Decellularized inner body membranes for tissue engineering: A review.

Body membranes are thin sheets/layers of cells or tissues which cover the surface of internal organs, the outside of the body and lines various body cavities. These membranes are separated into two main groups which are epithelial membranes and connective tissue membranes. Decellularized forms of inner body membranes in the groups of epithelial membranes (amniotic membrane, mesentery, omentum, pericardium, peritoneum, pleura) and connective tissue membranes (fascia, periosteum, synovial membrane) have been used in tissue engineering studies for preparation and regeneration of various tissues such as bone, tendon, cartilage, skin, cornea, ocular surface, uterine, periodontium, vascular and cardiovascular structures. Decellularized inner body membranes have high biocompatibility and support cell attachment, cell growth and angiogenesis which are desired properties for using as versatile tools in tissue engineering applications. Even though, decellularized forms of these membranes have been used in many studies, it is necessary to develop new decellularization methods for more effective cell removal and less destructive properties on tissue structures. Moreover, development of decellularization agents which target removal of antigens of donor tissues is also essential because these antigens are one of the main reasons for tissue-organ rejections in allogeneic and xenogeneic tissue-organ implantations. This review provides comprehensive information and analysis about the current state of the art in the literature on decellularized inner body membranes and applications of these membranes in tissue engineering.

Placental membrane grafts for urethral replacement in a rabbit model: a pilot study.

PURPOSE: Several graft materials are available for use in the treatment of urethral stricture disease. Placental membrane is being used in a variety of settings as a graft in wound healing and tissue repair. We aim to evaluate the effect of implanting decellularized human placental membrane into rabbit urethras. METHODS: Dorsal onlay graft urethroplasty using prepared human placental membrane was performed in 10 New Zealand White rabbits (Oryctolagus cuniculus). After 3 months, the rabbits underwent cystourethroscopy to evaluate urethral patency. The rabbits were then euthanized and the urethras examined for pathological findings. RESULTS: All urethroplasties were performed without complication. There were no observed episodes of urinary retention, infection, or renal failure. Urethral patency was achieved in all rabbits 3 months postoperatively. Urothelial replacement of the placental membrane graft was observed in all rabbits without malignant transformation. CONCLUSION: Dorsal onlay urethroplasty using decellularized human placental membrane can safely be performed in a rabbit model. This pilot study demonstrated urothelial replacement of human placental membrane in the rabbit urethra without stricture formation. Placental membrane is a promising biomaterial for urethral reconstruction.

Induced membrane maintains its osteogenic properties even when the second stage of Masquelet's technique is performed later.

PURPOSE: Previous clinical studies have shown the effectiveness of bone repair using two-stage surgery called the induced membrane (IM) technique. The optimal wait before the second surgery is said to be 1 month. We have been successfully performing the IM technique while waiting an average of 6 months to carry out the second stage. We hypothesised that the IM maintains its beneficial capabilities, even at a later second stage, and that there is no relation between the speed of bone union and the wait between the first and second stage. We sought to explore the biological properties of 'older' IMs sampled to substantiate our clinical observations. METHODS: Thirty-four patients with a critical size defect were treated with the IM technique. In seven of these patients, pieces of the IM were collected 4.2-14.7 months after the first surgery. IM-derived cell phenotype and osteogenic potential were investigated using in vitro studies (n = 4) while IM nature and function were investigated by histology and immunohistochemistry (n = 3). RESULTS: The median wait before the second surgery was 5.8 months [range 1.2-14.7] and bone healing occurred at 7.6 months [range 2.5-49.9] for 26 patients. IMs aged 4.2-14.7 months contained mesenchymal stromal cells with in vitro osteogenic potential and corresponded to a multipotent tissue with osteogenic and chondrogenic capabilities contributing to osteogenesis over time. CONCLUSION: This preliminary study suggests the IM retains its powerful osteogenic properties over time and that waiting longer between the two surgeries does not delay bone union.

Transcriptomic insights into citrus segment membrane's cell wall components relating to fruit sensory texture.

