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Collagen Solution (collagen + solution)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Tissue Engineered Artificial Skin Composed of Dermis and Epidermis

ARTIFICIAL ORGANS, Issue 1 2000
Eun Kyung Yang
Abstract: We made an artificial skin comprised of a stratified layer of keratinocytes and a dermal matrix with a type I collagen containing fibroblasts. In this work, we showed keratinocyte behavior under primary culture, gel contractions varying with concentration of collagen solution, and cell growth plots in the collagen gel. The optimum behavior of dermal equivalent could be obtained using 3.0 mg/ml collagen solution and attached gel culture. The attached gel culture had a jumping effect of growth factor on cell growth at the lag phase. To develop the artificial skin, 1× 105 cells/cm2 of keratinocytes were cultured on the dermal equivalent at air-liquid interface. Finally, to overcome the problem that artificial skin of collagen gel was torn easily during suturing of grafting, we prepared histocompatible collagen mesh and attached the mesh to the bottom of the gel. Cultured artificial skins were successfully grafted onto rats. [source]

Neurite growth in 3D collagen gels with gradients of mechanical properties

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009
Harini G. Sundararaghavan
Abstract We have designed and developed a microfluidic system to study the response of cells to controlled gradients of mechanical stiffness in 3D collagen gels. An ,H'-shaped, source,sink network was filled with a type I collagen solution, which self-assembled into a fibrillar gel. A 1D gradient of genipin,a natural crosslinker that also causes collagen to fluoresce upon crosslinking,was generated in the cross-channel through the 3D collagen gel to create a gradient of crosslinks and stiffness. The gradient of stiffness was observed via fluorescence. A separate, underlying channel in the microfluidic construct allowed the introduction of cells into the gradient. Neurites from chick dorsal root ganglia explants grew significantly longer down the gradient of stiffness than up the gradient and than in control gels not treated with genipin. No changes in cell adhesion, collagen fiber size, or density were observed following crosslinking with genipin, indicating that the primary effect of genipin was on the mechanical properties of the gel. These results demonstrate that (1) the microfluidic system can be used to study durotactic behavior of cells and (2) neurite growth can be directed and enhanced by a gradient of mechanical properties, with the goal of incorporating mechanical gradients into nerve and spinal cord regenerative therapies. Biotechnol. Bioeng. 2009;102: 632,643. © 2008 Wiley Periodicals, Inc. [source]

Dermal contributions to UVA-induced oxidative stress in skin

PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 2 2009
Hao Ou-Yang
Background: When the skin is exposed to solar irradiation, UVA photons interact with skin tissues and induce excessive reactive oxygen species, resulting in oxidative stress. We have shown in a previous study that in vivo chemiluminescence's measurement can be used to evaluate the overall level of UVA-induced oxidative stress in human skin. However, the origin of the observed chemiluminescence signals remains unclear. Methods: UVA-induced chemiluminescence measurements were conducted: (a) in vitro on collagen solutions and solid collagen sheet preparations, (b) ex vivo on human and mouse skin biopsies, and (c) in vivo on human skin of various constitutive pigmentation levels. Fluorescence was measured on collagen in vitro as well as on skin for the in vivo experiments. Results: We found in the in vitro experiments that UVA-induced chemiluminescence increases with the presence of collagen cross-links. When dermal sides were exposed to UVA irradiation, both mouse and human skin biopsies demonstrated significantly higher chemiluminescence levels than when epidermal sides were exposed to UVA. The amount of collagen cross-links decreases slightly following UVA exposure, as shown both by in vivo fluorescence and by UVA-induced chemiluminescence. Finally, there was less measurable UVA-induced chemiluminescence in dark skin compared with light pigmented skin in vivo. Conclusions: The dermis is very sensitive to UVA photons. Dermal cross-links are potential UVA sensitizers. The oxidative stress induced by UVA and measured by chemiluminescence may largely be attributed to the breakdown of dermal collagen cross-links. [source]

Effect of UV irradiation on type I collagen fibril formation in neutral collagen solutions

PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 3 2001
Julian M. Menter
Background: Collagens have the well-known ability to spontaneously self-associate to form fibrils at physiological temperature and neutral pH in vitro and in vivo. Because solar UV may photochemically alter collagen, the kinetics of fibril formation may be modified. Thus, we have begun a systematic study of the effect of various UV wavebands on fibril formation. Methods: Citrate-soluble calf skin collagen (Elastin Products) was dissolved at 0.05% in 0.5 M HOAc, dialyzed over 2 days into two changes of 0.0327 M phosphate buffer, pH 7.0 at 4 °C, and centrifuged at 48 000×g. Photolysis was carried out at 4 °C with either (a) UVC (UVG,11 lamp), (b) filtered solar-simulating radiation (SSR) or UVA (SSR or UVL,21 lamp filtered with a 2.0 mm Schott WG 345 filter). Gelation was commenced by rapidly raising the temperature from 8 °C to 33 °C. Nucleation and growth were followed by turbidimetric measurements at 400 nm. Results: UVC radiation (0,17.3 J/cm2) resulted in a dose-dependent decrease in the rate of fibril growth. Under these conditions, concomitant collagen cross-linking and degradation occurred. Fibril nucleation, a prerequisite for growth, was rapid (threshold , 2 min) and was not affected by UVC, UVA or SSR. SSR (0,1320 J/cm2) caused a small decrease in growth rate and in the degree of fibril formation. UVA radiation (0,1080 J/cm2) had a similar effect. "Direct" photochemical damage thus paralleled absorption via various collagen chromophores, with UVC>SSR,UVA. The presence of riboflavin (RF) resulted in ground-state interactions that markedly altered both nucleation and growth kinetics. Irradiation with 29.6 J/cm2 UVA in the presence of RF photosensitizer caused relatively minor additional changes in fibrillation kinetics. Conclusions: These results collectively indicate that fibril formation is markedly dependent on specific ground state interactions and relatively insensitive to nonspecific UV damage. On the other hand, fibrils thus formed from photochemically altered collagen may have altered structural properties that could have subtle but unfavorable effects on the local dermal milieu in vivo. Notwithstanding, the relative insensitivity of fibrillogenesis to non-specific photochemical damage probably represents a favorable adaptation, overall, which tends to conserve the mechanical integrity of the skin. [source]