Effectiveness of community-based oral antiviral treatments against severe COVID-19 outcomes in people 70 years and over in Victoria, Australia, 2022: an observational study.

Background: Oral Antiviral (OAV) COVID-19 treatments are widely used, but evidence for their effectiveness against the Omicron variant in higher risk, vaccinated individuals is limited. Methods: Retrospective study of two vaccinated cohorts of COVID-19 cases aged ≥70 years diagnosed during a BA.4/5 Omicron wave in Victoria, Australia. Cases received either nirmatrelvir-ritonavir or molnupiravir as their only treatment. Data linkage and logistic regression modelling was used to evaluate the association between treatment and death and hospitalisation and compared with no treatment. Findings: Of 38,933 individuals in the mortality study population, 13.5% (n = 5250) received nirmatrelvir-ritonavir, 51.3% (n = 19,962) received molnupiravir and 35.2% (n = 13,721) were untreated. Treatment was associated with a 57% (OR = 0.43, 95% CI 0.36-0.51) reduction in the odds of death, 73% (OR = 0.27, 95% CI 0.17-0.40) for nirmatrelvir-ritonavir and 55% (OR = 0.45, 95% CI 0.38-0.54) for molnupiravir. Treatment was associated with a 31% (OR = 0.69, 95% CI 0.55-0.86) reduction in the odds of hospitalisation, 40% (OR = 0.60, 95% CI 0.43-0.83) for nirmatrelvir-ritonavir and 29% (OR = 0.71, 95% CI 0.58-0.87) for molnupiravir. Cases treated within 1 day of diagnosis had a 61% reduction in the odds of death (OR = 0.39, 95% CI 0.33-0.46) compared with 33% reduction for a delay of 4 or more days (OR = 0.67, 95% CI 0.44-0.97). Interpretation: Treatment with both nirmatrelvir-ritonavir or molnupiravir was associated with a reduction in death and hospitalisation in vaccinated ≥70 years individuals during the Omicron era. Timely, equitable treatment with OAVs is an important tool in the fight against COVID-19. Funding: There was no funding for this study.

Effect of operative time on complications associated with free flap reconstruction of the head and neck.

OBJECTIVE: To evaluate whether prolonged operative time is negatively associated with post-operative complications and length of stay in patients undergoing microvascular free flap reconstruction for complex head and neck defects. METHODS: 342 consecutive patients undergoing microvascular reconstruction for head and neck defects between 2017-2019 at a single institution were evaluated. Operative outcomes and operative time were compared whilst controlling for patient and treatment related factors. RESULTS: Mean operative time was 551 min and length of stay was 16.2 days. An 11% increase in the risk of a post-operative complication was observed for every additional hour of operative time (OR 1.11, 95% CI 1.03-1.21, p = 0.011) after adjusting for patient and treatment factors. A cut-off of 9 h yielded a 92% increase in complications on either side of this (OR 1.92, 95% CI 1.18-3.13, p = 0.009). Increased operative time was also associated with increased length of stay and return to theatres, but not medical complications. CONCLUSION: Prolonged operative time is significantly associated with increased surgical complications, length of stay and return to theatres when performing microvascular reconstructive surgery for head and neck defects.

Membranes Prepared from Recombinant RGD-Silk Fibroin as Substrates for Human Corneal Cells.

A recombinant formulation of silk fibroin containing the arginine-glycine-aspartic acid (RGD) cell-binding motif (RGD-fibroin) offers potential advantages for the cultivation of corneal cells. Thus, we investigated the growth of corneal stromal cells and epithelial cells on surfaces created from RGD-fibroin, in comparison to the naturally occurring Bombyx mori silk fibroin. The attachment of cells was compared in the presence or absence of serum over a 90 min period and analyzed by quantification of dsDNA content. Stratification of epithelial cells on freestanding membranes was examined by confocal fluorescence microscopy and optimized through use of low molecular weight poly(ethylene glycol) (PEG; 300 Da) as a porogen, the enzyme horseradish peroxidase (HRP) as a crosslinking agent, and stromal cells grown on the opposing membrane surface. The RGD-fibroin reduced the tendency of stromal cell cultures to form clumps and encouraged the stratification of epithelial cells. PEG used in conjunction with HRP supported the fabrication of more permeable freestanding RGD-fibroin membranes, that provide an effective scaffold for stromal-epithelial co-cultures. Our studies encourage the use of RGD-fibroin for corneal cell culture. Further studies are required to confirm if the benefits of this formulation are due to changes in the expression of integrins, components of the extracellular matrix, or other events at the transcriptional level.