BACKGROUND: During fresh fruit consumption, sensory texture is one factor that affects the organoleptic qualities. Chemical components of plant cell walls, including pectin, cellulose, hemicellulose and lignin, play central roles in determining the textural qualities. To explore the genes and regulatory pathways involved in fresh citrus' perceived sensory texture, we performed mRNA-seq analyses of the segment membranes of two citrus cultivars, Shiranui and Kiyomi, with different organoleptic textures. RESULTS: Segment membranes were sampled at two developmental stages of citrus fruit, the beginning and end of the expansion period. More than 3000 differentially expressed genes were identified. The gene ontology analysis revealed that more categories were significantly enriched in 'Shiranui' than in 'Kiyomi' at both developmental stages. In total, 108 significantly enriched pathways were obtained, with most belonging to metabolism. A detailed transcriptomic analysis revealed potential critical genes involved in the metabolism of cell wall structures, for example, GAUT4 in pectin synthesis, CESA1, 3 and 6, and SUS4 in cellulose synthesis, CSLC5, XXT1 and XXT2 in hemicellulose synthesis, and CSE in lignin synthesis. Low levels, or no expression, of genes involved in cellulose and hemicellulose, such as CESA4, CESA7, CESA8, IRX9 and IRX14, confirmed that secondary cell walls were negligible or absent in citrus segment membranes. A chemical component analysis of the segment membranes from mature fruit revealed that the pectin, cellulose and lignin contents, and the segment membrane's weight (% of segment) were greater in 'Kiyomi'. CONCLUSION: Organoleptic quality of citrus is easily overlooked. It is mainly determined by sensory texture perceived in citrus segment membrane properties. We performed mRNA-seq analyses of citrus segment membranes to explore the genes and regulatory pathways involved in fresh citrus' perceived sensory texture. Transcriptomic data showed high repeatability between two independent biological replicates. The expression levels of genes involved in cell wall structure metabolism, including pectin, cellulose, hemicellulose and lignin, were investigated. Meanwhile, chemical component contents of the segment membranes from mature fruit were analyzed. This study provided detailed transcriptional regulatory profiles of different organoleptic citrus qualities and integrated insights into the mechanisms affecting citrus' sensory texture.

Suppressing membrane height fluctuations leads to a membrane-mediated interaction among proteins.

Membrane-induced interactions can play a significant role in the spatial distribution of membrane-bound proteins. We develop a model that combines a continuum description of lipid bilayers with a discrete particle model of proteins to probe the emerging structure of the combined membrane-protein system. Our model takes into account the membrane's elastic behavior, the steric repulsion between proteins, and the quenching of membrane shape fluctuations due to the presence of the proteins. We employ coupled Langevin equations to describe the dynamics of the system. We show that coupling to the membrane induces an attractive interaction among proteins, which may contribute to the clustering of proteins in biological membranes. We investigate the lateral protein diffusion and find that it is reduced due to transient fluctuations in membrane shape.

Waterjet cutting of periprosthetic interface tissue in loosened hip prostheses: an in vitro feasibility study.

Waterjet cutting technology is considered a promising technology to be used for minimally invasive removal of interface tissue surrounding aseptically loose hip prostheses. The goal of this study was to investigate the feasibility of waterjet cutting of interface tissue membrane. Waterjets with 0.2 mm and 0.6 mm diameter, a stand-off distance of 5 mm, and a traverse speed of 0.5 mm/s were used to cut interface tissue samples in half. The water flow through the nozzle was controlled by means of a valve. By changing the flow, the resulting waterjet pressure was regulated. Tissue sample thickness and the required waterjet pressures were measured. Mean thickness of the samples tested within the 0.2 mm nozzle group was 2.3 mm (SD 0.7 mm) and within the 0.6 mm nozzle group 2.6 mm (SD 0.9 mm). The required waterjet pressure to cut samples was between 10 and 12 MPa for the 0.2 mm nozzle and between 5 and 10 MPa for the 0.6 mm nozzle. Cutting bone or bone cement requires about 3 times higher waterjet pressure (30-50 MPa, depending on used nozzle diameter) and therefore we consider waterjet cutting as a safe technique to be used for minimally invasive interface tissue removal.

Slc26a7 chloride channel activity and localization in mouse Reissner's membrane epithelium.

