The effectiveness of a hydrocolloid crusting method versus standard care in the treatment of incontinence-associated dermatitis among adult patients in an acute care setting: A randomised controlled trial.

INTRODUCTION: Incontinence-associated dermatitis (IAD) is a type of irritant contact dermatitis due to prolonged exposure of the skin to moisture induced by urine or/and faeces. The main principles when treating IAD involves protecting the skin from further exposure to irritants, establishing a healing environment, and eradicating skin infections. This study aimed to evaluate the effectiveness of the hydrocolloid crusting method (HCM) versus the standard care method (SCM) in treating IAD. METHOD: A randomised controlled trial was conducted in an acute tertiary hospital in Singapore between August 2019 to September 2021. Using computer-generated numbers, patients were randomised into either HCM or SCM treatment groups. HCM treatment involved cleansing the affected area with a pH-neutral non-rinse moisturising cleanser, and the application of alternate layers of hydrocolloid powder, and non-sting film barrier spray (repeated three times during each use). Patients in the SCM treatment group received the same cleanser followed by a 30% zinc oxide barrier cream. IAD was assessed daily for up to seven days by the wound care nurses using the IAD severity tool. The primary outcome of the study was the mean difference in IAD score per day between both methods. RESULTS: Forty-four patients were eligible and recruited (22 in HCM; 22 in SCM). Patients in both groups were comparable in age and gender. IAD Category 2 was more predominant in both methods. The most common location of IAD was at the perianal skin and diarrhea related to gastroenteritis was the most prevalent cause of IAD. More patients in the SCM group (n = 12; 54.5%) had their IAD healed within seven days compared to HCM, (n = 7; 31.8%) group. However, the average decrease in IAD scores per day for both methods were found to be similar. CONCLUSION: HCM can be considered as a treatment of IAD along with the use of SCM. A skin care regimen should include effective cleansing, skin protection, and moisturization in IAD management.

The burden of costs on health services by patients with neuro-ischaemic ulcers in Singapore.

The economic burden of neuro-ischaemic ulcers (NIU) is expected to increase because of rising prevalence of comorbidities in an aging population. We aim to estimate healthcare resources consumed by NIU patients, and to quantify the extent to which factors explain variation in cost-related outcomes. We analysed retrospective patient-level cohort data for NIU patients from a tertiary hospital registry in Singapore, from 2013 to 2017, using generalised linear regression models. The outcome variables were the length of stay per admission; inpatient and outpatient bill per admission; and, if they had an Emergency Department visit. Cost outcomes were reported in Singapore dollars (S$). A total of 1682 patients were included, and the mean age was 69.9 years (±13.0). An average patient incurred a length of stay of 38.7 days, 7.9 inpatient dressing sessions, an inpatient bill of S$33 096, 11.3 outpatient dressing sessions, and an outpatient bill of S$8780. Inpatient services per patient cost 73.5% higher than outpatient services. NIU patients with multiple (>3) comorbid conditions, peripheral artery disease, or chronic kidney disease incurred longer hospitalisation and higher inpatient bill. Patients with diabetes mellitus and coronary artery disease had higher odds of incurring an ED visit. Patients with coronary artery disease, hyperlipidaemia, kidney complications, or obesity incurred higher outpatient bills. NIU treatment imposes a significant economic burden, especially with inpatient services.

The burden of costs on health services from patients with venous leg ulcers in Singapore.

Healthcare costs arising from venous leg ulcers (VLU) are expected to increase due to an aging population and increased prevalence of comorbidities. We aim to estimate the healthcare resources incurred by VLU patients, and to quantify the extent to which predictors explain variation in cost-related outcomes. Retrospective patient-level cohort data for VLU patients were analysed using generalised linear regression models. Data were extracted from a tertiary hospital registry in Singapore, between 2013 and 2017. The outcome variables were length of stay per admission; inpatient and outpatient bill per admission; whether a patient underwent a surgical treatment of the venous system; and, whether they visited the emergency department. Cost outcomes were reported in Singapore dollars (S$). A total of 162 VLU patients were included with a mean age of 67.5 (±14.4). For the inpatient setting the mean length of stay was 8.1 days and the mean inpatient bill was S$7886. For outpatients, the mean number of dressings was 29.4, and mean outpatient bill was S$6962. Heart disease patients incurred longer hospital stays and larger inpatient bills per admission and females had greater odds of undergoing a surgical procedure on the venous system. Certain VLU patient groups were found to be associated with larger cost outcomes.

