Biomimetic Poly(L-Lactic Acid) Scaffolds with Interconnected Macropores, Collagen-Like Nano-Scale Fibers, and Bone-Like Apatite

2002 ◽  
Vol 735 ◽  
Author(s):  
Victor J. Chen ◽  
Peter X. Ma
Keyword(s):  
Lactic Acid ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Type I Collagen ◽  
Three Dimensional ◽  
Bone Tissue Regeneration ◽  
Apatite Formation ◽  
Type I ◽  
Nano Scale ◽  
Fibrous Scaffolds

ABSTRACTHighly porous nano-fibrous poly(L-lactic acid) (PLLA) scaffolds were prepared and incubated in a simulated body fluid which resulted in the in situ formation of partially carbonated bone-like apatite. The macroporous interconnected architecture was created with a three-dimensional mold of thermally-bonded paraffin microspheres. PLLA solution was cast over the paraffin mold and was thermally induced to phase separate to form nano-scale fibers that mimic the fibrous structures of type I collagen. To potentially improve the osteoconductivity of these scaffolds, they were incubated in a buffered simulated body fluid at 37°C for certain periods of time to allow for apatite formation. It was seen that over time, the apatite particles increased in size. In addition, the growth of apatite particles on the nano-fibrous scaffolds was compared with the growth of particles on similar porous PLLA scaffolds with a solid-walled (not nano-fibrous) morphology. It was seen that the initial number of particles per unit area and the overall increase in mass of the scaffolds were significantly higher in the nano-fibrous scaffolds than in the solid-walled scaffolds. These novel scaffolds have well-defined architectures at three different size scales: (i) interconnected spherical pores ∼250–400 m in diameter; (ii) fibrous collagen-like matrix with fibers 50–500 nm in diameter; and (iii) carbonated bone-like apatite particles at the nanometer to micrometer scales; the scaffolds may serve as superior support for bone tissue regeneration.

Collagen-Inspired Nano-fibrous Poly(L-lactic acid) Scaffolds for Bone Tissue Engineering Created from Reverse Solid Freeform Fabrication

2004 ◽  
Vol 823 ◽  
Author(s):  
Victor J. Chen ◽  
Laura A. Smith ◽  
Peter X. Ma
Keyword(s):  
Tissue Engineering ◽  
Lactic Acid ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Computer Aided Design ◽  
Type I Collagen ◽  
Polymer Concentration ◽  
Three Dimensional ◽  
Type I ◽  
Fibrous Scaffold

AbstractReverse solid freeform (SFF) fabrication was used to create highly-controlled macroporous structures in nano-fibrous poly (L-lactic acid) (PLLA) scaffolds. By using a computer-aided design (CAD) program to create a negative template for the scaffold, the three-dimensional (3-D) mold was created on a 3-D printer using a wax. After the template was printed, a solution of PLLA in tetrahydrofuran (THF) was cast into the mold, and was subsequently phase separated at -70°C which gives the nano-fibrous morphology. This resulted in a 3-D nano-fibrous scaffold with a uniform fiber mesh throughout the entire matrix, and greatly increased the surface area within the scaffold. Fiber diameters in these scaffolds were 50-500 nm, similar to type I collagen, and the densities of the fiber meshes can be altered by changing the polymer concentration. To examine the scaffold's potential for tissue regeneration, MC3T3-E1 osteoblasts were seeded and cultured on the scaffolds. Results show that the osteoblasts attached and proliferated on the scaffolds. After 6 weeks in culture, bone-like tissue was evident within the nano-fibrous scaffolds. By having the ability to control the macroporous architecture, interconnectivity, orientation, and external shape of the scaffold, as well as the nanometer-scaled fibrous features in the pore walls, this SFF fabrication/phase separation technique has great potential to design and create ideal scaffolds for bone tissue engineering.

scholarly journals Preparation and In Vitro Behavior of a Poly(lactic acid)-Fiber/Hydroxyapatite Composite Sheet

2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
Yasuhiro Tanimoto ◽  
Norihiro Nishiyama
Keyword(s):  
Lactic Acid ◽  
Type I Collagen ◽  
Poly Lactic Acid ◽  
Apatite Formation ◽  
Type I ◽  
Composite Sheet ◽  
Precipitate Formation ◽  
Hydroxyapatite Composite ◽  
Fiber Sheet

This paper describes the processing and in vitro behavior of a poly(lactic acid) (PLA)-fiber/hydroxyapatite (HA) composite sheet consisting of a knitted PLA-fiber sheet and HA powder for bone tissue engineering. Type I collagen was used as a binding agent to combine the PLA fibers and the HA powder. Precipitate formation in Hanks' balanced salt (HBS) solution was monitored to evaluate the in vitro apatite formation ability of the PLA-fiber/HA composite sheet. Precipitate formation was observed on the surface of the PLA-fiber/HA composite sheet after immersion in HBS solution for only 1 day, while no precipitate formation was observed on the PLA-fiber sheet without HA as a control. In conclusion, a PLA-fiber/HA composite sheet for use as a scaffold was successfully prepared. Within the limitations of this investigation, we confirmed that the PLA-fiber/HA composite sheet has a high apatite formation activity compared with the PLA-fiber sheet and represents a promising material for use as a scaffold.

