Synergistic effects of overexpression of BMP‑2 and TGF‑β3 on osteogenic differentiation of bone marrow mesenchymal stem cells

The extracts of osteoblast developed from adipose-derived stem cell and its role in osteogenesis

Cell-based therapy has become an achievable choice in regenerative medicines, particularly for musculoskeletal disorders. Adipose-derived stem cells (ASCs) are an outstanding resource because of their ability and functions. Nevertheless, the use of cells for treatment comes with difficulties in operation and safety. The immunological barrier is also a major limitation of cell therapy, which can lead to unexpected results. Cell-derived products, such as cell extracts, have gained a lot of attention to overcome these limitations. The goal of this study was to optimize the production of ASC-osteoblast extracts as well as their involvement in osteogenesis. The extracts were prepared using a freeze-thaw method with varying temperatures and durations. Overall, osteogenic-associated proteins and osteoinductive potential of the extracts prepared from the osteogenic-induced ASCs were assessed. Our results demonstrated that the freeze-thaw approach is practicable for cell extracts production, with minor differences in temperature and duration having no effect on protein concentration. The ASC-osteoblast extracts contain a significant level of essential specialized proteins that promote osteogenicity. Hence, the freeze-thaw method is applicable for extract preparation and ASC-osteoblast extracts may be beneficial as an optional facilitating biologics in bone anabolic treatment and bone regeneration.

TGF-β promotes the proliferation and osteogenic differentiation of dental pulp stem cells a systematic review and meta-analysis

BACKGROUND

Dental pulp stem cells (DPSCs) are adult stem cells with multi-directional differentiation potential derived from ectoderm. Vitro experiments have shown that adding cytokines can help DPSCs to be transformed from multipotent stem cells to osteoblasts. TGF-β has been proved to have an effect on the proliferation and mineralization of bone tissue, but its effect on the osteogenesis and proliferation of dental pulp stem cells is still uncertain. We aim to determine the effect of TGF-β on the osteogenesis and proliferation of dental pulp stem cells.

METHODS

We have identified studies from the Cochrane Central Register of Controlled Trials, PubMed, Embase, and China national knowledge infrastructure (CNKI) for studies interested in TGF-β and proliferation and differentiation of dental pulp stem cells in the following indicators: A490 (an index for evaluating cell proliferation), bone sialoprotein (BSP), Col plasmid-1 (Col-1), osteocalcin (OCN), runt-related transcription factor 2 (Runx-2); and the number of mineralized nodules. Any language restrictions were rejected. Furthermore, we drew a forest plot for each outcome. We conducted a sensitivity analysis, data analysis, heterogeneity, and publication bias test. We evaluate the quality of each study under the guidance of Cochrane's tool for quality assessment.

RESULTS

The pooled data showed that TGF-β could promote the proliferation and ossification of dental pulp stem cells. All the included results support this conclusion except for the number of mineralized nodules: TGF-β increases the A490 index (SMD 3.11, 95% CI [0.54-5.69]), promotes the production of BSP (SMD 3.11, 95% CI [0.81-6.77]), promotes the expression of Col-1 (SMD 4.71, 95% CI [1.25-8.16]) and Runx-2 (SMD 3.37, 95% CI [- 0.63 to 7.36]), increases the content of OCN (SMD 4.32, 95% CI [1.20-7.44]) in dental pulp, and has no significant effect on the number of mineralized nodules (SMD 3.87, 95% CI [- 1.76 to 9.51]) in dental pulp stem cells.

CONCLUSIONS

TGF-β promotes the proliferation and osteogenesis of dental pulp stem cells.

