Spatio-temporal presentation of growth factors is one of the key attributes
of the cell's microenvironment. The design of macroporous alginate scaffolds,
wherein TGF-b1 or BMP-4 is electrostatically bound to affinity binding sites
of alginate sulfate, mimicking their presentation by the extracellular matrix
(ECM), was previously shown to enable sustained presentation and release of
each factor, thus increasing their biological activity. Specifically,
TGF-b1/affinity-bound scaffolds induced the chondrogenic differentiation of
human mesenchymal stem cells (hMSCs) seeded within these scaffolds. The
prolonged activity of the affinity-bound TGF-b1 enabled efficient induction
of signaling pathways leading to chondrogenesis, up to the appearance of
committed chondrocytes. Similarly, BMP-4 affinity-bound to the macroporous
alginate scaffold enabled efficient induction of osteogenic differentiation
in hMSC constructs. Subsequent construction of a multicompartment inductive
system, spatially-presenting TGF-b1 and BMP-4 in two distinct layers, enabled
complete differentiation of hMSC to chondrocytes and osteoblasts, depending
on the type of factor in use in the respective layer. This paper describes in
detail the preparation method of the TGF-b1 or BMP4/affinity-bound alginate
scaffolds, and the set of analyses performed to characterize the resultant
scaffolds, including release profile study, released factor bioactivity, and
functionality of the scaffolds as hMSC-inductive scaffolds.
Primary Side Circuit Design of a Multi-coil Inductive System for Powering Wireless Sensors