A new model for packing of type-I collagen molecules in the native fibril

1981 ◽  
Vol 1 (10) ◽  
pp. 801-810 ◽  
Author(s):  
Karl A. Piez ◽  
Benes L. Trus
Keyword(s):  
Type I Collagen ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Equatorial Region ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Left Handed ◽  
Crystal Model ◽  
Collagen Molecules

A specific fibril model is presented consisting of bundles of five-stranded microfibrils, which are usually disordered (except axially) but under lateral compression become ordered. The features are as follows (where D = 234 residues or 67 nm): (1) D-staggered collagen molecules 4.5 D long in the helical microfibril have a left-handed supercoil with a pitch of 400–700 residues, but microfibrils need not have helical symmetry. (2) Straight-tilted 0.5-D overlap regions on a near-hexagonal lattice contribute the discrete x-ray diffraction reflections arising from lateral order, while the gap regions remain disordered. (3) The overlap regions are equivalent, but are crystallographically distinguished by systematic displacements from the near-hexagonal lattice. (4) The unit cell is the same as in a recently proposed three-dimensional crystal model, and calculated intensities in the equatorial region of the x-ray diffraction pattern agree with observed values.

scholarly journals Protease-dependent versus -independent cancer cell invasion programs: three-dimensional amoeboid movement revisited

2009 ◽  
Vol 185 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Farideh Sabeh ◽  
Ryoko Shimizu-Hirota ◽  
Stephen J. Weiss
Keyword(s):  
Cancer Cells ◽  
Type I Collagen ◽  
Three Dimensional ◽  
Amoeboid Movement ◽  
Type I ◽  
Collagen Network ◽  
Normal Tissues ◽  
Tissue Invasion ◽  
Absolute Requirement ◽  
Cross Links

Tissue invasion during metastasis requires cancer cells to negotiate a stromal environment dominated by cross-linked networks of type I collagen. Although cancer cells are known to use proteinases to sever collagen networks and thus ease their passage through these barriers, migration across extracellular matrices has also been reported to occur by protease-independent mechanisms, whereby cells squeeze through collagen-lined pores by adopting an ameboid phenotype. We investigate these alternate models of motility here and demonstrate that cancer cells have an absolute requirement for the membrane-anchored metalloproteinase MT1-MMP for invasion, and that protease-independent mechanisms of cell migration are only plausible when the collagen network is devoid of the covalent cross-links that characterize normal tissues.

Formation of Hydroxycarbonate Apatite Layer on Poly(Lactic Acid) Composites in Simulated Body Fluid

2005 ◽  
Vol 284-286 ◽  
pp. 489-492 ◽  
Author(s):  
Hirotaka Maeda ◽  
Toshihiro Kasuga ◽  
Masayuki Nogami
Keyword(s):  
Lactic Acid ◽  
Simulated Body Fluid ◽  
Zeta Potential ◽  
Calcium Chloride ◽  
Composite Membrane ◽  
Body Fluid ◽  
Poly Lactic Acid ◽  
Zeta Potentials ◽  
Carbonate Ion ◽  
Ft Ir

Hydroxycarbonate apatite (HCA), which formed on a poly(lactic acid) (PLA) composite membrane containing vaterite or calcium chloride after soaking in simulated body fluid, was examined to clarify the importance of the ceramic phases in the composites. FT-IR spectra showed that the ratio of CO3/PO4 in the infrared adsorption bands of HCA formed on the PLA composite containing vaterite was much larger than that of HCA formed on the PLA composite containing calcium chloride. Substitution of carbonate ion in hydroxyapatite is believed to be strongly influenced by ceramic phases in the composites. The zeta potentials of HCA formed on the PLA composite containing vaterite or calcium chloride was -6 mV or -17 mV, respectively. The zeta potential may be influenced by the amount of carbonate ion in hydroxyapatite.