A prospective study on the wound healing and quality of life outcomes of patients with venous leg ulcers in Singapore-Interim analysis at 6 month follow up.

Venous leg ulceration results in significant morbidity. However, the majority of studies conducted are on Western populations. This study aims to evaluate the wound healing and quality of life for patients with venous leg ulcers (VLUs) in a Southeast Asian population. This is a multi-centre prospective cohort study from Nov 2019 to Nov 2021. All patients were started on 2- or 4-layer compression bandage and were reviewed weekly or fortnightly. Our outcomes were wound healing, factors predictive of wound healing and the EuroQol 5-dimensional 5-level (EQ-5D-5L) health states. Within our cohort, there were 255 patients with VLU. Mean age was 65.2 ± 11.6 years. Incidence of diabetes mellitus was 42.0%. Median duration of ulcer at baseline was 0.30 years (interquartile range 0.136-0.834). Overall, the median time to wound healing was 4.5 months (95% confidence interval [CI]: 3.77-5.43). The incidence of complete wound healing at 3- and 6-month was 47.0% and 60.9%, respectively. The duration of the wound at baseline was independently associated with worse wound healing (Hazard ratio 0.94, 95% CI: 0.89-0.99, P = .014). Patients with healed VLU had a significantly higher incidence of perfect EQ-5D-5L health states at 6 months (57.8% vs 13.8%, P < .001). We intend to present longer term results in subsequent publications.

Cancer-Associated Fibroblasts Influence the Biological Properties of Malignant Tumours via Paracrine Secretion and Exosome Production.

Cancer-associated fibroblasts (CAFs) are an essential component of the tumour microenvironment. They represent a heterogeneous group of cells that are under the control of cancer cells and can reversely influence the cancer cell population. They affect the cancer cell differentiation status, and the migration and formation of metastases. This is achieved through the production of the extracellular matrix and numerous bioactive factors. IL-6 seems to play the central role in the communication of noncancerous and cancer cells in the tumour. This review outlines the role of exosomes in cancer cells and cancer-associated fibroblasts. Available data on the exosomal cargo, which can significantly intensify interactions in the tumour, are summarised. The role of exosomes as mediators of the dialogue between cancer cells and cancer-associated fibroblasts is discussed together with their therapeutic relevance. The functional unity of the paracrine- and exosome-mediated communication of cancer cells with the tumour microenvironment represented by CAFs is worthy of attention.

Major limb amputation and mortality in patients with neuro-ischaemic lower extremity wounds managed in a tertiary hospital: Focus on the differences among patients with diabetes, peripheral arterial disease and both.

A majority of lower extremities neuro-ischaemic wounds (NIU) are related to: (a) only diabetes (DM); (b) only peripheral artery disease (PAD); (c) co-existing diabetes and peripheral artery disease (DM-PAD). This study aims to characterise the major clinical outcomes of forementioned three groups of lower extremity wound patients in Singapore. Patients hospitalised for lower extremity NIU between January 2014 and October 2017 in a tertiary hospital in Singapore were analysed. Patients' major limb amputation and mortality were assessed using Cox regression models. Cumulative survival and amputation-free survival among the three classified groups were calculated using Kaplan-Meier analysis. Compared with patients with only DM, those in the PAD group and the DM-PAD group had higher risk of major limb amputation (adjusted hazard ratio: 2.47, 95% CI: 1.65-3.70; adjusted hazard ratio: 2.01, 95% CI: 1.53-2.65 respectively) and mortality (adjusted hazard ratio: 2.36, 95% CI: 1.57-3.55; adjusted hazard ratio: 2.46, 95% CI: 1.86-3.26 respectively). The 3-year survival and amputation-free survival were lowest in the DM-PAD group (52.1% and 41.5% respectively), followed by the PAD group (53.3% and 44.6% respectively) and the DM group (74.2% and 68.5% respectively). Lower extremity NIU patients with PAD or DM-PAD were found to have poorer clinical prognosis than those with DM only.

