Photochemical bonding of epithelial cell-seeded collagen lattice to rat muscle layer for esophageal tissue engineering - A pilot study

The photochemical bonding of cell-seeded collagen lattice to muscle layer in rat, was investigated for esophageal tissue engineering. The esophageal epithelial cells of the rat were seeded on collagen lattice and together with the latissimus dorsi muscle layer, were exposed to a photosensitizer rose Bengal at the bonding surface. The photochemical bonding was found to significantly increase the adherence at the bonding interface without compromising the cell viability. The results show integration of the collagen lattice with the muscle layer at the bonding interface although the subsequent surgical manipulation disturbed the integration at some region.published_or_final_versio

Skin Cornification Proteins Provide Global Link between ROS Detoxification and Cell Migration during Wound Healing

Wound healing is a complex dynamic process characterised by a uniform flow of events in nearly all types of tissue damage, from a small skin scratch to myocardial infarction. Reactive oxygen species (ROS) are essential during the healing process at multiple stages, ranging from the initial signal that instigates the immune response, to the triggering of intracellular redox-dependent signalling pathways and the defence against invading bacteria. Excessive ROS in the wound milieu nevertheless impedes new tissue formation. Here we identify small proline-rich (SPRR) proteins as essential players in this latter process, as they directly link ROS detoxification with cell migration. A literature-based meta-analysis revealed their up-regulation in various forms of tissue injury, ranging from heart infarction and commensal-induced gut responses to nerve regeneration and burn injury. Apparently, SPRR proteins have a far more widespread role in wound healing and tissue remodelling than their established function in skin cornification. It is inferred that SPRR proteins provide injured tissue with an efficient, finely tuneable antioxidant barrier specifically adapted to the tissue involved and the damage inflicted. Their recognition as novel cell protective proteins combining ROS detoxification with cell migration will provide new venues to study and manage tissue repair and wound healing at a molecular level

Plasma Membrane Integrity and Survival of Melanoma Cells After Nanosecond Laser Pulses

Circulating tumor cells (CTCs) photoacoustic detection systems can aid clinical decision-making in the treatment of cancer. Interaction of melanin within melanoma cells with nanosecond laser pulses generates photoacoustic waves that make its detection possible. This study aims at: (1) determining melanoma cell survival after laser pulses of 6 ns at λ = 355 and 532 nm; (2) comparing the potential enhancement in the photoacoustic signal using λ = 355 nm in contrast with λ = 532 nm; (3) determining the critical laser fluence at which melanin begins to leak out from melanoma cells; and (4) developing a time-resolved imaging (TRI) system to study the intracellular interactions and their effect on the plasma membrane integrity. Monolayers of melanoma cells were grown on tissue culture-treated clusters and irradiated with up to 1.0 J/cm2. Surviving cells were stained with trypan blue and counted using a hemacytometer. The phosphate buffered saline absorbance was measured with a nanodrop spectrophotometer to detect melanin leakage from the melanoma cells post-laser irradiation. Photoacoustic signal magnitude was studied at both wavelengths using piezoelectric sensors. TRI with 6 ns resolution was used to image plasma membrane damage. Cell survival decreased proportionally with increasing laser fluence for both wavelengths, although the decrease is more pronounced for 355 nm radiation than for 532 nm. It was found that melanin leaks from cells equally for both wavelengths. No significant difference in photoacoustic signal was found between wavelengths. TRI showed clear damage to plasma membrane due to laser-induced bubble formation

Enhancement of porcine skin graft adherence using a light-activated process

Background. Skin grafts are widely used in plastic surgery, and burn and ulcer wound management. Rapid and sustained adherence, the ability to resist shear stress, and a void-free surface-to-surface contact are critical to the success of graft survival. Mechanical and adhesive fixation aids are currently used to achieve graft adherence and they are not free of problems. Photochemical tissue bonding (PTB) is an emerging laser technique with numerous applications in surgical specialties. In the current study, PTB was investigated as a means to bond and enhance the adherence of skin grafts. Methods. In this study, ex vivo porcine skin grafts treated with a photosensitizing dye, rose bengal (RB), were approximated dermis-to-dermis and irradiated with visible light from an argon laser at 514 nm. The adherence of the skin grafts was measured immediately after irradiation. Dose-response relationships between the light and the dye with adherence of the grafts were established. The surface temperature of the skin under irradiation was monitored and the viability of the skin cells in the grafts was also measured. Results. Results showed that the skin graft adherence was RB dose-dependent in a statistically significant manner with the concentration of RB reaching a plateau value of 0.1% (w/v) of RB. Graft adhesion also increased with laser fluence up to 504 J/cm2 in the presence of 0.1% RB. No fluence dependence was observed in the absence of RB. Thermogram results showed that the maximal surface temperature during irradiation was less than 40°C. Histological investigation and trypan blue exclusion assays demonstrated that skin grafts retained cell viability and collagen organization after PTB. Conclusion. This ex vivo study demonstrates that PTB using argon laser irradiation and RB enhances skin graft adherence by forming dermal-dermal bonding. The increase in adherence is a function of the concentration of RB and the laser fluence. The results also suggest that the PTB is a potentially safe procedure because it is nonthermal in nature and does not significantly affect the skin cell viability. © 2002 Elsevier Science (USA).link_to_subscribed_fulltex

Two-photon optical biopsy of thick tissues

Two-photon optical biopsy has been performed in human and mouse skin. Both cellular and extracellular tissue components have been visualized based on endogenous fluorescence

Minimal heating dose: a novel biological unit to measure infrared irradiation

BACKGROUND AND OBJECTIVE: Infrared (IR) rays, which comprise approximately 40% of the solar radiation which reaches the earth's surface, have received relatively scant attention. As no standard method has yet been agreed upon for the biological evaluation of IR irradiation, the objective of this study is to suggest a new unit for IR irradiation. METHODS: The skin temperature of 38 Korean volunteers was measured after IR irradiation with varying irradiance. RESULTS: Skin temperature after IR irradiation at an irradiance of 2.02 W/cm2 remained unchanged after 652+/-22 s (mean+/-standard error), which corresponds, in this case, to a total radiation dose of IR 1317.3+/-44.84 J/cm2. This quantity was designated as the minimal heating dose (MHD). We also demonstrated that MHD increased with increasing IR irradiance at lower IR irradiance (1.17 and 2.02 W/cm2), whereas it became constant at higher irradiance (2.87 and 3.22 W/cm2). No statistically significant correlations were detected between MHD and volunteers' ages, erythema index, or melanin index. CONCLUSION: We propose 'MHD' as a biological unit for the measurement of IR irradiation.This work was supported by a grant of the Korea Health 21 R&D Project (02-PJ1-PG1-CH10-0001), Ministry of Health & Welfare, Republic of Korea, and by a research agreement with Amore-Pacific Corporation