Several members of the SLC26 gene family have highly-restricted expression patterns in the auditory and vestibular periphery and mutations in mice of at least two of these (SLC26A4 and SLC26A5) lead to deficits in hearing and/or balance. A previous report pointed to SLC26A7 as a candidate gene important for cochlear function. In the present study, inner ears were assayed by immunostaining for Slc26a7 in neonatal and adult mice. Slc26a7 was detected in the basolateral membrane of Reissner's membrane epithelial cells but not neighboring cells, with an onset of expression at P5; gene knockout resulted in the absence of protein expression in Reissner's membrane. Whole-cell patch clamp recordings revealed anion currents and conductances that were elevated for NO3- over Cl- and inhibited by I- and NPPB. Elevated NO3- currents were absent in Slc26a7 knockout mice. There were, however, no major changes to hearing (auditory brainstem response) of knockout mice during early adult life under constitutive and noise exposure conditions. The lack of Slc26a7 protein expression found in the wild-type vestibular labyrinth was consistent with the observation of normal balance. We conclude that SLC26A7 participates in Cl- transport in Reissner's membrane epithelial cells, but that either other anion pathways, such as ClC-2, possibly substitute satisfactorily under the conditions tested or that Cl- conductance in these cells is not critical to cochlear function. The involvement of SLC26A7 in cellular pH regulation in other epithelial cells leaves open the possibility that SLC26A7 is needed in Reissner's membrane cells during local perturbations of pH.

Visualizing Ca(2+) signatures in plants.

Ca(2+) is a key player in an astonishing variety of plant signal transduction pathways where transient, spiking or oscillatory changes in cytosolic Ca(2+) levels help to couple environmental or developmental cues to appropriate cellular responses. Understanding whether and how much Ca(2+) signaling contributes to defining stimulus-response specificity has long been a challenge, but recent work has provided strong evidence that specific information can indeed be encoded in the spatiotemporal characteristics of Ca(2+) signals. Identification of the Ca(2+) binding proteins that transduce Ca(2+) signals by regulating downstream effector proteins has revealed a complex network of Ca(2+) sensor families, of which some members show distinct patterns of expression and subcellular localization. By utilizing genetically encoded fluorescent Ca(2+) probes to monitor Ca(2+) changes at high spatiotemporal resolution, it is now possible to explore whether such spatial heterogeneities in Ca(2+) sensor distribution are coordinated with subcellular microdomains of Ca(2+) signaling. Such visualization of Ca(2+) signaling will also help to address which cellular compartments and transporters contribute to mobilizing and sequestering Ca(2+) and thus define stimulus-specific Ca(2+) signatures.

Cells, tissues, organs and systems.

This article, which forms part of the life sciences series, examines cellular organisation in the formation of body tissues, membranes, organs and systems. Four main types of body tissue are described: epithelial, connective, muscle and nervous tissue. Each class of tissue is described in terms of its structure and function. Where appropriate, subgroups within the classifications are identified. Different membranes in the body are considered and the organisation of tissues and membranes into more complex structures, such as organs and body systems, is outlined.

Defects in the outer limiting membrane are associated with rosette development in the Nrl-/- retina.

The neural retinal leucine zipper (Nrl) knockout mouse is a widely used model to study cone photoreceptor development, physiology, and molecular biology in the absence of rods. In the Nrl(-/-) retina, rods are converted into functional cone-like cells. The Nrl(-/-) retina is characterized by large undulations of the outer nuclear layer (ONL) commonly known as rosettes. Here we explore the mechanism of rosette development in the Nrl(-/-) retina. We report that rosettes first appear at postnatal day (P)8, and that the structure of nascent rosettes is morphologically distinct from what is seen in the adult retina. The lumen of these nascent rosettes contains a population of aberrant cells protruding into the subretinal space that induce infolding of the ONL. Morphologically adult rosettes do not contain any cell bodies and are first detected at P15. The cells found in nascent rosettes are photoreceptors in origin but lack inner and outer segments. We show that the adherens junctions between photoreceptors and Müller glia which comprise the retinal outer limiting membrane (OLM) are not uniformly formed in the Nrl(-/-) retina and thus allow protrusion of a population of developing photoreceptors into the subretinal space where their maturation becomes delayed. These data suggest that the rosettes of the Nrl(-/-) retina arise due to defects in the OLM and delayed maturation of a subset of photoreceptors, and that rods may play an important role in the proper formation of the OLM.