Tracheostomy in free-flap reconstruction of the oral cavity: can it be avoided? A cohort study of 187 patients.

BACKGROUND: Head and neck surgeons are moving away from routine tracheostomy in free-flap reconstruction. We reviewed prophylactic tracheostomy use in patients undergoing oral cavity or oropharynx free-flap reconstruction to identify patient groups who avoided tracheostomy. Secondary aims were to describe complications associated with and without tracheostomy. METHODS: A retrospective cohort study was undertaken, using a prospectively maintained database. Inclusion criteria was free-flap reconstruction for an oral cavity or oropharyngeal defect, excluding partial or total laryngectomy. Variables collected included demographics, comorbidity, American Society of Anesthesiologists grade, Charlson Comorbidity Index, tumour site and subsite, extent of resection, surgery duration, tracheostomy, complications, return to theatre and re-intubation. RESULTS: A total of 344 head and neck free-flap reconstructions were performed between January 2017 and July 2019. A total of 164 (87.7%) oral cavity and 23 (12.3%) oropharyngeal reconstructions were included totalling 187 free flaps. A total of 107 (57.2%) were males and 80 (42.8%) females, mean age 62.4 years (range 21-89). Of 187 patients, 100 (53.5%) underwent prophylactic tracheostomy at time of reconstruction. Longer operative time (P < 0.001), resection site (P < 0.001), number of subsites resected (P = 0.007), segmental mandibulectomy (P = 0.04), lip-split (P = 0.05), floor of mouth resection (P < 0.001), lingual release (P = 0.007), glossectomy (P < 0.001), extent of tongue resection (P < 0.001), extent of hard palate resection (P = 0.04), soft palate resection (P < 0.001) and double free-flap reconstruction (P = 0.04) were associated with tracheostomy use. CONCLUSION: A personalized approach to postoperative airway management allowed almost half of our cohort to avoid tracheostomy. In high-volume institutions with the necessary expertise and support, appropriately selected patients may be safely managed without routine tracheostomy.

Microvascular reconstruction of head and neck defects in the elderly.

BACKGROUND: Microvascular free-flap reconstruction of the head and neck is a common technique utilized across many ages. The purpose of this study was to identify if advanced age or comorbidity was associated with worse post-operative outcomes in patients undergoing free-flap reconstruction. METHODS: A retrospective analysis was performed on 344 consecutive patients undergoing free-flap surgery of the head and neck. Demographic, clinical and pathological factors were considered along with Charlson Comorbidity Index (CCI) scores and American Society of Anesthesiologists (ASA) status. Logistic regression analysis was used to investigate the association of age, CCI or ASA with post-operative complications. RESULTS: Elderly patients (≥75 years) had a higher overall complication rate (odds ratio (OR) 1.7, P = 0.04) that was restricted to medical complications (OR 2.1, P = 0.05) and not surgical complications (OR 1.4, P = 0.14). Reconstructions of defects from cutaneous malignancy predominated in the elderly cohort (48% versus 29%, P < 0.01), but there was no difference in complication rate when cutaneous or mucosal subgroups were separated by age. ASA IV status was weakly associated with surgical complications (OR 3.89, P = 0.053), but CCI and elderly age were not associated with any outcome. Median length of stay was similar between age groups. CONCLUSION: Free-flap reconstruction in older patients was associated with increased medical complications, and surgical complications were weakly associated with ASA status. Advanced age or comorbidity should not preclude microvascular reconstruction, but comorbid status should be optimized pre-operatively and factors predisposing to medical complications minimized where possible.

TeenCovidLife: a resource to understand the impact of the COVID-19 pandemic on adolescents in Scotland.