BMP-2 (and partially GDF-5) coating significantly accelerates and augments bone formation close to hydroxyapatite/tricalcium-phosphate/brushite implant cylinders for tibial bone defects in senile, osteopenic sheep

Bilateral defects (diameter 8 mm) in the medial tibial head of senile, osteopenic female sheep (n = 48; 9.63 ± 0.10 years; mean ± SEM) were treated with hydroxyapatite (HA)/beta-tricalcium phosphate (β-TCP)/dicalcium phosphate dihydrate (DCPD; brushite) cylinders coated with BMP-2 (25 or 250 micrograms) or growth differentiation factor (GDF)-5 (125 or 1250 micrograms; left side); cylinders without BMP served as controls (right side). Three, 6, and 9 months post-operation (n = 6 each group), bone structure and formation were analyzed in vivo by X-ray and ex vivo by osteodensitometry, histomorphometry, and micro-computed tomography (micro-CT) at 3 and 9 months. Semi-quantitative X-ray evaluation showed significantly increasing bone densities around all implant cylinders over time. High-dose BMP-2-coated cylinders (3 and 9 months) and low-dose GDF-5-coated cylinders (3 and 6 months) demonstrated significantly higher densities than controls (dose-dependent for BMP-2 at 3 months). This was confirmed by osteodensitometry at 9 months for high-dose BMP-2-coated cylinders (and selected GDF-5 groups), and was again dose-dependent for BMP-2. Osteoinduction by BMP-2 was most pronounced in the adjacent bone marrow (dynamic histomorphometry/micro-CT). BMP-2 (and partially GDF-5) significantly increased the bone formation in the vicinity of HA/TCP/DCPD cylinders used to fill tibial bone defects in senile osteopenic sheep and may be suitable for surgical therapy of critical size, non-load-bearing bone defects in cases of failed tibial head fracture or defect healing.

Osteochondrogenesis by TGF-β3, BMP-2 and noggin growth factor combinations in an ex vivo muscle tissue model: Temporal function changes affecting tissue morphogenesis

In the absence of clear molecular insight, the biological mechanism behind the use of growth factors applied in osteochondral regeneration is still unresolved. The present study aimed to resolve whether multiple growth factors applied to muscle tissue in vitro, such as TGF-β3, BMP-2 and Noggin, can lead to appropriate tissue morphogenesis with a specific osteochondrogenic nature, thereby revealing the underlying molecular interaction mechanisms during the differentiation process. Interestingly, although the results showed the typical modulatory effect of BMP-2 and TGF-β3 on the osteochondral process, and Noggin seemingly downregulated specific signals such as BMP-2 activity, we also discovered a synergistic effect between TGF-β3 and Noggin that positively influenced tissue morphogenesis. Noggin was observed to upregulate BMP-2 and OCN at specific time windows of culture in the presence of TGF-β3, suggesting a temporal time switch causing functional changes in the signaling protein. This implies that signals change their functions throughout the process of new tissue formation, which may depend on the presence or absence of specific singular or multiple signaling cues. If this is the case, the signaling cascade is far more intricate and complex than originally believed, warranting intensive future investigations so that regenerative therapies of a critical clinical nature can function properly.

Preclinical Study of Human Bone Marrow-Derived Mesenchymal Stem Cells Using a 3-Dimensional Manufacturing Setting for Enhancing Spinal Fusion

Spinal fusion surgery is a surgical technique that connects one or more vertebrae at the same time to prevent movement between the vertebrae. Although synthetic bone substitutes or osteogenesis-inducing recombinant proteins were introduced to promote bone union, the rate of revision surgery is still high due to pseudarthrosis. To promote successful fusion after surgery, stem cells with or without biomaterials were introduced; however, conventional 2D-culture environments have resulted in a considerable loss of the innate therapeutic properties of stem cells. Therefore, we conducted a preclinical study applying 3D-spheroids of human bone marrow-dewrived mesenchymal stem cells (MSCs) to a mouse spinal fusion model. First, we built a large-scale manufacturing platform for MSC spheroids, which is applicable to good manufacturing practice (GMP). Comprehensive biomolecular examinations, which include liquid chromatography-mass spectrometry and bioinformatics could suggest a framework of quality control (QC) standards for the MSC spheroid product regarding the identity, purity, viability, and potency. In our animal study, the mass-produced and quality-controlled MSC spheroids, either undifferentiated or osteogenically differentiated were well-integrated into decorticated bone of the lumbar spine, and efficiently improved angiogenesis, bone regeneration, and mechanical stability with statistical significance compared to 2D-cultured MSCs. This study proposes a GMP-applicable bioprocessing platform and QC directions of MSC spheroids aiming for their clinical application in spinal fusion surgery as a new bone graft substitute.

