Mucoadhesive drug delivery systems which are being used from 1980’s to avoid first pass metabolism of drugs, commercially exist for only systemic drug delivery with fast erosion times (15-60 min), that may not be appropriate for local oral disorders. The goal of this research was to develop and characterize mucoadhesive films with flexibility of carrying different drugs and proteins and provide sustained release for local treatment of oral disorders. Mucoadhesive films composed of polyvinylpyrrolidone (PVP) and carboxymethlycellulose (CMC) were formulated with imiquimod, an immune response modifier. Problems such as solubilization of imiquimod to increase drug loading, uniformity in films and total amount of drug released into supernatants were addressed by use of acetate buffer after investigating multiple methods. Subsequently, other relevant properties of mucoadhesive systems, such as adhesion (shear, pull-off), tensile properties, swelling profiles, transport kinetics, and subsequent changes in release profiles as a function of film composition were characterized. The potential of the system for local retention of imiquimod, determined in oral mucosa of hamsters showed time dependent decrease in imiquimod amount through 12 hours, with no traces of drug in blood. Further testing in humans revealed that the residence time of the mucoadhesive films depended on the application site, increasing in the order of tongue < cheek < gingiva. In parallel, mucoadhesive films loaded with epidermal growth factor (EGF) were developed to promote treatment of oral mucosal wounds. Bioactivity was tested in vitro on buccal tissues by creating a wound followed by application of films. Although EGF-loaded films did not accelerate wound healing, but rather elicited a hyperparakeratotic response. In vitro buccal tissues may not be appropriate for testing the effects of EGF in wound healing without incorporation of other biochemical factors. Overall, a mucoadhesive system capable of delivering bioactive small molecules and proteins in sustained manner was developed in this work. A thorough understanding of the system properties was achieved to further tune for future applications. In vitro studies and in vivo studies in hamsters and humans clearly showed the potential and usefulness of the system to translate in to clinic for treatment of oral precancerous lesions.

PURPOSE:The limbus of the cornea is said to be the niche for limbal stem cells (LSCs) and the primary source of corneal epithelial maintenance. In this model, adult corneal epithelial cells are maintained by LSCs that cycle slowly and give rise to transient amplifying (TA) cells. These migrate centripetally, differentiate outwards to the surface, and are then lost by desquamation. This study set out to investigate the stem cell properties of human corneal epithelium and their contribution towards corneal epithelial regeneration after wounding. METHODS: Frozen sections of human corneal tissues were labelled with a number of putative stem cell markers. Human central and limbal corneal epithelial cells were isolated for holoclone formation assay and FACS isolation. Side population (SP) cells were separated based upon cell size and Hoechst dye efflux ability. A human corneal organotypic culture model was used to assess corneal healing in vitro. Injured corneas were analysed using cytokine antibody arrays and immunohistochemical markers for cell proliferation and stem cells. RESULTS: The expression of putative stem cell markers ΔNp63α and ABCG2 was clearly evident in the suprabasal and basal layers of the limbus, but was also observed in central epithelium. Human limbal and central corneal epithelial cells were both capable of forming holoclones in 2:1 ratio respectively. In FACS, central SP and limbal SP cells showed no significant difference based upon size and dye efflux. After wounding, the capacity for epithelial cell proliferation and migration appears to be as active in the central cornea as in the periphery/limbus. Central and peripheral epithelial recovery remains equal even after ablation of the limbus. CONCLUSION: Cells from the central human corneal epithelium have many putative stem cell properties. These results raise questions not only about the distribution and substance of stem cells in the cornea, but also the role of the limbus itself. The central epithelium is able to heal independently of the limbus.

Wound healing is governed by a complex cascade of related processes, involving cells, extracellular matrix and cytokines. In adults this always results in a scar whilst embryonic wound healing is scarless and extensive research worldwide is aimed at reducing scarring in adults. A mathematical framework for problems in dermal wound healing is developed that incorporates models of the individual processes involved. Cells are modelled as discrete individuals. Cytokines and other biologically active factors are modelled as continua. A novel tensorial approach is taken to modelling the extracellular matrix. The numeric and computational challenges associated with combining models for the individual processes are identified and investigated. These include the development of data structures and numeric methods for the continuous and discrete species. Effective visualisation methods for the large amounts of data generated by the model are also discussed. The possibilities offered by high performance computing in mathematical biology are highlighted in this work. The final part of this thesis gives an example of a combined model of the inflammatory and proliferative phases of dermal wound healing using the new computational framework. Both quantitative and qualitative methods are used to analyse the information-rich data sets generated by the model, offering insight into the dynamic systems that can be modelled using the new approach.

