Osteoblast differentiation of rabbit adipose-derived stem cells by polyethylenimine-mediated BMP-2 gene transfection in vitro

Osteogenesis Enhancement with 3D Printed Gene-Activated Sodium Alginate Scaffolds

Natural and synthetic hydrogel scaffolds containing bioactive components are increasingly used in solving various tissue engineering problems. The encapsulation of DNA-encoding osteogenic growth factors with transfecting agents (e.g., polyplexes) into such scaffold structures is one of the promising approaches to delivering the corresponding genes to the area of the bone defect to be replaced, providing the prolonged expression of the required proteins. Herein, a comparative assessment of both in vitro and in vivo osteogenic properties of 3D printed sodium alginate (SA) hydrogel scaffolds impregnated with model EGFP and therapeutic BMP-2 plasmids was demonstrated for the first time. The expression levels of mesenchymal stem cell (MSC) osteogenic differentiation markers Runx2, Alpl, and Bglap were evaluated by real-time PCR. Osteogenesis in vivo was studied on a model of a critical-sized cranial defect in Wistar rats using micro-CT and histomorphology. The incorporation of polyplexes comprising pEGFP and pBMP-2 plasmids into the SA solution followed by 3D cryoprinting does not affect their transfecting ability compared to the initial compounds. Histomorphometry and micro-CT analysis 8 weeks after scaffold implantation manifested a significant (up to 46%) increase in new bone volume formation for the SA/pBMP-2 scaffolds compared to the SA/pEGFP ones.

Advancements in nucleic acids-based techniques for bone regeneration

The dynamic biology of bone involving an enormous magnitude of cellular interactions and signaling transduction provides ample biomolecular targets, which can be enhanced or repressed to mediate a rapid regeneration of the impaired bone tissue. The delivery of nucleic acids such as DNA and RNA can enhance the expression of osteogenic proteins. Members of the RNA interference pathway such as miRNA and siRNA can repress negative osteoblast differentiation regulators. Advances in nanomaterials have provided researchers with a plethora of delivery modules that can ensure proper transfection. Combining the nucleic acid carrying vectors with bone scaffolds has met with tremendous success in accomplishing bone formation. Recent years have witnessed the advent of CRISPR and DNA nanostructures in regenerative medicine. This review focuses on the delivery of nucleic acids and touches upon the prospect of CRISPR and DNA nanostructures for bone tissue engineering, emphasizing their potential in treating bone defects.

Advances in mesenchymal stem cell transplantation for the treatment of osteoporosis

Osteoporosis is a systemic metabolic bone disease with characteristics of bone loss and microstructural degeneration. The personal and societal costs of osteoporosis are increasing year by year as the ageing of population, posing challenges to public health care. Homing disorders, impaired capability of osteogenic differentiation, senescence of mesenchymal stem cells (MSCs), an imbalanced microenvironment, and disordered immunoregulation play important roles during the pathogenesis of osteoporosis. The MSC transplantation promises to increase osteoblast differentiation and block osteoclast activation, and to rebalance bone formation and resorption. Preclinical investigations on MSC transplantation in the osteoporosis treatment provide evidences of enhancing osteogenic differentiation, increasing bone mineral density, and halting the deterioration of osteoporosis. Meanwhile, the latest techniques, such as gene modification, targeted modification and co-transplantation, are promising approaches to enhance the therapeutic effect and efficacy of MSCs. In addition, clinical trials of MSC therapy to treat osteoporosis are underway, which will fill the gap of clinical data. Although MSCs tend to be effective to treat osteoporosis, the urgent issues of safety, transplant efficiency and standardization of the manufacturing process have to be settled. Moreover, a comprehensive evaluation of clinical trials, including safety and efficacy, is still needed as an important basis for clinical translation.

Adipose Stem Cell Translational Applications: From Bench-to-Bedside

During the last five years, there has been a significantly increasing interest in adult adipose stem cells (ASCs) as a suitable tool for translational medicine applications. The abundant and renewable source of ASCs and the relatively simple procedure for cell isolation are only some of the reasons for this success. Here, we document the advances in the biology and in the innovative biotechnological applications of ASCs. We discuss how the multipotential property boosts ASCs toward mesenchymal and non-mesenchymal differentiation cell lineages and how their character is maintained even if they are combined with gene delivery systems and/or biomaterials, both in vitro and in vivo.

Spontaneous adipogenic differentiation potential of adipose‑derived stem cells decreased with increasing cell passages

Primary adipose-derived stem cells (ADSCs) are a mixture of cell types including preadipocytes having the ability to spontaneously differentiate into adipocytes. The aim of the present study was to compare the spontaneous adipogenic differentiation potential of ADSCs at different passages to determine whether it decreased with continuous cell passages. Mouse ADSCs (mADSCs) were harvested and cells from passages 1 to 5 were used for experiments. The proliferation of mADSCs at different passages was tested using the cell counting kit‑8 assay. Reverse transcription‑quantitative polymerase chain reaction was used to determine relative mRNA expression levels of CCAAT/enhancer binding protein α (Cebpa and C/EBPα) and peroxisome proliferator‑activated receptor γ (Pparg and PPARγ), and western blot analysis was used to investigate C/EBPα and PPARγ protein expression. The cells were cultured using DMEM. The fixed cells were then stained using Oil Red O on days 14 and 28, and the obtained extracted dye was monitored for absorbance. The 510 nm absorbance from passages 1 to 5 was observed to be statistically different. The relative expression levels of Cebpa and Pparg for mADSCs from passage 1 were significantly higher when compared with those for mADSCs from passages 2 to 5 on days 3, 5 and 7. However, no difference was identified in the expression levels of proteins C/EBPα and PPARγ for different passages. Although the mRNA expression levels of Pparg from passages 4 to 5 were significantly higher when compared with those from passage 1, the results of Oil Red O absorbance, mRNA expression levels of Cebpa, and the protein expression levels of C/EBPα and PPARγ exhibited no difference between mADSCs from passages 1 to 5 when cultured with induced adipogenic differentiation medium. Therefore, it was concluded that the spontaneous adipogenic differentiation potential of ADSCs decreased with continuous cell passages.