title: Directing osteogenesis of stem cells with hydroxyapatite precipitated electrospun eri-tasar silk fibroin nanofibrous scaffold.
abstract: Stimulating stem cell differentiation without growth factor supplement offers a potent and cost-effective scaffold for tissue regeneration. We hypothesise that surface precipitation of nano-hydroxyapatite (nHAp) over blends of non-mulberry silk fibroin with better hydrophilicity and RGD amino acid sequences can direct the stem cell towards osteogenesis. This report focuses on the fabrication of a blended eri-tasar silk fibroin nanofibrous scaffold (ET) followed by nHAp deposition by a surface precipitation (alternate soaking in calcium and phosphate solution) method. Morphology, hydrophilicity, composition, and the thermal and mechanical properties of ET/nHAp were examined by field emission scanning electron microscopy, TEM, FT-IR, X-ray diffraction, TGA and contact angle measurement and compared with ET. The composite scaffold demonstrated improved thermal stability and surface hydrophilicity with an increase in stiffness and elastic modulus (778 ± 2.4 N/m and 13.1 ± 0.36 MPa) as compared to ET (160.6 ± 1.34 N/m and 8.3 ± 0.4 MPa). Mineralisation studies revealed an enhanced and more uniform surface deposition of HAp-like crystals, while significant differences in cellular viability and attachment were observed through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and confocal microscopy study. The cell viability and expression of adhesion molecules (CD 44 and CD 29) are found to be optimum for subsequent stages of growth proliferation and differentiation. The rates of proliferation have been observed to decrease owing to the transition of MSC from a state of proliferation to a state of differentiation. The confirmation of improved osteogenic differentiation was finally verified through the alkaline phosphatase assay, pattern of gene expression related to osteogenic differentiation and morphological observations of differentiated cord blood human mesenchymal stem cells under fluorescence microscope. The results obtained showed the improved physicochemical and biological properties of the ET/nHAp scaffold for osteogenic differentiation without the addition of any growth factors.
authors.affiliation: a Department of Biotechnology and Medical Engineering, Center of Excellence for Tissue Engineering , National Institute of Technology, Rourkela , Rourkela 769008 , Odisha , India.
authors.forename: N
authors.initials: N
authors.lastname: Panda
authors.forename: A
authors.initials: A
authors.lastname: Bissoyi
authors.forename: K
authors.initials: K
authors.lastname: Pramanik
authors.forename: A
authors.initials: A
authors.lastname: Biswas
mesh_terms: D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D017886:Durapatite / Q000737:chemistry*; D055119:Elastic Modulus; D005349:Fibroins / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D057139:Nanofibers / Q000737:chemistry*; D010012:Osteogenesis / Q000502:physiology; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D015815:Cell Adhesion Molecules; D005349:Fibroins; D017886:Durapatite
keywords: bone tissue engineering; cell adhesion; differentiation; eri–tasar silk fibroin; hydroxyapatite; proliferation