The Design of Scaffolds for Use in Tissue Engineering. Part I. Traditional Factors

Yang, Shoufeng; Leong, Kah Fai; Du, Zhimin; Chua, Chee Kai

doi:10.1089/107632701753337645

Cited by 2,050 publications

(1,407 citation statements)

References 45 publications

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“…There have also been quite a few reports on the diffusion and cell migration limitations of the closed pore system resulting from the prefabrication processes. [3] Therefore, porosity and interconnectivity are key factors in the success of a matrix for promoting tissue in-growth and integration. [1, 32] In addition, the optimal pore diameters for neovascularization, osteoid, and mineralized bone formation have been reported to be in the range of 5-350 μm.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, these prefabricated structures lack predictable scaffold properties post-implantation that could lead to rate mismatch between scaffold degradation and tissue in-growth. [3] In the case of hydrophobic polymers that undergo surface erosion, degradation occurs at the implant surface with insignificant decrease in the molecular weight of the bulk material. The matrix becomes smaller but maintains its original geometric shape as a function of degradation time until the structure is completely eroded as indicated in Scheme 1b.…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Introductionmentioning

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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“…Several researchers have suggested that for a bone cell and nutrients to migrate into a scaffold, the pores should be at least the size of the cell. 183 Highly porous microscale scaffolds also allow for higher levels of nutrient diffusion, vascularization, and better spatial organization for cell growth and ECM production. 184,185 There is still some ambiguity surrounding the optimal porosity and pore size for a 3D bone scaffold.…”

Section: Physical Effectors In Synthetic Bone Scaffoldsmentioning

confidence: 99%

Bone tissue engineering: A review in bone biomimetics and drug delivery strategies

Porter

Ruckh

Popat

2009

Biotechnology Progress

685

499

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Critical‐sized defects in bone, whether induced by primary tumor resection, trauma, or selective surgery have in many cases presented insurmountable challenges to the current gold standard treatment for bone repair. The primary purpose of a tissue‐engineered scaffold is to use engineering principles to incite and promote the natural healing process of bone which does not occur in critical‐sized defects. A synthetic bone scaffold must be biocompatible, biodegradable to allow native tissue integration, and mimic the multidimensional hierarchical structure of native bone. In addition to being physically and chemically biomimetic, an ideal scaffold is capable of eluting bioactive molecules (e.g., BMPs, TGF‐βs, etc., to accelerate extracellular matrix production and tissue integration) or drugs (e.g., antibiotics, cisplatin, etc., to prevent undesired biological response such as sepsis or cancer recurrence) in a temporally and spatially controlled manner. Various biomaterials including ceramics, metals, polymers, and composites have been investigated for their potential as bone scaffold materials. However, due to their tunable physiochemical properties, biocompatibility, and controllable biodegradability, polymers have emerged as the principal material in bone tissue engineering. This article briefly reviews the physiological and anatomical characteristics of native bone, describes key technologies in mimicking the physical and chemical environment of bone using synthetic materials, and provides an overview of local drug delivery as it pertains to bone tissue engineering is included. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009

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“…In most cases, it is preferable to have the material's modulus close to that of the target tissue to avoid possible stressshielding effects and maintain sufficient mechanical support during in vitro and/or in vivo cell growth and tissue-remodeling processes. 27 For example, muscle cells are particularly anchorage-dependent due to the contractile behaviors of the natural tissue, which requires a compliant substrate for effective myogeneis 28 whereas bone cells prefer stiff substrates to enhance osteogenesis. 29 Mechanical properties of the nanofiber membrane were assessed by tensile tests (i.e., breaking strength and tensile modulus).…”

Section: Mechanical Testingmentioning

confidence: 99%

Poly(ε-caprolactone)/keratin-based composite nanofibers for biomedical applications

Edwards

Jarvis

Hopkins

et al. 2014

J. Biomed. Mater. Res.

114

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Keratin-based composite nanofibers have been fabricated by an electrospinning technique. Aqueous soluble keratin extracted from human hair was successfully blended with poly(e-caprolactone) (PCL) in different ratios and transformed into nanofibrous membranes. Toward the potential use of this nanofibrous membrane in tissue engineering, its physicochemical properties, such as morphology, mechanical strength, crystallinity, chemical structure, and integrity in aqueous medium were studied and its cellular compatibility was determined. Nanofibrous membranes with PCL/keratin ratios from 100/00 to 70/30 showed good uniformity in fiber morphology and suitable mechanical properties, and retained the integrity of their fibrous structure in buffered solutions.Experimental results, using cell viability assays and scanning electron microscopy imaging, showed that the nanofibrous membranes supported 3T3 cell viability. The ability to produce blended nanofibers from protein and synthetic polymers represents a significant advancement in development of composite materials with structural and material properties that will support biomedical applications. This provides new nanofibrous materials for applications in tissue engineering and regenerative medicine.

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The Design of Scaffolds for Use in Tissue Engineering. Part I. Traditional Factors

Cited by 2,050 publications

References 45 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)

Bone tissue engineering: A review in bone biomimetics and drug delivery strategies

Poly(ε-caprolactone)/keratin-based composite nanofibers for biomedical applications

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