Signaling network regulating osteogenesis in mesenchymal stem cells

Osteogenesis is an important developmental event that results in bone formation. Bone forming cells or osteoblasts develop from mesenchymal stem cells (MSCs) through a highly controlled process regulated by several signaling pathways. The osteogenic lineage commitment of MSCs is controlled by cell-cell interactions, paracrine factors, mechanical signals, hormones, and cytokines present in their niche, which activate a plethora of signaling molecules belonging to bone morphogenetic proteins, Wnt, Hedgehog, and Notch signaling. These signaling pathways individually as well as in coordination with other signaling molecules, regulate the osteogenic lineage commitment of MSCs by activating several osteo-lineage specific transcription factors. Here, we discuss the key signaling pathways that regulate osteogenic differentiation of MSCs and the cross-talk between them during osteogenic differentiation. We also discuss how these signaling pathways can be modified for therapy for bone repair and regeneration.

Directed Regeneration of Osteochondral Tissue by Hierarchical Assembly of Spatially Organized Composite Spheroids

The use of engineered scaffolds or stem cells is investigated widely in the repair of injured musculoskeletal tissue. However, the combined regeneration of hierarchical osteochondral tissue remains a challenge due to delamination between cartilage and subchondral bone or difficulty in spatial control over differentiation of transplanted stem cells. Here, two types of composite spheroids are prepared using adipose-derived stem cells (hADSCs) and nanofibers coated with either transforming growth factor-β3 or bone morphogenetic growth factor-2 for chondrogenesis or osteogenesis, respectively. Each type of spheroid is then cultured within a 3D-printed microchamber in a spatially arranged manner to recapitulate the bilayer structure of osteochondral tissue. The presence of inductive factors regionally modulates in vitro chondrogenic or osteogenic differentiation of hADSCs within the biphasic construct without dedifferentiation. Furthermore, hADSCs from each spheroid proliferate and sprout and successfully connect the two layers mimicking the osteochondral interface without apertures. In vivo transplantation of the biphasic construct onto a femoral trochlear groove defect in rabbit knee joint results in 21.2 ± 2.8% subchondral bone volume/total volume and a cartilage score of 25.0 ± 3.7. The present approach can be an effective therapeutic platform to engineer complex tissue.

Up-regulation of TβRIII facilitates the osteogenesis of supraspinous ligament-derived fibroblasts from patients with ankylosing spondylitis

Spinal supraspinous ligament (SL) osteogenesis is the key risk of ankylosing spondylitis (AS), with an unclear pathogenesis. We previously found that transforming growth factor β1 (TGF‐β1), bone morphogenetic proteins (eg BMP2) and type III TGF‐β1 receptor (TβRIII) expression were markedly up‐regulated in AS‐SLs. However, the roles of these closely related molecules in AS are unknown. Here, we showed that BMP2, TGF‐β1, TβRIII and S100A4 (a fibroblast marker) were abundant in active osteogenic AS‐SL tissues. In vitro, AS‐SL fibroblasts (AS‐SLFs) showed high BMP2, TGF‐β1 and TβRIII expression and auto‐osteogenic capacity. We further evaluated the role of TβRIII in the osteogenesis of normal SLFs. BMP2 combined with TGF‐β1 induced the osteogenesis of TβRIII‐overexpressing SLFs, but the activity was lost in SLFs upon TβRIII knockdown. Moreover, our data suggested that BMP2 combined with TGF‐β1 significantly activated both TGF‐β1/Smad signalling and BMP2/Smad/RUNX2 signalling to induce osteogenesis of SLFs with TβRIII up‐regulation. Furthermore, our multi‐strategy molecular interaction analysis approach indicated that TGF‐β1 presented BMP2 to TβRIII, sequentially facilitating BMP2 recognition by BMPR1A and promoting the osteogenesis of TβRIII‐overexpressing SLFs. Collectively, our results indicate that TGF‐β1 combined with BMP2 may participate in the osteogenic differentiation of AS‐SLF by acting on up‐regulated TβRIII, resulting in excessive activation of both TGF‐β1/Smad and BMP2/BMPR1A/Smad/RUNX2 signalling.

