Electrospun PLGA fibre sheets incorporating fluorescent nanosensors: self-reporting scaffolds for application in tissue engineering

Ratiometric analyte responsive nanosensors have been incorporated into electrospun poly(lactic-co-glycolic) acid (PLGA) fibres to create self-reporting scaffolds. It has been demonstrated that the self-reporting scaffolds could be utilised to monitor microenvironment conditions without damaging the fabricated scaffold or the cells being cultured upon the construct. This presents opportunities to fully understand, monitor and optimise the growth of 3D model tissue constructs in vitro. © 2013 The Royal Society of Chemistry

Controlled embryoid body formation via surface modification and avidin–biotin cross-linking

Cell–cell interaction is an integral part of embryoid body (EB) formation controlling 3D aggregation. Manipulation of embryonic stem (ES) cell interactions could provide control over EB formation. Studies have shown a direct relationship between EB formation and ES cell differentiation. We have previously described a cell surface modification and cross-linking method for influencing cell–cell interaction and formation of multicellular constructs. Here we show further characterisation of this engineered aggregation. We demonstrate that engineering accelerates ES cell aggregation, forming larger, denser and more stable EBs than control samples, with no significant decrease in constituent ES cell viability. However, extended culture ≥5 days reveals significant core necrosis creating a layered EB structure. Accelerated aggregation through engineering circumvents this problem as EB formation time is reduced. We conclude that the proposed engineering method influences initial ES cell-ES cell interactions and EB formation. This methodology could be employed to further our understanding of intrinsic EB properties and their effect on ES cell differentiation

Improved media compositions for the differentiation of embryonic stem cells into osteoblasts and chondrocytes

Differentiation procedures leading to osteogenic and chondrogenic differentiation of embryonic stem cells (ESCs) have been established and well upgraded over the past decade. Novel cell-culture conditions, signaling inducers, and chemical modifications of cellular environment have been found and optimized for use as steering or supporting modules in ESC differentiation. While most of the novel studies of osteoblasts or chondrocytes differentiated from ESCs deal with their regenerative potential, the "childhood diseases" of basic differentiation have not yet been quite solved. Purification procedures are still facing a lack of exclusive markers for osteogenic progenitors and a collateral development of other cell types at the end points of differentiation that possibly lead to teratomas. This chapter discusses the role of novel markers and inducers in osteogenic and chondrogenic differentiation, their effect on signaling pathways, particularly on that of Wnt/beta-catenin, and the time-specific manner of their action. We present an improved osteogenic differentiation protocol based on the hanging drop method and a time-optimized use of 1a,25-(OH)2 vitamin D3, all-trans retinoic acid, and bone morphogenetic protein 2 (BMP-2) with an end point efficiency increased up to 90% and a protocol for chondrogenic differentiation, which employs BMP-2 and transforming growth factor b1 as chondrogenic inducers, with 60% chondrogenic end point efficiency