Chronic ulcers are an important and costly medical issue, causing their sufferers a large amount of pain, immobility and decreased quality of life. The common pathology in these chronic wounds is often characterised by excessive proteolytic activity, leading to the degradation of both the extracellular matrix, as well as key factors critical to the ulcer's ability to heal. As matrix metalloproteinases (MMPs), a large family of zinc-dependent endopeptidases, have been shown to have increased activity in chronic wound fluid (CWF), it was hypothesised that this specific proteolytic activity was directly related to an ulcer's chronic nature. Although previous studies have identified elevated proteases in CWF, many have reported contradictory results and therefore the precise levels and species of MMPs in CWF are poorly understood. The studies reported herein demonstrate that MMP activity is significantly elevated in CWF compared with acute wound fluid (AWF). In particular, these studies demonstrate that this proteolytic activity can be specifically attributed to MMPs and not another class of proteases present in wound healing. Furthermore, it is shown that MMP-9 is the predominant protease responsible for matrix degradation by CWF and is an indicator of the clinical status of the wound itself. Moreover, MMP-9 can be inhibited with the bisphosphonate alendronate, in the form of a sodium salt, a functionalised analogue, and also tethered to a synthetic biocompatible hydrogel compromised of aqueous poly (2-hydroxy methacrylate) PHEMA synthesised in the presence of poly(ethylene glycol) (PEG). Together, these results highlight the potential use of a tethered MMP inhibitor as an improved ulcer treatment to inhibit protease activity in the wound fluid, while still allowing MMPs to remain active in the wound bed where they perform vital roles in the activation of growth-promoting agents and immune system regulation.

Problem investigated: Chronic wounds are not only a major burden to the patient arising from general pain and discomfort but also generate economic costs to both these individuals and the health care system. Various electrical stimulation regimes have been employed to study the effects of electrical stimulation on wound healing both in vivo and in vitro. In was hypothesised that electrical stimulation using various waveforms can modulate cell function, particularly cell migration. The aim of this thesis was to study the effects of electrical stimulation on cellular migration, in particular endothelial cells and fibroblasts, key cell types involved in wound healing. The impact of collagen matrix on cell migration was also assessed. Methods: Cells were seeded on either glass or collagen I substrate and stimulated with various electrical regimes via platinum electrodes connected to a constant current source. Cell migration was accessed by manual tracking of cell nuclei over a period of 3 hours from digital time-lapse images acquired during stimulation. Data from cell tracking were analysed for directional migration, migration rates and mean square displacement. Results: No directional cell migration for both endothelial cells and fibroblasts were observed when stimulated with either alternating or biphasic currents. However, surface substrate had impacted on cell motility with opposite effects being observed for the two cell types. Endothelial cells tended to migrate at a faster rate on collagen I substrate than on glass, compared with fibroblasts, which displayed a slower rate of migration on collagen I substrate. Significant changes in mean square displacement of biphasic current stimulated cells on collagen I substrate compared to unstimulated cells were also observed. Conclusion: This thesis has illustrated cell migration can be modulated by electrical stimulation, in particular asymmetric biphasic current. It has also been demonstrated surface substrate can impact cell migration.

Two leaves of errata and addenda pasted into back pages. / Bibliography: leaves 174-208. / xix, 208 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis aimed to determine general roles for insulin-like growth factor binding proteins (IGFBPs) in regulating insulin-like growth factor-I (IGF-I) actions in wound repair. Preliminary experiments sought to characterise alterations to IGF-I levels and IGFBP profiles that may occur during wound repair. The effects that interactions with IGFBPs may have on IGF actions in wounds were addressed. Final experiments aimed to determine whether IGFBP-3 proteolysis observed in the initial work of the thesis acted to increase IGF bioavailablity. The results are discussed. / Thesis (Ph.D.)--University of Adelaide, Dept. of Surgery, 2000

