Structural and human cellular assessment of a novel microsphere-based tissue engineered scaffold for bone repair

Borden, Mark; El-Amin, Saadiq F.; Attawia, Mohamed; Laurencin, Cato T.

doi:10.1016/s0142-9612(02)00374-5

Cited by 207 publications

(174 citation statements)

References 25 publications

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“…[31] In particular, a sintered microsphere matrix from PLAGA has attracted significant interest as a load-bearing scaffold for orthopaedic tissue engineering. [23, 34] However, for large porous structures the use of a bioreactor might be essential for complete cell infiltration, because the preformed structures present nutrient and oxygen diffusion limitations. [35] A 12-week of blend degradation in vivo resulted in a porosity of 82-87% which is structurally similar to cancellous bone.…”

Section: Discussionmentioning

confidence: 99%

Porous Structures: In situ Porous Structures: A Unique Polymer Erosion Mechanism in Biodegradable Dipeptide‐Based Polyphosphazene and Polyester Blends Producing Matrices for Regenerative Engineering (Adv. Funct. Mater. 17/2010)

Deng

Nair

Nukavarapu

et al. 2010

Adv Funct Materials

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Synthetic biodegradable polymers serve as temporary substrates that accommodate cell infiltration and tissue in-growth in regenerative medicine. To allow tissue in-growth and nutrient transport, traditional three-dimensional (3D) scaffolds must be prefabricated with an interconnected porous structure. Here we demonstrated for the first time a unique polymer erosion process through which polymer matrices evolve from a solid coherent film to an assemblage of microspheres with an interconnected 3D porous structure. This polymer system was developed on the highly versatile platform of polyphosphazene-polyester blends. Co-substituting a polyphosphazene backbone with both hydrophilic glycylglycine dipeptide and hydrophobic 4-phenylphenoxy group generated a polymer with strong hydrogen bonding capacity. Rapid hydrolysis of the polyester component permitted the formation of 3D void space filled with self-assembled polyphosphazene spheres. Characterization of such self-assembled porous structures revealed macropores (10-100 μm) between spheres as well as micro- and nanopores on the sphere surface. A similar degradation pattern was confirmed in vivo using a rat subcutaneous implantation model. 12 weeks of implantation resulted in an interconnected porous structure with 82-87% porosity. Cell infiltration and collagen tissue in-growth between microspheres observed by histology confirmed the formation of an in situ 3D interconnected porous structure. It was determined that the in situ porous structure resulted from unique hydrogen bonding in the blend promoting a three-stage degradation mechanism. The robust tissue in-growth of this dynamic pore forming scaffold attests to the utility of this system as a new strategy in regenerative medicine for developing solid matrices that balance degradation with tissue formation.

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Section: Discussionmentioning

confidence: 99%

Porous Structures: In situ Porous Structures: A Unique Polymer Erosion Mechanism in Biodegradable Dipeptide‐Based Polyphosphazene and Polyester Blends Producing Matrices for Regenerative Engineering (Adv. Funct. Mater. 17/2010)

Deng

Nair

Nukavarapu

et al. 2010

Adv Funct Materials

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“…In PLLA scaffolds, vascular smooth muscle cells preferentially bind to one range of pore sizes (63 -150 µm) while fibroblasts bind to a wider range (38 -150 µm) [12,13]. A number of cell types exhibit preferences to binding in scaffolds with pore sizes considerably larger than the characteristic cell size, often utilizing a characteristic bridging mechanism where adjacent cells act as support structures to assist bridging large pores; examples include fibrovascular tissue ingrowth into PLLA scaffolds, osteoblast adhesion to polylactide-co-glycolide (PLAGA) scaffolds, and rat marrow cells binding to PEOT/PBT scaffolds [7,14,15]. Additionally, the mean pore size of scaffolds has also been shown to significantly influence cell morphology and phenotypic expression [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

The effect of pore size on cell adhesion in collagen-GAG scaffolds

et al. 2005

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“…Formulations containing drug-loaded nanoparticles often allow for controlled and slow release. Recently reports were published on using PLGA microspheres as building blocks for the preparation of polymeric scaffolds with controlled porosity for tissue engineering [9,10].…”

Section: Introductionmentioning

confidence: 99%

Poly(L,L-lactide) and poly(L,L-lactide-co-glycolide) microparticles by dialysis

2005

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Formation of poly(L,L-lactide) (PLLA) and poly(D,L-lactide-co-glycolide) (PLGA) microparticles by dialysis from 1,4-dioxane, tetrahydrofuran (THF), acetonitrile, dimethyl sulfoxide (DMSO), and dimethylformamide (DMF) against water has been investigated. In some instances microparticles were obtained from a mixture of the above-mentioned polyesters and PLLA-block-polyglycidol-blockpoly(ethylene oxide) triblock copolymer containing a hydrophobic PLLA block as well as hydrophilic polyglycidol and poly(ethylene oxide) blocks, the former with functional -OH groups. The effects of the nature of polyester, solvent and concentration of triblock copolymer on particles morphology, size, size distribution, and degree of crystallinity have been determined. Dialysis of PLGA yielded particles in the form of microspheres regardless of the solvent. Diameters of these particles were in the range of 0.36 -1.77 µm and particles' diameter polydispersity ( D ) varied from 1.37 to 2.04, depending on the solvent. In the case of PLLA, microspheres were obtained only by dialysis from 1,4-dioxane solutions. Dialysis of PLLA solutions in THF, acetonitrile and DMF yielded particles in the form of microcrystals. In the case of dialysis of PLLA solutions in DMSO, the product was in form of crystalline flakes of c. 1 µm thickness. Microspheres composed of PLGA were amorphous. The degree of crystallinity of microparticles from PLLA was in the range of 39% -72%.

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Structural and human cellular assessment of a novel microsphere-based tissue engineered scaffold for bone repair

Cited by 207 publications

References 25 publications

Porous Structures: In situ Porous Structures: A Unique Polymer Erosion Mechanism in Biodegradable Dipeptide‐Based Polyphosphazene and Polyester Blends Producing Matrices for Regenerative Engineering (Adv. Funct. Mater. 17/2010)

Porous Structures: In situ Porous Structures: A Unique Polymer Erosion Mechanism in Biodegradable Dipeptide‐Based Polyphosphazene and Polyester Blends Producing Matrices for Regenerative Engineering (Adv. Funct. Mater. 17/2010)

The effect of pore size on cell adhesion in collagen-GAG scaffolds

Poly(L,L-lactide) and poly(L,L-lactide-co-glycolide) microparticles by dialysis

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