Bone-specific alkaline phosphatase as a good indicator of bone formation in sheepdogs

Electrical waveform dependent osteogenesis on PVDF/BaTiO3 composite using a customized and programmable cell stimulator

Directing cellular functionalities using biomaterial-based bioelectronic stimulation remains a significant constraint in translating research outcomes to address specific clinical challenges. Electrical stimulation is now being clinically used as a therapeutic treatment option to promote bone tissue regeneration and to improve neuromuscular functionalities. However, the nature of the electrical waveforms during the stimulation and underlying biophysical rationale are still not scientifically well explored. Furthermore, bone-mimicking implant-based bioelectrical regulation of osteoinductivity has not been translated to clinics. The present study demonstrates the role of the waveform in electrical signal to direct differentiation of stem cells on an electroactive polymeric substrate, using monophasic DC, square wave, and biphasic wave. In this regard, an in-house electrical stimulation device has been fabricated for the uninterrupted delivery of programmed electrical signals to stem cells in culture. To provide a functional platform for stem cells to differentiate, barium titanate (BaTiO₃ , BT) reinforced PVDF has been developed with mechanical properties similar to bone. The electrical stimulation of human mesenchymal stem cells (hMSCs) on PVDF/BT composite inhibited proliferation rate at day 7, indicating early commitment for differentiation. The phenotypical characteristics of DC stimulated hMSCs provided signatures of differentiation towards osteogenic lineage, which was subsequently confirmed using ALP assay, collagen deposition, matrix mineralization, and genetic expression. Our findings suggest that DC stimulation induced early osteogenesis in hMSCs with a higher level of intracellular reactive oxygen species (ROS), whereas the stimulation with square wave directed late osteogenesis with a lower ROS regeneration. In summary, the present study critically analyzes the role of electrical stimulation and its waveforms in regulating osteogenesis, without external biochemical differentiation inducers, on a bone-mimicking functional substrate. Such a strategy can potentially be adopted to develop orthopedic implant-based bioelectronic medicine for bone regeneration. This article is protected by copyright. All rights reserved.

Betulinic acid decreases lipid accumulation in adipogenesis-induced human mesenchymal stem cells with upregulation of PGC-1α and UCP-1 and post-transcriptional downregulation of adiponectin and leptin secretion

Background

Controlling cellular functions, including stem cell growth and differentiation, can be the key for the treatment of metabolic disorders, such as type II diabetes mellitus (T2DM). Previously identified as peroxisome proliferator-activated receptor gamma (PPARγ) antagonist, betulinic acid (BA) may have the capability to control stem cell homeostasis, benefiting T2DM treatment. In this study, the effects of BA on osteogenesis and adipogenesis mechanisms of human mesenchymal stem cells (hMSCs) were investigated.

Results

We observed that BA increased hMSC osteogenesis by enhancing the alkaline phosphatase activity, calcium deposition, and mRNA expressions of osteogenic markers, namely, runt-related transcription factor 2, osteocalcin, and osteopontin. In addition, BA decreased hMSC adipogenesis with the decrease in glycerol-3-phosphate dehydrogenase activity, reduced intracellular lipid accumulations, down-regulated CCAAT-enhancer-binding protein alpha, and suppressed post-transcriptional adiponectin and leptin secretion. BA increased the brown adipocyte characteristics with the increase in the ratio of small lipid droplets and glucose uptake. Furthermore, the mRNA expressions of brown adipocyte markers, namely, PPARγ coactivator one alpha, uncoupling protein 1, and interleukin-6 increased.

Conclusions

Our results uncovered the mechanisms of how BA improved glucose and lipid metabolisms by decreasing white adipogenesis and increasing brown adipogenesis. Altogether, BA may be used for balancing glucose metabolisms without the potential side effects on bone loss or weight gain.

Influence of gellan gum-hydroxyapatite spongy-like hydrogels on human osteoblasts under long-term osteogenic differentiation conditions

The scientific community has been doing significant efforts towards engineering new 3D bone models in recent years. Osteocytes are mechanosensitive cells that play significant roles in the maintenance of bone homeostasis. Currently, as far as we know, there are no 3D models that faithfully recapitulate a bone microenvironment capable of promoting the differentiation of osteoblasts towards osteocytes. Besides, in the existing models, the use of human cells does not prevail over the animal cell lines. For so, we propose a 3D model that may have important implications for ongoing efforts towards a better understanding of bone physiology and disease. The main aim of the current work was the promotion of an effective differentiation of osteoblasts into osteocytes by mean of using a 3D model composed of primary human osteoblasts (hOBs) cultured on Gellan Gum-Hydroxyapatite (GG-HAp) matrix under a long-term osteogenic culture. The results revealed that GG-HAp matrix stimulated a fast cell migration/entrapment, attachment, spreading, and mineralization. Moreover, the transition process from osteoblasts to osteocytes was confirmed by the expression of the osteogenic-related (ALP, Runx2, COL I, OC, OPN and OSX) and osteocyte-related (hPDPN) marker throughout the culture time. Overall, the developed 3D model holds a great promise for the treatment of various bone diseases, namely on diagnostic applications and for bone regeneration purposes.