TeenCovidLife is part of Generation Scotland's CovidLife projects, a set of longitudinal observational studies designed to assess the psychosocial and health impacts of the COVID-19 pandemic. TeenCovidLife focused on how adolescents in Scotland were coping during the pandemic. As of September 2021, Generation Scotland had conducted three TeenCovidLife surveys. Participants from previous surveys were invited to participate in the next, meaning the age ranges shifted over time. TeenCovidLife Survey 1 consists of data from 5,543 young people age 12 to 17, collected from 22 May to 5 July 2020, during the first school closures period in Scotland. TeenCovidLife Survey 2 consists of data from 2,245 young people aged 12 to 18, collected from 18 August to 14 October 2020, when the initial lockdown measures were beginning to ease, and schools reopened in Scotland. TeenCovidLife Survey 3 consists of data from 597 young people age 12 to 19, collected from 12 May to 27 June 2021, a year after the first survey, after the schools returned following the second lockdown in 2021. A total of 316 participants took part in all three surveys. TeenCovidLife collected data on general health and well-being, as well as topics specific to COVID-19, such as adherence to COVID-19 health guidance, feelings about school closures, and the impact of exam cancellations. Limited work has examined the impact of the COVID-19 pandemic on young people. TeenCovidLife provides relevant and timely data to assess the impact of the pandemic on young people in Scotland. The dataset is available under authorised access from Generation Scotland; see the Generation Scotland website for more information.

CovidLife: a resource to understand mental health, well-being and behaviour during the COVID-19 pandemic in the UK.

CovidLife is a longitudinal observational study designed to investigate the impact of the COVID-19 pandemic on mental health, well-being and behaviour in adults living in the UK. In total, 18,518 participants (mean age = 56.43, SD = 14.35) completed the first CovidLife questionnaire (CovidLife1) between April and June 2020. To date, participants have completed two follow-up assessments. CovidLife2 took place between July and August 2020 (n = 11,319), and CovidLife3 took place in February 2021 (n = 10,386). A range of social and psychological measures were administered at each wave including assessments of anxiety, depression, well-being, loneliness and isolation. Information on sociodemographic, health, and economic circumstances was also collected. Questions also assessed information on COVID-19 infections and symptoms, compliance to COVID-19 restrictions, and opinions on the UK and Scottish Governments' handling of the pandemic. CovidLife includes a subsample of 4,847 participants from the Generation Scotland cohort (N~24,000, collected 2006-2011); a well-characterised cohort of families in Scotland with pre-pandemic data on mental health, physical health, lifestyle, and socioeconomic factors, along with biochemical and genomic data derived from biological samples. These participants also consented to their study data being linked to Scottish health records. CovidLife and Generation Scotland data can be accessed and used by external researchers following approval from the Generation Scotland Access Committee. CovidLife can be used to investigate mental health, well-being and behaviour during COVID-19; how these vary according to sociodemographic, health and economic circumstances; and how these change over time. The Generation Scotland subsample with pre-pandemic data and linkage to health records can be used to investigate the predictors of health and well-being during COVID-19 and the future health consequences of the COVID-19 pandemic.

RuralCovidLife: A new resource for the impact of the pandemic on rural Scotland.

RuralCovidLife is part of Generation Scotland's CovidLife project, investigating the impact of the COVID-19 pandemic and mitigation measures on people in Scotland. The RuralCovidLife project focuses on Scotland's rural communities, and how they have been impacted by the pandemic. During survey development, Generation Scotland consulted with people living or working in rural communities, and collaborated with a patient and public involvement and engagement (PPIE) group composed of rural community leaders. Through this consultation work, the RuralCovidLife survey was developed to assess the issues most pertinent to people in rural communities, such as mental health, employment, transport, connectivity, and local communities. Between 14th October and 30th November 2020, 3,365 participants from rural areas in Scotland took part in the survey. Participant ages ranged from 16 to 96 (mean = 58.4, standard deviation [SD] = 13.3), and the majority of the participants were female (70.5%). Over half (51.3%) had taken part in the original CovidLife survey. RuralCovidLife includes a subsample (n = 523) of participants from the Generation Scotland cohort. Pre-pandemic data on health and lifestyle, as well as biological samples, are available for these participants. These participants' data can also be linked to past and future healthcare records, allowing analysis of retrospective and prospective health outcomes. Like Generation Scotland, RuralCovidLife is designed as a resource for researchers. RuralCovidLife data, as well as the linked Generation Scotland data, is available for use by external researchers following approval from the Generation Scotland Access Committee. RuralCovidLife can be used to investigate mental health, well-being, and behaviour in participants living in rural areas during the COVID-19 pandemic, as well as comparisons with non-rural samples. Moreover, the sub-sample with full Generation Scotland data and linkage can be used to investigate the long-term health consequences of the COVID-19 pandemic in rural communities.