The effect of absorbable packing on the healing of nasal respiratory epthelium after endoscopic sinus surgery (ESS) was examined in a diseased sheep model. Full thickness injuries were created on the lateral nasal wall of sheep infested with Oestrus ovi. Sites of injury were packed on one side with hyaluronic acid (HA) packing or hyaluronic acid packing impregnated with insulin-like growth factor- 1 (HA+IGF1) in a randomized fashion. The opposite side was left unpacked as a control. Biopsies were obtained for light microscopy, scanning electron microscopy, and ciliary beat frequency (CBF) analysis over a period of 16 weeks. Statistical analysis of results was performed in order to determine if any intervention had any impact on healing and to determine if there was any correlation between extent of regeneration as assessed by electron microscopy and CBF. Furthermore assessment of the effect of isotonic and hypertonic saline on ciliary beat frequency was performed in healthy human volunteers. Reepithelialization was increased in the HA+IGF1 group compared to the HA group and controls at eight weeks after injury but not at later time points. Cilial regeneration was improved in the HA+IGF1 group compared to the HA group and controls at 16 weeks. CBF was noted to be worse at the eight week time point with the HA+IGF1 group compared to the HA group and controls, but no other statistically significant effects on CBF were noted. This most likely represents a spurious finding. Wide distributions of CBF results were noted, reflecting numerous missing data points due to methodological difficulties. There was a trend noted toward increased CBF with improved grades of reciliation, although this correlation was not statistically significant. However this trend was supported by the finding of statistically significant differences between individual and combined grades of reciliation. Hypertonic saline was found to have a ciliostimulatory effect when compared to normal saline at 5 minutes after administration in healthy human subjects. This effect had disappeared by 60 minutes after administration. It is suggested that the presence of insulin-like growth factor- 1 at the time of mucosal injury improves epithelial regeneration in the short term, but is not sufficient for this effect to be sustained. This improved early epithelial regeneration forms a foundation for cilial regeneration, as is reflected in an improved grade of reciliation at 16 weeks. Our interventions had no effect on CBF, and various experimental problems made it difficult to provide further comment on CBF results. There is evidence that CBF improves as the grade of cilial regeneration improves following ESS. Furthermore, hypertonic saline appears to also have a positive impact on CBF, which is likely to reflect changes in the rheological properties of mucous. A number of possible avenues of enquiry are delineated and recommendations for future research are outlined. / Thesis (M.S.)--Department of Surgery, 2005.

Burn injuries represent a major cause of mortality and morbidity as well as a significant drain on limited resources, particularly in the developing world. Advances in resuscitation, critical care, protective ventilatory strategies, earlier complete debridement complemented by more aggressive treatment of burn wound sepsis have reduced the mortality of thermal injuries. There has also been a move to focus on education and prevention campaigns, which have borne fruit and resulted in some reduction in the incidence of burns in the paediatric population. Burn care, once a Cinderella specialty, has become a well focused multi-disciplinary specialty in its own right. Burn injury is dissimilar to many forms of trauma. In major burns, the initial trauma may be limited to the skin alone or skin and lungs, but all organ systems are rapidly involved as the physiological derangement becomes systemic. The burden of this multi-system insult is substantial. Globally, the World Health Organisation estimated that fire-associated burns alone directly resulted in over 320,000 deaths in 2002, and in the USA, approximately 1million children sustain burns each year. Australasian guidelines suggest that all adult burns with greater than 15% total body surface area (TBSA) and >10% TBSA burn in children will require fluid resuscitation and possibly critical care support at some point in their hospitalisation. Mortality in these patients with severe burns follows a bimodal pattern of early and late deaths. Causes of early death comprise refractory shock, inability to obtain a safe airway or provide adequate oxygenation, co-existent trauma, non-survivable carboxyhaemoglobin poisoning, and decisions that injuries are non-compatible with recovery, leading to therapy withdrawal. With improved resuscitation strategies, 95% of patients survive the early resuscitation phase. Late deaths are secondary to sepsis normally associated with wound infection and multiple organ failure. The morbidity associated with burn injury continues well after the acute hospital admission, frequently for up to several years post burn injury, as is witnessed by prolonged rise in basal metabolic rate and worsening scar tissue1, 2. It has been calculated that in children approximately 60% of the cost of burn care occurs post wound closure; that is, dealing with the disabling and disfiguring contractures associated with hypertrophic scar3, 4. Hence, research and new modalities are being aimed at reducing cost of treatment and improving quality of life for survivors of burn injury. Thus, this PhD aims to reflect the multidisciplinary nature of modern day burn care, with the inclusion of seven published papers and one book chapter covering prevention and education relevant to paediatric burns, treatment and minimisation of wound infection , and scar minimisation, along with the first study into the relevance of fetal wound healing post burn injury.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 134-155).

Diss. (sammanfattning) Linköping : Linköpings universitet, 2008. / Härtill 4 uppsatser.