INTRODUÇÃO: A matriz extracelular no endométrio fornece vasta gama de sinais envolvidos em diferentes processos celulares, tais como morte celular e proliferação. Neste sentido, os glicosaminoglicanos e os proteoglicanos, juntamente com os fatores de crescimento, modulam várias etapas da angiogênese, proliferação celular e remodelação do estroma, o que pode ser importante para o fluxo menstrual regular e a redução dos processos proliferativos. Além disso, são importantes para a adequada interação maternofetal. OBJETIVO: Avaliar a concentração de ácido hialurônico, das enzimas de biossíntese do ácido hialurônico - hialurônico sintases (HAS1, HAS2 e HAS3) e dos pequenos proteoglicanos ricos em leucina (decorim, biglicam, lumicam e fibromodulina) no endométrio de pacientes com síndrome dos ovários policísticos (SOP) e de mulheres eumenorreicas. MÉTODOS: Foram analisadas 20 amostras de endométrio, 10 provenientes de pacientes com SOP e 10 de mulheres com ciclos menstruais regulares na fase proliferativa do ciclo, com idade variando entre 20 e 35 anos, atendidas na Divisão de Clínica Ginecológica do Hospital das Clínicas da FMUSP (HC-FMUSP). A determinação do perfil e da concentração do ácido hialurônico foi efetuada por método bioquímico de ensaio fluorimétrico (ELISA-like). A sua localização no tecido endometrial, assim como as dosagens das enzimas sintases (HAS1, HAS2 e HAS3) e dos pequenos proteoglicanos ricos em leucina (decorim, biglicam, lumicam e fibromodulina e), foi feita por imunoistoquímica e \"western blotting\". Para a análise dos resultados foi utilizado o teste t de student (p<=0,05). Os cálculos foram realizados com auxílio do programa SPSS versão13 (SPSS, Chicago, IL). RESUTADOS: Houve maior concentração de ácido hialurônico no endométrio de mulheres eumenorreicas na fase proliferativa do ciclo menstrual do que no das com síndrome dos ovários policísticos. Com relação às sintases do ácido hialurônico, observou-se maior reatividade de HAS1 e HAS2 e menor reatividade de HAS3 no endométrio de mulheres com SOP em relação às mulheres com ciclos menstruais regulares na fase proliferativa. Quanto aos pequenos proteoglicanos ricos em leucina notou-se maior imunorreatividade de decorim e lumicam no endométrio de pacientes com SOP. CONCLUSÕES: As pacientes com SOP apresentam menor concentração de ácido hialurônico e maior reatividade ao decorim e lumicam em relação às mulheres com ciclos regulares na fase proliferativa. Esses dados sugerem que nas pacientes com SOP, o endométrio seria menos receptivo e teria mecanismos para evitar a proliferação excessiva / INTRODUCTION: Endometrium extracellular matrix provides wide range of signals at different cellular levels like cell death and proliferation. In this regard, glycosaminoglycans and proteoglycans, along with growth factors, modulate various stages of angiogenesis, cell proliferation and remodeling of the stroma, which can be important for regulating menses and reducing the proliferative processes. Additionally, it is important for proper fetal-maternal interactions. OBJECTIVE: Evaluate hyaluronic acid concentration, the enzymes of hyaluronic acid synthases (HAS1, HAS2 and HAS3) and small leucine-rich proteoglycans (decorin, lumican, fibromodulim and biglycan) in the endometrium of patients with polycystic ovary syndrome (PCOS) and eumenorrheic women. METHODS: A total of 20 endometrial samples from 10 patients with PCOS and 10 women with regular menstrual cycles in the proliferative phase, with ages ranging between 20 and 35 years, attended at Gynecology Division of Clinical Hospital of the FMUSP (HC-USP). Profile determination and the concentration of hyaluronic acid were performed by biochemical method of fluorimetric assay (ELISA-like). Its location in the endometrial tissue as well as the dosage of enzymes synthases (HAS1, HAS2 and HAS3) and small leucine-rich proteoglycans (decorin, lumican, fibromodulim and biglycan) was done by immunohistochemistry and western blotting. To analyze the results Student t test was used (p < 0.05). The calculations were performed with software SPSS version 13. RESULTS: A higher concentration of hyaluronic acid in eumenorrheic women endometrium in proliferative phase when compared with polycystic ovary syndrome. Regarding hyaluronic acid synthases, there was a higher HAS1 and HAS2 reactivity and lower HAS3 reactivity in the PCOS endometrium compared to women with regular menstrual cycles in the proliferative phase. Decorin and lumican showed higher immunoreactivity in PCOS endometrium. CONCLUSIONS: PCOS patients have a lower concentration of hyaluronic acid and greater reactivity to decorin and lumican than eumenorrheic women in proliferative phase. These data suggest that in patients with PCOS, the endometrium would be less receptive and have mechanisms to prevent excessive proliferation