Mitochondrial DNA Affects the Expression of Nuclear Genes Involved in Immune and Stress Responses in a Breast Cancer Model.

Tumor cells without mitochondrial (mt) DNA (ρ0 cells) are auxotrophic for uridine, and their growth is supported by pyruvate. While ATP synthesis in ρ0 cells relies on glycolysis, they fail to form tumors unless they acquire mitochondria from stromal cells. Mitochondrial acquisition restores respiration that is essential for de novo pyrimidine biosynthesis and for mitochondrial ATP production. The physiological processes that underpin intercellular mitochondrial transfer to tumor cells lacking mtDNA and the metabolic remodeling and restored tumorigenic properties of cells that acquire mitochondria are not well understood. Here, we investigated the changes in mitochondrial and nuclear gene expression that accompany mtDNA deletion and acquisition in metastatic murine 4T1 breast cancer cells. Loss of mitochondrial gene expression in 4T1ρ0 cells was restored in cells recovered from subcutaneous tumors that grew from 4T1ρ0 cells following acquisition of mtDNA from host cells. In contrast, the expression of most nuclear genes that encode respiratory complex subunits and mitochondrial ribosomal subunits was not greatly affected by loss of mtDNA, indicating ineffective mitochondria-to-nucleus communication systems for these nuclear genes. Further, analysis of nuclear genes whose expression was compromised in 4T1ρ0 cells showed that immune- and stress-related genes were the most highly differentially expressed, representing over 70% of those with greater than 16-fold higher expression in 4T1 compared with 4T1ρ0 cells. The monocyte recruiting chemokine, Ccl2, and Psmb8, a subunit of the immunoproteasome that generates MHCI-binding peptides, were the most highly differentially expressed. Early monocyte/macrophage recruitment into the tumor mass was compromised in 4T1ρ0 cells but recovered before mtDNA could be detected. Taken together, our results show that mitochondrial acquisition by tumor cells without mtDNA results in bioenergetic remodeling and re-expression of genes involved in immune function and stress adaptation.

Public involvement in the governance of population-level biomedical research: unresolved questions and future directions.

Population-level biomedical research offers new opportunities to improve population health, but also raises new challenges to traditional systems of research governance and ethical oversight. Partly in response to these challenges, various models of public involvement in research are being introduced. Yet, the ways in which public involvement should meet governance challenges are not well understood. We conducted a qualitative study with 36 experts and stakeholders using the World Café method to identify key governance challenges and explore how public involvement can meet these challenges. This brief report discusses four cross-cutting themes from the study: the need to move beyond individual consent; issues in benefit and data sharing; the challenge of delineating and understanding publics; and the goal of clarifying justifications for public involvement. The report aims to provide a starting point for making sense of the relationship between public involvement and the governance of population-level biomedical research, showing connections, potential solutions and issues arising at their intersection. We suggest that, in population-level biomedical research, there is a pressing need for a shift away from conventional governance frameworks focused on the individual and towards a focus on collectives, as well as to foreground ethical issues around social justice and develop ways to address cultural diversity, value pluralism and competing stakeholder interests. There are many unresolved questions around how this shift could be realised, but these unresolved questions should form the basis for developing justificatory accounts and frameworks for suitable collective models of public involvement in population-level biomedical research governance.

Fibroblasts from Distinct Pancreatic Pathologies Exhibit Disease-Specific Properties.