Self-improving dystrophic epidermolysis bullosa: First report of clinical, molecular, and genetic characterization of five patients from Southeast Asia.

Self-improving dystrophic epidermolysis bullosa is a rare subtype of dystrophic epidermolysis bullosa (DEB) characterized by significant improvement in skin fragility within the first few years of life. Genetic inheritance has previously been reported as autosomal dominant or recessive with both forms harboring mutations in COL7A1. To date, there have been no reports of this rare clinical entity from various Southeast Asian ethnicities. Here, we describe the clinical and molecular features of five patients from the Southeast Asia region who presented with predominantly acral-distributed blisters and erosions in the first few days of life. Blistering resolved over several months, without appearance of new blisters. By immunofluorescence, intraepidermal retention of Type VII collagen was observed in all patient skin biopsies when investigated with antibody staining. Genetic analysis of four patients revealed pathogenic variants in COL7A1 which have not been previously reported. The clinical diagnosis in these rare patients is confirmed with molecular histology and genetic characterization.

Epidermolysis bullosa with pyloric atresia associated with compound heterozygous ITGB4 pathogenic variants: Minimal skin involvement but severe mucocutaneous disease.

We report a case of junctional epidermolysis bullosa with pyloric atresia (JEB-PA) with minimal skin involvement but severe protein-losing enteropathy and airway involvement. Genetic analysis revealed heterozygous mutations in the ITGB4 gene encoding integrin ß4 protein. Parental testing confirmed inheritance of frameshift variant (c.794dupC) as maternal and splice site variant (c.1608C>T/p.Cys536Cys) as paternal. Immunofluorescence mapping of her skin revealed a subepidermal blister with decreased and frayed integrin ß4 at both the floor and the roof of the blister, while the intestinal mucosa showed complete absence of integrin ß4. We review the literature and discuss the differential expression of integrins in the skin and gastrointestinal tract, as well as the role of chronic inflammation in the pathogenesis of EB.

Human reconstructed skin xenografts on mice to model skin physiology.

Xenograft models to study skin physiology have been popular for scientific use since the 1970s, with various developments and improvements to the techniques over the decades. Xenograft models are particularly useful and sought after due to the lack of clinically relevant animal models in predicting drug effectiveness in humans. Such predictions could in turn boost the process of drug discovery, since novel drug compounds have an estimated 8% chance of FDA approval despite years of rigorous preclinical testing and evaluation, albeit mostly in non-human models. In the case of skin research, the mouse persists as the most popular animal model of choice, despite its well-known anatomical differences with human skin. Differences in skin biology are especially evident when trying to dissect more complex skin conditions, such as psoriasis and eczema, where interactions between the immune system, epidermis and the environment likely occur. While the use of animal models are still considered the gold standard for systemic toxicity studies under controlled environments, there are now alternative models that have been approved for certain applications. To overcome the biological limitations of the mouse model, research efforts have also focused on "humanizing" the mice model to better recapitulate human skin physiology. In this review, we outline the different approaches undertaken thus far to study skin biology using human tissue xenografts in mice and the technical challenges involved. We also describe more recent developments to generate humanized multi-tissue compartment mice that carry both a functioning human immune system and skin xenografts. Such composite animal models provide promising opportunities to study drugs, disease and differentiation with greater clinical relevance.

Automated Electrical Stimulation Therapy Accelerates Re-Epithelialization in a Three-Dimensional In Vitro Human Skin Wound Model.

