1,721,024 research outputs found
Stem cell-based therapies for musculoskeletal regeneration: role of the microenvironment in augmenting regenerative medicine therapies by elucidating stem cell physiology
No full textAll the information required to define a multicellular organism resides in asingle cell, the zygote or the single-cell embryo. And therein lies theorigins of the concept of a “stem cell” as a highly specialised cellcontaining all the information required to generate a complex multicellularorganism. Stem cells are a key component of the multidisciplinary tissueengineering paradigm used for the generation of living tissues and organsex vivo (outside the body). The bioengineered tissues and organs areimplanted in vivo to improve or restore normal biological function inregenerative medicine therapies for disorders of complex organ systemssuch as the musculoskeletal system. A wide array of regenerativemedicine strategies, ranging from stem cell-based therapies to theapplication of tissue-engineered products, have been applied for thetreatment of bone defects, articular cartilage lesions, disorders of thespine and tendon/ligament injuries. Further advances in the developmentof improved musculoskeletal regenerative medicine therapies will beguided by a detailed understanding of underlying mechanisms governingthe homeostasis between stem cell renewal and differentiation
Osteoblast-Stimulating Factor-1 (OSF-1) : a peptide with diverse roles in bone development
No full textIn search for anabolic agents that enhance osteoblast activity, the role of a 136-amino acid cytokine, referred to as osteoblast-stimulating factor-1 (OSF-1), was examined in transgenic mice over-expressing the human osf-1 gene, and its effects analysed in vitro. In keeping with earlier reports on the function of OSF-1 in stimulating new bone formation, the protein was found localised at sites of new periosteal and endochondral ossification in bones of control and transgenic mice. OSF-1 was synthesized by osteoblasts during early stages of osteogenic differentiation and secreted into the bone matrix. Although over-expression did not result in larger animals, calcium content/ unit dry bone weight in transgenic mice was 10% higher than in control mice. A distinct effect of osf-1 over-expression was the synthesis of the OSF-1 protein by growth plate and articular chondrocytes of only transgenic mice. Articular chondrocytes of transgenic mice were also found to synthesize Type 1 collagen, a bone-type protein. To confirm that over-expression of osf-1 had provided the stimulus, cartilaginous explants were cultured with recombinant OSF-1, which in turn induced Type 1 collagen synthesis by chondrocytes in vitro. Expression of osf-1 was demonstrated by in situ hybridization in human and mouse bone marrow cell cultures. In vitro, recombinant OSF-1 enhanced osteogenic differentiation of mouse bone marrow cells at an appreciably low (10 pg/ml) concentration in comparison to recombinant bone morphogenetic protein-2 (rhBMP-2), which served as the positive control. However, unlike BMP-2, OSF-1 was not osteoinductive as it failed to divert the multipotent, pre-myoblastic C2C12 cells along the osteogenic lineage. Interactions with BMP-2, studied using C2C12 cells, revealed OSF-1 to be a BMP-2 antagonist if added together with BMP-2.</p
Application of human follicular dendritic cells (HK) as an experimental model to study osteoblast function
No full textPolymer microarrays – a high-throughout approach to the identification and selection of tissue engineering scaffolds
No full textRaman spectroscopy and coherent anti-Stokes Raman scattering imaging: prospective tools for monitoring skeletal cells and skeletal regeneration
No full textThe use of skeletal stem cells (SSCs) for cell-based therapies is currently one of the most promising areas for skeletal disease treatment and skeletal tissue repair. The ability for controlled modification of SSCs could provide significant therapeutic potential in regenerative medicine, with the prospect to permanently repopulate a host with stem cells and their progeny. Currently, SSC differentiation into the stromal lineages of bone, fat and cartilage is assessed using different approaches that typically require cell fixation or lysis, which are invasive or even destructive. Raman spectroscopy and coherent anti-Stokes Raman scattering (CARS) microscopy present an exciting alternative for studying biological systems in their natural state, without any perturbation. Here we review the applications of Raman spectroscopy and CARS imaging in stem-cell research, and discuss the potential of these two techniques for evaluating SSCs, skeletal tissues and skeletal regeneration as an exemplar
Strategies for cell manipulation and skeletal tissue engineering using high-throughput polymer blend formulation and microarray techniques
No full textA combination of high-throughput material formulation and microarray techniques were synergistically applied for the efficient analysis of the biological functionality of 135 binary polymer blends. This allowed the identification of cell-compatible biopolymers permissive for human skeletal stem cell growth in both in vitro and in vivo applications. The blended polymeric materials were developed from commercially available, inexpensive and well characterised biodegradable polymers, which on their own lacked both the structural requirements of a scaffold material and, critically, the ability to facilitate cell growth. Blends identified here proved excellent templates for cell attachment, and in addition, a number of blends displayed remarkable bone-like architecture and facilitated bone regeneration by providing 3D biomimetic scaffolds for skeletal cell growth and osteogenic differentiation. This study demonstrates a unique strategy to generate and identify innovative materials with widespread application in cell biology as well as offering a new reparative platform strategy applicable to skeletal tissue
