Pulsed-low intensity ultrasound enhances extracellular matrix                     production by fibroblasts encapsulated in alginate

Bohari, Siti Pauliena Mohd; Grover, Liam M.; Hukins, D.W.L.

doi:10.1177/2041731412454672

Cited by 16 publications

(22 citation statements)

References 41 publications

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“…A broad band at 3400 cm −1 was indicative of the stretching vibration of OH. The peaks at 2988 and 2912 cm −1 correspond to the asymmetric and symmetric C–H stretching, indicating that some of the initial reagents were still left unreacted in the structure . On the other hand, gelatin also had clear peaks in the spectrum with three main peaks; the C–N stretching mode for the amide III that appeared at 1250 cm −1 , C=O stretching for the amide I at 1690 cm −1 and N–H deformation of the amide II at 1560 cm −1 …”

Section: Resultsmentioning

confidence: 69%

“…Additional factors that facilitate cell attachment and growth, whilst providing an appropriate environment for osteogenesis are also necessary. To this end, natural polymers like gelatin, collagen, chitosan, and alginate have been widely used for bone tissue engineering due to their biocompatibility and biodegradability . High biodegradability is, on the one hand, beneficial for rapidly releasing bioactive factors within a few hours of implantation but on the other hand would also greatly disrupt cell attachment and proliferation due to the rapid change in substrate dynamics, therefore impeding new bone formation.…”

Section: Introductionmentioning

confidence: 99%

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Hybrid scaffolds of gelatin–siloxane releasing stromal derived factor‐1 effective for cell recruitment

Dashnyam

Pérez

Lee

et al. 2013

J Biomedical Materials Res

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Scaffolds with the capacity to deliver signaling molecules are attractive for bone regeneration. Here, we developed bioactive siloxane-gelatin hybrid scaffolds via a sol gel process containing stromal derived factor-1 (SDF-1) to recruit osteoprogenitor/stem cells. The process was undertaken under room temperature aqueous conditions, which enabled therapeutic molecules to be effectively incorporated. After the sol-gel reaction and lyophilization process, well-crosslinked hybrid scaffolds were obtained with porosities of 80-90%. Dynamic mechanical analysis of the hybrid scaffolds showed significant improvement in storage modulus values (from 10 to 110 kPa) with increasing siloxane content. The protein release capacity of the scaffolds was investigated using a model protein cytochrome C (cyto C). The cyto C safely loaded onto the scaffolds exhibited, except the initial burst of 30% within a day, highly sustainable release, with approximately 70-80% of the loading amount for up to 4 weeks. Target molecule SDF-1 was loaded and released from the scaffolds, and the effects on the homing of mesenchymal stem cell were studied. Results demonstrated significant enhancement in the migration of cells to the SDF-1 loaded scaffolds. Taken together, the developed hybrid scaffolds are considered to be useful in loading and delivering signaling molecules such as SDF-1 to recruit osteoprogenitor /mesenchymal stem cells in the bone regeneration process.

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Section: Resultsmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Hybrid scaffolds of gelatin–siloxane releasing stromal derived factor‐1 effective for cell recruitment

Dashnyam

Pérez

Lee

et al. 2013

J Biomedical Materials Res

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“…[11][12][13] When compared to other types of natural polymer hydrogels such as collagen, alginate has a major advantage in that it does not disintegrate when placed in aqueous media and therefore may retain the initial shape also allowing to be formulated into different shapes, including microspheres and fibers.…”

Section: Introductionmentioning

confidence: 99%

Utilizing Core–Shell Fibrous Collagen-Alginate Hydrogel Cell Delivery System for Bone Tissue Engineering

