Nanoscale borosilicate bioactive glass for regenerative therapy of full-thickness skin defects in rabbit animal model

Ionic Dissolution Products of Lithium-, Strontium-, and Boron-Substituted Silicate Glasses Influence the Viability and Proliferation of Adipose Stromal Cells, Fibroblasts, Urothelial and Endothelial Cells

While bioactive glasses (BaGs) have been studied mainly for bone applications, studies have also shown their potential for soft tissue engineering. Incorporating therapeutic ions, such as lithium (Li+), strontium (Sr2+), and boron (B3+) into the BaGs, has been found to promote angiogenesis and wound healing. However, a systematic study on the impact of Li+, Sr2+, B3+, and the other ions in the BaGs, has not been conducted on a wide range of cells. Although the interactions between the BaGs and cells have been studied, it is difficult to compare the results between studies and conclude the impact of BaGs between cell types due to the variability of culture conditions, cells, and materials. We aim to evaluate the dissolution behavior of Li-, Sr-, and B-substituted BaGs and the effects of their ionic dissolution products on the viability, proliferation, and morphology of multiple cell types: human adipose stromal cells (hASCs), human lung fibroblasts (cell line WI-38), human urothelial cells (hUCs), and human umbilical vein endothelial cells (HUVECs). In the dissolution study, the B-substituted glasses induced a higher increase in pH and released more ions than the silicate glasses. The undiluted BaG extracts supported the viability and proliferation of all the other cell types except the hUCs. Diluting the BaG extracts to 1:10 restored the viability of hUCs but induced distinctive morphological changes. Diluting the extracts more (1:100) almost fully restored the hUC morphology. To conclude, the ionic dissolution products of Li-, Sr-, and B-substituted BaGs seem beneficial for hASCs, WI-38, hUCs, and HUVECs, but attention must be paid to the ion concentrations.

Advances in clinical applications of bioceramics in the new regenerative medicine era

In this editorial, we comment on the hard and soft tissue applications of different ceramic-based scaffolds prepared by different mechanisms such as 3D printing, sol-gel, and electrospinning. The new concept of regenerative medicine relies on biomaterials that can trigger in situ tissue regeneration and stem cell recruitment at the defect site. A large percentage of these biomaterials is ceramic-based as they provide the essential requirements of biomaterial principles such as tailored multisize porosity, antibacterial properties, and angiogenic properties. All these previously mentioned properties put bioceramics on top of the hierarchy of biomaterials utilized to stimulate tissue regeneration in soft and hard tissue wounds. Multiple clinical applications registered the use of these materials in triggering soft tissue regeneration in healthy and diabetic patients such as bioactive glass nanofibers. The results were promising and opened new frontiers for utilizing these materials on a larger scale. The same results were mentioned when using different forms and formulas of bioceramics in hard defect regeneration. Some bioceramics were used in combination with other polymers and biological scaffolds to improve their regenerative and mechanical properties. All this progress will enable a larger scale of patients to receive such services with ease and decrease the financial burden on the government.

Harnessing anti-inflammatory pathways and macrophage nano delivery to treat inflammatory and fibrotic disorders

Targeting specific organs and cell types using nanotechnology and sophisticated delivery methods has been at the forefront of applicative biomedical sciences lately. Macrophages are an appealing target for immunomodulation by nanodelivery as they are heavily involved in various aspects of many diseases and are highly plastic in their nature. Their continuum of functional "polarization" states has been a research focus for many years yielding a profound understanding of various aspects of these cells. The ability of monocyte-derived macrophages to metamorphose from pro-inflammatory to reparative and consequently to pro-resolving effectors has raised significant interest in its therapeutic potential. Here, we briefly survey macrophages' ontogeny and various polarization phenotypes, highlighting their function in the inflammation-resolution shift. We review their inducing mediators, signaling pathways, and biological programs with emphasis on the nucleic acid sensing-IFN-I axis. We also portray the polarization spectrum of macrophages and the characteristics of their transition between different subtypes. Finally, we highlighted different current drug delivery methods for targeting macrophages with emphasis on nanotargeting that might lead to breakthroughs in the treatment of wound healing, bone regeneration, autoimmune, and fibrotic diseases.

Nanofibrous Polycaprolactone Membrane with Bioactive Glass and Atorvastatin for Wound Healing: Preparation and Characterization

Skin wound healing is one of the most challenging processes for skin reconstruction, especially after severe injuries. In our study, nanofiber membranes were prepared for wound healing using an electrospinning process, where the prepared nanofibers were made of different weight ratios of polycaprolactone and bioactive glass that can induce the growth of new tissue. The membranes showed smooth and uniform nanofibers with an average diameter of 118 nm. FTIR and XRD results indicated no chemical interactions of polycaprolactone and bioactive glass and an increase in polycaprolactone crystallinity by the incorporation of bioactive glass nanoparticles. Nanofibers containing 5% w/w of bioactive glass were selected to be loaded with atorvastatin, considering their best mechanical properties compared to the other prepared nanofibers (3, 10, and 20% w/w bioactive glass). Atorvastatin can speed up the tissue healing process, and it was loaded into the selected nanofibers using a dip-coating technique with ethyl cellulose as a coating polymer. The study of the in vitro drug release found that atorvastatin-loaded nanofibers with a 10% coating polymer revealed gradual drug release compared to the non-coated nanofibers and nanofibers coated with 5% ethyl cellulose. Integration of atorvastatin and bioactive glass with polycaprolactone nanofibers showed superior wound closure results in the human skin fibroblast cell line. The results from this study highlight the ability of polycaprolactone-bioactive glass-based fibers loaded with atorvastatin to stimulate skin wound healing.