Abstract:Acellular soft hydrogels are not ideal for hard tissue engineering given their poor mechanical stability, however, in combination with cellular components offer significant promise for tissue regeneration. Indeed, nanocomposite bioinks provide an attractive platform to deliver human bone marrow stromal cells (HBMSCs) in three dimensions producing cellladen constructs that aim to facilitate bone repair and functionality. Here we present the in vitro, ex vivo and in vivo investigation of bioprinted HBMSCs encaps… Show more
“…The algMC blend was used in past years in our and other groups, as a suitable bioink for printing a variety of cell types such as human mesenchymal stem cells (hMSC) [20], chondrocytes [21,22], rat pancreatic islets [23], and microalgae [24,25]. To achieve further functionalities, this blend was also combined with blood plasma supporting cellular functions or with nanoclay laponite, allowing efficient loading with growth factors like VEGF or BMP-2 [26][27][28]. In the present study, we aimed to combine MBG with the algMC blend to develop an extrudable composite suitable for 3D (bio)printing and delivery of therapeutic metal ions for bone tissue engineering.…”
Bioactive glasses have been used for bone regeneration applications thanks to their excellent osteoconductivity, an osteostimulatory effect, and high degradation rate, releasing biologically active ions. Besides these properties, mesoporous bioactive glasses (MBG) are specific for their highly ordered mesoporous channel structure and high specific surface area, making them suitable for drug and growth factor delivery. In the present study, calcium (Ca) (15 mol%) in MBG was partially and fully substituted with zinc (Zn), known for its osteogenic and antimicrobial properties. Different MBG were synthesized, containing 0, 5, 10, or 15 mol% of Zn. Up to 7 wt.% of Zn-containing MBG could be mixed into an alginate-methylcellulose blend (algMC) while maintaining rheological properties suitable for 3D printing of scaffolds with sufficient shape fidelity. The suitability of these composites for bioprinting applications has been demonstrated with immortalized human mesenchymal stem cells. Uptake of Ca and phosphorus (P) (phosphate) ions by composite scaffolds was observed, while the released concentration of Zn2+ corresponded to the initial amount of this ion in prepared glasses, suggesting that it can be controlled at the MBG synthesis step. The study introduces a tailorable bioprintable material system suitable for bone tissue engineering applications.
“…The algMC blend was used in past years in our and other groups, as a suitable bioink for printing a variety of cell types such as human mesenchymal stem cells (hMSC) [20], chondrocytes [21,22], rat pancreatic islets [23], and microalgae [24,25]. To achieve further functionalities, this blend was also combined with blood plasma supporting cellular functions or with nanoclay laponite, allowing efficient loading with growth factors like VEGF or BMP-2 [26][27][28]. In the present study, we aimed to combine MBG with the algMC blend to develop an extrudable composite suitable for 3D (bio)printing and delivery of therapeutic metal ions for bone tissue engineering.…”
Bioactive glasses have been used for bone regeneration applications thanks to their excellent osteoconductivity, an osteostimulatory effect, and high degradation rate, releasing biologically active ions. Besides these properties, mesoporous bioactive glasses (MBG) are specific for their highly ordered mesoporous channel structure and high specific surface area, making them suitable for drug and growth factor delivery. In the present study, calcium (Ca) (15 mol%) in MBG was partially and fully substituted with zinc (Zn), known for its osteogenic and antimicrobial properties. Different MBG were synthesized, containing 0, 5, 10, or 15 mol% of Zn. Up to 7 wt.% of Zn-containing MBG could be mixed into an alginate-methylcellulose blend (algMC) while maintaining rheological properties suitable for 3D printing of scaffolds with sufficient shape fidelity. The suitability of these composites for bioprinting applications has been demonstrated with immortalized human mesenchymal stem cells. Uptake of Ca and phosphorus (P) (phosphate) ions by composite scaffolds was observed, while the released concentration of Zn2+ corresponded to the initial amount of this ion in prepared glasses, suggesting that it can be controlled at the MBG synthesis step. The study introduces a tailorable bioprintable material system suitable for bone tissue engineering applications.