Mechanical Stress-Induced Orientation and Ultrastructural Change of Smooth Muscle Cells Cultured in Three-Dimensional Collagen Lattices

1994 ◽  
Vol 3 (6) ◽  
pp. 481-492 ◽  
Author(s):  
Keiichi Kanda ◽  
Takehisa Matsuda
Keyword(s):  
Smooth Muscle ◽  
Tensile Stress ◽  
Smooth Muscle Cells ◽  
Type I Collagen ◽  
Dynamic Stress ◽  
Three Dimensional ◽  
Muscle Cells ◽  
The Other ◽  
Type I ◽  
Oriented Parallel

The effect of tensile stress on the orientation and phenotype of arterial smooth muscle cells (SMCs) cultured in three-dimensional (3D) type I collagen gels was morphologically investigated. Ring-shaped hybrid tissues were prepared by thermal gelation of a cold mixed solution of type I collagen and SMCs derived from bovine aorta. The tissues were subjected to three different modes of tensile stress. They were floated (isotonic control), stretched isometrically (static stress) and periodically stretched and recoiled by 5% above and below the resting tissue length at 60 RPM frequency (dynamic stress). After incubation for up to four wk, the tissues were investigated under a light microscope (LM) and a transmission electron microscope (TEM). Hematoxylin and eosinstained LM samples revealed that, irrespective of static or dynamic stress loading, SMCs in stress-loaded tissues exhibited elongated bipolar spindle shape and were regularly oriented parallel to the direction of the strain, whereas those in isotonic control tissues were polygonal or spherical and had no preferential orientation. In Azan-stained samples, collagen fiber bundles in isotonic control tissues were somewhat retracted around the polygonal SMCs to form a random network. On the other hand, those in statically and dynamically stressed tissues were accumulated and prominently oriented parallel to the stretch direction. Ultrastructural investigation using a TEM showed that SMCs in control and statically stressed tissues were almost totally filled with synthetic organelles such as rough endoplasmic reticulums, free ribosomes, Golgi complexes and mitochondria, indicating that the cells remained in the synthetic phenotype. On the other hand, SMCs in dynamically stressed tissues had increased fractions of contractile apparatus, such as myofilaments, dense bodies and extracellular filamentous materials equivalent to basement membranes, that progressed with incubation time. These results indicate that periodic stretch, in concert with 3-D extracellular collagen matrices, play a significant role in the phenotypic modulation of SMCs from the synthetic to the contractile state, as well as cellular and biomolecular orientation.

The apatite formation ability of CaF 2 doping tricalcium silicates in simulated body fluid

2009 ◽  
Vol 4 (4) ◽  
pp. 045005 ◽  
Author(s):  
Qing Lin ◽  
Yanbao Li ◽  
Xianghui Lan ◽  
Chunhua Lu ◽  
Yixin Chen ◽  
...  
Keyword(s):  
Simulated Body Fluid ◽  
Body Fluid ◽  
Apatite Formation

scholarly journals Maintenance of chondrocyte phenotype during expansion on PLLA microtopographies

2018 ◽  
Vol 9 ◽  
pp. 204173141878982 ◽  
Author(s):  
Elisa Costa ◽  
Cristina González-García ◽  
José Luis Gómez Ribelles ◽  
Manuel Salmerón-Sánchez
Keyword(s):  
Lactic Acid ◽  
Type I Collagen ◽  
Collagen Type ◽  
Articular Chondrocytes ◽  
Collagen Type I ◽  
Cell Phenotype ◽  
Type I ◽  
Type Ii ◽  
Collagen Type Ii ◽  
Chondrocyte Phenotype

Articular chondrocytes are difficult to grow, as they lose their characteristic phenotype following expansion on standard tissue culture plates. Here, we show that culturing them on surfaces of poly(L-lactic acid) of well-defined microtopography allows expansion and maintenance of characteristic chondrogenic markers. We investigated the dynamics of human chondrocyte dedifferentiation on the different poly(L-lactic acid) microtopographies by the expression of collagen type I, collagen type II and aggrecan at different culture times. When seeded on poly(L-lactic acid), chondrocytes maintained their characteristic hyaline phenotype up to 7 days, which allowed to expand the initial cell population approximately six times without cell dedifferentiation. Maintenance of cell phenotype was afterwards correlated to cell adhesion on the different substrates. Chondrocytes adhesion occurs via the α5 β1 integrin on poly(L-lactic acid), suggesting cell–fibronectin interactions. However, α2 β1 integrin is mainly expressed on the control substrate after 1 day of culture, and the characteristic chondrocytic markers are lost (collagen type II expression is overcome by the synthesis of collagen type I). Expanding chondrocytes on poly(L-lactic acid) might be an effective solution to prevent dedifferentiation and improving the number of cells needed for autologous chondrocyte transplantation.

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