Role Of Extracellular Matrices Research Articles

Spatial and temporal changes in extracellular elastin and laminin distribution during lung alveolar development

Lung alveolarization requires precise coordination of cell growth with extracellular matrix (ECM) synthesis and deposition. The role of extracellular matrices in alveogenesis is not fully understood, because prior knowledge is largely extrapolated from two-dimensional structural analysis. Herein, we studied temporospatial changes of two important ECM proteins, laminin and elastin that are tightly associated with alveolar capillary growth and lung elastic recoil respectively, during both mouse and human lung alveolarization. By combining protein immunofluorescence staining with two- and three-dimensional imaging, we found that the laminin network was simplified along with the thinning of septal walls during alveogenesis, and more tightly associated with alveolar endothelial cells in matured lung. In contrast, elastin fibers were initially localized to the saccular openings of nascent alveoli, forming a ring-like structure. Then, throughout alveolar growth, the number of such alveolar mouth ring-like structures increased, while the relative ring size decreased. These rings were interconnected via additional elastin fibers. The apparent patches and dots of elastin at the tips of alveolar septae found in two-dimensional images were cross sections of elastin ring fibers in the three-dimension. Thus, the previous concept that deposition of elastin at alveolar tips drives septal inward growth may potentially be conceptually challenged by our data.

The Role of Extracellular Matrices in Retinal Pigment Epithelial Cell Migration

Background: To identify which extracellular matrix components modify retinal pigment epithelial cell migration and their interplay with matrix metalloproteinases in directing the behaviour of the cells in agarose droplets, an in-vitro model for cellular migration. Methods: Migration of the cells from agarose droplets on coated tissue culture plastic (fibronectin, laminin and collagen types: I and IV) in the presence as well as absence of serum was evaluated by using phase contrast microscopy and computer analysis of captured images. Expression of metalloproteinases -1, 2 and 9 by retinal pigment epithelial cells was determined by immunocytochemistry and was confirmed by western blotting. In addition, the effect of metalloproteinases inhibitor, batimastat (BB-94), on the cell migration and expression of MMPs were studied. Results: Retinal pigment epithelial cells migrated from agarose droplets in the presence of serum and fibronectin acted as an additional stimulus to migration, while laminin and collagen type IV inhibited migration in a dose dependent manner. Metalloproteinases -1, 2 and 9 were expressed by retinal pigment epithelial cells in culture as shown by immunocytochemistry and by western blotting. Expression of metalloproteinases on western blots was inhibited by use of BB-94. BB-94, also inhibited cellular migration from agarose droplets in a dose dependent manner. Conclusions: Retinal pigment epithelial cells migrate in the presence of fibronectin while expression of metalloproteinases may reflect cellular behaviour during PVR in which migration of cells from their basement membrane on to retinal surfaces requires an interaction between ECM protein and enzymes such as metalloproteinases to permit cellular invasion.

The effect of spacer arm length of an adhesion ligand coupled to an alginate gel on the control of fibroblast phenotype

Tissue engineering requires the use of polymeric scaffolds that mimic many roles of extracellular matrices (ECM) in the body. Controlling cell–scaffold interactions is one of the most critical parameters for regulating cell phenotype in tissue engineering, and a peptide with the sequence of RGD has been widely exploited for this purpose. We hypothesized that the spacer arm length of adhesion ligands coupled to synthetic ECMs could be vital for regulation of cell–scaffold interactions. We prepared alginate gels modified with RGD peptides containing varying spacer arm lengths and cultured primary human fibroblasts either on the gels (2-D) or within the gels (3-D). The spacer arm length of the RGD peptides significantly influenced the adhesion and proliferation of fibroblasts in both the 2-D and 3-D studies. We found that a minimum number of four glycine units in the spacer arm was essential for enhanced adhesion and growth of the cells in vitro. An optimal spacer arm length of the RGD peptides was also necessary for minimizing cellular stress responses as determined by analyzing expression of heat shock proteins and Bcl-2 in cultured cells. This approach to controlling cell phenotype using adhesion peptides with various spacer arm lengths could be useful for designing novel scaffolds in tissue engineering applications.

Design parameters of polymers for tissue engineering applications

The loss or failure of an organ or tissue can occur because of accident or disease, for which tissue or organ transplantation is a generally accepted treatment. However, this approach is extremely limited due to donor shortage. Tissue engineering is a new and exciting strategy, in which patients who need a new organ or tissue are supplied with a synthetic organ or tissue. In this approach, tissues are engineered using a combination of the patient’s own cells and a polymer scaffold. The polymer scaffold potentially mimics many roles of extracellular matrices in the body. Various polymers have been studied and utilized to date in tissue engineering approaches. However, no single polymer has been considered ideal for all types of tissues and approaches. This paper discusses the design parameters of those polymers potentially useful in tissue regeneration.