Efficient Delivery of Transducing Polymer Nanoparticles for Gene-Mediated Induction of Osteogenesis for Bone Regeneration

Developing non-viral gene therapy vectors that both protect and functionally deliver nucleic acid cargoes will be vital if gene augmentation and editing strategies are to be effectively combined with advanced regenerative medicine approaches. Currently such methodologies utilize high concentrations of recombinant growth factors, which result in toxicity and off-target effects. Herein we demonstrate the use of modified cell penetrating peptides (CPPs), termed Glycosaminoglycan (GAG)-binding Enhanced Transduction (GET) peptides with plasmid DNA (pDNA) encapsulated poly (lactic-co-glycolic acid) PLGA nanoparticles (pDNA-encapsulated PLGA NPs). In order to encapsulate the pDNA, it was first condensed with a cationic low molecular weight Poly L-Lysine (PLL) into 30-60 nm NPs followed by encapsulation in PLGA NPs by double emulsion; yielding encapsulation efficiencies (EE) of ∼30%. PLGA NPs complexed with GET peptides show enhanced intracellular delivery (up to sevenfold) and transfection efficiencies (up to five orders of magnitude). Moreover, the pDNA cargo has enhanced protection from nucleases (such as DNase I) promoting their translatability. As an example, we show these NPs efficiently deliver pBMP2 which can promote osteogenic differentiation in vitro. Gene delivery to human Mesenchymal Stromal Cells (hMSCs) inducing their osteogenic programming was confirmed by Alizarin red calcium staining and bone lineage specific gene expression (Q RT-PCR). By combining simplistic and FDA-approved PLGA polymer nanotechnology with the GET delivery system, therapeutic non-viral vectors could have significant impact in future cellular therapy and regenerative medicine applications.

Experimental study of the synergistic effect and network regulation mechanisms of an applied combination of BMP-2, VEGF, and TGF-β1 on osteogenic differentiation

The study aimed to explore the osteogenic effect induced by the combined use of bone morphogenetic protein-2 (BMP-2), vascular endothelial growth factor (VEGF), and transforming growth factor-β1 (TGF-β1), attain the best combination for osteogenic quality and efficiency, and explore the network regulation mechanisms of induced osteogenesis. MC3T3-E1 cells were cultured in vitro, and BMP-2, VEGF, and TGF β1 were added to osteogenic induction mediums in different combinations to conduct experiments. At 7 and 14 days, the alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining of the applied BMP-2 and VEGF combination were deeper and the quantitative analysis were higher than those of the other groups. After optimizing the time-effect relationship of the combined application, with BMP-2, VEGF, and TGF-β1 adding in the early stage and BMP-2 and VEGF adding in the late, the ALP and ARS staining of these groups were deeper and the quantitative analyses were meaningfully higher than the BMP-2 and VEGF combination group at 7 and 14 days. The expression of the RUNX2 gene and the Smad1 signaling pathway in the optimized combination group was also significantly higher. The results demonstrate that the combination of BMP-2, VEGF, and TGF-β1 applied according to the time-effect relationship can significantly promote osteogenic differentiation mainly through the classical BMP-receptor-Smad signal pathway.

Synergistic effects of recombinant Lentiviral-mediated BMP2 and TGF-beta3 on the osteogenic differentiation of rat bone marrow mesenchymal stem cells in vitro

BACKGROUND

Bone marrow mesenchymal stem cells (BMSCs) are considered good candidates for seed cells in bone engineering. The study aim to investigate the synergistic effects of human bone morphogenetic protein 2 (hBMP2) and transforming growth factor beta3 (hTGF-beta3) modified BMSCs on inducing osteogenic differentiation in vitro.

