Administration of Human Non-Diabetic Mesenchymal Stromal Cells to a Murine Model of Diabetic Fracture Repair: A Pilot Study

Optimization of 3D Extrusion-Printed Particle-Containing Hydrogels for Osteogenic Differentiation

There is a continued increase in demand for novel bone grafting substitutes to reduce reliance on and address challenges associated with allograft and autograft bone grafts. Current synthetic bone grafting substitutes exhibit low mechanical strength and bioactivity, which has inspired the development of novel grafting materials. Accelerating the translation of new bone graft substitutes requires workflows for high-throughput fabrication and analysis of particle-containing models. This study utilized 3D sacrificial printing for the fabrication of reproducible, cellular scaffolds containing tricalcium phosphate (TCP), hydroxyapatite (HA), or natural coral particles. High-throughput analysis of the cellular scaffolds included quantifying cell metabolism, viability, and calcium consumption, as well as nondestructive analysis of collagen accumulation and destructive methods for assessing cell number and morphological changes. Both particle- and non-particle-containing inks sustained cell metabolism with low and decreasing cell death for 7 days post-printing. Collagen staining, scanning electron microscopy imaging, and calcium and collagen quantification suggested that, under osteogenic induction conditions, cells migrated to the surface of the scaffolds and formed a sheet of cells and a collagen-containing extracellular matrix, thereby indicating osteogenic differentiation. The workflow described herein enables the creation of in vitro models to study the osteogenic nature of new bone grafting substitute materials. High-throughput printing combined with non-destructive screening techniques resulted in reduced time, resources, and associated costs and could be applicable to a broader range of cell types.

Advantages and Limitations of Diabetic Bone Healing in Mouse Models: A Narrative Review

Diabetes represents a major risk factor for impaired fracture healing. Type 2 diabetes mellitus is a growing epidemic worldwide, hence an increase in diabetes-related complications in fracture healing can be expected. However, the underlying mechanisms are not yet completely understood. Different mouse models are used in preclinical trauma research for fracture healing under diabetic conditions. The present review elucidates and evaluates the characteristics of state-of-the-art murine diabetic fracture healing models. Three major categories of murine models were identified: Streptozotocin-induced diabetes models, diet-induced diabetes models, and transgenic diabetes models. They all have specific advantages and limitations and affect bone physiology and fracture healing differently. The studies differed widely in their diabetic and fracture healing models and the chosen models were evaluated and discussed, raising concerns in the comparability of the current literature. Researchers should be aware of the presented advantages and limitations when choosing a murine diabetes model. Given the rapid increase in type II diabetics worldwide, our review found that there are a lack of models that sufficiently mimic the development of type II diabetes in adult patients over the years. We suggest that a model with a high-fat diet that accounts for 60% of the daily calorie intake over a period of at least 12 weeks provides the most accurate representation.

Advances in Musculoskeletal Cell Therapy: Basic Science and Translational Approaches

Nowadays, the real need in orthopedic research is to strictly validate advanced regenerative medicine approaches in preclinical models, with the hope that this unique and straightforward approach can facilitate a safe and effective translation into everyday clinical practice [...].

Regenerative and Anti-Inflammatory Potential of Regularly Fed, Starved Cells and Extracellular Vesicles In Vivo

Background: Mesenchymal stem/stromal cells (MSC) have been employed successfully in immunotherapy and regenerative medicine, but their therapeutic potential is reduced considerably by the ischemic environment that exists after transplantation. The assumption that preconditioning MSC to promote quiescence may result in increased survival and regenerative potential upon transplantation is gaining popularity. Methods: The purpose of this work was to evaluate the anti-inflammatory and regenerative effects of human bone marrow MSC (hBM-MSC) and their extracellular vesicles (EVs) grown and isolated in a serum-free medium, as compared to starved hBM-MSC (preconditioned) in streptozotocin-induced diabetic fractured male C57BL/6J mice. Results: Blood samples taken four hours and five days after injection revealed that cells, whether starved or not, generated similar plasma levels of inflammatory-related cytokines but lower levels than animals treated with EVs. Nonetheless, starved cells prompted the highest production of IL-17, IL-6, IL-13, eotaxin and keratinocyte-derived chemokines and induced an earlier soft callus formation and mineralization of the fracture site compared to EVs and regularly fed cells five days after administration. Conclusions: Preconditioning may be crucial for refining and defining new criteria for future MSC therapies. Additionally, the elucidation of mechanisms underpinning an MSC’s survival/adaptive processes may result in increased cell survival and enhanced therapeutic efficacy following transplantation.

Exosomes Derived from Bone Marrow-Derived Mesenchymal Stem Cells (BM-MSC) Protect Submandibular Glands in Diabetic Rats

Our study assess whether exosomes derived from bone marrow mesenchymal stem cells (BM-MSC) ameliorates diabetic salivary gland complications. 10 SD rats were assigned into diabetes group I and exosome treatment group II. Diabetic rats were induced by streptozotocin (STZ) and injected with DMSO or exosomes through tail vein followed by collection of submandibular salivary gland samples for histological analysis and TGFβ, Smad2 and Smad3 level by PCR, saliva IgA and serum amylase level. Compared with control mice, exosome treatment mice showed less fibrosis of the submandibular salivary glands and duct components with a more complete structure. Exosome treatment inhibited TGFβ, Smad2 and Smad3 level to reduce diabetic salivary gland complications, effectively decreased blood sugar level, improved salivary glands function with significantly reduced serum amylase and salivary IgA levels. In conclusion, BM-MSC-derived exosomes may be a new therapeutic strategy for treating diabetic salivary gland complications.