Live-imaging of bioengineered cartilage tissue using multimodal non-linear molecular imaging
No full textCoherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) are non-linear techniques that allow label-free, non-destructive and non-invasive imaging for cellular and tissue analysis. Although live-imaging studies have been performed previously, concerns that they do not cause any changes at the molecular level in sensitive biological samples have not been addressed. This is important especially for stem cell differentiation and tissue engineering, if CARS/SHG microscopy is to be used as a non-invasive, label-free tool for assessment of the developing neo-tissue. In this work, we monitored the differentiation of human fetal-femur derived skeletal cells into cartilage in three-dimensional cultures using CARS and SHG microscopy and demonstrate the live imaging of the same developing neo-tissue over time. Our work conclusively establishes that non-linear label-free imaging does not alter the phenotype or the gene expression at the different stages of differentiation and has no adverse effect on human skeletal cell growth and behaviour. Additionally, we show that CARS microscopy allows imaging of different molecules of interest, including lipids, proteins and glycosaminoglycans, in the bioengineered neo-cartilage. These studies demonstrate the label-free and truly non-invasive nature of live CARS and SHG imaging and their value and translation potential in skeletal research, regeneration medicine and tissue engineering
Microscale approaches for molecular regulation of skeletal development
No full textCells reside in dynamic, three-dimensional (3-D) microenvironments, which regulate their ability to respond to the spatiotemporal cues, such as neighbouring cells, the extracellular matrix, soluble factors and physical forces. Microscale technologies are rapidly emerging as key strategies to recapitulate the 3-D microarchitecture of the tissue, and the complex biochemical milieu and dynamic biomechanical cues of the in vivo cellular microenvironment. An overview of principal microscale approaches that have been successfully applied to promote skeletal development through augmentation of skeletal cell growth and differentiation is presented in this chapter. The microscale approaches include micropatterning techniques to fabricate defined microtopographies for directing skeletal cell differentiation; high-throughput material formulation and microarray techniques, in combination with microfabrication approaches, for rapid screening, selection and fabrication of 3-D biomaterial scaffolds with microscale resolution, which offers increased control of the cellular microenvironment and improved ability to direct skeletal stem cell fate; application of microbioreactors and microfluidic scaffolds for culturing skeletal cells in closely regulated 3-D microenvironments that recapitulate the organ-specific microarchitecture and dynamic physical forces crucial for manipulation of long-term skeletal cell growth and differentiation; and microinjection/micromanipulation techniques for modulation of skeletal development in ex vivo models, followed by analyses of skeletal development and 3-D bone microarchitecture using microcomputed tomography. Thus, microscale technologies have enhanced our ability to generate physiologically relevant ex vivo microscale skeletal tissue models, which effectively recapitulate in vivo tissue development and function, and have the potential to be used for the development of skeletal disease models and for pharmacological and toxicological drug screenin
Augmentation of musculoskeletal regeneration: role for pluripotent stem cells
No full textThe rise in the incidence of musculoskeletal diseases is attributed to an increasing ageing population. The debilitating effects of musculoskeletal diseases, coupled with a lack of effective therapies, contribute to huge financial strains on healthcare systems. The focus of regenerative medicine has shifted to Pluripotent Stem Cells (PSCs), namely human Embryonic Stem Cells (hESCs) and human induced PSCs (hiPSCs), due to the limited success of adult stem-cell (ASC) based interventions. PSCs constitute a valuable cell source for musculoskeletal regeneration due to their capacity for unlimited self-renewal, ability to differentiate into all cell lineages of the three germ layers and perceived immunoprivileged characteristics. This review summarises methods for chondrogenic, osteogenic, myogenic and adipogenic differentiation of PSCs and their potential for therapeutic applications
A scaffold-free approach to cartilage tissue generation using human embryonic stem cells
No full textArticular cartilage functions as a shock absorber and facilitates the free movement of joints. Currently, there are no therapeutic drugs that promote the healing of damaged articular cartilage. Limitations associated with the two clinically relevant cell populations, human articular chondrocytes and mesenchymal stem cells, necessitate finding an alternative cell source for cartilage repair. Human embryonic stem cells (hESCs) provide a readily accessible population of self-renewing, pluripotent cells with perceived immunoprivileged properties for cartilage generation. We have developed a robust method to generate 3D, scaffold-free, hyaline cartilage tissue constructs from hESCs that are composed of numerous chondrocytes in lacunae, embedded in an extracellular matrix containing Type II collagen, sulphated glycosaminoglycans and Aggrecan. The elastic (Young’s) modulus of the hESC-derived cartilage tissue constructs (0.91 ± 0.08 MPa) was comparable to full-thickness human articular cartilage (0.87 ± 0.09 MPa). Moreover, we have successfully scaled up the size of the scaffold-free, 3D hESC-derived cartilage tissue constructs to between 4.5 mm and 6 mm, thus enhancing their suitability for clinical application
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