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| 3. |
- Diez-Escudero, Anna, et al.
(författare)
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Effect of calcium phosphate heparinization on the in vitro inflammatory response and osteoclastogenesis of human blood precursor cells
- 2019
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : WILEY. - 1932-6254 .- 1932-7005. ; 13:7, s. 1217-1229
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Tidskriftsartikel (refereegranskat)abstract
- The immobilization of natural molecules on synthetic bone grafts stands as a strategy to enhance their biological interactions. During the early stages of healing, immune cells and osteoclasts (OC) modulate the inflammatory response and resorb the biomaterial, respectively. In this study, heparin, a naturally occurring molecule in the bone extracellular matrix, was covalently immobilized on biomimetic calcium-deficient hydroxyapatite (CDHA). The effect of heparin-functionalized CDHA on inflammation and osteoclastogenesis was investigated using primary human cells and compared with pristine CDHA and beta-tricalcium phosphate (beta-TCP). Biomimetic substrates led to lower oxidative stresses by neutrophils and monocytes than sintered beta-TCP, even though no further reduction was induced by the presence of heparin. In contrast, heparinized CDHA fostered osteoclastogenesis. Optical images of stained TRAP positive cells showed an earlier and higher presence of multinucleated cells, compatible with OC at 14 days, while pristine CDHA and beta-TCP present OC at 21-28 days. Although no statistically significant differences were found in the OC activity, microscopy images evidenced early stages of degradation on heparinized CDHA, compatible with osteoclastic resorption. Overall, the results suggest that the functionalization with heparin fostered the formation and activity of OC, thus offering a promising strategy to integrate biomaterials in the bone remodelling cycle by increasing their OC-mediated resorption.
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- Greuel, Selina, et al.
(författare)
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Online measurement of oxygen enables continuous noninvasive evaluation of human-induced pluripotent stem cell (hiPSC) culture in a perfused 3D hollow-fiber bioreactor
- 2019
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : WILEY. - 1932-6254 .- 1932-7005. ; 13:7, s. 1203-1216
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Tidskriftsartikel (refereegranskat)abstract
- For clinical and/or pharmaceutical use of human-induced pluripotent stem cells (hiPSCs), large cell quantities of high quality are demanded. Therefore, we combined the expansion of hiPSCs in closed, perfusion-based 3D bioreactors with noninvasive online monitoring of oxygen as culture control mechanism. Bioreactors with a cell compartment volume of 3 or 17 ml were inoculated with either 10 x 10(6) or 50 x 10(6) cells, and cells were expanded over 15 days with online oxygen and offline glucose and lactate measurements being performed. The CellTiter-Blue (R) Assay was performed at the end of the bioreactor experiments for indirect cell quantification. Model simulations enabled an estimation of cell numbers based on kinetic equations and experimental data during the 15-day bioreactor cultures. Calculated oxygen uptake rates (OUR), glucose consumption rates (GCR), and lactate production rates (LPR) revealed a highly significant correlation (p amp;lt; 0.0001). Oxygen consumption, which was measured at the beginning and the end of the experiment, showed a strong culture growth in line with the OUR and GCR data. Furthermore, the yield coefficient of lactate from glucose and the OUR to GCR ratio revealed a shift from nonoxidative to oxidative metabolism. The presented results indicate that oxygen is equally as applicable as parameter for hiPSC expansion as glucose while providing an accurate real-time impression of hiPSC culture development. Additionally, oxygen measurements inform about the metabolic state of the cells. Thus, the use of oxygen online monitoring for culture control facilitates the translation of hiPSC use to the clinical setting.
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- Hulsart-Billström, Gry, et al.
