Layered Double Hydroxides Are Promising Nanomaterials for Tissue Bioengineering Application

Layered double hydroxides (LDHs) have emerged as promising nanomaterials for human health and although it has achieved some progress on this matter, their application within bioengineering is not fully addressed. This prompted to subject fibroblasts to two compositions of LDHs (Mg₂ Al-Cl and Zn₂ Al-Cl), considering an acute response. First, LDH particles are addressed by scanning electron microscopy, and no significant effect of the cell culture medium on the shape of LDHs particles is reported although it seems to adsorb some soluble proteins as proposed by energy-dispersive X-ray analysis. These LDHs release magnesium, zinc, and aluminum, but there is no cytotoxic or biocompatibility effects. The data show interference to fibroblast adhesion by driving the reorganization of actin-based cytoskeleton, preliminarily to cell cycle progression. Additionally, these molecular findings are validated by performing a functional wound-healing assay, which is accompanied by a dynamic extracellular matrix remodeling in response to the LDHs. Altogether, the results show that LDHs nanomaterials modulate cell adhesion, proliferation, and migration, delineating new advances on the biomaterial field applied in the context of soft tissue bioengineering, which must be explored in health disorders, such as wound healing in burn injuries.

The Role of Thyroid Hormone 3,3 ‘, 5 - Triiodothyronine (T3) in the Expression of Osteocalcin and Lipocalin 2 (LCN2) in Osteoblasts

Introduction: The thyroid hormone 3,3 ‘, 5 - triiodothyronine (T3) has an important role in bone physiology and metabolism, stimulating osteodifferentiation and bone homeostasis. Although there is this evidence, little is known about the synergistic events of T3 together with the endocrine role of other players that interfere with osteoblast metabolism, such as Lipocalin 2 (LCN2) and its hypothalamic-located MCR4 receptor. It is also known that LCN2 interferes at a physiological level with the parameters of food intake. Objective: To evaluate the role of the thyroid hormone 3,3 ‘, 5 - Triiodothyronine (T3) in the control of the expression of both Osteocalcin (OCN) and Lipocalin 2 (LCN2) in osteoblasts. Materials and Methods:. In order to understand the molecular and physiological mechanisms about that probable synergism, the experiments were as follows: Mouse pre-osteoblasts were challenged with T3 hormone treatments in three levels (1nM; 1.5nM; 2.0nM) and different times (0h; 24h; 72h). The samples were collected to perform gene expression of the main osteodifferentiation markers (RUNX2, OTX, BSP), matrix remodeling (MMPs, TIMPs, BMPII) and zymography assay for analysis of metalloproteinase activities (MMPs). Results and Discussion: Preliminarily, it was founded a synergism between the hormone T3 and LCN2 expression in osteoblasts, occurring the modulation of the marker genes of differentiation, extracellular matrix and hormonal synthesis. The T3 hormone acts in the modulation of RUNX2, OTX, BMP2, favoring osteodifferentiation and the remodeling of the matrix, probably activating the TIMP1-MMP9 and TIMP2-MMP2 complexes, mainly in hyperthyroid conditions. In addition, we note a direct influence of T3 on the both expression of both Osteocalcin (OCN) and Lipocalin 2 (LCN2). Final Considerations: Our preliminary data indicates that the hormone T3 acts on the metabolism of osteoblasts through the modulation of LCN2 and BMPII. These molecular findings need to be confronted with further analyzes in vivo for more conclusive physiological conclusions.

Epigenetic changes in shear-stressed endothelial cells

Epigenetic changes, particularly histone compaction modifications, have emerged as critical regulators in the epigenetic pathway driving endothelial cell phenotype under constant exposure to laminar forces induced by blood flow. However, the underlying epigenetic mechanisms governing endothelial cell behavior in this context remain poorly understood. To address this knowledge gap, we conducted in vitro experiments using human umbilical vein endothelial cells subjected to various tensional forces simulating pathophysiological blood flow shear stress conditions, ranging from normotensive to hypertensive forces. Our study uncovers a noteworthy observation wherein endothelial cells exposed to high shear stress demonstrate a decrease in the epigenetic marks H3K4ac and H3K27ac, accompanied by significant alterations in the levels of HDAC (histone deacetylase) proteins. Moreover, we demonstrate a negative regulatory effect of increased shear stress on HOXA13 gene expression and a concomitant increase in the expression of the long noncoding RNA, HOTTIP, suggesting a direct association with the suppression of HOXA13. Collectively, these findings represent the first evidence of the role of histone-related epigenetic modifications in modulating chromatin compaction during mechanosignaling of endothelial cells in response to elevated shear stress forces. Additionally, our results highlight the importance of understanding the physiological role of HOXA13 in vascular biology and hypertensive patients, emphasizing the potential for developing small molecules to modulate its activity. These findings warrant further preclinical investigations and open new avenues for therapeutic interventions targeting epigenetic mechanisms in hypertensive conditions.

