No description available.

No description available.

Thesis--Copenhagen. / Published also without thesis note. "Résumé" (in Danish): p. [311]-315. Bibliography: p. [273]-305.

Airway remodeling characteristic of asthma involves structural changes altering the elasticity of the airway smooth muscle (ASM) microenvironment potentially leading to ASM dysfunction. This effect of matrix stiffness was investigated using a physiologically relevant 3D culture model. Characterisation of microtissue responses with regards to contractile function and gene expression were studied varying the ECM stiffness and through stimulation with epithelial cell (AEC) conditioned media. ASM microtissues were fabricated under four different loading conditions and the matrix stiffness was increased by crosslinking through non-enzymatic glycation and increasing the collagen density. Function was assessed through the use of pharmacological agents and by imaging microcantilever deflection, used to calculate force generation. Crosslinking microtissues enhanced contractile function in response to agonists; however, this effect disappeared in microtissues tethered to stiff microcantilevers suggesting a limit of contractility within this model. Remarkably, there was a differential response in ASM function where increasing the collagen density (stiffness) significantly attenuated function. Additionally, contractility was significantly enhanced when chronically stimulated with AEC media. ASM tissue in 3D culture is responsive to the microenvironment stiffness and increases contractility in the presence of a stiffer ECM. This could occur with thickening of the airway wall in asthma. Decreased contractility with increased collagen density is in agreement with previous studies where it was shown that type I collagen is pro-proliferative and attenuates the contractile phenotype. We show the models ability to quantitatively demonstrate the impact of biomechanical cues on ASM function providing provides new ways to elucidate the mechanisms of cellular remodeling.

Experimental studies indicate that culturing chondrocytes on biodegradable polymeric scaffolds may yield“engineered" cartilage for the replacement of tissue lost to injury or diseases such as osteoarthritis. A method of estimating the outcome of cell-polymer cultures would aid in the design and evaluation of engineered tissue for therapeutic use. The goals of this project were to develop, validate, and apply first-generation mathematical models that describe the kinetics of extracellular matrix (ECM) deposition and scaffold degradation in cell-polymer constructs cultured in vitro. The ECM deposition model is based on a product-inhibition mechanism and predicts an asymptotic, exponential increase in the concentration of ECM molecules found in cartilage, including collagen and glycosaminoglycans (GAG). The scaffold degradation model uses first-order kinetics to describe the hydrolysis of biodegradable polyesters in systems not limited by diffusion. Each model was fit to published data describing the accumulation of GAG and collagen, as well as the degradation of poly glycolic acid (PGA) and poly lactic acid (PLA), respectively. As experimental validation, cell-polymer constructs (n = 24) and unseeded scaffolds (n = 24) were cultured in vitro, and biochemical assays for GAG and collagen content, as well as scaffold mass measurements, were performed at 1, 2, 4, 6, 8, or 10 weeks of culture (n = 8 per time point). The mathematical models demonstrate a moderate to strong goodness of fit with the previously published data and our experimental results (R2=0.75-0.99). These models were also combined to predict the temporal evolution of total construct mass with reasonable accuracy (30% RMS deviation). In ongoing work, estimates of biochemical composition derived from these models are being proposed to predict the mechanical properties and functionality of the constructs. This modeling scheme may be useful in elucidating more specific mechanisms governing ECM accumulation. Given their potential predictive power, these models may also reduce the cost of performing long-term culture experiments.

No description available.

No description available.

No description available.

Donor cells for nuclear transfer are usually prepared by the culture of fresh tissue. However, animal carcasses are sometimes frozen without cryoprotectants and if it were possible to obtain live cells from carcasses (tissue) preserved in this manner, it could be very beneficial in nuclear transfer cloning of trophy or extinct animals. This study tested the hypothesis that tissue samples of skin, muscle, and oral mucosa could be cryopreserved without cryoprotection. The tissue samples were taken from euthanized goats and placed into a -20°C freezer for varying lengths of time. The samples were thawed by two different methods. One method was in 37°C water bath and the other was on ice, thawing to room temperature from 1°C to 25°C. The samples were then processed and placed into an incubator to evaluate cell growth. Skin samples frozen for up to 34 days obtained cell growth to confluency and the cells were then cryopreserved with cryoprotectant. The cells were able to tolerate the potentially lethal effects of ice nucleation and dehydration brought about by ice formation and colligative factors. Although this method of cryopreservation has been shown to yield growth of cells that might be useful for nuclear transfer cloning, it is not the recommended method to cryopreserve tissues if cryoprotectants are available or if only short term storage is needed. These procedures would be especially useful when a precious animal dies unexpectedly and cryoprotectant is not available and the sample can not be processed before 10 days.

Thesis (D.Eng.)--Cleveland State University, 2009. / Abstract. Title from PDF t.p. (viewed on Jan. 13, 2010). Includes bibliographical references (p. 139-151). Available online via the OhioLINK ETD Center and also available in print.