METHODS

Lentivirus (LV) carrying hBMP2 and/or hTGF-beta3 genes were constructed and used to transduce rat BMSCs. The expression of osteogenic molecules was detected by qRT-PCR and western blotting.

RESULTS

Targeted genes were PCR-amplified and confirmed by DNA sequencing and BLAST analysis. BMSCs infected by vectors effectively resulted in the overexpressions of hBMP2 and hTGF-beta3 and higher levels of hBMP2 and hTGF-beta3 in the culture supernatant. The co-transduction of hBMP2 and hTGF-beta3 induced BMSCs osteogenic differentiation more effectively than the transduction of hBMP2 or hTGF-beta3 individually. The expression levels of osteopontin (OPN), osteocalcin (OCN), and osteoprotegerin (OPG) in LV-hBMP2 + LV-hTGF-beta3 group (BMSCs transfected by vectors respectively carrying hBMP-2 gene and hTGF-beta3 gene) and LV-hBMP2-hTGF-beta3 group (BMSCs transfected by vector carrying hBMP2 and hTGF-beta3 fusion gene) were significantly higher than in LV-BMP2 (BMSCs transfected by vector carrying hBMP2 gene) and LV-TGF-beta3 (BMSCs transfected by vector carrying hTGF-beta3 gene) groups (P < 0.05). The hBMP2 and/or hTGF-beta3 overexpression upregulated alkaline phosphatase (ALP) activity.

CONCLUSION

The present study showed that hBMP2 and/or hTGF-beta3 genes can be successfully overexpressed in BMSCs. Our study proved that the two cytokines (hBMP2 and hTGF-beta3) could induce bone differentiation synergistically, which foresees the use of the combination of these two cytokines as a therapeutic strategy in the future.

Recent Advances and Future of Gene Therapy for Bone Regeneration

PURPOSE OF REVIEW

The purpose of this review is to discuss the recent advances in gene therapy as a treatment for bone regeneration. While most fractures heal spontaneously, patients who present with fracture nonunion suffer from prolonged pain, disability, and often require additional operations to regain musculoskeletal function.

RECENT FINDINGS

In the last few years, BMP gene delivery by means of electroporation and sonoporation resulted in repair of nonunion bone defects in mice, rats, and minipigs. Ex vivo transfection of porcine mesenchymal stem cells (MSCs) resulted in bone regeneration following implantation in vertebral defects of minipigs. Sustained release of VEGF gene from a collagen-hydroxyapatite scaffold to the mandible of a human patient was shown to be safe and osteoinductive. In conclusion, gene therapy methods for bone regeneration are systematically becoming more efficient and show proof-of-concept in clinically relevant animal models. Yet, on the pathway to clinical use, more investigation is needed to determine the safety aspects of the various techniques in terms of biodistribution, toxicity, and tumorigenicity.

Identification of genomic differences among peripheral arterial beds in atherosclerotic and healthy arteries

Calcification is independently associated with cardiovascular events and morbidity. The calcification burden in atherosclerotic lesions quantitatively and qualitatively differs between arterial beds. Cardiovascular risk factors (CVRF) differentially affect plaque development between arterial beds. The aim of this study was to evaluate the impact of CVRF on atherosclerotic plaque calcification and to further study the molecular arterial heterogeneity that could account for these differences. Histological analysis was performed on atherosclerotic plaques from 153 carotid, 97 femoral and 28 infrapopliteal arteries. CVRF showed minor associations with plaque calcification: age and hypertension affected only the overall presence of calcification but not the type of the calcification, which significantly differed between arterial beds. Transcriptome analysis revealed distinct gene expression profiles associated with each territory in atherosclerotic and healthy arteries. Canonical pathway analysis showed the preferential involvement of immune system-related processes in both atherosclerotic and healthy carotid arteries. Bone development-related genes were among those mostly enriched in atherosclerotic and healthy femoral arteries, which are more prone to developing endochondral calcification. This study highlights the heterogeneous nature of arteries from different peripheral vascular beds and contributes to a better understanding of atherosclerosis formation and evolution.

