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Injectable composite colloidal gels are developed for regeneration of osteoporotic bone defects through a bottom-up assembly from bisphosphonate-functionalized gelatin and bioactive glass particles. Upon bisphosphonate functionalization, gelatin nanoparticles show superior adhesion toward bioactive glass particles, resulting in elastic composite gels. By tuning their composition, these composite colloidal gels combine mechanical robustness with self-healing ability. The composite colloidal gels support cell proliferation and differentiation in vitro without requiring any osteogenic supplement. In vivo evaluation of the composite colloidal gels reveals their capacity to support the regeneration of osteoporotic bone defects. Furthermore, the bisphosphonate modification of gelatin induces a therapeutic effect on the peri-implantation region by enhancing the bone density of the osteoporotic bone tissue. Consequently, these composite colloidal gels offer new therapeutic opportunities for treatment of osteoporotic bone defects. [ABSTRACT FROM AUTHOR]

Enthralling evidence of the potential of graphene-based materials for neural tissue engineering is motivating the development of scaffolds using various structures related to graphene such as graphene oxide (GO) or its reduced form. Here, we investigated a strategy based on reduced graphene oxide (rGO) combined with a decellularized extracellular matrix from adipose tissue (adECM), which is still unexplored for neural repair and regeneration. Scaffolds containing up to 50 wt% rGO relative to adECM were prepared by thermally induced phase separation assisted by carbodiimide (EDC) crosslinking. Using partially reduced GO enables fine-tuning of the structural interaction between rGO and adECM. As the concentration of rGO increased, non-covalent bonding gradually prevailed over EDC-induced covalent conjugation with the adECM. Edge-to-edge aggregation of rGO favours adECM to act as a biomolecular physical crosslinker to rGO, leading to the softening of the scaffolds. The unique biochemistry of adECM allows neural stem cells to adhere and grow. Importantly, high rGO concentrations directly control cell fate by inducing the differentiation of both NE-4C cells and embryonic neural progenitor cells into neurons. Furthermore, primary astrocyte fate is also modulated as increasing rGO boosts the expression of reactivity markers while unaltering the expression of scar-forming ones., (Copyright © 2023. Published by Elsevier B.V.)

The composition of calcium phosphate (CaP) ceramics in combination with surface features have been shown to influence biological performance, and micro- and nano-scale topography is known to stimulate osteogenic differentiation of mesenchymal stromal cells (MSCs). In view of this, adipose tissue derived MSCs were cultured on CaP disks featuring hemispherical concavities of various sizes (440, 800 or 1800 μm diameter). It was hypothesized that (i) surface concavities would promote cell proliferation, cellular organization within the concavities, and osteogenic differentiation, as a result of a more pronounced 3D micro-environment and CaP nucleation in concavities, and (ii) MSC proliferation and osteogenic differentiation would increase with smaller concavity size due to more rapidly occurring 3D cell-cell interactions. We found that concavities indeed affect cell proliferation, with 440 μm concavities increasing cell proliferation to a larger extent compared to 800 and 1800 μm concavities as well as planar surfaces. Additionally, concavity size influenced 3D cellular organization within the concavity volume. Interestingly, concavity size promoted osteogenic differentiation of cells, as evidenced by increased osteocalcin gene expression in 440 μm concavities, and osteocalcin staining predominantly for 440 and 800 μm concavities, but not for 1800 μm concavities and only slightly for planar surface controls.

Bone-implant material development is proceeding at a high pace, and has shifted from straightforward biomaterial testing to more advanced cell-targeted approaches for surface modification and design. It has been long known that cells can recognize and respond to topographical features by changing their morphology and behavior. The progress in surface analytical devices, as well as in techniques for production of topographical features on the nanometer scale allow for the characterization of natural tissues and the reproduction of biomimetic nanofeatures in material surfaces. In this review some of the most common surface-characterization and surface-manufacturing techniques will be addressed and results from in vitro and in vivo studies will be presented. Knowledge on biomaterial nanotopography can be exploited for active stimulation and control of cellular behavior like attachment, migration, spreading, gene expression, proliferation, differentiation and secretion of matrix components.