(författare)
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A uni-cortical femoral defect model in the rat : evaluation using injectable hyaluronan hydrogel as a carrier for bone morphogenetic protein-2
- 2015
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 9:7, s. 799-807
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Tidskriftsartikel (refereegranskat)abstract
- The development of biomaterial for bone regeneration requires animal models that are reliable and designed to mimic clinically relevant situations. We have previously investigated hydrogels comprised of modified hyaluronic acid and polyvinyl alcohol in models of ectopic bone formation. This hydrogel induces bone regeneration when loaded with bone morphogenetic proteins (BMPs). To allow further optimization of hydrogels, we developed a new, femoral, non-critical-sized cortical defect model. In the rat femur, we drilled standardized, elongated unilateral cortical defects that did not require stabilization and that could be created bilaterally to allow paired comparisons of biomaterials. After optimizing the defect size, subsequent stress fractures occurred in only 8% and the defect healed partially over the 40 day study period. In a time-course experiment, we treated bone defects with the previously studied hyaluronan hydrogel loaded with 10 µg hydroxyapatite and 6 µg BMP-2. The shape of the defect allowed controlled containment of the material within the defect. The defect in the right leg was left untreated, while the left defect was filled with 40 µl of the BMP hydrogel. As determined by pQCT analysis, the treated defects had a higher bone mineral content, bone area and bone density than control defects. The relative difference was greatest between the groups at 10 and 20 days and diminished as the defect healed in the untreated legs. We conclude that this animal model allows facile and rapid screening of biomaterials for bone regeneration in cortical femoral defects without requiring external fixation.
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| 7. |
- Jones, Iwan, et al.
(författare)
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Regenerative effects of human embryonic stem cell-derived neural crest cells for treatment of peripheral nerve injury
- 2018
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 12:4, s. E2099-E2109
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Tidskriftsartikel (refereegranskat)abstract
- Surgical intervention is the current gold standard treatment following peripheral nerve injury. However, this approach has limitations, and full recovery of both motor and sensory modalities often remains incomplete. The development of artificial nerve grafts that either complement or replace current surgical procedures is therefore of paramount importance. An essential component of artificial grafts is biodegradable conduits and transplanted cells that provide trophic support during the regenerative process. Neural crest cells are promising support cell candidates because they are the parent population to many peripheral nervous system lineages. In this study, neural crest cells were differentiated from human embryonic stem cells. The differentiated cells exhibited typical stellate morphology and protein expression signatures that were comparable with native neural crest. Conditioned media harvested from the differentiated cells contained a range of biologically active trophic factors and was able to stimulate in vitro neurite outgrowth. Differentiated neural crest cells were seeded into a biodegradable nerve conduit, and their regeneration potential was assessed in a rat sciatic nerve injury model. A robust regeneration front was observed across the entire width of the conduit seeded with the differentiated neural crest cells. Moreover, the up-regulation of several regeneration-related genes was observed within the dorsal root ganglion and spinal cord segments harvested from transplanted animals. Our results demonstrate that the differentiated neural crest cells are biologically active and provide trophic support to stimulate peripheral nerve regeneration. Differentiated neural crest cells are therefore promising supporting cell candidates to aid in peripheral nerve repair.
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| 8. |
- Kettenberger, Ulrike, et al.
(författare)
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In vitro and in vivo investigation of bisphosphonate-loaded hydroxyapatite particles for peri-implant bone augmentation
- 2017
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 11:7, s. 1974-1985
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Tidskriftsartikel (refereegranskat)abstract
- Locally applied bisphosphonates, such as zoledronate, have been shown in several studies to inhibit peri-implant bone resorption and recently to enhance peri-implant bone formation. Studies have also demonstrated positive effects of hydroxyapatite (HA) particles on peri-implant bone regeneration and an enhancement of the anti-resorptive effect of bisphosphonates in the presence of calcium. In the present study, both hydroxyapatite nanoparticles (nHA) and zoledronate were combined to achieve a strong reinforcing effect on peri-implant bone. The nHA-zoledronate combination was first investigated in vitro with a pre-osteoclastic cell assay (RAW 264.7) and then in vivo in a rat model of postmenopausal osteoporosis. The in vitro study confirmed that the inhibitory effect of zoledronate on murine osteoclast precursor cells was enhanced by loading the drug on nHA. For the in vivo investigation, either zoledronate-loaded or pure nHA were integrated in hyaluronic acid hydrogel. The gels were injected in screw holes that had been predrilled in rat femoral condyles before the insertion of miniature screws. Micro-CT-based dynamic histomorphometry and histology revealed an unexpected rapid mineralization of the hydrogel in vivo through formation of granules, which served as scaffold for new bone formation. The delivery of zoledronate-loaded nHA further inhibited a degradation of the mineralized hydrogel as well as a resorption of the peri-implant bone as effectively as unbound zoledronate. Hyaluronic acid with zoledronate-loaded nHA, thanks to its dual effect on inducing a rapid mineralization and preventing resorption, is a promising versatile material for bone repair and augmentation.
