Nanofibrous Scaffolds Containing Hydroxyapatite and Microfluidic-Prepared Polyamidoamin/BMP-2 Plasmid Dendriplexes for Bone Tissue Engineering Applications.

OBJECTIVE: The aim of this study is to fabricate functional scaffolds to gene delivery bone morphogenetic protein-2 (BMP-2) plasmid for bone formation in bone tissue engineering. METHODS: Dendriplexes (DPs) of generation 4 polyamidoamin (G4-PAMAM)/BMP-2 plasmid were prepared through microfluidic (MF) platform. The physiochemical properties and toxicity of DPs were evaluated by DLS, AFM, FESEM and MTT assay. In order to create a suitable environment for stem cell growth and differentiation, poly-l-lactic acid (PLLA) and poly-l-lactic acid/poly (ethylene oxide) (PLLA/PEO) scaffolds containing hydroxyapatite nanoparticles (HA) and DPs were fabricated by the electrospinning method. The osteogenic potency of the scaffolds on human adipose tissue-derived mesenchymal stem cells (hASCs) was investigated. RESULTS: The results revealed that tuning the physical properties of DPs by adjusting flow parameters in microfluidic platform can easily improve the cell viability compared to conventional bulk mixing method. Also, the result showed that the presence of HA and DPs in PLLA/PEO scaffold enhanced alkaline phosphatase (ALP) activity and increased the amount of deposited Ca, as well as, related to osteogenesis gen markers. CONCLUSION: This study indicated that on using the MF platform in preparation of DPs and loading them along with HA in PLLA/PEO scaffold, the osteogenic differentiation of hASCs could be tuned.

Microfluidic fabrication of alendronate-loaded chitosan nanoparticles for enhanced osteogenic differentiation of stem cells.

AIMS: In this study, we used a cross-junction microfluidic device for preparation of alendronate-loaded chitosan nanoparticles with desired characteristics to introduce a suitable element for bone tissue engineering scaffolds. MAIN METHODS: By controlling the reaction condition in microfluidic device, six types of alendronate-loaded chitosan nanoparticles were fabricated which had different physical properties. Hydrodynamic diameter of synthetized particles was evaluated by dynamic light scattering (102 to 215 nm). Nanoparticle morphology was determined by SEM and AFM images. The osteogenic effects of prepared selected nanoparticles on human adipose stem cells (hA-MSCs) were evaluated by assessment of alkaline phosphatase (ALP) activity, calcium deposition, ALP and osteopontin gene expression. KEY FINDINGS: The highest loading efficiency percentage (%LE) was %32.42 ± 2.02. Based on MTT assessment, two samples which had no significant cytotoxicity were chosen for further studies (particle sizes and %LE were 142 ± 6.1 nm, 198 ± 16.56 nm, %16.76 ± 3.91 and %32.42 ± 2.02, respectively). In vitro release behavior of nanoparticles displayed pH responsive characteristics. Significant faster release was seen in acidic pH = 5.8 than neutral pH = 7.4. The selected nanoparticles demonstrated higher ALP activity at 14 days in comparison to selected blank sample and osteogenic differentiation media (ODM) and a downregulation at 21 days in comparison to 14 days. Calcium content assay at 21 days displayed significant differences between alendronate-loaded nanoparticles and ODM. ALP and osteopontin mRNA expression was significantly higher than the cells cultured in ODM at 14 and 21 days. SIGNIFICANCE: We concluded that our prepared nanoparticles significantly enhanced osteogenic differentiation of hA-MSCs and can be a suitable compartment of bone tissue engineering scaffolds.

Multiple functions of microfluidic platforms: Characterization and applications in tissue engineering and diagnosis of cancer.

Microfluidic system, or lab-on-a-chip, has grown explosively. This system has been used in research for the first time and then entered in the clinical section. Due to economic reasons, this technique has been used for screening of laboratory and clinical indices. The microfluidic system solves some difficulties accompanied by clinical and biological applications. In this review, the interpretation and analysis of some recent developments in microfluidic systems in biomedical applications with more emphasis on tissue engineering and cancer will be discussed. Moreover, we try to discuss the features and functions of microfluidic systems.