Although fibrotic stroma forms an integral component of pancreatic diseases, whether fibroblasts programmed by different types of pancreatic diseases are phenotypically distinct remains unknown. Here, we show that fibroblasts isolated from patients with pancreatic ductal adenocarcinoma (PDAC), chronic pancreatitis (CP), periampullary tumors, and adjacent normal (NA) tissue (N = 34) have distinct mRNA and miRNA profiles. Compared with NA fibroblasts, PDAC-associated fibroblasts were generally less sensitive to an antifibrotic stimulus (NPPB) and more responsive to positive regulators of activation such as TGFß1 and WNT. Of the disease-associated fibroblasts examined, PDAC- and CP-derived fibroblasts shared greatest similarity, yet PDAC-associated fibroblasts expressed higher levels of tenascin C (TNC), a finding attributable to miR-137, a novel regulator of TNC. TNC protein and transcript levels were higher in PDAC tissue versus CP tissue and were associated with greater levels of stromal activation, and conditioned media from TNC-depleted PDAC-associated fibroblasts modestly increased both PDAC cell proliferation and PDAC cell migration, indicating that stromal TNC may have inhibitory effects on PDAC cells. Finally, circulating TNC levels were higher in patients with PDAC compared with CP. Our characterization of pancreatic fibroblast programming as disease-specific has consequences for therapeutic targeting and for the manner in which fibroblasts are used in research. SIGNIFICANCE: Primary fibroblasts derived from various types of pancreatic diseases possess and retain distinct molecular and functional characteristics in culture, providing a series of cellular models for treatment development and disease-specific research.

Whole genome landscapes of uveal melanoma show an ultraviolet radiation signature in iris tumours.

Uveal melanoma (UM) is the most common intraocular tumour in adults and despite surgical or radiation treatment of primary tumours, ~50% of patients progress to metastatic disease. Therapeutic options for metastatic UM are limited, with clinical trials having little impact. Here we perform whole-genome sequencing (WGS) of 103 UM from all sites of the uveal tract (choroid, ciliary body, iris). While most UM have low tumour mutation burden (TMB), two subsets with high TMB are seen; one driven by germline MBD4 mutation, and another by ultraviolet radiation (UVR) exposure, which is restricted to iris UM. All but one tumour have a known UM driver gene mutation (GNAQ, GNA11, BAP1, PLCB4, CYSLTR2, SF3B1, EIF1AX). We identify three other significantly mutated genes (TP53, RPL5 and CENPE).

The Impact of Limbal Mesenchymal Stromal Cells on Healing of Acute Ocular Surface Wounds Is Improved by Pre-cultivation and Implantation in the Presence of Limbal Epithelial Cells.

While limbal epithelial cells are used for treating ocular surface wounds, the therapeutic potential of mesenchymal cells cultivated from the limbal stroma (LMSC) is less clear. We have therefore examined the effects of LMSC when applied to acute ocular surface wounds. LMSC derived from male rabbits (RLMSC) were applied to the ocular surface of female rabbits immediately following removal of the corneal and limbal epithelium. Human amniotic membrane (HAM) was used as the vehicle for implanting the RLMSC. The effects of RLMSC were examined when applied alone (n = 3) and in conjunction with a stratified culture of human limbal epithelial cells (HLE) grown on the opposing surface of the HAM (n = 3). Outcomes were monitored over 3 months in comparison with animals receiving no treatment (n = 3) or treatment with HLE alone on HAM (n = 3). Animals treated with RLMSC (n = 6) displayed faster re-epithelialization (∼90% versus 70% healing after 12 weeks), with best results being observed when RLMSC were pre-cultivated and implanted in the presence of HLE (p < 0.01; 90% healing by 7 weeks). While all animals displayed conjunctival cells on the corneal surface (by presence of goblet cells and/or keratin 13 expression) and corneal neovascularization, evidence of corneal epithelial regeneration was observed in animals that received RLMSC in the presence of HLE (by staining for keratin 3 and the absence of goblet cells). Conversely, corneal neovascularization was significantly greater when RLMSC were applied in the absence of HLE (<0.05; 90% of cornea compared with 20-30% in other cohorts). Nevertheless, neither human nuclear antigen nor rabbit Y chromosome were detected within the regenerated epithelium. Our results demonstrate that while cultured LMSC encourage corneal re-epithelialization, healing is improved by the pre-cultivation and implantation of these mesenchymal cells in the presence of limbal epithelial cells.

Optically robust, highly permeable and elastic protein films that support dual cornea cell types.