Diversos experimentos em humanos e equinos discutem a eficácia do uso intra-articular do ácido hialurônico (AH). Pouco se sabe a respeito de seu potencial pró ou anti-inflamatório, bem como sobre a eficácia das moléculas de AH de diferentes pesos moleculares. O objetivo deste estudo foi avaliar os efeitos anti-inflamatórios, anabólicos e antioxidantes da aplicação intra-articular de AH em sinovite aguda induzida por lipopolissacarídeo (LPS) em equinos. Foram utilizadas 24 articulações metacarpofalangeanas hígidas de 12 equinos jovens, avaliadas por exame físico, radiográfico e ultrassonográfico. As articulações foram divididas aleatoriamente em três grupos de oito, sendo o grupo controle tratado com triancinolona (TA) (10 mg), o grupo AH de baixo peso molecular (AH-BPM), e o grupo AH de alto peso molecular (AH-APM). Inicialmente, foram aplicados 0,25 ng de LPS por via intra-articular (momento 0). Após uma hora (momento 1), coletou-se líquido sinovial (LS) para contagem celular e imediatamente após realizado o tratamento com TA, AH-BPM ou AH-APM. Posteriormente, LS foi coletado nos momentos 8, 24 e 48 horas para contagem celular, avaliação do burst oxidativo, quantificação de prostaglandina E2 (PGE2), condroitim sulfato (CS), AH e mensuração do peso molecular do AH. Exame físico dos animais, incluindo mensuração da circunferência articular e avaliação de claudicação por meio do equipamento Lameness Locator&reg; foi realizado em todos os momentos. As frequências cardíaca e respiratória dos animais aumentaram em todos os grupos às 8 horas (P&lt;0,05), sendo menor no grupo TA. Em relação à circunferência articular o grupo AH-BPM apresentou maior aumento às 24 e 48 horas em relação aos outros grupos (p&lt;0,05). O grau de claudicação do grupo AHAPM foi maior que o do grupo TA às 8 e 24 horas, mas similar ao grupo AH-BPM. O grupo TA apresentou maior quantidade de células nucleadas no LS do que o grupo AH-BPM as 24 e 28 horas e do que o grupo AH-APM às 48 horas. A concentração de PGE2 foi menor no grupo TA em relação ao grupo AH-APM às 8 horas, e a ambos os grupos que receberam AH às 48 horas (p&lt;0,05). O grupo AH-APM mostrou maior concentração de AH às 8 horas do que os outros grupos, contudo às 48 horas o grupo TA mostrou maior concentração de AH do que os outros grupos (p&lt;0,05). Também às 48 horas o grupo TA foi o que apresentou a menor porcentagem de AH de alto peso molecular (p&lt;0,05). A maior concentração de CS no LS às 24 e 48 horas ocorreu no grupo TA, também observou-se o grupo TA foi o único em que a concentração de CS aumentou as 8 horas em relação aos valores basais. O grupo AH-APM foi o que apresentou menor concentração de CS às 8 horas (p&lt;0,05). O grupo tratado com AHBPM apresentou maior intensidade de fluorescência nos momentos 24 e 48 horas (p&lt;0,05). Apesar da triancinolona possuir efeito superior ao ácido hialurônico no controle da inflamação, ela possui efeito catabólico sobre a cartilagem articular, demonstrado pelo aumento da concentração de CS, além de quebra da molécula de AH no líquido sinovial. O AH-APM é mais indicado para terapia intra-articular em equinos uma vez que demonstrou menor efeito catabólico e oxidativo do que o AH-BPM / Several experiments have compared the efficacy of intra-articular usage of yaluronic acid (HA) within horses. Little is known about the effectiveness of different subtypes of HA in terms of its pro- and anti-inflammatory potential. The goal of this study was to investigate the anti-inflammatory, anabolic and antioxidant effects of intra-articular application of HA in acute synovitis induced by lipopolysaccharide (LPS) in horses. 