Objective: Electrical Stimulation Therapy (EST) shows promise for the purpose of accelerating wound healing, but the right electrical stimulation parameters and its mode of action remain unclear. We aim to evaluate the effect of a new EST clinical device on epidermal repair using an in vitro human skin wound model. Approach: We scaled up a well-established 3D De-Epidermized Dermis-Human Skin Equivalent (DED-HSE) wound model to fit a clinically used device that delivers preprogrammed microcurrent EST. The impact of EST on re-epithelialization of 4-mm circular epidermal wounds was assessed after 4 and 7 days of treatment, using metabolic activity assay, immunohistochemistry (IHC) staining, and RNA in situ hybridization. Results: EST was successfully applied to the wounded in vitro skin model. Large DED-HSEs retained good cell viability for up to 7 days of EST treatment. Excisional wounds subjected to EST for 4 days consistently exhibited faster closure (mean 65.8%, n = 9) compared to untreated wounds (mean 49.7%, n = 9) (p < 0.05). Wounds exposed to EST exhibited significantly longer epithelial tongues (re-epithelialization mean 50.3%, n = 9) than untreated wounds (mean 26.2%, n = 9) (p < 0.001), suggesting faster keratinocyte migration and proliferation. Increased MMP1 transcription (p < 0.05) in ES-treated periwound suggests a mechanism for enhanced keratinocyte migration. IHC staining showed advanced epidermal proliferation (p63) and differentiation (K10) in EST-exposed wounds (n = 15), as well as stronger attachment of the newly formed epidermis into the dermis compared to untreated controls (n = 15) (p < 0.001). Innovation: We present a novel approach to assess an EST clinical device designed to stimulate wound healing. Using a scaled-up 3D human skin wound model, we could demonstrate the positive effect of EST on epithelial cell responses and shed light on possible mechanism. Conclusion: Our study provides experimental evidence that microcurrent therapy accelerates wound closure and improves the quantity and quality of re-epithelialization.

Early Prediction of Wound Healing Outcome Based on Chronic Wound Registry Database.

Chronic wounds cause a number of unnecessary amputations due to a delay in proper treatment. To expedite timely treatment, this paper presents an algorithm which uses a logistic regression classifier to predict whether the wound will heal or not within a specified time. The prediction is made at three time-points: one month, three months, and six months from the first visit of the patient to the healthcare facility. This prediction is made using a systematically collected chronic wound registry and is based entirely on data collected during patients' first visit. The algorithm achieves an area under the receiver operating characteristic curve (AUC) of 0.75, 0.72, and 0.71 for the prediction at the three time-points, respectively.Clinical relevance- Using the proposed prediction model, the clinicians will have an early estimate of the time taken to heal thereby providing appropriate treatments. We hope this will ensure timely treatments and reduce the number of unnecessary amputations.

Chronic wounds in a multiethnic Asian population: a cost of illness study.

OBJECTIVE: To estimate the 'cost of illness' arising from chronic wounds in Singapore. DESIGN: Incidence-based cost of illness study using evidence from a range of sources. SETTING: Singapore health services. PARTICIPANTS: We consider 3.49 million Singapore citizens and permanent residents. There are 16 752 new individuals with a chronic wound in 2017, with 598 venous ulcers, 2206 arterial insufficiency ulcers, 6680 diabetic ulcers and 7268 pressure injuries.Primary outcome measures expressed in monetary terms are the value of all hospital bed days lost for the population; monetary value of quality-adjusted life years (QALYs) lost in the population; costs of all outpatient visits; and costs of all poly clinic, use of Community Health Assist Scheme (CHAS) and emergency departments (EDs) visits. Intermediate outcomes that inform the primary outcomes are also estimated. RESULTS: Total annual cost of illness was $350 million (range $72-$1779 million). With 168 503 acute bed days taken up annually (range 141 966-196 032) that incurred costs of $139 million (range 117-161 million). Total costs to health services were $184 million (range $120-$1179 million). Total annual costs of lost health outcomes were 2077 QALYs (range -2657 to 29 029) valued at $166 million (range -212 to 2399 million). CONCLUSIONS: The costs of chronic wounds are large to Singapore. Costs can be reduced by making positive investments for comprehensive wound prevention and treatment programmes.

Prospective study on the clinical and economic burden of venous leg ulcers in the tropics.