BMP4 knockdown of NCSCs leads to aganglionosis in the middle embryonic stage

Transplacental bone morphogenetic protein (BMP)4 RNA interference (RNAi) is a technique used to knockdown genes in embryos. BMP4 are essential for the development of nervous system in the differentiation of neural crest stem cells (NCSCs). The failure of differentiation and migration of NCSCs may lead to aganglionosis. In the present study, pregnant mice were divided into three groups: Ringer's group, pSES group and RNAi‑BMP4 group. In order to silence the BMP4 gene in the first generation (F1), 11.5 day pregnant mice were injected with the small interfering RNA BMP4 plasmid, pSES or Ringer's solution via the tail vein. Semi‑quantitative reverse transcriptase‑polymerase chain reaction (RT‑PCR)and western blotting were employed to ensure the downregulation of BMP4. Finally, X‑rays were performed following a barium enema. Aganglionosis was diagnosed by general anatomy and immunohistochemistry. Compared with the control group, transplacental RNAi was able to downregulate the BMP4‑Smad4 of 11.5 day embryos, as determined by semi‑quantitative RT‑PCR and western blotting. The megacolons of the mice were demonstrated by X‑ray and confirmed by general anatomy. Aganglionosis of colonic mucosa and submucosa were diagnosed by pathology, and immunohistochemistry. Knockdown of BMP4 in pregnant mice at the middle embryonic stage led to aganglionosis. It was therefore demonstrated that BMP‑Smad was essential to the NCSCs of middle stage embryos. BMP‑Smad served important roles in the generation of aganglionosis. This technique of knockdown BMP4 gene may be used to establish an aganglionosis mouse model.

Relationship between heterotopic ossification and traumatic brain injury: Why severe traumatic brain injury increases the risk of heterotopic ossification

Heterotopic ossification (HO) is a pathological phenomenon in which ectopic lamellar bone forms in soft tissues. HO involves many predisposing factors, including congenital and postnatal factors. Postnatal HO is usually induced by fracture, burn, neurological damage (brain injury and spinal cord injury) and joint replacement. Recent studies have found that patients who suffered from bone fracture combined with severe traumatic brain injury (S-TBI) are at a significantly increased risk for HO occurrence. Thus, considerable research focused on the influence of S-TBI on fracture healing and bone formation, as well as on the changes in various osteogenic factors with S-TBI occurrence. Brain damage promotes bone formation, but the exact mechanisms underlying bone formation and HO after S-TBI remain to be clarified. Hence, this article summarises the findings of previous studies on the relationship between S-TBI and HO and discusses the probable causes and mechanisms of HO caused by S-TBI. The translational potential of this article: A better understanding of the probable causes of traumatic brain injury-induced HO can provide new perspectives and ideas in preventing HO and may support to design more targeted therapies to reduce HO or enhance the bone formation.

Stem cells applications in bone and tooth repair and regeneration: New insights, tools, and hopes

The exploration of stem and progenitor cells holds promise for advancing our understanding of the biology of tissue repair and regeneration mechanisms after injury. This will also help in the future use of stem cell therapy for the development of regenerative medicine approaches for the treatment of different tissue-species defects or disorders such as bone, cartilages, and tooth defects or disorders. Bone is a specialized connective tissue, with mineralized extracellular components that provide bones with both strength and rigidity, and thus enable bones to function in body mechanical supports and necessary locomotion process. New insights have been added to the use of different types of stem cells in bone and tooth defects over the last few years. In this concise review, we briefly describe bone structure as well as summarize recent research progress and accumulated information regarding the osteogenic differentiation of stem cells, as well as stem cell contributions to bone repair/regeneration, bone defects or disorders, and both restoration and regeneration of bones and cartilages. We also discuss advances in the osteogenic differentiation and bone regeneration of dental and periodontal stem cells as well as in stem cell contributions to dentine regeneration and tooth engineering.