Reconstituted type V collagen fibrils as cementing materials in the formation of cell clumps in culture

Extraction and characterization of bovine collagen type and its effects on cell behaviors

Collagen Type V (Col. V) plays an essential role in cell behaviors and has attracted increasing attention in recent years. High-purity Col. V is needed for evaluating its biological properties. In this research, the enzymatic hydrolysis process was combined with ultrafiltration to purify Col. V from the bovine cornea. The purity of Col. V was determined to be above 90% by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high-performance liquid chromatography methods. The effect of Col. V on cell behaviors was evaluated. The circular dichroism spectroscopy results demonstrated that the extracted Col. V exhibited a complete triple helix structure. SDS-PAGE suggested that the molecular weight of Col. V was 440 kDa. The self-assembly experiment revealed that the proportion of Col. V in the collagen mixture can affect the Col. I fiber diameter. The cell culture results implied that Col. V can inhibit fibroblasts (L929) proliferation. The L929 showed maximum mobility when the addition of Col. V was 30%. Thus, Col. V has the effect of inhibiting L929 proliferation and promoting migration. The high-purity Col. V provides useful information for further understanding its biological implications.

Mechanobiology in the Comorbidities of Ehlers Danlos Syndrome

Ehlers-Danlos Syndromes (EDSs) are a group of connective tissue disorders, characterized by skin stretchability, joint hypermobility and instability. Mechanically, various tissues from EDS patients exhibit lowered elastic modulus and lowered ultimate strength. This change in mechanics has been associated with EDS symptoms. However, recent evidence points toward a possibility that the comorbidities of EDS could be also associated with reduced tissue stiffness. In this review, we focus on mast cell activation syndrome and impaired wound healing, comorbidities associated with the classical type (cEDS) and the hypermobile type (hEDS), respectively, and discuss potential mechanobiological pathways involved in the comorbidities.

The Th17 pathway in the peripheral lung microenvironment interacts with expression of collagen V in the late state of experimental pulmonary fibrosis

BACKGROUND

Myofibroblasts derived from fibroblasts in the pathogenesis of pulmonary fibrosis causes excessive and disordered deposition of matrix proteins, including collagen V, which can cause a Th17-mediated immune response and lead to apoptosis. However, whether the intrinsic ability of lung FBs to produce the matrix depends on their site-specific variations is not known.

AIM

To investigate the link between Th17 and collagen V that maintains pulmonary remodeling in the peripheral lung microenvironment during the late stage of experimental pulmonary fibrosis.

METHODS

Young male mice including wild Balb/c mice (BALB, n=10), wild C57 Black/6J mice (C57, n=10) and IL-17 receptor A knockout mice (KO, n=8), were sacrificed 21 days after treatment with bleomycin. Picrosirius red staining, immunohistochemistry for IL-17-related markers and "in situ" detection of apoptosis, immunofluorescence for collagen types I and V, primary cell cultures from tissue lung explants for RT-PCR and electron microscopy were used.

RESULTS

The peripheral deposition of extracellular matrix components by myofibroblasts during the late stage is maintained in C57 mice compared with that in Balb mice and is not changed in the absence of IL-17 receptor A; however, the absence of IL-17 receptor A induces overexpression of type V collagen, amplifies the peripheral expression of IL-17 and IL-17-related cytokines and reduces peripheral lung fibroblast apoptosis.

CONCLUSION

A positive feedback loop between the expression patterns of collagen V and IL-17 may coordinate the maintenance of peripheral collagen I in the absence of IL-17 receptor A in fibrosis-susceptible strains in a site-specific manner.

Fragility of reconstituted type V collagen fibrils with the chain composition of α1(V)α2(V)α3(V) respective of the D-periodic banding pattern

The triple-helical domains of two subtypes of type V collagen were prepared from human placenta, one with the chain composition of [α1(V)](2)α2(V) (Vp112) and the other with the chain composition of α1(V)α2(V)α3(V) (Vp123) with limited pepsin treatment. In order to characterize the triple-helical domain of the type Vp123 collagen molecule, the reconstituted aggregate structure formed from the pepsin-treated collagen was compared by using transmission electron microscopy. The diameter of the fibrils reconstituted from types pepsin-treated type Vp123 collagen and type Vp112 collagen was highly uniform and less than the D-periodicity at all the temperatures examined, suggesting that the major triple-helical domain of both subtypes has a potency to limit their lateral growth. Both fibrils were approximately 45 nm in width and showed the D-periodic banding pattern along their axes at 34°C. In contrast to type Vp112, the reconstituted type Vp123 fibrils showed no banding pattern along their axes when they were reconstituted at 37°C. The banded fibrils once reconstituted from type Vp123 at 34°C tend to lose their characteristic pattern within 60 min when they were incubated at 37°C. One explanation is that a slightly higher content of hydrophobic residues of type Vp123 collagen than those of type V112p collagen augmented the intermolecular interaction that disturbs the D-periodicity governed essentially by electrostatic interactions. Taken together with recent data in Col5a3 gene-targeted mice, the results suggest that type V123 collagen exists not only as a periodic banded fibril but also as nonfibrillar meshwork structures.

Applying macromolecular crowding to enhance extracellular matrix deposition and its remodeling in vitro for tissue engineering and cell-based therapies

With the advent of multicellular organisms, the exterior of the cells evolved dramatically from highly aqueous surroundings into an extracellular matrix and space crowded with macromolecules. Cell-based therapies require removal of cells from their crowded physiological context and propagating them in dilute culture medium to attain therapeutically relevant numbers whilst preserving their phenotype. However, bereft of their microenvironment, cells under perform and lose functionality. Major efforts currently aim to modify cell culture surfaces and build three dimensional scaffolds to improve this situation. We discuss here alternative strategies that enable cells to re-create their own microenvironment in vitro, using carbohydrate-based macromolecules as culture media additives that create an excluded volume effect at defined fraction volume occupancies. This biophysical approach dramatically enhances extracellular matrix deposition by differentiated cells and stem cells, and boosts progenitor cell differentiation and proliferation. We begin to understand how well cells really can perform ex vivo if given the chance.

Collagen type V enhances matrix contraction by human periodontal ligament fibroblasts seeded in three-dimensional collagen gels

Extracellular matrix components play an important role in modulating cellular activity. To study such capacities of the matrix, fibroblasts are frequently cultured in a three-dimensional gel and contraction is assessed as a measure of cellular activity. Since a connective tissue contains several types of collagen, we investigated the effect of gels composed of collagen I alone or in combination with 10% collagen III and/or 5% collagen V on contraction by human periodontal ligament fibroblasts. Gels containing collagen V contracted much faster than those without this type of collagen. Blocking of the integrin beta1-subunit with an activity-blocking antibody delayed (gels with collagen V) or almost completely blocked (gels without collagen V) contraction. Use of an antibody directed against integrin alpha2beta1 resulted in delay of gel contraction for gels both with and without collagen V. Anti-integrin alpha v beta3 or RGD peptides partially blocked contraction of gels containing collagen V, but had no effect on gels consisting of collagen I alone. The beta1-containing integrins are involved in the basal contraction by fibroblasts that bind to collagens I and III. The enhanced contraction, stimulated by collagen V, appears to be mediated by integrin alpha v beta3. We conclude that collagen V may play an important modulating role in connective tissue contraction. Such a modulation may occur during the initial stages of wound healing and/or tissue regeneration.