Toward the next generation tissue engineering, we have developed a novel technology called “cells sheet engineering”. By covalently grafting a temperature-responsive polymer, temperature-responsive culture surfaces are prepared in order to harvest cell sheets non-invasively without proteolytic enzymes such as trypsin. Since harvested cell sheets retain extracellular matrix on the basal surface of cell sheets, cell sheets readily adhere to another surfaces such as wound beds and apical cell surfaces. The technology has been clinically applied in part and would open the way to reconstruct complicated tissue structures including lung alveoli.

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Fetal lung epithelium secretes fluid into its cavity. This lung fluid plays an important role in fetal lung development, differentiation and growth by providing a positive pressure in its cavity. However, at birth the lung fluid must be cleared for gas (O₂and CO₂) exchange after birth. Stress at birth elevates the level of blood catecholamine, which stimulates translocation of the amiloride-blockable nonselective cation (NSC) channel to the apical membrane of the alveolar type II epithelium, and also activates the channel, producing an osmotic gradient through stimulation of Na⁺absorption. This osmotic gradient induces water absorption across the lung epithelium from the lung cavity to the interstitium. However, the regulatory mechanism of the ion channels by catecholamine is still unclear. In this review article, we describe the mechanism of the clearance of the lung fluid by catecholamine, which acts through a beta 2 adrenoceptor in the lung epithelium.

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Lung surfactant plays an important role of normal respiration to reduce the surface tension at the air-liquid interface of the alveoli and prevents collapse of the lung. The deficiency of lung surfactants causes respiratory distress syndrome (RDS) in premature infants. Thus, many synthetic lung surfactants for RDS treatment have so far been studied and developed by many researchers.The aerosol delivery of dipalmitoyl phosphatidyl choline (DPPC) as a principal ingredient of lung surfactant was attempted for RDS treatment, but it had no effect. On the other hand the effective synthetic lung surfactant for RDS including surfactant proteins extracted from bovine lung, named TA, has been developed by Fujiwara et al.
The characteristics of synthetic lung surfactants with or without the surfactant proteins, SP-B, SP-C and SP-BC, were evaluated on the basis of surface modulus and viscosity obtained by applying the Maxwell model to the relaxation of the surface pressure produced by an area strain of 10% on a monolayer on the surface of a buffer solution and were compared with those of the synthetic lung surfactant TA developed earlier. The surface shear modulus and viscosity characteristic of the surface rheology for synthetic lung surfactant TA containing a trace of SP-BC showed a constant value for area strain of 10% under all equilibrium surface pressures and coincided with values of the mixed monolayers obtained by adding SP-BC and SP-B + C to the other components of lung surfactant (except surfactant proteins), but these moduli and viscosities for the systems without surfactant proteins increased with increase in equilibrium surface pressures. These results suggest that the existence of a trace of SP-BC in the synthetic lung surfactant TA improves its effectiveness and may serve as a 'cushion' among dipalmitoyl lecithin molecules in the monolayers during surface compression and expansion of these monolayers.

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Macrophages are the cells which play the central role in maintaining homeostasis in the body. Macrophages, called as tissue specific macrophages, are distributed in almost all organs. Additionally, they play the central role in innate immunity, which is contrast to acquired immunity, which mainly depends on T and/or B lymphocytes. Among tissue specific macrophages, alveolar macrophages are quite unique in view of both anatomical and physiological points compared to other macrophages. In this review, we would like to review the unique feature of alveolar macrophages based on their biologic characteristics. Also, we would like to present that alveolar macrophages are one of the most attractive cells to investigate the membrane functions because these cells, are located in the interface between outer and inner environment of the body.

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A sonicated dispersion of the lipid A analog, E5531 was freeze-dried in the presence of various additives such as saccharides and polyalchols and their cryoprotective effects were investigated. Fusion of the vesicles was measured by determining fluorescence energy transfer and size distribution. The ability of the additives as cryoprotectants was varied. The addition of polyalcohols led to considerable fusion. Although monosaccharides, similar to disaccharides, completely prevented the fusion of the vesicles during lyophilization, they showed far less ability to retain the entrapped calcein of the vesicles compared to disaccharides. Differential scanning calorimetry heating profiles of vesicles that had been lyophilized with various additives were obtained. Disaccharides and monosaccharides again markedly differed in the thermal properties. This variety in cryoprotective ability can be attributed to differences in the extent of their interaction with the E5531 head group.

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Self-assembled lipid membranes formed onto gold surfaces by several methods were examined in seeking membranes suitable for detecting membrane active compounds, especially, ion-channel forming peptides. Dielectric spectroscopy was used for monitoring the membrane formation and for characterizing the electrical and structural properties of the membranes. With the membrane of a thiophospholipid/phosphatidyl choline mixture, voltage-dependent conductance changes were found when the membrane was subjected to alamethicin, a channel forming peptide. The conductance changes were characteristic of the alamethicin channel formation, suggesting the feasibility of the membrane for the sensor of membrane active compounds.

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In recent years, the total internal reflection fluorescence microscopy (TIRFM) has become popular due to the fact the TIRFM has an ability of high sensitive fluorescence observation, especially for single moleculeimaging and analysis for biological functions around cell membrane such as exocytosis. However, optical alignment of incident laserhad been so complicated until now that we could notset up illumination for total internal reflection correctly in some cases. This time, we developed an equipment for TIRFM with easy handling. Ultra high NA objective lenses (Apo 100X NA 1.65 and Plan Apo 60X NA 1.45) enable high contrast and bright images of fluorescence because of high numerical aperture over 1.4. In TIRFM illuminator, the laser and illuminator are connected with the fiber, so almost no additional optical alignment is necessary.

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