Collagen barrier membranes are frequently used in both guided tissue regeneration (GTR) and guided bone regeneration (GBR). Collagen used for these devices is available from different species and is often processed to alter the properties of the final product. This is necessary because unprocessed collagen is rapidly resorbed in vivo and demands for barrier membranes are different in GTR and GBR. This systematic literature review attempts to evaluate possible effects of collagen origin and mode of cross-linking on the potential of different cells to attach to, proliferate on, and migrate over barrier membranes in vitro. Seventeen original studies, selected by a systematic process, are included in this review. The results show that fibroblasts of different species and originating tissues as well as bone-forming cells are able to attach to collagen membranes irrespective of collagen origin or mode of processing. Different cell types behave differently on identical membranes. Many pieces of evidence are currently available, and we attempted to elucidate the effects of collagen origin and mode of processing on cellular behavior, but further research will be required before it will be possible to predict for certain the effect a specific procedure will have with a given product.
"Once cells are inserted, growth may be able to continue as normal in the tissue.25–28 However, defects that limit the application of collagen include its rapid degradation, lack of mechanical properties, and poor stability.29 To overcome these problems, we introduced two further constituents, ie, genipin for crosslinking collagen and PCL to reform the properties of the scaffold. "
[Show abstract][Hide abstract] ABSTRACT: Periodontal repair is a complex process in which regeneration of alveolar bone is a vital component. The aim of this study was to develop a biodegradable scaffold with good biocompatibility and osteoinductive ability. Two types of composite fibrous scaffolds were produced by electrospinning, ie, type I collagen/poly(ε-caprolactone) (COL/PCL) and type I collagen/poly(ε-caprolactone)/nanoscale hydroxyapatite (COL/PCL/nHA) with an average fiber diameter of about 377 nm. After a simulated body fluid (SBF) immersion test, the COL/PCL/nHA-SBF scaffold developed a rough surface because of the calcium phosphate deposited on the fibers, suggesting that the presence of nHA promoted the mineralization potential of the scaffold. Energy dispersive X-ray spectroscopy clearly showed the calcium and phosphorus content in the COL/PCL/nHA and COL/PCL/nHA-SBF scaffolds, confirming the findings of nHA and calcium phosphate precipitation on scanning electron micrographs. Water contact analysis revealed that nHA could improve the hydrophilic nature of the COL/PCL/nHA-SBF scaffold. The morphology of periodontal ligament cells cultured on COL/PCL-SBF and COL/PCL/nHA-SBF was evaluated by scanning electron microscopy. The results showed that cells adhered to either type of scaffold and were slightly spindle-shaped in the beginning, then extended gradually with stretched filopodia, indicating an ability to fill the fiber pores. A Cell Counting Kit-8 assay showed that both scaffolds supported cell proliferation. However, real-time quantitative polymerase chain reaction analysis showed that expression of the bone-related markers, alkaline phosphatase and osteocalcin, was upregulated only on the COL/PCL/nHA-SBF scaffold, indicating that this scaffold had the ability to induce osteogenic differentiation of periodontal ligament cells. In this study, COL/PCL/nHA-SBF produced by electrospinning followed by biomimetic mineralization had combined electrospun fibers with nHA in it. This scaffold has good biocompatibility and osteoinductive ability as a result of the characteristics of nHA, so could be innovatively applied to periodontal tissue engineering as a potential scaffold.