“…8 B). The high density definition of bone generated here by GET-RUNX scaffolds is based on the intensity of signal measured by μCT as we have previously published [ 33 ] (lowest density bone set at 0.25 g/cm 3 ). Fig.…”
Section: Resultsmentioning
confidence: 99%
“…The images are semi-transparent and represent the bone density for the entire 3D reconstruction. High density bone was defined based on the intensity of signal measured by μCT as we have previously published [ 33 ] (lowest density bone set at 0.25 g/cm 3 ).…”
Additive manufacturing processes used to create regenerative bone tissue engineered implants are not biocompatible, thereby restricting direct use with stem cells and usually require cell seeding post-fabrication. Combined delivery of stem cells with the controlled release of osteogenic factors, within a mechanically-strong biomaterial combined during manufacturing would replace injectable defect fillers (cements) and allow personalized implants to be rapidly prototyped by 3D bioprinting.
Through the use of direct genetic programming
via
the sustained release of an exogenously delivered transcription factor
RUNX2
(delivered as recombinant GET-RUNX2 protein) encapsulated in PLGA microparticles (MPs)
,
we demonstrate that human mesenchymal stromal (stem) cells (hMSCs) can be directly fabricated into a thermo-sintered 3D bioprintable material and achieve effective osteogenic differentiation. Importantly we observed osteogenic programming of gene expression by released GET-RUNX2 (8.2-, 3.3- and 3.9-fold increases in
OSX, RUNX2
and
OPN
expression, respectively) and calcification (von Kossa staining) in our scaffolds. The developed biodegradable PLGA/PEG paste formulation augments high-density bone development in a defect model (~2.4-fold increase in high density bone volume) and can be used to rapidly prototype clinically-sized hMSC-laden implants within minutes using mild, cytocompatible extrusion bioprinting.
The ability to create mechanically strong 'cancellous bone-like’ printable implants for tissue repair that contain stem cells and controlled-release of programming factors is innovative, and will facilitate the development of novel localized delivery approaches to direct cellular behaviour for many regenerative medicine applications including those for personalized bone repair.
“…Laponite-alginate-methylcellulose (3-3-3) bioink was applied to the CAM and the addition of VEGF and human umbilical vein endothelial cells (HUVECs) was found to induce a significantly greater angiogenic response than the material alone, without VEGF or without the addition of HUVECs. 91 BMP-2 (10 µg/mL) was then adsorbed onto '3-3-3' bioink scaffolds for evaluation in a murine subcutaneous implant model and the results showed significantly greater mineralisation in the '3-3-3' scaffolds with or without BMP-2 compared with alginate controls. 91 Modelling potential pathways of angiogenesis was investigated by Bai et al 92 using a polymer scaffold with VEGF and FGF-2 in combination with platelet-derived growth factor (PDGF) in microspheres to create sequential delivery of growth factors.…”
Section: Hydrogels On the Cammentioning
confidence: 99%
“…91 BMP-2 (10 µg/mL) was then adsorbed onto '3-3-3' bioink scaffolds for evaluation in a murine subcutaneous implant model and the results showed significantly greater mineralisation in the '3-3-3' scaffolds with or without BMP-2 compared with alginate controls. 91 Modelling potential pathways of angiogenesis was investigated by Bai et al 92 using a polymer scaffold with VEGF and FGF-2 in combination with platelet-derived growth factor (PDGF) in microspheres to create sequential delivery of growth factors. The authors reported a significant increase in mature blood vessels and thickness of the mesodermal tissue on histology.…”
The chick chorioallantoic membrane model has been around for over a century, applied in angiogenic, oncology, dental and xenograft research. Despite its often perceived archaic, redolent history, the chorioallantoic membrane assay offers new and exciting opportunities for material and growth factor evaluation in bone tissue engineering. Currently, superior/improved experimental methodology for the chorioallantoic membrane assay are difficult to identify, given an absence of scientific consensus in defining experimental approaches, including timing of inoculation with materials and the analysis of results. In addition, critically, regulatory and welfare issues impact upon experimental designs. Given such disparate points, this review details recent research using the ex vivo chorioallantoic membrane assay and the ex vivo organotypic culture to advance the field of bone tissue engineering, and highlights potential areas of improvement for their application based on recent developments within our group and the tissue engineering field.
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