OBJECTIVE: Venous leg ulcers (VLUs) are both chronic and recurrent. The treatment of such ulcers often require multiple outpatient visits and dressing changes. Several reports on the costs of treating such VLUs have been reported in the west. We prospectively evaluated the clinical and economic burden of VLUs in a population of Asian patients in the tropics. METHODS: Patients from a prospective two-center study conducted at two tertiary hospitals in Singapore, as a part of the Wound Care Innovation in the Tropics program, between August 2018 and September 2021 were recruited. The patients were followed up for 12 weeks (visit 1 to visit 12), until index ulcer healing, death, or lost to follow-up (whichever came first). These patients were then followed up 12 weeks later to determine the longer term outcome of the wound (healed, recurrence, remained unhealed). The itemized costs derived from the medical service were retrieved from the relevant departments of the study sites. The patients' health-related quality of life was assessed at baseline and the last visit of the 12-week follow-up period (or until index ulcer healing), using the official Singapore version of the EuroQol five-dimension-5L questionnaire, which also includes a visual analog scale (EQ-VAS). RESULTS: A total of 116 patients were enrolled; 63% were men, and the mean patient age was 64.7 years. Of the 116 patients, 85 (73%) had a healed ulcer at 24 weeks (mean duration to ulcer healing, 49 days), and 11 (12.9%) had experienced ulcer recurrence within the study period. Within the 6-month follow-up period, the mean direct healthcare cost per patient was USD$1998. The patients with healed ulcers had significantly lower costs per patient compared with those with unhealed ulcers (USD$1713 vs USD$2780). Regarding health-related quality of life, 71% of the patients had a lower quality of life at baseline, which had improved at 12 weeks of follow-up, with only 58% of the patients reported to have a lower quality of life. Also, the patients with healed ulcers scored higher for both utilities (societal preference weights) and EQ-VAS at follow-up (P < .001). In contrast, patients with unhealed ulcers only scored higher EQ-VAS at follow-up (P = .003). CONCLUSIONS: The findings from this exploratory study provide information on the clinical, quality of life, and economic burden of VLUs in an Asian population and suggest the importance of healing VLUs to reduce the effects on patients. The present study provides data as a basis for economic evaluation as a consideration for the treatment of VLUs.

Mechano-Activated Cell Therapy for Accelerated Diabetic Wound Healing.

Chronic diabetic wounds are a significant global healthcare challenge. Current strategies, such as biomaterials, cell therapies, and medical devices, however, only target a few pathological features and have limited efficacy. A powerful platform technology combining magneto-responsive hydrogel, cells, and wireless magneto-induced dynamic mechanical stimulation (MDMS) is developed to accelerate diabetic wound healing. The hydrogel encapsulates U.S. Food and Drug Administration (FDA)-approved fibroblasts and keratinocytes to achieve ∼3-fold better wound closure in a diabetic mouse model. MDMS acts as a nongenetic mechano-rheostat to activate fibroblasts, resulting in ∼240% better proliferation, ∼220% more collagen deposition, and improved keratinocyte paracrine profiles via the Ras/MEK/ERK pathway to boost angiogenesis. The magneto-responsive property also enables on-demand insulin release for spatiotemporal glucose regulation through increasing network deformation and interstitial flow. By mining scRNAseq data, a mechanosensitive fibroblast subpopulation is identified that can be mechanically tuned for enhanced proliferation and collagen production, maximizing therapeutic impact. The "all-in-one" system addresses major pathological factors associated with diabetic wounds in a single platform, with potential applications for other challenging wound types.

Proteomic analysis of colorectal cancer metastasis: stathmin-1 revealed as a player in cancer cell migration and prognostic marker.

Metastasis accounts largely for the high mortality rate of colorectal cancer (CRC) patients. In this study, we performed comparative proteome analysis of primary CRC cell lines HCT-116 and its metastatic derivative E1 using 2-D DIGE. We identified 74 differentially expressed proteins, many of which function in transcription, translation, angiogenesis signal transduction, or cytoskeletal remodeling pathways, which are indispensable cellular processes involved in the metastatic cascade. Among these proteins, stathmin-1 (STMN1) was found to be highly up-regulated in E1 as compared to HCT-116 and was thus selected for further functional studies. Our results showed that perturbations in STMN1 levels resulted in significant changes in cell migration, invasion, adhesion, and colony formation. We further showed that the differential expression of STMN1 correlated with the cells' metastatic potential in other paradigms of CRC models. Using immunohistochemistry, we also showed that STMN1 was highly expressed in colorectal primary tumors and metastatic tissues as compared to the adjacent normal colorectal tissues. Furthermore, we also showed via tissue microarray analyses of 324 CRC tissues and Kaplan-Meier survival plot that CRC patients with higher expression of STMN1 have poorer prognosis.

Incidence of chronic wounds in Singapore, a multiethnic Asian country, between 2000 and 2017: a retrospective cohort study using a nationwide claims database.