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| 9. |
- König, Niclas, et al.
(författare)
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Murine neural crest stem cells and embryonic stem cell derived neuron precursors survive and differentiate after transplantation in a model of dorsal root avulsion
- 2017
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : John Wiley & Sons. - 1932-6254 .- 1932-7005. ; 11:1, s. 129-137
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Tidskriftsartikel (refereegranskat)abstract
- Spinal root avulsion results in paralysis and sensory loss, and is commonly associated with chronic pain. In addition to the failure of avulsed dorsal root axons to regenerate into the spinal cord, avulsion injury leads to extensive neuroinflammation and degeneration of second order neurons in the dorsal horn. The ultimate objective with the treatment of this condition is to counteract degeneration of spinal cord neurons and to achieve functionally useful regeneration/reconnection of sensory neurons with spinal cord neurons. Here we explore if stem cells transplanted on the surface of avulsed spinal cord can survive, differentiate and migrate into the damaged spinal cord during the first few weeks after this intervention. Murine boundary cap neural crest stem cells (bNCSCs) or embryonic stem cell (ESC)-derived, pre-differentiated neuron precursors were implanted acutely at the junction between avulsed dorsal roots L3-L6 and the spinal cord. Both types of cells survived transplantation, but showed distinctly different modes of differentiation. Thus, bNCSCs migrated into the spinal cord, expressed glial markers, and formed elongated tubes in the peripheral nervous system (PNS) compartment of the avulsed dorsal root transitional zone(DRTZ) area. In contrast, the ESC-transplants remained at the site of implantation and differentiated to motor neurons and interneurons. These data show that both stem cell types successfully survive implantation to the acutely injured spinal cord and maintained their differentiation and migration potential. These data suggest that depending on the source of neural stem cells, they can play different beneficial roles for recovery after dorsal root avulsion.
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| 10. |
- Lauvrud, Anne Therese, et al.
(författare)
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Characterization of human adipose tissue-derived stem cells with enhanced angiogenic and adipogenic properties
- 2017
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : John Wiley & Sons. - 1932-6254 .- 1932-7005. ; 11:9, s. 2490-2502
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Tidskriftsartikel (refereegranskat)abstract
- Autologous fat grafting is a popular method for soft tissue reconstructions but graft survival remains highly unpredictable. Supplementation of the graft with the stromal vascular fraction (SVF) or cultured adipose tissue-derived stem cells (ASCs) can enhance graft viability. In this study we have examined the phenotypic properties of a selected population of cells isolated from ASCs, with a view to determining their suitability for transplantation into grafts. ASCs were isolated from the SVF of human abdominal fat (n = 8 female patients) and CD146(+) cells were selected using immunomagnetic beads. The angiogenic and adipogenic properties of the positively selected cells were compared with the negative fraction. CD146(+) cells expressed the immunophenotypic characteristics of pericytes. With prolonged in vitro expansion, CD146(-) cells exhibited increased population doubling times and morphological signs of senescence, whereas CD146(+) cells did not. CD146(+) cells expressed higher levels of the angiogenic molecules VEGF-A, angiopoietin-1 and FGF-1. Conditioned medium taken from CD146(+) cells significantly increased formation of in vitro endothelial cell tube networks, whereas CD146(-) cells did not. CD146(+) cells could be differentiated into adipocytes in greater numbers than CD146(-) cells. Consistent with this, differentiated CD146(+) cells expressed higher levels of the adipocyte markers adiponectin and leptin. These results suggest that CD146(+) cells selected from a heterogeneous mix of ASCs have more favourable angiogenic and adipogenic properties, which might provide significant benefits for reconstructive and tissue-engineering applications. Copyright © 2016 John Wiley & Sons, Ltd.
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