells, which confirmed the survival of implanted cells. In conclusion, osteogenically-induced human dermal fibroblasts survived in this new niche, and bone-like structures were apparent in the defects.

The microenvironment of wound healing.

This review summarizes experiments performed by us and others, examining the importance of the microenvironment to wound healing. The development of a sealed polyurethane wound chamber has allowed us to perform studies evaluating the effects of growth factors, transplanted cells, and other bioactive substances on wound healing. Studies have compared wet, moist, and dry healing, with the conclusion that a wet, incubator-like microenvironment provides the fastest healing with fewest aberrations and least scar formation. The wet environment is also paramount for the survival and proliferation of transplanted cells or tissue, which has been shown in studies of porcine and human wounds. Moreover, high concentrations of antibiotics and other agents can be introduced in the wound chamber, thereby effectively fighting infection, while maintaining safe systemic concentrations. These findings have been used in clinical settings to treat wounds of different types. A titanium chamber has been developed to create an in vivo incubator, which will serve as a regenerative platform for in vivo tissue engineering.

Clinical Impact Upon Wound Healing and Inflammation in Moist, Wet, and Dry Environments.

SIGNIFICANCE: Successful treatment of wounds relies on precise control and continuous monitoring of the wound-healing process. Wet or moist treatment of wounds has been shown to promote re-epithelialization and result in reduced scar formation, as compared to treatment in a dry environment. RECENT ADVANCES: By treating wounds in a controlled wet environment, delivery of antimicrobials, analgesics, other bioactive molecules such as growth factors, as well as cells and micrografts, is allowed. The addition of growth factors or transplantation of cells yields the possibility of creating a regenerative wound microenvironment that favors healing, as opposed to excessive scar formation. CRITICAL ISSUES: Although several manufacturers have conceived products implementing the concept of moist wound healing, there remains a lack of commercial translation of wet wound-healing principles into clinically available products. This can only be mitigated by further research on the topic. FUTURE DIRECTIONS: The strong evidence pointing to the favorable healing of wounds in a wet or moist environment compared to dry treatment will extend the clinical indications for this treatment. Further advances are required to elucidate by which means this microenvironment can be optimized to improve the healing outcome.