[Effects of surface roughness of bone cements on histological characteristics of induced membranes].

OBJECTIVE: To explore surface roughness of bone cement and surround tissue on histological characteristic of induced membranes. METHODS: Bone cements with smooth and rough surface were implanted in radius bone defect, intramuscular and subcutaneous sites of rabbits, and formed induced membranes. Membranes were obtained and stained (HE) 6 weeks later. Images of membrane tissue were obtained and analyzed with an automated image analysis system. Five histological parameters of membranes were measured with thickness,area,cell density,ECM density and microvessel density. Double factor variance analysis was used to evaluate the effect of the two factors on histological characteristics of induced membranes. RESULTS: Membranes can be induced by each kind of bone cement and at all the three tissue sites. In histological parameters of thickness,area and micro vessel,there were significant differences among the membranes induced at different tissue sites (P = 0.000, P = 0.000, P = 0.000); whereas, there were no significant differences in histological parameters of cell density and ECM density (P = 0.734, P = 0.638). In all five histological parameters of membranes, there were no significant differences between the membranes induced by bone cements with different surface roughness (P = 0.506, P = 0.185, P = 0.883, P = 0.093, P = 0.918). CONCLUSION: Surround tissue rather than surface roughness of bone cements can affect the histological characteristics of induced membranes. The fibrocystic number, vascularity, mechanical tension and micro motion of the surround tissue may be closely correlated with the histological characteristics of induced membranes.

Ontogenic change in tissue osmolality and developmental sequence of mitochondria-rich cells in Mozambique tilapia developing in freshwater.

We investigated a change in tissue fluid osmolality and developmental sequences of mitochondria-rich (MR) cells during embryonic and larval stages of Mozambique tilapia, Oreochromis mossambicus, developing in freshwater. Tissue osmolality, representing body fluid osmolality, ranged from 300 to 370 mOsm/kg during embryonic and larval stages. This suggests that tilapia embryos and larvae are also able to regulate body fluid osmolality to some extent, although the levels are somewhat higher and fluctuate more greatly in embryos and larvae than in adults. Na(+)/K(+)-ATPase-immunoreactive MR cells were first detected in the yolk-sac membrane 3 days before hatching (day -3), followed by their appearance in the body skin on day -2. Subsequently, MR cells in both the yolk-sac membrane and body skin increased in number, and most densely observed on days -1 and 0. Whereas yolk-sac and skin MR cells decreased after hatching, MR cells in turn started developing in the gills after hatching. Thus, the principal site for MR cell distribution shifted from the yolk-sac membrane and body skin during embryonic stages to the gills during larval stages, and tilapia could maintain continuously their ion balance through those MR cells during early life stages.

Histologic changes in the maxillary sinus membrane after sinus membrane elevation and the simultaneous insertion of dental implants without the use of grafting materials.

OBJECTIVE: The aim of this study was to evaluate the histologic changes in the maxillary sinus membrane after sinus membrane elevation and the simultaneous insertion of dental implants without additional grafting material. STUDY DESIGN: In 6 mongrel dogs, bilateral edentulated flat alveolar ridges were created in the maxilla. After 3 months of healing, an implant was unilaterally placed in the maxillary sinus in such a way that it protruded 5 mm into the maxillary sinus after sinus membrane elevation. On the opposite side, the maxillary sinus was left untreated as a control site. The animals were killed 6 months after surgery. The maxillary sinus mucosa was examined using light microscopy and scanning and transmission electronic microscopy. RESULTS: There were no morphologic or ultrastructural differences in the sinus membrane between groups. CONCLUSION: The results indicate that the surgical procedure by which implants are inserted into the sinus cavity by elevating the sinus membrane without adding any graft material appears to have little influence on the histologic characteristics of the sinus membrane.

Pitfalls in the use of electron microscopy to study the mitochondrial membrane permeability transition in apoptotic cells and pellets: where do we stand in relation to the incidence of mitochondrial swelling in apoptosis?