Interaction of high lipogenic states with titanium on osteogenesis

As obesity rates continue to rise, the prevalence of metabolic dysfunction and alcohol-associated steatotic liver disease (MetALD), a new term for Nonalcoholic Fatty Liver Disease (NAFLD), also increases. In an aging population, it is crucial to understand the interplay between metabolic disorders, such as MetALD, and bone health. This understanding becomes particularly significant in the context of implant osseointegration. This study introduces an in vitro model simulating high lipogenesis through the use of human Mesenchymal Stroma Cells-derived adipocytes, 3D intrahepatic cholangiocyte organoids (ICO), and Huh7 hepatocytes, to evaluate the endocrine influence on osteoblasts interacting with titanium. We observed a significant increase in intracellular fat accumulation in all three cell types, along with a corresponding elevation in metabolic gene expression compared to the control groups. Notably, osteoblasts undergoing mineralization in this high-lipogenesis environment also displayed lipid vesicle accumulation. The study further revealed that titanium surfaces modulate osteogenic gene expression and impact cell cycle progression, cell survival, and extracellular matrix remodeling under lipogenic conditions. These findings provide new insights into the challenges of implant integration in patients with obesity and MetALD, offering a deeper understanding of the metabolic influences on bone regeneration and implant success.

Development of a natural rubber latex-based biodevice with mesenchymal stem cells as a potential treatment for skeletal muscle regeneration in gestational diabetes-induced myopathy

Women with gestational diabetes mellitus show a high risk of developing Gestational Diabetes Induced Myopathy (GDiM). GDiM is characterized by significant pelvic floor skeletal muscle atrophy and urinary incontinence. This study aimed to develop a natural rubber latex (NRL) based biodevice with mesenchymal/stromal stem cells (MSCs) for skeletal muscle regeneration for women with GDiM. NRL showed porosity, roughness, biocompatibility, and bioactivity. MSCs adhesion on the NRL scaffold surface was assessed by scanning electron microscopy (SEM), confocal microscopy, and zymography. The scaffold's physicochemical and biological properties were carried out by Fourier transform infrared spectroscopy (FTIR), swelling and degradation studies, hemolytic activity, and antioxidant activity (AA), using Electronic Paramagnetic Resonance (EPR). MSCs in culture expressed CD90, adhered to plastic, differentiated, and produced fibroblast colonies. A high rate of cell proliferation was seen in MSCs on the NRL scaffold. FTIR analysis confirmed protein structures and polyisoprene in the scaffold. Swelling and degradation showed low water uptake and weight loss. Furthermore, NRL presented a hemolytic rate of 2.90 ± 0.26 % for 24 h, and EPR revealed the scaffold's strong AA. The generated biodevice has potential for muscle regeneration and may be useful as a therapeutic option for skeletal muscle disorders in GDiM or urinary incontinence.

Adipogenesis-Related Metabolic Condition Affects Shear-Stressed Endothelial Cells Activity Responding to Titanium

PURPOSE

Obesity has increased around the world. Obese individuals need to be better assisted, with special attention given to dental and medical specialties. Among obesity-related complications, the osseointegration of dental implants has raised concerns. This mechanism depends on healthy angiogenesis surrounding the implanted devices. As an experimental analysis able to mimic this issue is currently lacking, we address this issue by proposing an in vitro high-adipogenesis model using differentiated adipocytes to further investigate their endocrine and synergic effect in endothelial cells responding to titanium.

MATERIALS AND METHODS

Firstly, adipocytes (3T3-L1 cell line) were differentiated under two experimental conditions: Ctrl (normal glucose concentration) and High-Glucose Medium (50 mM of glucose), which was validated using Oil Red O Staining and inflammatory markers gene expression by qPCR. Further, the adipocyte-conditioned medium was enriched by two types of titanium-related surfaces: Dual Acid-Etching (DAE) and Nano-Hydroxyapatite blasted surfaces (nHA) for up to 24 h. Finally, the endothelial cells (ECs) were exposed in those conditioned media under shear stress mimicking blood flow. Important genes related to angiogenesis were then evaluated by using RT-qPCR and Western blot.

RESULTS

Firstly, the high-adipogenicity model using 3T3-L1 adipocytes was validated presenting an increase in the oxidative stress markers, concomitantly with an increase in intracellular fat droplets, pro-inflammatory-related gene expressions, and also the ECM remodeling, as well as modulating mitogen-activated protein kinases (MAPKs). Additionally, Src was evaluated by Western blot, and its modulation can be related to EC survival signaling.

CONCLUSION

Our study provides an experimental model of high adipogenesis in vitro by establishing a pro-inflammatory environment and intracellular fat droplets. Additionally, the efficacy of this model to evaluate the EC response to titanium-enriched mediums under adipogenicity-related metabolic conditions was analyzed, revealing significant interference with EC performance. Altogether, these data gather valuable findings on understanding the reasons for the higher percentage of implant failures in obese individuals.