24 metacarpophalangeal joints of 12 young horses without musculoskeletal alterations were subjected to lameness examination (Lameness Locator&reg;), radiography and ultrasound. These joints were divided into three groups: a positive control group treated with triamcinolone acetonide (TA) (10mg) and 2 experimental groups treated with either hyaluronic acid of low molecular weight (HALMW) or hyaluronic acid of high molecular weight (HA- HWM). Initially, all joints were injected with 0.25ng of LPS. After an hour, synovial fluid (SF) was collected for cell counting. TA, HA- HWM or HA- LMW treatments were then applied to the joints. After treatment applications, SF was collected at 3 different time points (8, 24 and 48 hours) for cell counts, oxidative burst evaluation, prostaglandin E2 (PGE2) quantification, chondroitin sulfate (CS), HA and molecular weight measurements. Physical examinations, circumference measurements and lameness evaluations were carried out at each time point. The heart and respiratory rate of the animals increased in all groups at 8 hours (p &lt;0.05), that increase was lower in the TA group. Regarding the circumference of the joint the HA-LMW group showed a greater increase at 24 and 48 hours compared to the other groups (p &lt;0.05). The lameness of the HA-HMW group was higher than the TA group at 8 and 24 hours, but similar to the HALMW group. The TA group had a higher nucleated cells count in the SF compared to the HALMW group at 24 hours and 28 hours, and higher than the HA-HMW group at 48 hours. The PGE2 concentration was lower in the TA group in relation to the HA-HMW group at 8 hours, and lower than both groups that received HA at 48 hours (p &lt;0.05). The HA-HMW group showed higher HA concentration at 8 hours than the other groups at 48 hours. However, the TA group showed higher HA concentration than the other groups (p &lt;0.05). Also, at 48 hours the TA group was the one with the lowest percentage of high molecular weight HA (p &lt;0.05). The highest concentration of CS in SF at 24 and 48 hours occurred in the TA group, and it was also observed in the TA group was the only one in which the concentration of CS increased at eight hours compared to baseline. The HA-HMW group showed the lowest concentration of CS at 8 hours (p &lt;0.05). The group treated with HA-LMW showed higher fluorescence intensity at 24 and 48 hours (p &lt;0.05). Although triamcinolone have an superior effect of hyaluronic acid in controlling inflammation, it has catabolic effects on cartilage, shown by increased concentration of CS, and breakage of the HA molecule in synovial fluid. The HA-HMW is recommended for intra-articular therapy in equine joints since it showed less oxidative and catabolic effects

No description available.

A osteocondrite dissecante (OCD) é uma doença que surge nos equinos durante a fase de desenvolvimento sendo caracterizada pela presença de fragmento osteocondral intra-articular. Pouco se sabe sobre a condição da articulação doente em animais mais velhos, principalmente nos casos assintomáticos, que são operados muitas vezes com a finalidade de comercialização posterior ou para impedir a progressão da doença. A finalidade deste estudo, portanto, foi analisar as articulações tíbio-társicas de equinos com idade superior a um ano apresentando OCD na crista intermédia da tíbia, e comparar animais saudáveis (grupo controle) com animais acometidos de OCD nas formas sintomática e assintomática, empregando análise física; contagem de células totais, dosagem de proteína total, análise de glicosaminoglicanos (GAGs) e da proteína oligomérica da matriz cartilagínea (COMP) no líquido sinovial; análise dos GAGs urinários e análise histológica da membrana sinovial e fragmento osteocondral. Os eqüinos utilizados foram divididos em três grupos. No Grupo I foram utilizados eqüinos clinicamente sadios, livres de doença na articulação tíbiotársica. Os Grupos II e III foram constituídos por animais portadores de OCD nas formas sintomática e assintomática respectivamente, atendidos e operados no Serviço de Cirurgia de Grandes Animais do Hospital Veterinário FMVZ-USP. A presença de sinais clínicos esteve mais relacionada com a presença de múltiplos fragmentos do que com a de fragmento osteocondral único, independente de seu tamanho. O sinal clínico mais observado nos animais do Grupo III foi a efusão articular. As principais alterações encontradas no líquido sinovial foram: o aumento na concentração de condroitim sulfato (CS) no Grupo II (P<0,01) e no Grupo III (P<0,001) em relação ao Grupo I; o aumento na concentração de ácido hialurônico associado à diminuição da viscosidade