The importance of apoptosis as a form of programmed cell death was recognized in the 1980s, whereas the central role of mitochondria in controlling this process was identifi ed in the mid-1990s. An important event in apoptosis is the collapse of the mitochondrial transmembrane potential (ÃØm), with the ensuing loss of the selective permeability of the inner membrane resulting in swelling of the hyperosmolar mitochondrial matrix. This event is known as the mitochondrial permeability transition (MPT). After swelling of the intermembrane space, the outer membrane ruptures, exposing the permeable inner membrane. An increasingly swollen matrix covered by the inner membrane eventually herniates into the cytoplasm through the breach formed in the outer membrane (OM). The increase in surface area of the inner mitochondrial membrane (IMM) involves the unfolding of membrane stored in the cristae. This membrane movement is osmotically driven since the cytoplasm has a lower osmolality. The proteins partly embedded in the inner membrane are thus exposed to the cytoplasm. In nine out of ten electron microscopy studies of isolated mitochondria expressing the permeability transition, the existing ruptures of the OMM were overlooked. The MPT can also be recognized in individual mitochondria by using fl uorescent probes that are not retained in these organelles once the ÃØm is lost. In cases in which there is no rupture of the OMM, cytochrome c must be released from mitochondria with impermeable inner membranes. Examination of several hundred of the more than 61,000 published papers on programmed cell death revealed that the key signaling events of apoptosis, such as the onset of the MPT, mitochondrial swelling and cytochrome c release to the cytoplasm, are infl uenced by factors such as the cell type and presence of apoptogenic agents...

Characterization and adsorption properties of eggshells and eggshell membrane.

The objective of this work was to study the chemical and physical characterization of eggshell and eggshell membrane particles prepared from the hen eggshell waste. Under the characterization measurements investigated, it was found that the pore structures of the two biomaterials belong to a typical Type II, indicating that they should be basically characteristic of nonporous materials or materials with macropores or open voids. Further, the chemical composition of the resulting eggshell particle was strongly associated with the presence of carbonate minerals from the Fourier transform infrared (FTIR) spectra. In contrast to the resulting eggshell membrane particle, the presence of functional groups of amines and amides was observable because of its chemical composition of fibrous proteins. From the isotherm data of methylene blue at 25 degrees C, the Freundlich model yielded a somewhat better fit than the Langmuir model. The adsorption isotherms revealed the eggshell biosorbents could only uptake the basic dye of less than 1.0mg/g in aqueous medium, which was attributed to their poor pore properties.

The endothelin system and renin in human fetal membranes.

Term human fetal membranes express prorenin, a key enzyme within the renin-angiotensin system. High levels of another vasoactive peptide, endothelin-1 (ET-1), are found in human amniotic fluid. To address the question of the relationship between these two vasoactive systems, we analyzed the expression of the components of the ET-1 system in fetal membranes in which cell types had been identified using different markers. Immunohistochemistry was performed with antibodies raised against the human proteins of the ET system. Term fetal membranes displayed ubiquitous labeling of endothelin-converting enzyme-1 (ECE-1) and ET-1. ETA receptors were detected in the chorionic connective tissue and the attached decidua; ETB receptors were localized to chorionic trophoblast cells and decidua. The localization of the ET-1 receptor subtype was confirmed by in-situ receptor binding. Renin immunoreactivity was detected in the chorionic connective tissue and the decidua. These findings suggest that ET-1 is produced ubiquitously in human fetal membranes, and its targets may be, trophoblast cells following ETB receptor activation, vascular structures and fibroblasts in the connective tissue and decidua via ETA and ETB receptors. It appears possible that renin and ET may contribute to the pathophysiological changes associated with premature labor and preeclampsia.

Glial limitans elasticity subjacent to the supraoptic nucleus.