OBJECTIVES: Chronic wounds are common, costly and impair quality of life, yet epidemiological data are scarce. We aimed to estimate the incidence trend of a multiethnic Asian population. DESIGN: Retrospective cohort study. SETTING: Singapore's nationwide claims database. PARTICIPANTS: Singaporeans and permanent residents. OUTCOMES: Patients were identified by International Classification of Disease, Ninth Revision, Australian Modification (ICD-9-AM) and ICD-10-AM codes from all admissions between 2000 and 2017, and categorised according to aetiology: venous, arterial, diabetic and pressure. Comorbidities were extracted from a national database of Charlson Comorbidity Index scores. RESULTS: Between 2000 and 2017, 124 023 wound-related claims among 86 631 patients were identified. Age-specific rate (ASR) and age-adjusted incidence rates of all wounds increased over 18 years, with greatest increases among those aged ≥80. In 2017, the median age of patients was 74 (IQR 63-84). Half were male (51%). 70% were ethnic Chinese, 15% Malay and 9% Indian. In 2017, the crude incidence rate (CIR) was 15 per 100 000 persons (95% CI 14 to 16) for venous wounds, 56 (95% CI 53 to 58) for arterial, 168 (95% CI 164 to 173) for diabetic and 183 (95% CI 179 to 188) for pressure wounds. The CIR of any chronic wound was 296 (95% CI 291 to 301). ASRs were greatest in patients aged ≥80: 92 (95% CI 74 to 112) for venous, 478 (95% CI 436 to 522) for arterial, 1791 (95% CI 1710 to 1876) for diabetic, 3647 (95% CI 3530 to 3766) for pressure and 4277 (95% CI 4151 to 4407) for any wound. Compared with the Chinese, Indians had thrice the ASRs of venous and arterial wounds and double the ASR of diabetic wounds. Malays had double the ASRs of arterial and diabetic wounds. CONCLUSIONS: Chronic wounds are common in the elderly with significant ethnic disparities in this Asian cohort. With the incidence expected to rise with ageing populations, it is crucial to address health disparities and evaluate utilisation and cost to inform clinical practice and health policy.

Arrays of Biocompatible and Mechanically Robust Microchambers Made of Protein-Polyphenol-Clay Multilayer Films.

There is a growing demand for biocompatible and mechanically robust arrays of microcompartments loaded with minute amounts of active substances for sensing or controlled release applications. Here we report on a novel biocompatible composite material, protein-polyphenol-clay (PPC) multilayer film. The material is shown to be strong enough to make robust microchambers retaining the shape and dimensions of truncated square pyramids. We study the mechanical properties and biocompatibility of the PPC microchambers and compare them to those made of synthetic polyelectrolyte multilayer film, poly(styrenesulfonate)-poly(allylammonium) (PSS-PAH). The mechanical properties of the microchambers were characterized under uniaxial compression using nanoindentation with a flat-punch tip. The effective Young's modulus of PPC microchambers, 166 ± 53 MPa, is found to be lower than that of PSS-PAH microchambers, 245 ± 52 MPa. However, the capacity to elastically absorb the energy of the former, 2.4 ± 1.0 MPa, is marginally higher than of the latter, 2.0 ± 1.3 MPa. Arrays of microchambers were sealed onto a polyethylene film, loaded with a model oil-soluble drug, and their biocompatibility was tested using an ex vivo 3D human skin reconstruct model. We found no evidence for toxicity with the PPC microchambers; however, PSS-PAH microchambers stimulated reduced cell density in the epidermis and significantly affected epidermal-dermal attachment. Both materials do not alter skin cell proliferation but affect skin cell differentiation. We interpret that rather than affecting epidermal barrier function, these data suggest the applied plastic films with microchamber arrays affect transpiration, normoxia, and moisture exchange.

Assays to Study Consequences of Cytoplasmic Intermediate Filament Mutations: The Case of Epidermal Keratins.