nos animais do Grupo III; e a redução na presença de fragmentos de alto peso molecular associado ao aumento de fragmentos de baixo peso molecular de COMP nos animais dos Grupos II e III. A análise dos GAGs urinários evidenciou aumento na proporção de CS nos animais dos Grupos II e III em relação ao Grupo I. Na análise histológica dos fragmentos osteocondrais foram observadas alterações na integridade da cartilagem articular, associada a proliferação de condrócitos e a redução na presença de proteoglicanos tanto no Grupo II como no Grupo III. As amostras de membrana sinovial do Grupo I apresentaram presença discreta de vilos e sinoviócitos. No Grupo II houve aumento moderado nas vilosidades sinoviais, e na maior parte das amostras avaliadas no Grupo III, além da presença moderada a severa de vilosidades sinoviais, foi observada proliferação intensa de sinoviócitos. Os resultados obtidos no presente estudo demonstram que a OCD na articulação tíbio-társica de equinos com idade superior a um ano representa processo ativo, com degradação da MEC da cartilagem articular, independente da presença de sinais clínicos, e que o tratamento cirúrgico é indicado, mesmo em animais assintomáticos, buscando interromper o processo de degradação cartilagínea e prevenir o desenvolvimento de doença articular degenerativa, particularmente em equinos que irão iniciar treinamento atlético esportivo. / Osteochondritis dissecans (OCD) is an orthopedic disease that appears in foals during growth phase and is characterized by the presence (occurrence???) of an osteochondral fragment in the articular space. There are few studies in the literature concerning the follow up of the disease in adult horses, mainly those without clinical signs, which are submitted to surgical treatment to commercial proposes or to prevent the progression of the disease. The objective of the present study was to analyze tibiotarsal joints of horses older than one year with OCD in the intermediate ridge of distal tibia and compare healthy animals (control group) with OCD horses, either with or without clinical signs. Synovial fluid was analyzed to total cell count, total protein concentration, and cartilage oligomeric matrix protein (COMP) fragmentation. The synovial fluid and urine glycosaminoglycans (GAGs) were evaluated. The synovial membrane and osteochondral fragment were analyzed by istological assessment. Horses were divided in three groups: healthy horses without joint disease (Group I), horses with OCD without clinical sings (Group II) and horses with OCD and clinical signs (Group III). Horses of Groups II and III were admitted to the Large Animal Surgery Session of the Veterinary Hospital FMVZ USP. The presence of clinical signs was more related with multiple articular fragments than with one fragment, irrespective of the size. The most common clinical sign observed in Group III was joint effusion. The main changes in synovial fluid were: increase in chondroitin sulfate (CS) in Groups II (P<0,01) and III (P<0,001) when compared with Group I; increase in hyaluronic acid (HA) concentration associated with decrease in the viscosity in Group III; and the decrease of COMP fragments of higher molecular weight associated with increase of fragments of low molecular weight in Group II and III. The proportion of urinary CS was increased in Group II and III when compared with Group I. Alterations in the articular cartilage integrity associated with chondrocytes proliferation and loss of proteoglycan were observed in the histological analysis of the osteochondral fragments. In Group I the presence of synovial vilos and synoviocytes in the synovial membrane samples was discreet. In Group II samples there were a moderate increase in the presence of synovial vilos and synoviocytes. In almost samples analyzed in Group III the presence of synovial vilos was moderate to severe and synoviocytes proliferation was intense. Our results indicate that OCD in tibiotarsal joint of horses older than one year represents an active process, with degradation of the extra cellular matrix of the articular cartilage, regardless the presence of clinical signs, indicating surgical treatment, even in assymptomatic horses, avoiding the progression of cartilage degradation process and preventing the development of degenerative joint disease, mainly in horses that are going to begin athletic training.