Two previous studies from our laboratory have indicated that the ventral glial limitans subjacent to the hypothalamic supraoptic nucleus (SON-VGL) undergoes a reversible thinning upon chronic activation of the magnocellular neuroendocrine cells (MNCs) of the supraoptic nucleus (SON). Numerous other studies have shown that MNC somata hypertrophy with activation. One aim of the current study was to understand better how SON-VGL thinning occurs. A second aim was to quantify overall changes of the MNC somata region due to cellular hypertrophy to compare relative changes in dimensions. Here, we undertook a light microscopic stereological investigation of the SON and the subjacent SON-VGL of Nissl stained material under basal and activated conditions. Astrocyte numbers in the underlying SON-VGL remained stable across hydration state as did the overall volume of the SON-VGL and dendritic zone reference area. How these data are consistent with our earlier observations of SON-VGL thinning was resolved by the finding of a highly significant, 30% increase in the mediolateral dimension of the SON-VGL in dehydrated rats. These observations fit well with previous work from our laboratory that demonstrates a reorientation of SON-VGL astrocytes, from vertical to horizontal, which occurs in the activated SON-VGL. We found a significant, approximately 54%, increase in the overall volume of the MNC region of the SON. No significant rostrocaudal lengthening of the SON was detected, although a trend was evident. All the observed changes reversed with rehydration. These data indicate that elasticity of the SON-VGL acts to accommodate the volume expansion of the MNCs and enables the SON-VGL to continue as an interface between the underlying cerebrospinal fluid in the subarachnoid space and the expanded SON above.

Characteristics of non-opioid beta-endorphin receptor.

Tritium-labeled selective agonist of non-opioid beta-endorphin receptor, the decapeptide immunorphine ([3H]SLTCLVKGFY) with specific activity of 24 Ci/mmol has been prepared. By its use, non-opioid beta-endorphin receptors were revealed and characterized on mouse peritoneal macrophages and rat myocardium, spleen, adrenal, and brain membranes. The non-opioid beta-endorphin receptor of macrophages has in addition to immunorphine (Kd of the [3H]immunorphine-receptor complex was 2.4 +/- 0.1 nM) and beta-endorphin (Ki of the [3H]immunorphine specific binding was 2.9 +/- 0.2 nM) a high affinity for Fc-fragment of human IgG1, pentarphine (VKGFY), cyclopentarphine [cyclo(VKGFY)], and [Pro3]pentarphine (VKPFY) (Ki values were 0.0060 +/- 0.0004, 2.7 +/- 0.2, 2.6 +/- 0.2, and 2.8 +/- 0.2 nM, respectively) and is insensitive to naloxone and [Met5]enkephalin (Ki > 100 microM). Treatment of macrophages with trypsin resulted in the loss of their ability for the specific binding of [3H]immunorphine. Values of the specific binding of 8.4 nM [3H]immunorphine to rat adrenal, spleen, myocardium, and brain membranes were determined to be 1146.0 +/- 44.7, 698.6 +/- 28.1, 279.1 +/- 15.4, and 172.2 +/- 1.8 fmol/mg protein, respectively. Unlabeled beta-endorphin, pentarphine, [Pro3]pentarphine, cyclopentarphine, cyclodipentarphine [cyclo(VKGFYVKGFY)], and Fc-fragment of IgG1 inhibited the binding of [3H]immunorphine to membranes from these organs. No specific binding of [3H]immunorphine to rat liver, lung, kidney, and intestine membranes was found.

Studies on 1-arylpiperazine derivatives with affinity for rat 5-HT7 and 5-HT1A receptors.

Several 1-aryl-4-(2-arylethyl)piperazine derivatives were synthesized and tested in-vitro for their binding affinity for 5-HT(7) and 5-HT(1A) receptors. These compounds displayed 5-HT(7 )receptor affinity ranging between K(i) = 474 nM and K(i) = 8.2 nM, besides high affinity for the 5-HT(1A) receptor. Intrinsic activity of the most potent compounds was assessed. 4-[2-(3-Methoxyphenyl)ethyl]-1-(2-methoxyphenyl)piperazine (16) and 1-(1,2-benzisoxazol-3-yl)-4-[2-(3-methoxyphenyl)ethyl]piperazine (20) (K(i) = 24.5 and 8.2 nM, respectively) behaved as partial agonist and full agonist, respectively, when tested for 5-HT(7) receptor-mediated relaxation of substance P-induced guinea-pig ileum contraction.