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I Collagen Gels (i + collagen_gel)
Kinds of I Collagen Gels Selected AbstractsFabrication of endothelialized tube in collagen gel as starting point for self-developing capillary-like network to construct three-dimensional organs in vitroBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006Takayuki Takei Abstract A possible strategy for creating three-dimensional (3D) tissue-engineered organs in vitro with similar volumes to the primary organs is to develop a capillary network throughout the constructs to provide sufficient oxygenation and nutrition to the cells composing them. Here, we propose a novel approach for the creation of a capillary-like network in vitro, based on the spontaneous tube-forming activity of vascular endothelial cells (ECs) in collagen gel. We fabricated a linear tube of 500 µm in diameter, the inner surface of which was filled with bovine carotid artery vascular endothelial cells (BECs), in type I collagen gel as a starting point for the formation of a capillary-like network. The BECs exposed to a medium containing vascular endothelial growth factor (VEGF) migrated into the ambient gel around the tube. After 2 weeks of VEGF exposure, the distance of the migration into the ambient gel in the radial direction of the tube reached approximately 800 µm. Cross-sections of capillary-like structures composed of the migrating BECs, with a lumen-like interior space, were observed in slices of the gel around the tube stained with hematoxylin,eosin (H&E). These results demonstrate that this approach using a pre-established tube, which is composed of ECs, as a starting point for a self-developing capillary-like network is potentially useful for constructing 3D organs in vitro. © 2006 Wiley Periodicals, Inc. [source] Loss of intercellular adhesion activates a transition from low- to high-grade human squamous cell carcinomaINTERNATIONAL JOURNAL OF CANCER, Issue 4 2006Alexander Margulis Abstract The relationship between loss of intercellular adhesion and the biologic properties of human squamous cell carcinoma is not well understood. We investigated how abrogation of E-cadherin-mediated adhesion influenced the behavior and phenotype of squamous cell carcinoma in 3D human tissues. Cell-cell adhesion was disrupted in early-stage epithelial tumor cells (HaCaT-II-4) through expression of a dominant-negative form of E-cadherin (H-2Kd -Ecad). Three-dimensional human tissue constructs harboring either H-2Kd -Ecad-expressing or control II-4 cells (pBabe, H-2Kd -Ecad,C25) were cultured at an air-liquid interface for 8 days and transplanted to nude mice; tumor phenotype was analyzed 2 days and 2 and 4 weeks later. H-2Kd -Ecad-expressing tumors demonstrated a switch to a high-grade aggressive tumor phenotype characterized by poorly differentiated tumor cells that infiltrated throughout the stroma. This high-grade carcinoma revealed elevated cell proliferation in a random pattern, loss of keratin 1 and diffuse deposition of laminin 5 ,2 chain. When II-4 cell variants were seeded into type I collagen gels as an in vitro assay for cell migration, we found that only E-cadherin-deficient cells detached, migrated as single cells and expressed N-cadherin. Function-blocking studies demonstrated that this migration was matrix metalloproteinase-dependent, as GM-6001 and TIMP-2, but not TIMP-1, could block migration. Gene expression profiles revealed that E-cadherin-deficient II-4 cells demonstrated increased expression of proteases and cell-cell and cell-matrix proteins. These findings showed that loss of E-cadherin-mediated adhesion plays a causal role in the transition from low- to high-grade squamous cell carcinomas and that the absence of E-cadherin is an important prognostic marker in the progression of this disease. © 2005 Wiley-Liss, Inc. [source] MT1-MMP, but not secreted MMPs, influences the migration of human microvascular endothelial cells in 3-dimensional collagen gelsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2002Teruhiko Koike Abstract Matrix metalloproteinases (MMPs) and their specific inhibitors the TIMPs play significant roles in angiogenesis. We investigated how the expression of specific MMPs and TIMPs by human microvascular endothelial cells (hmECs) was modulated by culture of the cells in 3-dimensional (3D) type I collagen gels versus 2-dimensional (2D) collagen-coated surfaces. By reverse-transcription polymerase chain reaction (RT-PCR), levels of mRNA for MMPs-1, -2, and -13, MT1-MMP, and TIMPs-1 and -2 were similar in 2D versus 3D cultures. By Western blot assay, TIMP-1 and proMMP-1 were present and were expressed similarly in media from 2D versus 3D cultures, whereas active MMPs-1, -9, and -13 were not detected. Active MMP-13 was present in cell lysates (CL) and was increased in lysates from 3D cultures relative to 2D cultures. Relative to 2D cultures, CL and media from 3D cultures exhibited a decrease in expression of TIMP-2 and an increased conversion of proMMP-2 and proMT1-MMP to active or processed forms. The MMP inhibitor GM6001 interfered with the migration of hmECs in 3D cultures, but not in 2D cultures. Addition of active MMP-1 or blocking antibodies to TIMP-1 did not affect the migration of hmECs in 3D collagen. Migration in 3D collagen was decreased by TIMP-2 (an inhibitor of MT1-MMP), but not by TIMP-1 (a poor inhibitor of MT1-MMP, but an efficient inhibitor of MMP-2). Collectively, our data indicate that MT1-MMP contributes significantly to the movement of hmECs through 3D collagen, in contrast to secretory-type MMPs-1, -2, -9, and -13, which are not critical for this movement. J. Cell. Biochem. 86: 748,758, 2002. © 2002 Wiley-Liss, Inc. [source] Fabrication of Artificial Endothelialized Tubes with Predetermined Three-Dimensional Configuration from Flexible Cell-Enclosing Alginate FibersBIOTECHNOLOGY PROGRESS, Issue 1 2007Takayuki Takei One possible strategy for creating three-dimensional (3D) tissue-engineered organs in vitro is to develop a vasculature for sufficient transport of oxygen and nutrients within these constructs. Here, we describe a novel technique to fabricate endothelialized tubes with predetermined 3D configuration, as a starting point for self-developing capillary-like networks in vitro. Calcium-alginate hydrogel fibers of ca. 250 and 500 ,m in diameter, enclosing bovine carotid artery vascular endothelial cells (BECs), were used as templates for endothelialized tubes. Fibers were prepared by extruding a 2% (w/v) sodium alginate solution containing BECs into a 100 mM calcium chloride solution flowing in the same direction. Fibers were embedded in type I collagen gels and enzymatically degraded by alginate lyase, resulting in channels with predetermined 3D configuration filled with a BEC suspension. Cells attached to and covered the surfaces of the channels. Exposing the cells to medium containing basic fibroblast growth factor resulted in their migration into the ambient collagen gel and self-assembly into capillary-like structures. These results demonstrate that using artificial endothelialized tubes with predetermined 3D configuration, as a starting point for a self-developing capillary-like network, could be potentially useful for constructing 3D tissue-engineered organs. [source] | ||||||||||