A pele tem como principal função manter o isolamento do meio interior com o exterior. Quando esse órgão sofre uma lesão o organismo tenta reparar essa agressão ao promover a substituição do tecido por meio de um processo complexo dividido em fases. O ácido hialurônico está presente em todas as fases dessa reparação tecidual. Contudo a sua presença em adultos reduz cerca de 50% comparado ao recém-nascido, o que reduz a regeneração tecidual drasticamente. Este trabalho teve como objetivo analisar o efeito de uma pomada utilizando veículo comercial composto de lanolina e vaselina manipulada com ácido hialurônico, extraído da crista do frango, no processo cicatricial de feridas cutâneas em dorso de ratos. Para atingir o objetivo desse trabalho o ácido hialurônico foi extraído e purificado da crista do frango e foi acrescido ao veículo comercial composto de 10% lanolina e 90% vaselina. A pomada obtida foi analisada por meio de um reômetro de tensão controlada. Para os estudos in vivo, foram separados aleatoriamente 28 animais em 4 grupos. Em cada animal do grupo efetuou-se duas lesões em seu dorso, uma para a aplicação da pomada, com ou sem ácido, e a outra lesão para controle. A pomada foi aplicada diariamente durante 7 e 14 dias conforme protocolo estabelecido. Os resultados mostraram que as propriedades viscoelásticas da pomada, quando acrescentou o ácido hialurônico, tiveram pequenas alterações, porém não de forma significativa, o que possibilitou sua utilização. Como resultados dos testes in vivo, o grupo tratado com a pomada com ácido hialurônico durante 7 dias, obteve menor média da área da lesão com 0,07 cm² contra 0,11 cm² do seu controle, 0,09 cm² do grupo tratado com a pomada placebo e 0,10 cm² do controle do placebo. Ainda, os grupos tratados com a pomada com AH durante 7 e 14 dias obtiveram uma maior média na porcentagem de colágeno, e o grupo tratado com a pomada com AH por 14 dias, resultou em uma melhor cicatrização da lesão. / The skin has as main function to maintain the insulation of the inner tissues of the body from the external environment. When this organ is injured, the organism attempts to repair the damage with a tissue replacement, in a complex process divided into several stages. Hyaluronic acid is present in all phases of this process, although its expression in adults is reduced to approximately 50% compared to newborn individuals, leading to drastically reduced tissue regeneration. This study aimed to analyze the effect of an ointment composed of a commercial vehicle of lanolin and vaseline, manipulated with chicken crest-extracted hyaluronic acid, in skin wounds healing in rats. Hyaluronic acid was extracted and purified from chicken crests, and the extract was added to the commercial vehicle composed of 10% lanolin and 90% vaseline. The obtained ointment was analyzed using a controlled stress rheometer. For in vivo studies, 28 rats were randomly separated into four groups. Each animal was injured twice in the back, one lesion destined to the ointment application, and the other lesion as a control injury. The ointment was applied for 7 to 14 days according to the protocol established. Results showed that the viscoelastic properties of the ointment mixed with hyaluronic acid changed slightly, but not significantly, allowing its use in vivo. The group of animals treated with the ointment for seven days showed lower average lesion area, with 0.07 cm² against the control area of 0.11 cm². The animals treated with a placebo ointment showed an average lesion area of 0.09 cm² against a 0.10 cm² area of controls. The animals treated with the ointment with hyaluronic acid for 7 and 14 days had a higher average percentage of collagen, and the group treated for 14 days exhibited an improved wound healing.

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.

In this work, the synthesis of biopolymer-based hydrogel networks with defined architecture is presented. In order to obtain materials with defined properties, the chemoselective copper-catalyzed azide-alkyne cycloaddition (or Click Chemistry) was used for the synthesis of gelatin-based hydrogels. Alkyne-functionalized gelatin was reacted with four different diazide crosslinkers above its sol-gel transition to suppress the formation of triple helices. By variation of the crosslinking density and the crosslinker flexibility, the swelling (Q: 150-470 vol.