International Journal of Nanomedicine 08/2014; 9:4135-43. DOI:10.2147/IJN.S65272 · 4.38 Impact Factor
"It plays critical roles in many supporting and connecting tissues such as tendon, ligament, bone, blood vessels, skin, etc. Collagen gel prepared from commercially available collagen solution have been broadly used as a biomaterial in tissue engineering, drug delivery, and wound healing for its biocompatibility, low toxicity, and well-documented physical, chemical, and immunological properties.1-3 Collagen gel is also used as three-dimensional model systems of extracellular matrix (ECM) in numerous studies of cell-ECM interactions under physiological and pathological conditions.4-7 Collagen thin film, or dehydrated collagen gel, has been used as a two-dimensional platform in a number of studies to examine cell-ECM interactions.8 "
[Show abstract][Hide abstract] ABSTRACT: This study aims to provide understanding of the macroscopic viscoelastic behavior of collagen matrices through studying the relaxation time distribution spectrum obtained from stress relaxation tests. Hydrated collagen gel and dehydrated collagen thin film was exploited as two different hydration levels of collagen matrices. Genipin solution was used to induce crosslinking in collagen matrices. Biaxial stress relaxation tests were performed to characterize the viscoelastic behavior of collagen matrices. The rate of stress relaxation of both hydrated and dehydrated collagen matrices shows a linear initial stress level dependency. Increased crosslinking reduces viscosity in collagen gel, but the effect is negligible for thin film. Relaxation time distribution spectrum was obtained from the stress relaxation data by inverse Laplace transform. For most of the collagen matrices, three peaks at the short (0.3s ~1 s), medium (3s ~90 s), and long relaxation time (> 200 s) were observed in the continuous spectrum, which likely corresponds to relaxation mechanisms involve fiber, inter-fibril, and fibril sliding. Splitting of the middle peak was observed at higher initial stress levels suggesting increased structural heterogeneity at the fibril level with mechanical loading. The intensity of the long-term peaks increases with higher initial stress levels indicating the engagement of collagen fibrils at higher levels of tissue strain.
"Some of these additional, here disregarded, factors are (i) additional matrix deposition of moving individuals, leading to altered traction generation, adhesion and contact guidance; (ii) soluble or matrix-bound gradients of chemoattractants; (iii) molecular signals transmitted from the ECM to cells (outside-in signaling), thereby changing the activity of polarization-or contractilitymediating proteins (Rac, Rho) ; or (iv) inside-out signaling for reinforcement of adhesion . Despite the limitations of theoretical modeling, our approach could be applied to the design of synthetic implant materials, i.e., acellular scaffolds with optimal values of pore size and stiffness that may accelerate cell in-growth, critically for regenerative treatments    . Further, applying our modeling approach on defined cancer invasion and inhibition studies in vitro and in vivo may assist in predicting some outcomes on therapeutic interventions. "
[Show abstract][Hide abstract] ABSTRACT: Cell migration on and through extracellular matrix is fundamental in a wide variety of physiological and pathological phenomena, and is exploited in scaffold-based tissue engineering. Migration is regulated by a number of extracellular matrix- or cell-derived biophysical parameters, such as matrix fiber orientation, pore size, and elasticity, or cell deformation, proteolysis, and adhesion. We here present an extended Cellular Potts Model (CPM) able to qualitatively and quantitatively describe cell migration efficiencies and phenotypes both on two-dimensional substrates and within three-dimensional matrices, close to experimental evidence. As distinct features of our approach, cells are modeled as compartmentalized discrete objects, differentiated into nucleus and cytosolic region, while the extracellular matrix is composed of a fibrous mesh and a homogeneous fluid. Our model provides a strong correlation of the directionality of migration with the topological extracellular matrix distribution and a biphasic dependence of migration on the matrix structure, density, adhesion, and stiffness, and, moreover, simulates that cell locomotion in highly constrained fibrillar obstacles requires the deformation of the cell's nucleus and/or the activity of cell-derived proteolysis. In conclusion, we here propose a mathematical modeling approach that serves to characterize cell migration as a biological phenomenon in healthy and diseased tissues and in engineering applications.
Kapil Saxena, Sarah E Blutt, Khalil Ettayebi, Xi-Lei Zeng, James R Broughman, Sue E Crawford, Umesh Karandikar, Narayan P Sastri, Margaret E Conner, Antone Opekun, David Y Graham, Waqar Qureshi, Vadim Sherman, Jennifer Foulke-Abel, Julie In, Olga Kovbasnjuk, Nicholas C Zachos, Mark Donowitz, Mary K Estes
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