Identification of type VI collagen synthesizing cells in human diabetic glomerulosclerosis using renal biopsy sections.

Although the role of extracellular matrices in the development of glomerulosclerosis has been discussed widely, the cellular origin of type VI collagen in diabetic nephropathy (DN) has remained relatively unexplored. This study reports the distribution and cellular origin of type VI collagen in DN. Type VI collagen‐specific oligonucleotide probes and monoclonal antibody were used to assess the relative expression of mRNA for \\alpha1 (VI) chain and its translated protein in paraffin‐embedded renal biopsy sections of DN. By immunohistochemistry, compared to the control, increased deposition of type VI collagen was noted in the diffuse and nodular lesions of diabetic glomeruli. For cellular localization of type VI collagen mRNA, paraffin‐embedded renal sections of the control and DN were hybridized in situ with digoxigenin (Dig)‐labeled antisense oligo‐DNA probe complementary to a part of \\alpha1 (VI) mRNA. In comparison to the control kidney sections, increased numbers of intraglomerular cells (both mesangial and epithelial cells) were positive for α1 (VI) mRNA in renal biopsy sections of DN. From the results, we conclude that overexpression of type VI collagen by intraglomerular cells with its increased deposition might significantly contribute to the glomerulosclerosis found in DN.

Role of Extracellular Matrices, Matrix Receptors, and Cytokines in Granulomatous Lung Inflammation

Role of Extracellular Matrices, Matrix Receptors, and Cytokines in Granulomatous Lung Inflammation

The Role of Extracellular Matrices During the Development of Intramural Ganglion Cells in the Gut

The Role of Extracellular Matrices During the Development of Intramural Ganglion Cells in the Gut

Chapter 2. Role of Extracellular Matrices in Palatal Shelf Closure

Publisher Summary This chapter focuses on the role of extracellular matrices in palatal shelf closure. The palatal shelves themselves play a direct and active role in their reorientation from a vertical position on either side of the tongue to a horizontal one above it. One of the oldest proposed mechanisms for the motive force underlying palatal shelf movement is a rapid increase in shelf volume due to increased cellular volume in the “connective tissue.” Histochemical and autoradiographic evidence suggested that acid mucopolysaccharides [glycosaminoglycans (GAGS)], principally those that are sulfated, are present in the palatal shelves at the time of shelf reorientation. Biochemical data has confirmed that GAGs are present and synthesized before and during shelf reorientation. Extracellular matrices both within the mesenchymal compartment, probably existing as a GAG–collagen gel–fiber matrix, and at the epithelial–mesenchymal interface, organized as a basal lamina, appear to play vital roles in palatal shelf reorientation. One hypothesis that explains their possible roles is that posterior palatal shelf remodeling results largely from the expansion of hyaluronate-rich gel–fiber network within the mesenchymal compartment.

Intracellular and extracellular control of the differentiation of cartilage and bone.

This paper provides an overview of one aspect of the differentiation of cartilage and bone, namely, the degree of control provided by the extracellular matrix and microenvironment. A brief review of the diagnostic features of cartilage and bone is followed by a discussion of stem cells, emphasizing how to identify them using cytochemical, ultrastructural or experimental procedures. The role of extracellular matrices in the initiation of differentiation is discussed with reference to the initiation of chondrogenesis in the vertebral skeleton of the embryonic chick and of osteogenesis in the mandibular skeletons of embryonic chick and mice. The role of extracellular matrices in the maintenance of the differentiated state is discussed with reference to the ability of chondrocytes to compensate for depletion of their extracellular matrices and to the maintenance of altered differentiated states in achondroplasia. Some emphasis is placed on the notion that skeletal cells can neither be considered nor studied in isolation. The epigenetic approach used in studies of growth and morphogenesis needs to be applied to studies on both the initiation and the maintenance of cytodifferentiation.

An effect of accumulated matrix on sulfation among cells in a cartilage colony: An autoradiographic study

In this report an autoradiographic approach is used to compare synthetic activities of cells within differentiated cartilage colonies. While amino acid incorporation is umiform throughout the colony, H-3-uridine is incorporated more actively by cells having little matrix, cells which are typically in the peripheral regions of a colony. On the other hand S-35-O4 is incorporated most actively by cells in the colony centers. This difference in sulfation appears to occur independently of the mitotic state of the cells, since it is apparent in both growing and near-stationary cultures. Instead, there is a correlation between the accumulation of extracellular matrix and more active levels of sulfation. In support of the idea that matrix creates a microenvironment more favorable to chondrogenesis is the observation that a brief treatment with hyaluronidase, which removes about 60% of the S-35-O4 from prelabeled cultures, depresses isolation of labeled glycosaminoglycans. The possible role of extracellular matrices in altering the expression of differentiated functions by creating a more favorable microenvironment is considered.