-%;) and the Young’s and shear moduli (E: 50 kPa - 635 kPa, G’: 0.1 kPa - 16 kPa) could be tuned in the kPa range. In order to understand the network structure, a method based on the labelling of free functional groups within the hydrogel was developed. Gelatin-based hydrogels were incubated with alkyne-functionalized fluorescein to detect the free azide groups, resulting from the formation of dangling chains. Gelatin hydrogels were also incubated with azido-functionalized fluorescein to check the presence of alkyne groups available for the attachment of bioactive molecules. By using confocal laser scanning microscopy and fluorescence spectroscopy, the amount of crosslinking, grafting and free alkyne groups could be determined. Dangling chains were observed in samples prepared by using an excess of crosslinker and also when using equimolar amounts of alkyne:azide. In the latter case the amount of dangling chains was affected by the crosslinker structure. Specifically, 0.1% of dangling chains were found using 4,4’-diazido-2,2’-stilbene-disulfonic acid as cosslinker, 0.06% with 1,8-diazidooctane, 0.05% with 1,12-diazidododecane and 0.022 % with PEG-diazide. This observation could be explained considering the structure of the crosslinkers. During network formation, the movements of the gelatin chains are restricted due to the formation of covalent netpoints. A further crosslinking will be possible only in the case of crosslinker that are flexible and long enough to reach another chain. The method used to obtain defined gelatin-based hydrogels enabled also the synthesis of hyaluronic acid-based hydrogels with tailorable properties. Alkyne-functionalized hyaluronic acid was crosslinked with three different linkers having two terminal azide functionalities. By variation of the crosslinking density and crosslinker type, hydrogels with elastic moduli in the range of 0.5-3 kPa have been prepared. The variation of the crosslinking density and crosslinker type had furthermore an influence also on the hydrolytic and enzymatic degradation of gelatin-based hydrogels. Hydrogels with a low crosslinker amount experienced a faster decrease in mass loss and elastic modulus compared to hydrogels with higher crosslinker content. Moreover, the structure of the crosslinker had a strong influence on the enzymatic degradation. Hydrogels containing a crosslinker with a rigid structure were much more resistant to enzymatic degradation than hydrogels containing a flexible crosslinker. During hydrolytic degradation, the hydrogel became softer while maintaining the same outer dimensions. These observations are in agreement with a bulk degradation mechanism, while the decrease in size of the hydrogels during enzymatic degradation suggested a surface erosion mechanism. Because of the use of small amount of crosslinker (0.002 mol.% 0.02 mol.%) the networks synthesized can still be defined as biopolymer-based hydrogels. However, they contain a small percentage of synthetic residues. Alternatively, a possible method to obtain biopolymer-based telechelics, which could be used as crosslinkers, was investigated. Gelatin-based fragments with defined molecular weight were obtained by controlled degradation of gelatin with hydroxylamine, due to its specific action on asparaginyl-glycine bonds. The reaction of gelatin with hydroxylamine resulted in fragments with molecular weights of 15, 25, 37, and 50 kDa (determined by SDS-PAGE) independently of the reaction time and conditions. Each of these fragments could be potentially used for the synthesis of hydrogels in which all components are biopolymer-based materials. / In dieser Arbeit wird die Synthese Biopolymer-basierter Hydrogelnetzwerke mit definierter Architektur beschrieben. Um Materialien mit definierten und einstellbaren Eigenschaften zu erhalten, wurde die chemoselektive Kupferkatalysierte Azid-Alkin-Cycloadditionsreaktion (auch als Click-Chemie bezeichnet) für die Synthese Gelatine-basierter Netzwerke eingesetzt. Alkin-funktionalisierte Gelatine wurde mit vier verschiedenen Diazid-Quervernetzern oberhalb der Gel-Sol-Übergangstemperatur umgesetzt, um die Formierung tripelhelikaler Bereiche durch Gelatineketten zu unterdrücken. Durch Variation der Menge an Quervernetzer (und damit der Netzdichte) sowie der Länge und Flexibilität der Quervernetzer konnten u.a. die Quellung (Q: 150-470 vol.-%) sowie der Young’s - und Schermodul im kPa Bereich eingestellt werden (E: 50 kPa - 635 kPa, G’: 0.1 kPa - 16 kPa). Um die Netzwerkarchitektur zu verstehen, wurde eine Methode basierend auf dem Labeln unreagierter Azid- und Alkingruppen im Hydrogel entwickelt. Die Gelatine-basierten Hydrogele wurden mit Alkin-funktionalisiertem Fluorescein umgesetzt, um freie Azidgruppen zu detektieren, die bei einem Grafting entstehen. Darüber hinaus wurden die Hydrogele mit Azid-funktionalisiertem Fluorescein reagiert, um die Menge an freien Alkingruppen zu bestimmen, die zudem potentiell für die Anbindung bioaktiver Moleküle geeignet sind. Quervernetzung, Grafting, und die Anzahl freier Alkingruppen konnten dann mit Hilfe der konfokalen Laser Scanning Mikroskopie und der Fluoreszenzmikroskopie qualitativ und quantitativ nachgewiesen werden. Gegraftete Ketten wurden in Systemen nachgewiesen, die mit einem Überschuss an Quervernetzer hergestellt wurden, entstanden aber auch beim Einsatz äquimolarer Mengen Alkin- und Azidgruppen. Im letzteren Fall wurde in Abhängigkeit von der Struktur des Diazids unterschiedliche Anteile gegrafteter Ketten festgestellt. 