Damaged corneas can lead to blindness. Due to the worldwide shortage of donor corneas there is a tremendous unmet demand for a robust corneal replacement that supports growth of the major corneal cell types. Commercial artificial corneas comprise plastic polymers that do not adequately support diverse cell growth. We present a new class of protein elastomer-dominated synthetic corneas with attractive performance that intimately couple biologically active tropoelastin to mechanically robust and durable protein silk. Fabricated films substantially replicate the natural cornea physically and by interacting with both key cells types used in cornea repair. Performance encompasses optical clarity at high transmittance, compatible refractive index, substantial glucose permeability, compliant mechanical properties, and support of both growth and function of corneal epithelial and endothelial cells.

Intercellular Communication in Tumor Biology: A Role for Mitochondrial Transfer.

Intercellular communication between cancer cells and other cells in the tumor microenvironment plays a defining role in tumor development. Tumors contain infiltrates of stromal cells and immune cells that can either promote or inhibit tumor growth, depending on the cytokine/chemokine milieu of the tumor microenvironment and their effect on cell activation status. Recent research has shown that stromal cells can also affect tumor growth through the donation of mitochondria to respiration-deficient tumor cells, restoring normal respiration. Nuclear and mitochondrial DNA mutations affecting mitochondrial respiration lead to some level of respiratory incompetence, forcing cells to generate more energy by glycolysis. Highly glycolytic cancer cells tend to be very aggressive and invasive with poor patient prognosis. However, purely glycolytic cancer cells devoid of mitochondrial DNA cannot form tumors unless they acquire mitochondrial DNA from adjacent cells. This perspective article will address this apparent conundrum of highly glycolytic cells and cover aspects of intercellular communication between tumor cells and cells of the microenvironment with particular emphasis on intercellular mitochondrial transfer.

Demonstration of P-selectin expression and potential function in human corneal epithelial cells.

In response to an unexpected observation of apparent localisation by immunocytochemistry, we have investigated the potential expression and function of P-selectin (CD62P) in human corneal epithelial cells. The SV40 immortalised cell line, HCE-T (validated by STR profiling), along with multiple donor corneal-limbal tissue samples, were examined for P-selectin expression using a combination of immunocytochemistry, Western blotting, RT-PCR and immunohistochemistry. Potential expression of the major ligand for P-selectin (P-selectin glycoprotein ligand-1; PSGL-1; CD162) was also examined by immunocytochemistry and RT-PCR. A selective inhibitor of P-selectin-PSGL-1 binding (KF38789) was subsequently tested for effects on HCE-T cells using a cell culture gap-closure assay. HCE-T cells as well as primary epithelial cultures derived from donor corneal-limbal tissue, displayed positive immunostaining for P-selectin. Staining was particularly evident at cell-cell boundaries and at the outer edge of expanding epithelial islands. P-selectin expression was confirmed by Western blotting and RT-PCR (validated by product sequencing), as well as by immunohistochemistry performed on serial sections of corneal-limbal tissue stained for P-selectin, keratin 3 and p63. PSGL-1 was detected by RT-PCR and immunocytochemistry in both corneal epithelial cells as well as human limbal fibroblasts (HLF). KF38789 (5 µM) significantly reduced closure of a 500-µm gap between confluent sheets of HCE-T cells over an 8-hr period (by ∼40%, p < 0.01; paired two-tailed T test), but had no effect on culture gap-closure by either HLF or murine 3T3 fibroblasts. These results provide evidence of P-selectin expression in human corneal epithelial cells and suggest a potential role for this glycoprotein in facilitating the net movement of confluent sheets of human corneal epithelial cells.

Mounting of Biomaterials for Use in Ophthalmic Cell Therapies.

When used as scaffolds for cell therapies, biomaterials often present basic handling and logistical problems for scientists and surgeons alike. The quest for an appropriate mounting device for biomaterials is therefore a significant and common problem. In this review, we provide a detailed overview of the factors to consider when choosing an appropriate mounting device including those experienced during cell culture, quality assurance, and surgery. By way of example, we draw upon our combined experience in developing epithelial cell therapies for the treatment of eye diseases. We discuss commercially available options for achieving required goals and provide a detailed analysis of 4 experimental designs developed within our respective laboratories in Australia, the United Kingdom, and Belgium.