Clinical assessment of growth performance, bone morphometry, bone quality, and serum indicators in broilers affected by valgus-varus deformity

The large economic losses caused by leg disorders have raised concerns in the broiler industry. Several types of leg disorders in broilers have been identified, such as tibial dyschondroplasia (TD), femoral head necrosis (FHN), and valgus-varus deformity (VVD). In this study, phenotypic changes associated with VVD were examined using clinical diagnosis, anatomical examination, measured growth performance, bone traits, and serum indicators. The incidence of VVD among the chicken population at a commercial facility in Tangshan China was 1.75% (n = 52,000), distributed about 1:1 (n = 122), between females and males. A majority of chickens were characterized by a unilaterally abnormality, while appropriately 17.6% by bilateral abnormality. Approximately 97.9% of affected broilers were classified as the "valgus" type. Growth traits, including body weight, shank length, and shank girth, were significantly lower in chickens with VVD, while tibia and metatarsal bone indexes were about 1.3-fold higher in the affected birds than in the normal birds. Bone mineral density, bone breaking strength, and several serum indicators were significantly different between affected and normal broilers. Sparse and disarranged bony trabecular was observed in abnormal broilers by histological analysis. Generally, leg disorders are associated with compromised growth, bone quality, bone structure, and lipid metabolism. This study provides a reference for clinical diagnosis of VVD and lays a foundation for exploring its underlying mechanisms.

Rapamycin promotes osteogenesis under inflammatory conditions

Chronic periodontitis, a common oral disease, usually results in irreversible bone resorption. Bone regeneration is a complex process between bone-forming activity of osteoblasts and bone-resorbing activity of osteoclasts, and still remains a challenge for physicians clinically. A previous study demonstrated that the mechanistic target of rapamycin signaling pathway is involved in osteogenic differentiation of mesenchymal stromal cells. Herein, whether rapamycin could be used to induce osteogenic differentiation of primary bone marrow-derived mesenchymal stem cells (BMSCs) in vitro and promote new bone formation in vivo were evaluated. The results demonstrated that rapamycin alone was not enough to fully induce osteoblast differentiation in vitro and enhanced bone regeneration in vivo. Interestingly, rapamycin in rapamycin plus lipopolysaccharide (LPS)-treated BMSCs significantly increased the gene expression levels of Sp7 transcription factor, runt related transcription factor 2, alkaline phosphatase (ALP) and collagen I (Col I), ALP activity, and calcium nodule at different time points in vitro, indicating that osteoblast differentiation occurs by rapamycin when BMSCs are exposed to LPS simultaneously. It was also demonstrated that rapamycin in rapamycin plus LPS-treated rats promoted bone regeneration in vivo. These results suggest that rapamycin may influence osteoblast differentiation and new bone formation after LPS induces an inflammatory environment. Rapamycin may be used to treat periodontitis associated with bone loss in future clinical practice.

Drug intercalation in layered double hydroxide clay: application in the development of a nanocomposite film for guided tissue regeneration

It has been proposed that localized and controlled delivery of alendronate and tetracycline to periodontal pocket fluids via guided tissue regeneration (GTR) membranes may be a valuable adjunctive treatment for advanced periodontitis. The objectives of this work were to develop a co-loaded, controlled release tetracycline and alendronate nanocomposite plasticized poly(lactic-co-glycolic acid) (PLGA) film that would form a suitable matrix supporting osteoblast proliferation and differentiation. Alendronate release was successfully controlled, with complete suppression of the burst phase of release by intercalation of alendronate anions in magnesium/aluminum layered double hydroxide (LDH) clay nanoparticles and dispersed in the PLGA film matrix. Tetracycline, loaded as free drug into the film together with alendronate-LDH clay complex released more rapidly than alendronate, but showed evidence of intercalation in the LDH clay particles. The dual drug loaded nanocomposite films were biocompatible with osteoblasts and after 5 week incubations, significant increase in alkaline phosphatase activity and bone nodule formation were observed.