0.1 mol-% von gegrafteten Ketten wurden für 4,4’-Diazido-2,2’-stilbendisulfonsäure gefunden, 0.06 mol-% für 1,8-Diazidooktan, 0.05 mol% für 1,12-diazidododecan und 0.022 mol-% für PEG-Diazid. Diese Beobachtung kann durch die unterschiedliche Flexibilität der Vernetzer erklärt werden. Während der Netzwerkbildung werden die Bewegungen der Gelatineketten eingeschränkt, so dass kovalente Netzpunkte nur erhalten werden können, wenn der Vernetzer lang und flexibel genug ist, um eine andere Alkingruppe zu erreichen. Die Strategie zur Synthese von Biopolymer-basierten Hydrogelen mit einstellbaren Eigenschaften wurde von Gelatine- auf Hyaluronsäure-basierte Gele übertragen. Alkin-funktionalisierte Hyaluronäure wurde mit drei verschiedenen Diaziden quervernetzt, wobei Menge, Länge, und Flexibilität des Quervernetzers variiert wurden. In dieser Weise wurden sehr weiche Hydrogele mit E-Moduli im Bereich von 0.5-3 kPa hergestellt. Die Variation der Vernetzungsdichte und des Vernetzertyps beeinflusste weiterhin den hydrolytischen und enzymatischen Abbau der Hydrogele. Hydrogele mit einem geringerem Anteil an Quervernetzer wurden schneller abgebaut als solche mit einem höheren Quervernetzeranteil. Darüber hinaus konnte gezeigt werden, dass Hydrogele mit Quervernetzern mit einer rigiden Struktur deutlich langsamer degradierten als Hydrogele mit flexibleren Quervernetzern. Während des hydrolytischen Abbau wurden die Materialien weicher, behielten aber ihre Form bei, was mit einem Bulk-Abbau-Modell übereinstimmt. Während des enzymatischen Abbaus hingegen änderten sich die Materialeigenschaften kaum, jedoch wurden die Proben kleiner. Diese Beobachtung stimmt mit einem Oberflächenabbaumechanismus überein. Da in allen vorgestellten Systemen nur eine kleine Menge synthetischer Vernetzer eingesetzt wurde (0.002 – 0.02 mol%), können die Materialien noch als Biopolymer-basierte Materialien klassifiziert werden. Jedoch enthalten die Materialien synthetische Abschnitte. In Zukunft könnte es interessant sein, einen Zugang zu Materialien zu haben, die ausschließlich aus Biopolymeren aufgebaut sind. Daher wurde der Zugang zu Biopolymer basierten Telechelen untersucht, die potentiell als Vernetzer dienen können. Dazu wurden durch die kontrollierte Spaltung von Gelatine mit Hydroxylamin Gelatinefragmente mit definiertem Molekulargewicht hergestellt. Hydroxalamin reagiert unter Spaltung mit der Amidbindung zwischen Asparagin und Glycin, wobei Aspartylhydroxamate und Aminoendgruppen entstehen. Die Reaktion von Gelatine mit Hydroxylamin ergab Fragmente mit Molekulargewichten von 15, 25, 37, und 50 kDa (bestimmt mit SDS-PAGE), und die Formierung dieser Fragmente war unabhängig von den weiteren Reaktionsbedingungen und der Reaktionszeit. Jedes dieser Fragmente kann potentiell für die Synthese von Hydrogelen eingesetzt werden, die ausschließlich aus Biopolymeren bestehen.

This thesis demonstrated the effects of exogenous stimuli on engineered articular cartilage constructs and elucidated mechanisms underlying the responses to these agents. In particular, a series of studies detailed the effects of chondroitinase-ABC (C-ABC), hyaluronic acid (HA), and TGF-β1 on the biochemical and biomechanical properties of self-assembled articular cartilage. Work with C-ABC showed that this catabolic agent can be employed to improve the tensile properties of constructs. When constructs were cultured for 6 weeks, treating with C-ABC at 2 weeks enhanced the tensile stiffness. Furthermore, treating at 2 and 4 weeks synergistically increased tensile properties and allowed compressive stiffness to recover to control levels. Another study showed that combining C-ABC and TGF-β1 synergistically enhanced the biochemical and biomechanical properties of neotissue. Microarray analysis demonstrated that TGF-β1 increased MAPK signaling in self-assembled neocartilage whereas C-ABC had minimal effects on gene expression. SEM analysis showed that C-ABC increased collagen fibril diameter and fibril density, indicating that C-ABC potentially acts via a biophysical mechanism. Constructs treated with C-ABC and TGF-β1 also showed stability and maturation in vivo , exhibiting a tensile stiffness of 3.15±0.47 MPa compared to a pre-implantation stiffness of 1.95±0.62 MPa. To assess the response to HA application, studies were conducted to optimize HA administration and examine its effects in conjunction with TGF-β1. Applying HA increased the compressive stiffness 1-fold and increased GAG content by 35%, with these improvements depending on HA molecular weight, application commencement time, and concentration. Microarray and PCR analyses showed that HA also influenced genetic signaling, up-regulating multiple genes associated with the TGF-β1 pathway. In addition to genetic effects, the enhanced GAG retention due to HA treatment could increase the fixed charge density of the matrix and thereby increase resistance to compressive loading. Additive effects were observed when HA was applied in conjunction with TGF-β1, with the combined treatment increasing compressive stiffness and GAG content by 150% and 65%, respectively. In general, results demonstrated mechanisms underlying C-ABC, HA, and TGF-β1 treatments and showed how these agents can be applied to improve cartilage regeneration efforts.

