NANOFIBER TECHNOLOGY FOR CONTROLLING STEM CELL FUNCTIONS AND TISSUE ENGINEERING - Micro and Nanotechnologies in Engineering Stem Cells and Tissues - page 28

Application of nanotechnology in life sciences research, particularly at the cellular
level, sets the stage for an exciting role of nanotechnology in nanomedicine for health
care. The potential medical applications are predominantly in detection, diagnostics
(disease diagnosis and imaging), monitoring, and therapeutics. The availability of
more durable and better prosthetics and new drug-delivery systems are of great
scientific interest and give hope for cancer treatment and minimum invasive
treatments for heart disease, diabetes, and other diseases. 1 Nanofibers are potentially
recent additions to materials in relation to tissue engineering (TE). Tissue engineer-
ing is the application of knowledge and expertise from a multidisciplinary field to
develop and manufacture therapeutic products that use the combination of matrix
scaffolds with viable human cell systems or cell responsive biomolecules derived
from such cells for the repair, restoration, or regeneration of cells or tissue damaged
by injury, disease, or congenital defects. 2
Tissues in the body are made up of cells and insoluble materials present between
the cells known as the extracellular matrix (ECM). ECM is composed of various
biomacromolecules secreted by surrounding cells and is responsible for the structural
support and tensile strength of the tissue. It provides a substrate for cell adhesion and
migration and regulates cellular differentiation. The interaction between cells and
ECM is mediated by the process of biorecognition whereby the transmembrane
protein receptors on the cell membrane combine specifically with specific ligands in
the ECM, triggering a series of events in the signal transduction cascade within the
cells and eventually influencing their gene expression. For example, growth factors
such as fibroblast growth factor combine with their receptors on cell surfaces and
stimulate their proliferation and differentiation. 3
Recently, nanofiber-based scaffolds are being explored as scaffolds for tissue
engineering applications. TE is an interdisciplinary field of research whereby diverse
cell-based and cell-free strategies are being investigated in the quest for a sustainable
therapeutic for refurbishment of organ functionality. Essentially, TE is an attempt at
bringing about repair by mimicking nature. It is aimed at boosting the low
regenerative capacity of the damaged myocardium by applying principles of
engineering, material chemistry, and cell biology. The classical strategy used in
tissue engineering is the provision of external help in the form of biomaterials and
biomolecules with properties bearing close resemblance to their natural counterparts.
However, owing to the uniqueness of each organ, the quest for optimal biomaterials
and an efficient strategy for TE remain persistent. A bioengineered construct is
desired to possess certain essential characteristics, such as appropriate physical and
mechanical properties, ready adherence, nontoxicity, nonantigenicity, noninvasive
applicability, and ability for complete integration with the host. 4,5 An ideal poly-
meric scaffold satisfies several structural and chemical features: (1) a three-dimen-
sional architecture with a desired volume, shape, and mechanical strength; 6 (2) a
highly porous and well-interconnected open pore structure to allow high cell seeding
density and tissue ingrowth; (3) chemical compositions such that its surface and
degradation products are biocompatible, causing minimal immune or inflammatory
responses; 7 and (4) their degradation rate finely tuned in a pattern that it provides
sufficient support until the full regrowth of impaired tissues. Several scaffold
fabrication techniques, namely, electrospinning (random, aligned, vertical, and