Pérez

Kim

et al. 2014

Tissue Engineering Part A

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Three-dimensional matrices that encapsulate and deliver stem cells with defect-tuned formulations are promising for bone tissue engineering. In this study, we designed a novel stem cell delivery system composed of collagen and alginate as the core and shell, respectively. Mesenchymal stem cells (MSCs) were loaded into the collagen solution and then deposited directly into a fibrous structure while simultaneously sheathing with alginate using a newly designed core-shell nozzle. Alginate encapsulation was achieved by the crosslinking within an adjusted calcium-containing solution that effectively preserved the continuous fibrous structure of the inner cell-collagen part. The constructed hydrogel carriers showed a continuous fiber with a diameter of *700-1000 mm for the core and 200-500 mm for the shell area, which was largely dependent on the alginate concentration (2%-5%) as well as the injection rate (20-80 mL/h). The water uptake capacity of the core-shell carriers was as high as 98%, which could act as a pore channel to supply nutrients and oxygen to the cells. Degradation of the scaffolds showed a weight loss of *22% at 7 days and *43% at 14 days, suggesting a possible role as a degradable tissue-engineered construct. The MSCs encapsulated within the collagen core showed excellent viability, exhibiting significant cellular proliferation up to 21 days with levels comparable to those observed in the pure collagen gel matrix used as a control. A live/dead cell assay also confirmed similar percentages of live cells within the core-shell carrier compared to those in the pure collagen gel, suggesting the carrier was cell compatible and was effective for maintaining a cell population. Cells allowed to differentiate under osteogenic conditions expressed high levels of bone-related genes, including osteocalcin, bone sialoprotein, and osteopontin. Further, when the core-shell fibrous carriers were implanted in a rat calvarium defect, the bone healing was significantly improved when the MSCs were encapsulated, and even more so after an osteogenic induction of MSCs before implantation. Based on these results, the newly designed core-shell collagen-alginate fibrous carrier is considered promising to enable the encapsulation of tissue cells and their delivery into damaged target tissues, including bone with defect-tunability for bone tissue engineering.

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“…The compressive modulus of alginate also increases with concentration (LeRoux et al 1999). Bohari et al found that increased alginate concentration also gave lower proliferation rate for embedded fibroblasts over 16 days of culture (Bohari et al 2011). …”

Section: Resultsmentioning

confidence: 96%

Alginate core-shell beads for simplified three-dimensional tumor spheroid culture and drug screening

Grist

et al. 2015

Biomed Microdevices

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We demonstrate that when using cell-laden core-shell hydrogel beads to support the generation of tumor spheroids, the shell structure reduces the out-of-bead and monolayer cell proliferation that occurs during long-term culture of tumor cells within core-only alginate beads. We fabricate core-shell beads in a two-step process using simple, one-layer microfluidic devices. Tumor cells encapsulated within the bead core will proliferate to form multicellular aggregates which can serve as three-dimensional (3-D) models of tumors in drug screening. Encapsulation in an alginate shell increased the time that cells could be maintained in three-dimensional culture for MCF-7 breast cancer cells prior to out-of-bead proliferation, permitting formation of spheroids over a period of 14 days without the need move the cell-laden beads to clean culture flasks to separate beads from underlying monolayers. Tamoxifen and docetaxel dose response shows decreased toxicity for multicellular aggregates in three-dimensional core-shell bead culture compared to monolayer. Using simple core-only beads gives mixed monolayer and 3-D culture during drug screening, and alters the treatment result compared to the 3-D core-shell or the 2-D monolayer groups, as measured by standard proliferation assay. By preventing the out-of-bead proliferation and subsequent monolayer formation that is observed with core-only beads, the core-shell structure can obviate the requirement to transfer the beads to a new culture flask during drug screening, an important consideration for cell-based drug screening and drugs which have high multicellular resistance index.

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Pulsed-low intensity ultrasound enhances extracellular matrix production by fibroblasts encapsulated in alginate

Cited by 16 publications

References 41 publications

Hybrid scaffolds of gelatin–siloxane releasing stromal derived factor‐1 effective for cell recruitment

Hybrid scaffolds of gelatin–siloxane releasing stromal derived factor‐1 effective for cell recruitment

Utilizing Core–Shell Fibrous Collagen-Alginate Hydrogel Cell Delivery System for Bone Tissue Engineering

Alginate core-shell beads for simplified three-dimensional tumor spheroid culture and drug screening

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