Immune cells such as neutrophils and monocytes enter tissues after tissue damage and clear cell debris to allow repair cells such as fibroblasts to close the wound. Monocytes also differentiate into fibroblast-like cells called fibrocytes to mediate wound healing, similar to fibroblasts. However, in abnormal wound healing such as acute respiratory distress syndrome (ARDS) and fibrosing diseases, the accumulation of immune cells such as neutrophils or fibrocytes become detrimental to health. In ARDS, neutrophils accumulate in the lungs and causes additional damage by producing reactive oxygen species (ROS). In fibrosing diseases, increased fibrocyte differentiation is one of the causes that increase extracellular matrix deposition, which leads to severe scar tissue build up. Since there are no effective treatments for ARDS or fibrosing diseases, understanding the regulation of neutrophil activation or fibrocyte differentiation could be helpful to develop new effective therapies. The Gomer lab has found several factors that either promote or inhibit fibrocyte differentiation. The pro-fibrotic cytokines such as IL-4 and IL-13 potentiate fibrocyte differentiation while the plasma protein serum amyloid P (SAP), crosslinked IgG, and the pro-inflammatory cytokines IFN-γ and IL-12 inhibit fibrocyte differentiation. In this thesis, I have now shown that additional factors such as toll-like receptor 2 (TLR2) agonists and low molecular weight hyaluronic acid (LMWHA) inhibit fibrocyte differentiation, while high molecular weight hyaluronic acid (HMWHA) potentiate fibrocyte differentiation. The accumulation of neutrophils in the lungs is one of the major factors that debilitate the health of a patient in ARDS. Since neutrophils have Fc receptors, I examined the effect of SAP on neutrophil spreading, adherence, activation, and accumulation. SAP inhibits neutrophil spreading induced by cell debris and TNF-α induced adhesion, but SAP is unable to have any effect on classic neutrophil adhesion molecules or the production of hydrogen peroxide. SAP inhibits neutrophil accumulation in the lungs of bleomycin-injured mice. There is an exciting possibility of using SAP as a therapeutic agent to treat ARDS.

In this study we fabricated free standing multilayer films of polyelectrolyte complexes for potential use in tissue engineering of corneal stroma by using the layer-by-layer (LbL) approach. In the formation of these LbL films negatively charged, photocrosslinkable (methacrylated) hyaluronic acid (MA-HA) was used along with polycations polyethyleneimine (PEI) and poly(L-lysine) (PLL). Type I collagen (Col) was blended in with PLL for improving the water absorption and cell attachment properties of the films. It was shown that the LbL films could be easily peeled off from glass substrates due to the photocrosslinking of one of the LbL components, the hyaluronic acid. Film growth and composition were monitored with FTIR-ATR. Heights of peaks at 3383 cm-1, and 2958 cm-1increased along with the bilayer number confirming the polymer build-up. Film integrity and thickness were investigated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Films thicker than 5 bilayers (BLs) were found to be uniform in appearance and 10 BL (PEI/MeHA) films were calculated to be ca. 6 &mu / m thick. Atomic force microscopy (AFM) revealed that as the number of BLs increased, surface roughness decreased. Activity of methacrylated hyaluronic acid was shown by the increased resistance of photocrosslinked multilayer films against hydrolysis by hyaluronidase. Patterns could be created on the films by photocrosslinking further proving that the crosslinking step is successful. Since the ultimate goal was to construct a corneal stroma PEI/MA-HA films were tested with corneal stroma cells, keratocytes. Cell proliferation on PEI/MA-HA films was quite poor in comparison to TCPS. In order to improve the cell adhesion the tests were repeated with PLL/MA-HA. Collagen was added to decrease the hydrophilicity and introduce cell adhesion sequences (Arg-Gly-Asp, RGD) to improve cell proliferation on the films and thus PLL+Col/MA-HA films were also tested. Introduction of collagen to the PLL/MA-HA films was found to decrease water retention of the multilayer films and improve cell viability and proliferation. Col+PLL/MA-HA LbL thus appear to be a promising platform for tissue engineering, especially of corneal stroma.