Severe hypoxia and malnutrition collectively contribute to scar fibroblast inhibition and cell apoptosis.

This study aims to investigate whether severe hypoxia and malnutrition in scar tissue play key roles to induce hypertrophic scar regression. And scar-derived fibroblasts were treated with moderate/severe hypoxia and malnutrition to model condition of proliferative and regressive scar (5%O2 +5%FCS and 0.5%O2 + 0.5%FCS), and normoxia with well nutrition as control (10%O2 + 10%FCS). Our results demonstrated that severe hypoxia and malnutrition resulted in significantly reduced cell viability and collagen production, as well as HIF-1, VEGF, TGF-ß1, and Bcl-2 protein expression when compared with control, and cell apoptosis occurred. Therefore, the severe hypoxia and malnutrition in scar tissue contribute to fibroblast inhibition and cell apoptosis, which is correlated with scar regression.

Treatment of Silk Fibroin with Poly(ethylene glycol) for the Enhancement of Corneal Epithelial Cell Growth.

A silk protein, fibroin, was isolated from the cocoons of the domesticated silkworm (Bombyx mori) and cast into membranes to serve as freestanding templates for tissue-engineered corneal cell constructs to be used in ocular surface reconstruction. In this study, we sought to enhance the attachment and proliferation of corneal epithelial cells by increasing the permeability of the fibroin membranes and the topographic roughness of their surface. By mixing the fibroin solution with poly(ethylene glycol) (PEG) of molecular weight 300 Da, membranes were produced with increased permeability and with topographic patterns generated on their surface. In order to enhance their mechanical stability, some PEG-treated membranes were also crosslinked with genipin. The resulting membranes were thoroughly characterized and compared to the non-treated membranes. The PEG-treated membranes were similar in tensile strength to the non-treated ones, but their elastic modulus was higher and elongation lower, indicating enhanced rigidity. The crosslinking with genipin did not induce a significant improvement in mechanical properties. In cultures of a human-derived corneal epithelial cell line (HCE-T), the PEG treatment of the substratum did not improve the attachment of cells and it enhanced only slightly the cell proliferation in the longer term. Likewise, primary cultures of human limbal epithelial cells grew equally well on both non-treated and PEG-treated membranes, and the stratification of cultures was consistently improved in the presence of an underlying culture of irradiated 3T3 feeder cells, irrespectively of PEG-treatment. Nevertheless, the cultures grown on the PEG-treated membranes in the presence of feeder cells did display a higher nuclear-to-cytoplasmic ratio suggesting a more proliferative phenotype. We concluded that while the treatment with PEG had a significant effect on some structural properties of the B. mori silk fibroin (BMSF) membranes, there were minimal gains in the performance of these materials as a substratum for corneal epithelial cell growth. The reduced mechanical stability of freestanding PEG-treated membranes makes them a less viable choice than the non-treated membranes.

Insulin-like growth factor-I and UVB photoprotection in human keratinocytes.

Ultraviolet radiation (UVR), in particular the UVB spectrum, is a risk factor for skin cancer development. The generation and accumulation of UVB-induced genetic mutations are fundamental premalignant events. Keratinocyte interactions between other cutaneous cell populations and the surrounding microenvironment determine cell fate and acute photoresponses. In this study, the importance of the insulin-like growth factor (IGF) system, in particular the insulin-like growth factor-I (IGF-I), on influencing key processes in the keratinocyte acute photoresponse was investigated. Exogenous IGF-I and other growth factors present in dermal fibroblast-conditioned media (CM) were found to significantly enhance keratinocyte survival following UVB irradiation in vitro. This pretreatment was also shown to cause a shift in the expression levels of various DNA damage response proteins. Consequently, this was associated with accelerated rates of UVB-induced cyclobutane pyrimidine dimer removal in these samples. Finally, activation of the IGF system influenced cell cycle progression in UVB-irradiated keratinocytes. Taken together, these results highlight the importance of the IGF signalling network in initiating the repair of potentially mutagenic DNA damage in human keratinocytes. The dysregulation of these processes may therefore have significant implications in the aetiology of skin cancers and other cutaneous diseases.