The discovery of the causative link between keratin mutations and a growing number of human diseases opened the way for a better understanding of the function of the whole intermediate filament families of cytoskeleton proteins. This chapter describes analytical approaches to identification and interpretation of the consequences of keratin mutations, from the clinical and diagnostic level to cells in tissue culture. Intermediate filament pathologies can be accurately diagnosed from skin biopsies and DNA samples. The Human Intermediate Filament Database collates reported mutations in intermediate filament genes and their diseases, and can help clinicians to establish accurate diagnoses, leading to disease stratification for genetic counseling, optimal care delivery, and future mutation-aligned new therapies. Looking at the best-studied keratinopathy, epidermolysis bullosa simplex, the generation of cell lines mimicking keratinopathies is described, in which tagged mutant keratins facilitate live-cell imaging to make use of today's powerful enhanced light microscopy modalities. Cell stress assays such as cell spreading and cell migration in scratch wound assays can interrogate the consequences of the compromised cytoskeletal network. Application of extrinsic stresses, such as heat, osmotic, or mechanical stress, can enhance the differentiation of mutant keratin cells from wild-type cells. To bring the experiments to the next level, 3D organotypic human cultures can be generated, and even grafted onto the backs of immunodeficient mice for greater in vivo relevance. While development of these assays has focused on mutant K5/K14 cells, the approaches are often applicable to mutations in other intermediate filaments, reinforcing fundamental commonalities in spite of diverse clinical pathologies.

Tissue engineering of tumor stromal microenvironment with application to cancer cell invasion.

3D organotypic cultures of epithelial cells on a matrix embedded with mesenchymal cells are widely used to study epithelial cell differentiation and invasion. Rat tail type I collagen and/or matrix derived from Engelbreth-Holm-Swarm mouse sarcoma cells have been traditionally employed as the substrates to model the matrix or stromal microenvironment into which mesenchymal cells (usually fibroblasts) are populated. Although experiments using such matrices are very informative, it can be argued that due to an overriding presence of a single protein (such as in type I Collagen) or a high content of basement membrane components and growth factors (such as in matrix derived from mouse sarcoma cells), these substrates do not best reflect the contribution to matrix composition made by the stromal cells themselves. To study native matrices produced by primary dermal fibroblasts isolated from patients with a tumor prone, genetic blistering disorder (recessive dystrophic epidermolysis bullosa), we have adapted an existing native matrix protocol to study tumor cell invasion. Fibroblasts are induced to produce their own matrix over a prolonged period in culture. This native matrix is then detached from the culture dish and epithelial cells are seeded onto it before the entire coculture is raised to the air-liquid interface. Cellular differentiation and/or invasion can then be assessed over time. This technique provides the ability to assess epithelial-mesenchymal cell interactions in a 3D setting without the need for a synthetic or foreign matrix with the only disadvantage being the prolonged period of time required to produce the native matrix. Here we describe the application of this technique to assess the ability of a single molecule expressed by fibroblasts, type VII collagen, to inhibit tumor cell invasion.

Fibroblast-derived dermal matrix drives development of aggressive cutaneous squamous cell carcinoma in patients with recessive dystrophic epidermolysis bullosa.

Patients with the genetic skin blistering disease recessive dystrophic epidermolysis bullosa (RDEB) develop aggressive cutaneous squamous cell carcinoma (cSCC). Metastasis leading to mortality is greater in RDEB than in other patient groups with cSCC. Here we investigate the dermal component in RDEB using mRNA expression profiling to compare cultured fibroblasts isolated from individuals without cSCC and directly from tumor matrix in RDEB and non-RDEB samples. Although gene expression of RDEB normal skin fibroblasts resembled that of cancer-associated fibroblasts, RDEB cancer-associated fibroblasts exhibited a distinct and divergent gene expression profile, with a large proportion of the differentially expressed genes involved in matrix and cell adhesion. RDEB cancer-associated fibroblasts conferred increased adhesion and invasion to tumor and nontumor keratinocytes. Reduction of COL7A1, the defective gene in RDEB, in normal dermal fibroblasts led to increased type XII collagen, thrombospondin-1, and Wnt-5A, while reexpression of wild type COL7A1 in RDEB fibroblasts decreased type XII collagen, thrombospondin-1, and Wnt-5A expression, reduced tumor cell invasion in organotypic culture, and restricted tumor growth in vivo. Overall, our findings show that matrix composition in patients with RDEB is a permissive environment for tumor development, and type VII collagen directly regulates the composition of matrix proteins secreted by dermal and cancer-associated fibroblasts.